SBI3U Lesson 1: DNA structure
• DNA stands for __________________________________________
• There are 2 types of nitrogenous base:
• DNA forms from _______________________________groups form the ____________________________of DNA
• DNA uses the nucleotides containing ________________________ • DNA molecules are helical in structure, and ___________________ coil
around each other.
• The two strands in DNA are __________________________________________________ _____________________________________ on adjacent strands.
• Base pairing occurs between ______________________ and between _________________ • Each strand of the DNA molecule has a free phosphate group at one end and a free sugar
(deoxyribose) at the other end. • The two strands are said to run ____________________________ • Every nucleotide pair is composed of a _________________________________________
SBI3U Lesson 3: Meiosis Meiosis is the process by which __________________________________________
• involves __________________________________________ Purpose
• _____________________ amount of _________________________________ • _______________________________________________________________
Each gamete will contain:
• both the __________________________________ • ____________________________ of chromosomes. • has a ________________ # of chromosomes ( n )
Note: the ___________ of chromosomes is _______________________ (2n)
• receive _____________________________________________ and __________________________________________
• Humans have ________________ of chromosomes called _______________________________________
• genes in homologous chromosomes deal with the same traits • involves _____________________________
SBI3U Interphase
Prophase I
• nuclear membrane = dissolves • ______________________________, move to opposite poles, spindle
fibres are formed. • Homologous pairs come together (form _____________ • This process is referred to as _____________________ • Sometimes the intertwined chromatids exchange segments
________________________________ Metaphase I
• ___________________________ attach themselves to the spindle fibres and __________________________________
Anaphase I
• Homologous pairs of chromosomes ___________________ • known as _____________________________
Telophase I
• Membrane begins to form around each nucleus. • Unlike in mitosis, the ___________________________________________
SBI3U Meiosis II During meiosis II:
• pairs of ______________________________________ and move to opposite poles • Prophase, metaphase, anaphase and telophase are all _______________________ • ______________________________ are produced from each meiotic division • The formation of sex cells during meiosis is referred to as ____________________
SBI3U
Mitosis Meiosis
Cell Type
Number of Daughter Cells
Similarity to Parent Cells
Chromosome Numbers
Lesson 5: Abnormal Meiosis Meiosis is ________________________________
• Nondisjunction occurs when ____________________________________________ move to the __________________________ during meiosis
• This ________________________ if it happens during the __________________________ In humans, _______________________________________________________________ can form
• This results in a zygote containing 47, or 45 chromosomes) • If the zygote has __________________________________ it is referred to as ___________ • If the zygote has only ________________________________ it is called _______________
Genetic Disorders
SBI3U Disease Genetic Problem Traits Occurrenc
e
Producing a Karyotype Karyotype preparation and analysis
1. Cells are grown in vitro (in a cell culture dish) to increase their number. 2. Cell division is stopped in metaphase with colchicine (prevents mitotic spindle from forming). 3. Cells are centrifuged and lysed to release chromosomes. 4. Chromosomes are stained, photographed, and grouped by size and banding patterns.
SBI3U Lesson 6: Inheritance of Traits
• Traits – specific characteristics that are _________________________________________ o Ex. Earlobes, Dimples, Curved Fingers, Rolling Tongue
• Inheritance – The mechanism that _____________________________________________ • Genetics – biology that deals with the ___________________________________________ • ________________________________________________ and variation for thousands of years
before these principles were scientifically proven. • People have been ______________________ domesticated animal and plant species for millennia
A few theories of inheritance arise. . . .The Greek philosophers: Hippocrates (460-‐377 B.C.E.)
• suggested that the ___________________________________ and that these ________________ to give rise to a new individual
Aristotle, (384-‐322 B.C.E.)
• proposed that ____________________________________ upon conception 1500’s
• English physician, ______________________________ theorized that a process called ________________ was how inheritance occurred
• A process based upon the _________________________________________________, and _____________________________________________ both inside and outside the mother
1600s
• Dutch Scientist and Microscopist, ___________________________, used a microscope to ________________________ of humans and other animals
• Leeuwenhoek later proposed that the male ______________________________ ____________________ which would later be developed in the mother’s uterus
Mid 1800s
• ________________ suggested that children had characteristics that were _____________________________________________ traits, but he was __________________________________________________________
• answers of inheritance were answered by the research of ___________________ Inheritance of One Trait
• Gregor Mendel • Austrian monk, studied the principles of inheritance • Used the ________________________________, Pisum sativum as an experimental model
Why Pea Plants?
• readily available • ___________________ and reaches ________________ • differences in traits is easy to quantify • sex organs contained within the flower = _______________________
SBI3U • The plants exhibited seven distinct traits that could be easily observed between generations • __________________________________________________________________
How did Mendel set up his experiment?
