PPT - 1 Before Birth the first life stage ?

The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

http://www.youtube.com/watch?v=mdGsLRGBsCU&NR=1&feature=fvwp

http://www.youtube.com/watch?v=duPxBXN4qMg&NR=1&feature=fvwp

DNA – fetal development

http://www.youtube.com/watch?v=AoisqOGQIVE

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http://www.youtube.com/watch?v=UgT5rUQ9EmQ

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

1. Fertilization begins when the sperm penetrates the egg and ends with the production of a zygote. This normally takes 24 hours. This is significant as it is the very first stage of embryonic and fetal development.

Tasks 1 – handout Using the pattern parts of the egg and sperm – and the drawings on the board put

together an information diagram that you feel could help you revise from for your examination. Label each part and explain what is happening during each process.

4. Cardiac Muscle Contraction BeginsNeural Folds/Heart Folds begin to fuse. This happens within 21-23 days from fertilization.The two endocardial tubes formed previously now fuse. Together they form one single tube generated from the cells of the “roof” of the nueral tube. The heart tube takes on an S-shape establishing the asymetry of the heart. As the S-shape forms, cardiac muscle contraction begins.5. Kidneys Start to Produce Urine- this happens around 44-48 days. Kidneys remove toxins and waste from the body and are essential to survival.6. Brain Structure Complete – at 61-68 days. This is necessary to control thinking, breathing, movement, etc.7. Fetus is Able to Hear- 22 weeks. 8. Lung Development- at 26 weeks the lungs are developed enough to breath oxygen.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

9. Use of Eyes- at 32 weeks the baby can open and close its eyes.10. Birth- the baby is fully developed and ready to be born at 40 weeks.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Handout – label the different stages of fetal development – task 1

Part two - Chromosomes and

genes Once the baby is born it

will be made up of all millions of pieces of genetic information past on from its parents. This means everything from the colour of the eyes, hair, shape of hands, nails, height the baby will grow to and any other inherited weaknesses – such as illness – also emotions, intelligence and so on.

Have people ever said to you, "It's in your genes?" They were probably talking about a physical characteristic, personality trait, or talent that you share with other members of your family. We know that genes play an important role in shaping how we look and act and even whether we get sick. Now scientists are trying to use that knowledge in exciting new ways, such as preventing and treating health problems.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

9. Use of Eyes- at 32 weeks the baby can open and close its eyes.10. Birth- the baby is fully developed and ready to be born at 40 weeks.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

The nucleus of every cell in the human body contains 23 pairs of chromosomes and each chromosome, made of DNA, carries units of inheritance known as genes.

Although most DNA is packaged in chromosomes within the nucleus, mitochondria also have a small amount of their own DNA.

Mitochondria are structures within cells that convert the energy from food into a form that cells can use. 37 genes contain the DNA to help break down food

What Is a Gene? To understand how genes

(pronounced: jeens) work, let's review some biology basics. Most living organisms are made up of cells that contain a substance called deoxyribonucleic (pronounced: dee-ahk-see-rye-bow-noo-klee-ik) acid (DNA).

DNA is wrapped together to form structures called chromosomes (pronounced: krow-muh-soams).

Most cells in the human body have 23 pairs of chromosomes, making a total of 46. Individual sperm and egg cells, however, have just 23 unpaired chromosomes. You received half of your chromosomes from your mother's egg and the other half from your father's sperm cell. A male child receives an X chromosome from his mother and a Y chromosome from his father; females get an X chromosome from each parent.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Male and Female

Thousands of genes are packed together to form chromosomes. Most people have 46 chromosomes (23 pairs). There are 44 “non-sex” chromosomes, numbered in pairs from 1-22, that are the same in males and females.

We call the 23rd pair the “sex” chromosomes because they determine a person’s sex (male or female). In females, both sex chromosomes are similar and are called “X” chromosomes. Males have one “X” and one “Y” chromosome.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Female Male

We are going to concentrate on the inheritance genes that consist of between 25,000 and 35,000 found inside each chromosome

Chromosomes are the packaging for our genetic material, or DNA (deoxyribonucleic acid). DNA carries a specific code that gives instructions to our body on how to grow, develop and function. The instructions are organized into units called genes.

Some characteristics come from a single gene, whereas others come from gene combinations. Because every person has from 25,000 to 35,000 different genes, there is an almost endless number of possible combinations!

How the process starts

We start this reduction process with a double set of chromosomes (one from dad and one set from mum) and reduce it down to one set.

