Genetics

Inheritance through Evolution

Essential Ideas

3.1 Every living organism inherits a blueprint for life from its parents

All members of a species have the same number of chromosomes- each with the same genes in the same gene

loci.

Understanding

A gene is a heritable factor that consists of a length of DNA and influences a specific characteristic.

The number of chromosomes

varies between species.

So what is a gene?

Start at 51

seconds through

1.27

Understandings

A gene occupies a specific position on a chromosome.

Genes at particular loci

A gene for a specific trait occupies a corresponding place, a locus, on a chromosome.

Remember, you have two copies of each gene, one from mom and one from dad.

Understandings

The various specific forms of a gene are alleles.

Alleles differ from each other by one or only a few bases.

Review: gene lociTP53

Alleles: versions of genes

Variations of a gene

Differs by only a few base pairs

Transducin enables colour vision

Single base pair mutation at position 235 (T instead of C)

Colour vision vs. or no colour vision

Allele differences

Single nucleotide

polymorphism

Cystic Fibrosis

CFTR gene

Cystic Fibrosis

Mucous – necessary for proper fluid movement in the lungs and intestines

CFTR gene on chromosome 7

Can mutate to form excessive quantities

Autosomal recessive

Understandings

New alleles are formed by mutations.

How are new alleles produced?

Point mutation

Mutations- Good or Bad?

Gene therapy is an experimental technique that uses genes to treat or prevent disease. In the future, this technique may allow doctors to treat a disorder by inserting a gene into a patient's

cells instead of using drugs or surgery.

Good or Bad?

Mystery of the Black Death

LRP5 gene – creates a protein receptor on immune system cell surface

Mechanism for HIV to infect cells

Missing the gene – can’t get HIV

Sickle cell disease

A base pair mutation to haemoglobin

Sickle cell disease (anemia)

Glutamic acid Valine

What differences in properties can

we deduce from the

structures?

How might this change the quaternary protein structure?

https://www.youtube.com/watch?v=R4-c3hUhhyc

How about advantages?

Malaria and Sickle Cell Disease

Malaria

A parasitic disease

Caused by a plasmodium cell which causes cells to lyse

Carried by the Anopheles mosquito

Occurs in tropical regions

Symptoms: fever, shivering, vomiting and anemia

Death is common: kidney failure or severe anemia

Malaria

Malaria can’t infect sickled cells

Sickle cell trait (one copy of each allele)

Heterozygotes have a chemical imbalance with Potassium

Insufficient potassium cause Plasmodium to die

Understandings

The genome is the whole of the genetic information of an organism.

The entire base sequence of human genes was sequenced in the Human Genome Project.

Human Genome

The whole of the genetic information of an organism

Begun in 1990Completed in 2003

Essential Ideas

3.2 Chromosomes carry genes in a linear sequence that is shared by members of a species.

Key vocabulary

Homologous

Diploid

Haploid

Karyotypes

Sex-determination

autosome

Essential Ideas

3.3 Alleles segregate during meiosis allowing new combinations to be formed by the fusion of gametes.

Meiosis

Previously covered

Amniocentesis

Chorionic villus sampling

Essential Ideas

3.4 The inheritance of genes follows patterns.

Understandings

Mendel discovered the principles of inheritance with experiments in which large numbers of pea plants were crossed. I used the

word factor, not

gene

More Vocabulary

Genotype

Phenotype

Dominant allele

Recessive allele

Co-dominant alleles

Locus

Heterozygous

Homozygous

Carrier

Test-cross

Understanding

Gametes are haploid so contain only one allele of each gene.

The two alleles of each gene separate into different haploid daughter nuclei during meiosis.

Fusion of gametes results in diploid zygotes with two alleles of each gene that may be the same allele or different alleles.

Punnett Square

Lab Time: Monohybrid and Dihybrid Crosses with true dominance

Mendelian Genetics of Corn

Arabidopsis- Playing Mendel

Application

Inheritance of ABO blood groups

Blood Types = Multiple alleles

What are the 4 blood types in humans?

We use the letter to “I” to represent them

Time for blood lab

Understanding

Dominant alleles mask the effects of recessive alleles but co-dominant alleles have joint effects.

Many genetic diseases in humans are due to recessive alleles of autosomal genes although some genetic diseases are due to dominant or co-dominant alleles.

Some genetic disorders are sex linked. The patterns of inheritance is different with sex-linked genes.

Many genetic diseases have been identified in humans but most are very rare.

Sex-linked genes

Size of sex chromosomes

Types of traits

Colour blindness

Haemophilia

Duchene muscular dystrophy

Sample Punnett squares

Huntington’s disease

Dominant allele

Nerve damage

Co-dominant genes

Both expressed at the same time

Sample Punnett square

10.2 Understanding

Chi-squared tests are used to determine whether the difference between an observed and expected frequency distribution is statistically significant.