• _______________________________________ for each trait tested • truebreeding plants = known traits • _________________________________________________ and then observed outcomes • used his mathematical background to __________________________ = predict genetic
outcomes A Monohybrid Cross – Mendel’s first experiment
• _____________________ plant with a __________________plant • Mendel called this the ___________________________________ • Offspring are called the ______________________ because they
are a hybrid of both parents • ______________________________________________________
What Happened?
SBI3U Dominant & Recessive Traits
• Dominant Trait – a characteristic that is ____________________________ in an individual • Only ___________________________ must be present for the dominant trait to be
______________________________________________ • Recessive Trait – a trait that is ___________________________________ for the recessive trait
are present. • In Mendel’s experiments, he found that _________________________________________ over
another characteristic Mendel’s Principle of Dominance When ________________________ purebred individuals are crossed, the offspring will ____________ ____________________________________________ Mendel’s Experiment – Monohybrid Cross
Punnett Square
Mendel's 2nd Experiment
• _____________________________________ plants from experiment one • allowed the hybrid tall plants of the ________________________________________________
Punnett Square
SBI3U • produced a ___________________________________ that Mendel called the F2 generation • 75% (3/4) of plants in the F2 generation were tall while 25% (1/4) was short. • This ratio of ________ has become known as the _____________________________
Mendel drew 4 conclusions from his experiments:
1. Each parent in the __________________________________________ Individual factors are either dominant, or recessive.
2. The factors are separated in he parent and _________________________________________ 3. Each offspring inherits one factor from each parent. If the dominant factor is inherited by the
offspring, it will be expressed; even if the recessive factor is also present. 4. The _________________________________________________________________________
Law of Segregation
• Inherited traits are determined by pairs of “factors” • _______________________________________________________________ • One factor from each pair is present in each gamete.
The arrangement of alleles
• Alleles can be identified by using a conventional two-‐letter code system. i.e. T (tall) or t (short)
• 2 same = _________________________ • 2 different = _____________________________
Sample Problem 1 Consider a cross between a pea plant that is heterozygous for round seeds and a pea plant that has wrinkled seeds. Determine the genotypes of the possible offspring.
SBI3U Sample Problem 2 A plant that is homozygous for purple flowers is crossed with a plant that has white flowers. If the purple condition is dominant over the white condition, what are the genotypes and phenotypes of the F1 generation? Practice Set 1: Monohybrid Cross with Single Dominance
1. In humans tongue rolling is dominant to non-‐tongue rolling. What would be the expected type of offspring if a homozygous tongue roller was crossed to a heterozygous tongue roller? 2. In a certain plant yellow fruit is dominant to white fruit. A heterozygous plant with yellow fruit is crossed with a plant with white fruit. Determine the probable offspring. 3. In a certain animal, black fur is dominant to white fur. Determine the possible offspring from crosses between: a. Homozygous black x white b. Heterozygous black x heterozygous black 4. In garden peas, round peas are dominant to wrinkled peas. If you crossed a homozygous dominant and homozygous recessive what would be the genotype and phenotype of the offspring? 5. In corn, normal kernels are dominant to waxy kernels. If you crossed a waxy kernel plant to a heterozygous normal plant what type of seeds would be produced? 6. A Tall plant (T) is dominant to short plant (t). If all offspring of a cross are heterozygous, what were the genotypes of the parents? 7. A round seeded plant (R) is dominant to a wrinkled seeded plant (r). What parental genotypes will produce offspring that are 50% homozygous dominant and 50% heterozygous? 8. A homozygous round seeded plant is crossed with a homozygous wrinkled seeded plant. What percentage of the offspring will also be homozygous? 9. In pea plants purple flowers are dominant to white flowers. What parental genotypes would produce offspring that are all heterozygous for the purple trait? 10. If out of 100 offspring 74 are purple flowered and 26 are white, what were the probable genotypes AND phenotypes of the parents? 11. In guinea pigs, the allele for short hair is dominant. If all the guinea pigs are born short haired what are the possible genotypes of the parents? (There are two possible combinations.) 12. If a second cross is made using these offspring and results are 3⁄4 short haired while 1⁄4 are long haired can you now determine the exact genotypes of the parents and if so what are they?
SBI3U Lesson 7: Mendelian Genetics – Inheritance of 2 Traits Mendel’s 2nd Experiment
• involved the ___________________ pea plants that __________________________________ • Mendel wanted to discover if the inheritance of ______________________________________
_________________________________ (i.e. Did pea colour influence pea shape?)
• When generating the possible gametes, all combinations are considered
Parent Genotypes Gametes Made
RRYY rryy Dihybrid Cross of 2 Traits Mendel’s Law of Independent Assortment
• inheritance of alleles for _____________________________________ of alleles for another trait. • the combination of alleles in the offspring ______________________________________. (i.e.
they sort independently.)