The double set consists of 23 pairs of homologous chromosomes, or homologues, one of each pair from one parent, the other from the other parent.

The genes are arranged along both homologues in the same order but carry different types of information---blue vs brown eyes and so on.

In the context of chromosomes, "gene" is not used but instead "locus" and "allele" are the correct terms.

So what makes up the gene? Each allele is a packet of information made of sugars, phosphates, nitrogen bases and hydrogen bonds!

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

The structure of chromosomes

Imagine a chromosome as being a shoelace. The plastic bits at the end of the shoelace keep the material which makes up the shoelace from unravelling. Chromosomes have similar 'plastic bits' at each end called telomeres. They protect the ends of the chromosome from degradation.

Now imagine that a shoelace also has another plastic bit in the middle, and through this you can connect a pair of shoelaces together for storage. This is called a centromere on a chromosome, and it is where the chromosome pairs connect.

The structure of chromosomes – handout now draw up possible homologues of your genetic combination from your mother and father.

Task 1

Task 2-3

1. Draw up a pair of homologues that could relate to the DNA of your mother or father.

2. Now think about you – what DNA homologue information have you inherited from your mother and father.

1. Now draw a diagram of the homologue with the information you think has been linked (allele or locus)

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

AfL Task 4

Discuss as a group what DNA (genetic) information has been past onto you.

Now looking at the gene pool – begin to compile diagrams – again to help you memorise and revise from.

What are Chromosomes?1. How many from the female egg

and male sperm make up a zygote?

2. What is DNA?3. Looking at the pictures you have

brought from home, look at the similarities between your siblings, mother and father and aunts and uncles and grandparents.

4. List these similarities5. Now draw a diagram of two X

chromosomes and the short strand P and long Strand Q chromosome information - explain how your parents genetic information has resulted in your identified similarities.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Genes and genetic makeup Genes play an important role in shaping what we are today and for all our so-called genetic traits. The genetic information of parents is passed down to their children, grand children, or even great grand children. Similarly we have also inherited a number of genetic traits from our ancestors.

All our physical characteristics, personality traits, and talents can be the result of the genetic make up of our ancestors.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Genes

The chromosomes carry genes, which are the segments of DNA that determine factors and a whole range of characteristics. The color of our hair, our height, and even our predisposition to health concerns are some of the genetic traits that we have inherited from out parents.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Genetic information

Genetic information is contained in the genes of a person and as the cells of the body duplicate, the genetic information is passed to the new cells.

In our genetic make up, certain genes are dominant and influence the genetic trait of a person even if only one copy of that dominant gene is present in that pair of chromosomes. On the other hand, certain genes are recessive and do not affect the genetic trait of a person even if they are present on both chromosome pairs.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Why are some chromosomes defective?

Our genetic make-up is also responsible for a number of health problems that we face. Some examples of genetic, or inherited, health problems include obesity, heart disease, cancer, diabetes, and hypertension.

Many health concerns come about due to a combination of our inherited genetic make- up and environmental triggers, such as unbalanced diet, chemical exposure, and unhealthy lifestyle.

For example, spina bifida (a neural tube defect) in newborns can be avoided if their mothers take folic acid during early pregnancy and continue taking it until their doctor advises them to stop. L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

What is cri-du-chat syndrome?

Cri-du-chat (cat's cry) syndrome, also known as 5p- (5p minus) syndrome, is a chromosomal condition that results when a piece of chromosome 5 is missing. Infants with this condition often have a high-pitched cry that sounds like that of a cat. The disorder is characterized by intellectual disability and delayed development, small head size (microcephaly), low birth weight, and weak muscle tone (hypotonia) in infancy. Affected individuals also have distinctive facial features, including widely set eyes (hypertelorism), low-set ears, a small jaw, and a rounded face. Some children with cri-du-chat syndrome are born with a heart defect.

How common is cri-du-chat syndrome? Cri-du-chat syndrome occurs in an estimated 1 in 20,000 to

50,000 newborns. This condition is found in people of all ethnic backgrounds.

What are the genetic changes related to cri-du-chat syndrome?

Cri-du-chat syndrome is caused by a deletion of the end of the short (p) arm of chromosome 5. This chromosomal change is written as 5p-. The size of the deletion varies among affected individuals; studies suggest that larger deletions tend to result in more severe intellectual disability and developmental delay than smaller deletions.

The signs and symptoms of cri-du-chat syndrome are probably related to the loss of multiple genes on the short arm of chromosome 5. Researchers believe that the loss of a specific gene, CTNND2, is associated with severe intellectual disability in some people with this condition. They are working to determine how the loss of other genes in this region contributes to the characteristic features of cri-du-chat syndrome.