Bozeman Science

10.2 Application

Completion and analysis of Punnett squares

Dihybrid Crosses

Dihybrid Cross

Application

Pedigrees

worksheets

Understanding

Radiation and mutagenic chemicals increase the mutation rate and can cause genetic diseases and cancer.

Previously covered

Essential Ideas

3.5 Biologists have developed techniques for artificial manipulation of DNA, cells and organisms.

Understandings

Gel electrophoresis is used to separate proteins or fragments of DNA according to size.

PCR can be used to amplify small amounts of DNA.

DNA profiling involves comparison of DNA

Genetic modification is carried out by gene transfer between species.

Understandings

Clones are groups of genetically identical organisms derived from a single original parent cell.

Many plant species and some animal species have natural methods of cloning.

Animals can be cloned at the embryo stage by breaking up the embryo into more than one group of cells.

Methods have been developed for cloning adult animals using differentiated cells.

Cloning

Cutting DNA

Use restriction enzymes (endonucleases)

Recognize a set of base pairs (4 or 6)

Pasting DNA

Use DNA ligase

Recognizes sticky ends and attaches them

Copying DNA

Need a host cell

Most popular is Escherichia coli

Plasmids

Small circles of extra DNA

To copy a gene – glue it into a plasmid

How to insert in a plasmid

Plasmid removed from the host cell

Cut open with a restriction enzyme

Place copied gene into open plasmid

gene splicing

Pasted using DNA ligase

Now a RECOMBINANT PLASMID (vector)

Vector placed in bacterium

Human Insulin Production

Makes copies of gene

Express the gene

Genetically Modified Organisms (GMO)

Has an artificial genetic change

Gene transfer OR recombinant DNA

More competitive in the food market OR

Medical applications

Transgenic Plants

Flavr Savr

Delayed ripening and rotting

Some are more resistant to salt in the soil

Golden Rice

Added beta carotene

Helps with deficiency in vitamin A

Body uses beta carotene to make vitamin A

Maintains skin, teeth, aids in vision in low light

Transgenic animals

Used in medical treatment

Haemophilia – Factor IX

Natural cloning

Strawberry plants

Potato

Animal - hydra

IA idea Check out page 165

Cloning an Embryo Naturally

History of cloning

1890 – Hans Dreisch

Used sea urchins 1embryo to grow 2 identical embryos

Was not attempting to clone

kljlj

Animal cloning – Hello Dolly

Unfertilized cell

Remove nucleus

Cultured cells

Cloning

Reproductice

Makes an entire organism

Somatic cell nuclear transfer

Therapeutic

Develop cells that have not differentiated

Ethical Issues

Start with human embryos

Skin to repair burns

New heart muscle to repair an ailing heart

New kidney tissue to rebuild a failing kidney

Previously covered

Gel electrophoresis

PCR

DNA profiling

Linkage Groups

Thomas Hunt Morgan

Early 1900’s

Worked with Drosophila melanogaster

Did not get 3:1 ratios

BGSU – Fruit fly research!

Reproduce every 2 weeks

Thousands of crosses

White eye vs. red eye

(mutants vs. wild type

Fruit fly ratios

White-eyed male x red-eyed female

3:1 (red to white)

White-eyed female x red-eyed male

2:2 (red to white)

How they discovered sex-linked genes

Understanding

Gene loci are said to be linked if on the same chromosome

Linked groups

Any two genes that are found on the same chromosome

Usually passed on to the next generation together

Can be autosomal or sex-linked

Drosophila gene map

Genotype notation

For linked genes

Skill

Identification of recombinants in crosses involving two linked genes

Gene linkage notation

Two horizontal bars symbolize homologous chromosomes and that locus of G is on the same chromosome as L

One G is on the maternal chromosome and one G is on the paternal homologue.

Read the pairs vertically; GGLL

G L____________________ G L

Example problemCross a GGLL with a ggll (G = grey, g = black; L = long-winged, l = short-winged)

G L____________________ G L

g l____________________ g l

x What will the

offspring look like?

All grey with long wings

Test cross problem

Take one of the previous offspring and mate it with a _______.

G L g l______ x ____ = g l g l

ggll

gl

GL

G L_____g l

Gl

G l_____ g l

gL

g L____g l

Gl

g l_____g l

Recombinants

Go back and look at the 2nd and 3rd possible offspring.

How do these compare to the parents?

These new combinations are known as recombinants.

Refers to both the new chromosome and resulting organism

Recombinants

Formed by

A way to increase genetic variability

Crossing over

Understanding

Variation can be discrete or continuous

The phenotypes of polygenic characteristics tend to show continuous variation

Application

Polygenic traits such as human height may also be influenced by environmental factors

Polygenic Inheritance

Involves two or more genes to control one phenotype

Continuous and discrete

Epigenetics

Time for a video

Epigenetics: How food upsets our genes

How do you tell if a trait is continuous?

Is it either/or? (ear wax)

Is it a multiple allele? (blood type)

Displayed as bar charts

Polygenic traits

Will plot as a bell curve