SBI3U Sample Problem 1 What are the probabilities of obtaining F1 offspring with the following characteristics if one parents is homozygous dominant for both traits and the other is heterozygous for both ?
• widow’s peak and free earlobes • straight hairline and free earlobes • widow’s peak and attached earlobes • straight hairline and attached earlobes
Sample Problem 2 What is the probability that a child from the mating of the EeHh × EeHh parents would be a male with a widow’s peak and have attached earlobes? Write your probability as a percentage!
SBI3U Practice Problems – Dihybrid Cross
1. In pigeons the checkered pattern is caused by a dominant allele. A plain (non-‐checkered) pattern is recessive. Red color is also caused by a dominant allele and brown color by a recessive allele.
a. Show the expected offspring of a cross between a homozygous checkered red bird and a plain brown one. Carry out this cross through the F2 generation.
b. Carry out to the F2 generation a cross between a homozygous plain red bird and its homozygous checkered brown mate.
c. A plain brown female pigeon laid five eggs. The young turned out to be: 2 plain red, 2 checkered red, and 1 checkered brown. Describe the father pigeon. Give the genotypes of all birds in this cross. Could any other types of offspring been produced by this pair?
2. In horses, black is dependent upon a dominant gene, B, and chestnut upon its recessive allele, b. The trotting gait is due to a dominant gene, T, the pacing gait to its recessive allele, t. If a homozygous black pacer is mated to a homozygous chestnut trotter, what will be the appearance of the F1 generation?
3. In summer squash, white fruit color (F) is dominant over yellow fruit color (f) and disk-‐shaped fruit (D) is dominant over sphere-‐shaped fruit (d).. If a squash plant true-‐breeding for white, disk-‐shaped fruit is crossed with a plant true-‐breeding for yellow, sphere-‐shaped fruit,
4. Imagine that a couple is planning to have children. The male is heterozygous for Huntington’s
disease and homozygous dominant for Tay-‐Sachs. The female is homozygous recessive for Huntington’s disease and heterozygous for Tay-‐Sachs. The couple is curious about the possibility and probability of their offspring inheriting Tay-‐Sachs and/or Huntington’s. For humans, Huntington’s disease is dominant (H) over the “normal” condition (h), and the “normal” condition is dominant (T) over Tay-‐Sachs (t). Complete a Punnett square for this cross and record the probabilities for genotypes and phenotypes of the offspring as ratios.
5. In rabbits, the coat color black dominant (B) over brown (b). Short hair is dominant (H) over long
(h). In a cross between a homozygous black short-‐haired male and a brown homozygous long-‐haired female, what would be the ratios for genotype and phenotype of the F1 generation?
6. In aquatic arthropod called a Cyclops has antennae that are either smooth or barbed. The allele for barbs (B) is dominant over smooth (b). In the same organism Non-‐resistance to pesticides (N) is dominant over resistance to pesticides (n). Make a "key" to show all the possible genotypes (and phenotypes) of this organism.
SBI3U Lesson 8: Beyond Mendel’s Laws Although his research and examination of patterns of inheritance in the pea plant was revolutionary in genetics; Mendel did not have a complete understanding of the patterns of inheritance. There are three other mechanisms of inheritance:
• • •
Incomplete Dominance
• ___________ traits are _______________________________________ as Mendel suggested. • Some traits are __________________________ is, there can be an ___________________ of a
particular trait when the genotype is ___________________________________
Sample 1. Determine the F1 phenotypic ratio of a cross between a pink and a white snapdragon. Co-‐Dominance Inheritance
• In some cases ___________________ for a trait may be ________________________ • Such alleles are said to be co-‐dominant ______________________________________________
______________________________________________
SBI3U Shorthorn cattle show Co-‐Dominance inheritance Sample 1. Find the F1 phenotypes of a cross between a red cow and a roan bull. Multiple Allelic Inheritances
• For some traits _____________________________________________________ in a species • Although a single individual ___________________________________________________
different individuals can have different pairs of alleles. Sample Problem – Drosophila Eye Colour
SBI3U Sex Linkage – X & Y
• Some traits are inherited from _____________________________________________ • This is known as _________________________________ (most often X-‐linked) inheritance • Colour blindness, hemophilia, and baldness are sex-‐linked traits.
Sample Problem 1 A male with hemophilia mates with a woman with no hemophiliac gene. What is the probability of producing sons or daughters who have hemophilia? Pedigree Charts
• Pedigree analysis is useful when the ______________________________of offspring have been recorded.