Read more about the CTNND2 gene and chromosome 5.

Can cri-du-chat syndrome be inherited?

Most cases of cri-du-chat syndrome are not inherited. The deletion occurs most often as a random event during the formation of reproductive cells (eggs or sperm) or in early fetal development. Affected people typically have no history of the disorder in their family.

About 10 percent of people with cri-du-chat syndrome inherit the chromosome abnormality from an unaffected parent. In these cases, the parent carries a chromosomal rearrangement called a balanced translocation, in which no genetic material is gained or lost. Balanced translocations usually do not cause any health problems; however, they can become unbalanced as they are passed to the next generation. Children who inherit an unbalanced translocation can have a chromosomal rearrangement with extra or missing genetic material. Individuals with cri-du-chat syndrome who inherit an unbalanced translocation are missing genetic material from the short arm of chromosome 5, which results in the intellectual disability and health problems characteristic of this disorder.

Cri-du-chat syndrome

What are the symptoms of Cri-du-Chat syndrome?

Babies with cri-du-chat are usually small at birth, and may have respiratory problems. Often, the larynx doesn't develop correctly, which causes the signature cat-like cry. People who have cri-du-chat have very distinctive features. They may have a small head (microcephaly), an unusually round face, a small chin, widely set eyes, folds of skin over their eyes, and a small bridge of the nose.Several problems occur inside the body, as well. A small number of children have heart defects, muscular or skeletal problems, hearing or sight problems, or poor muscle tone. As they grow, people with cri-du-chat usually have difficulty walking and talking correctly. They may have behavior problems (such as hyperactivity or aggression), and severe mental retardation. If no major organ defects or other critical medical conditions exist, life expectancy is normal.

How is cri-du-chat syndrome treated?

Although there is no real treatment for cri-du-chat syndrome, children with the disorder can go through therapy to improve their language skills, motor skills, and to help them develop as normally as possible.

In 80 percent of the cases, the chromosome carrying the deletion comes from the father's sperm rather than the mother's egg.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

What is Down’s Syndrome and what genetic condition has caused this

Down syndrome is a genetic condition in which a person has 47 chromosomes instead of the usual 46.

Chromosome 21

In most cases, Down syndrome occurs when there is an extra copy of chromosome 21. This form of Down syndrome is called Trisomy 21. The extra chromosome causes problems with the way the body and brain develop.

Common physical signs include:Decreased muscle tone at birthExcess skin at the nape of the neckFlattened noseSeparated joints between the bones of the skull (sutures)Single crease in the palm of the handSmall earsSmall mouthUpward slanting eyesWide, short hands with short fingersWhite spots on the colored part of the eye (Brushfield spots) Long-term (chronic) constipation problemsSleep apnea (because the mouth, throat, and airway are narrowed in children with Down syndrome)Teeth that appear later than normal and in a location that may cause problems with chewingUnderactive thyroid (hypothyroidism)

Down's syndrome is caused by having an extra copy of chromosome 21

Down syndrome development

Physical development is often slower than normal. Most children with Down syndrome never reach their average adult height.

Children may also have delayed mental and social development. Common problems may include:

Impulsive behavior Poor judgment Short attention span Slow learning As children with Down syndrome grow and become aware of their limitations, they

may also feel frustration and anger. Many different medical conditions are seen in people with Down syndrome, including: Birth defects involving the heart, such as an atrial septal defect or ventricular septal

defect Dementia may be seen Eye problems, such as cataracts (most children with Down syndrome need glasses) Early and massive vomiting, which may be a sign of a gastrointestinal blockage, such

as esophageal atresia and duodenal atresia Hearing problems, probably caused by regular ear infections Hip problems and risk of dislocation

AfL – examination

style questions

Williams Syndrome

Williams Syndrome is a rare genetic condition, found in one in about 7500 newborns. These children are hyper- social, with personalities you hardly see outside the world of this syndrome. They demonstrate extreme empathy and show warmth and openness even to strangers.

These children or adults are extremely empathetic in nature. They can’t see anyone in pain, and if such a situation arises they are the first ones to extend help. An experiment was carried out in which a girl hit her knee on the table. A typical child just watched her cry, while the child having Williams Syndrome showed more concern. He went to her and rubbed her knee. He even asked “What happened?”.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Williams Syndrome – their personal characteristics

With such empathy comes lack of fear. These children are not aware of somebody’s ill intensions to harm them, neither are they scared of dangerous situations or objects. If they are given a spider, they’ll most likely pet it, rather than being scared. Such extreme innocence can have real life consequences, and for the same reason, such people are always in need of protection, since they are incapable of detecting danger or defending themselves on their own.