• A pedigree chart can be _____________________________________________ from parents to offspring.
Sample Problem
SBI3U Practice Problems – Incomplete & Codominance
1. In a particular plant, purple flowers (“P”) and yellow flowers (“Y”) are codominant. Heterozygotes of this species are purple and yellow striped.
a) If a plant with purple flowers is crossed with a plant that has striped flowers, what will be the possible genotypes and phenotypes of the F1 plants?
b) What will the possible genotypes and phenotypes be if a plant with yellow flowers is crossed with a plant with striped flowers?
2. In one species of plants, red flower colour (“R”) is codominant with yellow flower colour (“Y”). In
a heterozygous plant, the flower will be yellow with red-‐edged petals.
a) Predict the possible genotypes and phenotypes of the F1 and F2 plants that result when a red-‐flowered plant is crossed with a yellow-‐flowered plant.
b) Predict the possible genotypes and phenotypes that result when a red-‐flowered plant is crossed with a yellow flower with red edges.
3. In one species of Asian bird, black feathers (“B”) are incompletely dominant over white feathers
(“W”). In a heterozygous bird, the feather colour will be grey. Predict the possible genotypes and phenotypes of the F1 and F2 generation birds that result when a black-‐feathered bird is crossed with a white-‐feathered bird.
4. A woman whose blood type is B (heterozygous) gives birth to a child whose blood type is O. The
woman claims that there are two possible fathers: one with blood type A (heterozygous) and the other with blood type AB. Showing all work, determine which man cannot be the father.
5. A woman homozygous for type B blood gave birth to a child. There was a blackout on the night
before the woman was to leave the hospital, and it’s possible that some of the babies got mixed up in the confusion. The woman’s husband has blood type A (heterozygous) and the baby the couple took home from the hospital has blood type O. Could this baby belong to this couple?
6. Thalassemia is a type of human anemia that is rather common in Mediterranean populations but
relatively rare in other peoples. The disease occurs in two forms; minor and major (the major form is much more severe). People with Thalassemia major are homozygous for the anemia (“A”) allele, while those with Thalassemia minor are heterozygous. People lacking the disease are homozygous for the normal allele (“N”)
a. A man with Thalassemia minor marries a normal woman. What percentage of their
children will show some form of the disease? (indicate if it is major or minor). b. Both father and mother in a particular family have Thalassemia minor. What is the
chance that their baby will suffer from the major form of this disease? Suffer from the minor form? Be perfectly normal with respect to this disease?
SBI3U Practice Problems – Sex-‐linked Inheritance
1. In humans, normal vision (XC) is dominant to colorblindness (Xc) and is sex-‐linked. A normal-‐visioned man, whose father was colorblind, marries a colorblind woman. What are the chances that a son will be colorblind. A daughter? Explain.
2. Hemophilia is due to a sex-‐linked recessive gene (Xh) and the normal condition to the gene (XH). A hemophiliac man marries a woman who is not. Their first son has hemophilia. What are the chances that their daughter, if they had one, will be hemophilic?
3. Hairy pinna (hairy ears) has been found in males, but not in females. Suggest an explanation for
this.
4. Coat color in cats is a co-‐dominant trait and is also located on the X chromosome. Cats can be black, yellow or calico. A calico cat has black and yellow splotches. In order to be calico, the cat must have an allele for the black color and an allele for the yellow color. Use a punnet square to show why there are no male calico cats. (use the letter “Y” for yellow and “B” for black)
5. A female calico cat is crossed with a male black cat. What are the phenotypes of the offspring?
6. Also located on the X chromosome of a cat is a gene that codes for deafness. This gene is
recessive. A female cat that is heterozygous for deafness is crossed with a male cat that is not deaf. What are the genotypes and phenotypes of the offspring? (use the letter “D” for hearing)
7. A man files his wife for divorce on the grounds of infidelity. Both man and wife have normal eyes,
but there is a baby daughter who has coloboma iridis (a fissure in the iris of the eye). This characteristic is known to be inherited as a sex-‐linked, recessive trait. If you were the man’s lawyer, could you use this fact as evidence? If so, how would you explain the case to the jury?
8. In man, muscular dystrophy is a condition in which the muscles waste away during early life and
may result in a shorter life-‐expectancy. It is due to a sex-‐linked, recessive gene. A certain couple has five children – three boys (ages 1yr, 3yrs, and 10yrs old) and two girls (ages 5yrs and 7yrs old). The oldest boy shows the symptoms of this disease. You are their family physician and they come to you for advice. What would you tell them about the chances of their other children developing the disease?
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