Studies show that the Syndrome is caused by the absence of around 26 genes on chromosome 7, and it can have extreme effects on physical, behavioural or cognitive composition of a person. This deletion of chromosomes takes place during the production of a sperm or egg cell. However, the reason as to why the absences of these genes result in hyper social behavior remains a mystery.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Williams Syndrome

http://geneticsf.labanca.net/

Most adults and children with Williams syndrome lead full, active and healthy lives, but it's important to be aware of the possible problems that may arise and to address them as soon as possible. For this reason, an expert team is needed that includes doctors and nurses, as well as the skills of occupational speech therapists, physiotherapists and teachers.

What is Turners Disease – and what genetics are missing?

Turner’s Syndrome is a medical disorder that can only occur in girls because they only have two X chromosomes. The disease consists of one X chromosome’s parts missing or not there altogether. Boys with this disorder do not finish developing because they have an X and Y chromosome. Without the X chromosome, no one could live off of a Y chromosome. This disorder was founded by Dr. Henry H. Turner (an endocrinologist) in 1938.

One in every 2,500 births will be diagnosed with Turner’s Syndrome. Some of the physical symptoms of this disorder are a short stature, lack of menstruation and breast development, infertility, a “webbed”neck, abnormal bone growth (especially in the hands and elbows), and edema (extra fluid) in the hands and feet as infants. Girls with this disorder may also have a low-self esteem due to their different appearance, difficulties with math, and skills like visual organisation and map-reading.

There is no specific cure for this disorder. If diagnosed as a growing child, growth hormones could be given. When the girl reaches 12 or 13 years old, estrogen levels can be given as well. This disorder has an unknown cause, therefore, there is no prevention.GKDEhttp://ghr.nlm.nih.gov/chromosome/7

Duchenne’s muscular dystrophy Multifactorial disorders

Another sex-linked genetic condition is Duchenne’s muscular dystrophy, which cause progressive deterioration in muscle fibres. It affects about one in 3,000 boys and there is no effective cure. A blood test looks for the enzymes released from damaged muscles.

Large numbers of disorders are caused by additive effects of certain genes together with various environmental factors, but the actual pattern of inheritance is complex: these care called multifactorial disorders. Asthma, insulin-dependent (Type 1) diabetes mellitus, schizophrenia and some congenital birth defects such as cleft palate are classed as multifactorial disorders.

Genes on chromosome 7 Genetics Home Reference includes these genes on chromosome 7

Genetics Home Reference includes these genes on chromosome 7:•AASS•ABCB4•ASL•BRAF•C7orf11•CCM2•CFTR•CLCN1•CLIP2•COL1A2•DDC•DFNA5•DLD•ELN•FAM126A•GARS

•GARS•GLI3•GTF2I•GTF2IRD1•GUSB•HOXA13•HSPB1•KCNH2•KRIT1•LFNG•LIMK1•NCF1•OPN1SW•PEX1•PMS2•POR•PRKAG2•SBDS•SGCE•SHH•SLC25A13•SLC26A4•TFR2•TWIST1

What is chromosome 7?Humans normally have 46 chromosomes in each cell, divided into 23 pairs. Two copies of chromosome 7, one copy inherited from each parent, form one of the pairs. Chromosome 7 spans about 159 million DNA building blocks (base pairs) and represents more than 5 percent of the total DNA in cells.Identifying genes on each chromosome is an active area of genetic research. Because researchers use different approaches to predict the number of genes on each chromosome, the estimated number of genes varies. Chromosome 7 likely contains about 1,150 genes. These genes perform a variety of different roles in the body.

Task – to secure your understanding of chromosomes and genes

You are requested to find out about a syndrome we have not discussed in lesson.

Put together a display about the syndrome you have researched and what chromosomes and then genes are missing or appear to be extra. Present to the group

http://geneticsf.labanca.net/

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Plenary – identify the chromosome batches

45 chromosomes

In each human cell, except the egg and sperm cells, there are 46 chromosomes, made up of 23 pairs (see Genetics Fact Sheet 1). There are

22 pairs of autosomes that scientists have numbered 1-22 according to their size from the largest to the smallest

Two sex chromosomes: X and Y When egg and sperm cells are formed, the chromosome pairs separate so that

there is only one of each pair in these cells ie. 23 chromosomes instead of 46. A baby is conceived when the egg from the mother and the sperm from the

father come together. The baby would then have two copies of each chromosome (46 chromosomes in total) just like the parents.

One copy of each chromosome would have come from the mother and one copy from the father.

Sometimes, when the egg and sperm are forming, a mistake occurs so that the chromosome pairs do not separate in an ordered fashion.

The result is an egg or sperm cell that has only 22 chromosomes while others have 24 chromosomes

If an egg or sperm carrying 22 chromosomes combines with an egg or sperm carrying the usual 23 chromosomes, the result would be an individual with cells in which there are 45 chromosomes instead of the usual.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Very rarely part of Y chromosome may be present in a female that has turners syndrome.

Missing (deleted) portions of the short ('p'), or the long ('q') arm of the X chromosome One of the X chromosomes arranged in a ring form The two long ('q') arms of the X chromosomes joined together in an arrangement called isochromosome Xq

Very rarely, cells that contain part of the Y chromosome may be present

Can people have more that 47 chromosomes?

Males and females can inherit up to 3 extra sex chromosomes possibly bringing their total count up to even 49 chromosomes.

In the case of Tetra X syndrome, females have four X chromosomes instead of two. Therefore, they have 48 chromosomes (48, XXXX) instead of 46. In the case of Penta X syndrome, there are five X chromosomes or a total of 49 chromosomes (49, xxxxx). Tetra/Pentasomy X occurs only in females. There are approximately 60 known females worldwide with this rare condition, although it is believed that there are probably many more who are undiagnosed. The condition was first identified in 1961.

Homework Examination style questions –

please carry these out and hand in this lesson next week

What is the life expectancy of a child with Krabbe disease?

What are the symptoms? What are the signs at birth to

indicate that a child has Krabbe?

In Israel there are know to be a higher percentage of Krabbe disease babies born. This means that over time what?

Explain where the genetic information linked to Krabbe disease is found.

Explain how mothers/parents could prevent a child being born with Krabbe disease?

Edexcel – Paper What is Krabbe disease? Krabbe disease (also called globoid cell

leukodystrophy) is a degenerative disorder that affects the nervous system. It is caused by the shortage (deficiency) of an enzyme called galactosylceramidase. This enzyme deficiency impairs the growth and maintenance of myelin, the protective covering around certain nerve cells that ensures the rapid transmission of nerve impulses. Krabbe disease is part of a group of disorders known as leukodystrophies, which result from the loss of myelin (demyelination). This disorder is also characterized by the abnormal presence of globoid cells, which are globe-shaped cells that usually have more than one nucleus.

The symptoms of Krabbe disease usually begin before the age of 1 year (the infantile form). Initial signs and symptoms typically include irritability, muscle weakness, feeding difficulties, episodes of fever without any sign of infection, stiff posture, and slowed mental and physical development. As the disease progresses, muscles continue to weaken, affecting the infant's ability to move, chew, swallow, and breathe. Affected infants also experience vision loss and seizures.

Less commonly, onset of Krabbe disease can occur in childhood, adolescence, or adulthood (late-onset forms). Visual problems and walking difficulties are the most common initial symptoms in this form of the disorder, however, signs and symptoms vary considerably among affected individuals.

How common is Krabbe disease? In the United States, Krabbe disease affects

about 1 in 100,000 individuals. A higher incidence (6 cases per 1,000 people) has been reported in a few isolated communities in Israel.L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Part three – Dominant and recessive genes

In our genetic make up, certain genes are dominant and influence the genetic trait of a person even if only one copy of that dominant gene is present in that pair of chromosomes. On the other hand, certain genes are recessive and do not affect the genetic trait of a person even if they are present on both chromosome pairs.Mechanisms of recessive and dominant inheritance. Recessive Inheritance Both parents carry a normal gene (N), and a faulty, recessive, gene (n). The parents, although carriers, are unaffected by the faulty gene. Their offspring are affected, not affected, or carriers. This type of inheritance was first shown by Mendel.

Dominant Inheritance One parent has a single, faulty dominant gene (D), which overpowers its normal counterpart (d), affecting that parent. When the affected parent mates with an unaffected and non-carrier mate (dd), the offspring are either affected or not affected, but they are not carriers.

http://www.accessexcellence.org/RC/VL/GG/index.php#Anchor-From-14210

Tasks - numeracy

For each trait you select, build a Punnett square that could produce your family's results. A sample is shown below. Mother has green eyes, father has brown eyes, child has green eyes. In this case, the brown gene is dominant over the green gene. This could occur in either of the combinations on the right.

On a piece of paper, decide which gene will be represented by heads and which will be tails for each coin you will be flipping. It might be easier to use different coins to represent each parent.

Toss both coins 20 times for each trait. Count the number of times you get a result that matches your own results (in our example, the result we're looking for is that the child has green eyes) and divide that number by 20. This is your experimental probability.

Compare your experimental probability with your theoretical probability and present your findings.

dominant genes

recessive genes

Carrying out your experiment

Key term Define phenotype and genotype.Phenotype – the appearance of an organismGenotype – What causes the appearance of an organism

B = Brown eyes (dominant)b = blue eyes (recessive)

Top green is Mum = B (From her mum) and B (From her dad) = Brown eyesSide  greenis Dad =  b (From his Mum) and b (From his Dad) = Blue eyed

The child or offspring are therefore the boxes in yellow! All end up with a dominant B gene so all children will be brown eyed!

However if this were to happen!

Again:B = Brown eyes (dominant)b = blue eyes (recessive)Mum in this case has one B (brown gene) and one b (blue gene) She is still brown because brown is dominant!Dad still has the two blue eyes genes!

The yellow off spring as you can see, 2 have the dominant B gene so will be brown eyed and two have the recessive b gene so will be blue eyed. It now is a 50/50 chance!

Carrying out your experiment

Last one! In this case both parents are brown eyed as they both have the dominant brown eyed gene but they both carry the recessive blue eyed gene! As you can see from the grid, one offspring is totally dominant brown eyed BB (25% chance) Two are dominant but carry the brown eyed gene (50%) and only one had two blue genes! Only a 25% chance you will have blue eyed children!

Now draw your Punnet square – think about the colours of eyes your family have, you can usually work out this equation from the visual information alone.

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Once infertility or genetic disorders have been diagnosed, a number of options are available, depending on the cause of the problem.

In vitro fertilisation (IVF)What is it? Eggs and sperm are collected and fertilised in the laboratory before the resulting embryo is transferred to the womb. The woman takes fertility drugs to stimulate the production of eggs. Once these are mature, they're collected by the doctor, using ultrasound to guide the collecting tube. The man produces a sperm sample, which is prepared before being put with the eggs in a Petri dish and left for a few days to see if fertilisation takes place. If a healthy embryo develops, this is placed in the womb using a catheter (a very fine needle or probe). Usually, no more than one or two are placed. Any remaining embryos suitable for freezing may be stored for future use. The sperm and/or eggs used may be the couple's own or donated.

IVF

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Fertility drugs

Fertility drugs are often the first treatment for women who aren't ovulating. They work in the same way as the body's own hormones, triggering the ovaries to release eggs.

This method, known as ovulation induction, can sometimes lead to conception after a few months without further intervention.

Possible side effects include premenstrual symptoms such as nausea, headaches and weight gain.

Such drugs are also used as part of other more complicated treatments, such as in vitro fertilisation and intrauterine insemination (see below). Other drugs - to help control the menstrual cycle or thicken the lining of the womb to prepare it for pregnancy, for example - may also be used. These can also cause side effects, such as hot flushes, headaches, nausea and swollen breasts.

Pre-implantation genetic diagnosis (PGD)

What is it? PGD involves checking the genes of embryos aged between two and five days, created by IVF for genetic diseases such as haemophilia and cystic fibrosis, as well as for some inherited diseases of later life such as breast, ovarian and bowel cancer. Disease-free embryos may then be transferred to the womb.

When it's used: if a couple has a child with a genetic disease and is at risk of having another; if there have been several terminations because a genetic disorder was diagnosed; if there's a strong family history of breast, bowel or ovarian cancer.

L/O The moment of conception – lesson objective to learn what happens during the first moments of human development and how chromosome and genetic information can often predetermine our life chances.

Bio-News - discussion

17 January 2011

By Lucy Freem Appeared in BioNews 591 Clinics should warn patients about the

increased risk of birth defects for children conceived using fertility treatment, say the Human Fertilisation and Embryology Authority (HFEA).

The HFEA, the body which regulates all UK fertility treatment centres, is planning to release new guidelines. They will ask clinics to inform people seeking treatment about the association between birth defects and assisted reproductive technologies (ART) such as IVF.

Health problems including low birth weight and neurological conditions such as cerebral palsy are more likely to occur in children conceived through fertility treatment, although the increase is only slight.

risk of brain disorders in any resulting children. The overall risk associated with fertility treatments is small, however. Previous estimates from the HFEA indicate that the risk of developing birth defects increases from a general population level of 2 percent to 2.6 percent with fertility treatment. After a comprehensive review, the HFEA is updating its guidelines on patient information to reflect current scientific research on the possible side effects of ART.

According to the Sunday Times, the HFEA believes that: ‘The birth defects issue is certainly something that clinics should talk to their patients about. At the moment there is not anything in the code of practice [on the subject]. There is an intention to tell patients about possible health risks... so they can make informed choices about their treatment’.

Individual procedures may carry specific warnings under the new guidelines. For example, couples who choose to have ICSI (intracytoplasmic sperm injection) - a procedure of particular use in the treatment of male fertility problems - are already told that this procedure may result in children with a higher risk of infertility.

The HFEA now believes that clinics should also warn patients who choose to have embryos screened for disease-associated genetic defects, because the screening process can increase the http://truthonmedecine.wordpress.co

m/2011/02/02/ivf-why-we-must-be-told-the-truth-over-birth-defects/

Further report Chromosome defects in eggs were previously

considered to have resulted in the first stage of cell division, which occurs when a woman was herself a foetus in the womb. Finding them during the second stage, which occurs at ovulation, therefore suggests they may have resulted from the hyperstimulation of the ovaries during IVF treatment.

The defects included abnormal variations from the usual number of 23 pairs of chromosomes. Three copies of chromosome 21 instead of the normal two, for instance, leads to babies with Down's syndrome. As women get older it becomes increasingly difficult for them to produce enough viable eggs for IVF treatment. It is common practice for older women to have their ovaries stimulated with stronger doses of drugs than is the case for younger women.

The results of the study are to be presented at a fertility conference in Stockholm this week but the scientists behind the research said that they wanted to reassure older women considering IVF treatment. They said further work needs to be done fully to explain the findings and there is no evidence to suggest that IVF babies of older women are at any higher risk of birth defects than babies conceived naturally by women of the same age.

"We found that some IVF eggs have up to seven chromosome abnormalities. This suggests the possibility that ovarian stimulation during the treatment may have caused some of these defects," said Professor Alan Handyside, director of the London Bridge Fertility, Gynaecology and Genetics Centre, who led the study.

"These defects are unexpected and it may be that this is just an undiscovered aspect of biology. At the moment all we can say is that this is part of the natural process as women get older."

The study, which will be presented at the European Society of Human Reproduction and Embryology, analysed more than 100 egg cells from 34 couples undergoing IVF treatment. The average maternal age was 40.

Scientists screened the chromosomes of the eggs and structures known as "polar bodies" that result from a type of cell division known as meiosis. Meiosis is a specialised form of division that results in eggs with half the normal complement of chromosomes – crucial to ensuring that the fertilised egg has the full complement of 46 chromosomes when it fuses with a sperm cell.

The first stage of meiosis occurs when the woman's ovary is developing in the foetus before birth, when the dividing chromosomes are held together by a kind of cellular "glue" ready for the second stage of division at ovulation.

Task – also finish for Homework

Carry out a survey using published information from the Internet on the rising number of mothers struggling to conceive a child. Why are women waiting longer to conceive a child? What are the environmental/biological and economic factors that are affecting these statistics?

Now using the research write up a small report (using the information we have discusses) about the genetic defects that some IVF treatment is causing embryos.

Negative and positive effects of parent screening 1. False Security2. People who do not receive adequate information or

counseling about the limitations of genetic testing may falsely assume that a negative test result eliminates their risk for developing a disease. Many genetic tests check for the most common gene mutations responsible for a disease, but do not rule out the possibility of a person developing that disease.

3. Abortion rate being increased4. Religion dictating /objecting to the ethics of interfered

selection of births5. 16-18 weeks Amniocentesis – this can cause natural

abortion 6. Timing considerations – 24 weeks is the limit for

abortion, at 26 weeks an infant can survive7. Parental rejection of fetus due to stress8. Bad karma – in some regions 9. legal aspects – the unborn rights of a child10. Incapable adults not being able to make the correct

decisions due to metal illness11. Consent from both parents (sometimes grandparents

have taken sons and daughters to court over their rights as grandparents.

12. Concerns About Discrimination – if genetics abnormalities are found out could you be discriminated against during health insurance (US and other countries mainly)

13. Designer babies – Victoria Beckham having a girl recently?

14. China – only allowed one child , all families want boys. 15. Adoptions16. Individual choice can be made to go ahead or

terminate a pregnancy.

What tests are carried out1. 9-10 weeks in the US chorion-biopsy (The basic

invasive prenatal diagnostic tests consist of puncture of the uterus to obtain amniotic fluid (amniocentesis), the removal of placentary tissue (chorion biopsy) or obtaining blood from the umbilical cord (umbilical blood sampling). Villious chorion biopsy

2. Pre-implantation genetic diagnosis - People who discover before starting a family that both partners are carriers have several options. They may choose to stay together but not to have any children. They may decide to separate and find a different partner. They may choose to stay together and have prenatal diagnosis in each pregnancy to check if the baby is affected. Or they may decide to go ahead with having children without prenatal diagnosis, and accept what comes.

A new possibility for people who want to stay together but do not want to consider prenatal diagnosis and termination is pre-implantation genetic diagnosis (PGD or sometimes PIGD). This is a procedure where the woman's eggs are fertilised by her partner's sperm using in vitro fertilisation (IVF), a procedure normally used to treat infertility. Before the embryos are placed in the mother's womb, they can be screened for genetic conditions. The aim is to ensure only those embryos which are not affected by a sickle cell disorder or beta thalassaemia major are implanted.

3. Amniocentesis represents an additional invasive prenatal diagnostic possibility. Here in the 13th – 15th WoP (15 - 17 weeks after the LMP) 10 - 20 ml of amniotic fluid is obtained via a puncture. This examination is performed with ultrasound supervision in order to reduce the danger of hitting the fetus or placenta and thereby harming the gestation .http://www.youtube.com/watch?v=P_vBDSH3bg0&feature=related

Triple blood screening

How is the triple screen test performed?

The triple screen test involves drawing blood from the mother which takes about 5 to 10 minutes. The blood sample is then sent to the laboratory for testing. The results usually take a few days to receive.

What are the risks and side effects to the mother or baby?

Except for the discomfort of drawing blood, there are no known risks or side effects associated with the triple screen test.

When is the triple screen test performed?

The triple screen test is performed between the 15th and 20th week of pregnancy although results obtained in the 16th -18th week are said to be the most accurate.

All pregnant women should be offered the triple screen, but it is recommended for women who:

Have a family history of birth defects Are 35 years or older Used possible harmful medications or

drugs during pregnancy Have diabetes and use insulin Had a viral infection during pregnancy Have been exposed to high levels of

radiation

What does the triple screen test look for?The triple screen is measuring high and low levels of AFP and abnormal levels of hCG and estriol. The results are combined with the mother's age, weight, ethnicity and gestation of pregnancy in order to assess probabilities of potential genetic disorders.

High levels of AFP may suggest that the developing baby has a neural tube defect such as spina bifida or anencephaly. However, the most common reason for elevated AFP levels is inaccurate dating of the pregnancy.

Low levels of AFP and abnormal levels of hCG and estriol may indicate that the developing baby has Trisomy 21( Down syndrome), Trisomy 18 (Edwards Syndrome) or another type of chromosome abnormality.

Although the primary reason for conducting the test is to screen for genetic disorders, the results of the triple screen can also be used to identify:

http://www.prolifecampaign.ie/

Finding cures we can all live with!There has been a lot of publicity about the potential of stem cell therapies in curing chronic diseases and disabilities. These breakthroughs in stem cell science are exciting and heartening. Much of the coverage, however, has blurred the distinction between destructive human embryonic research and the perfectly ethical adult stem cell research.

So far, all the scientific breakthroughs are in the field of adult stem cell research. Nonetheless, the campaign for public funds to allow research that destroys living human embryos continues unabated.

Why is there controversy involving stem-cell research? There are two different kinds of stem cells: adult stem cells (ASC) and embryonic stem cells (ESC). Adult stem cells can be found in the blood, bone marrow, skin, brain, liver, pancreas, fat, hair follicle, placenta, umbilical cord and amniotic fluid.

As well as showing great scientific promise in repairing damaged organs and tissues, adult stem cell research is ethically non-problematic. However, embryonic stem cell research (ESCR) requires the destruction of an embryo, which is a human being at the beginning of life.  

Task – You are requested to compile a newspaper article giving people all the pros and cons of stem cell research- Images, notes and QWC in your arguments for and against could also be included in your report.

http://thegreengeeks.wordpress.com/2011/03/08/why-im-horrified-by-the-pro-life-campaign/

Examination style questions