February 16, 2015

Unit A: Chapter 2 - GENETICS

· Try This Activity - pg. 77 - Tongue Rolling (#1-5)

Rollers Non-rollers

Section 2.1 - What is Genetics?

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Chromosomes, DNA and Genes

What is the nucleus?

What are chromosomes?

How many chromosomes do humans have?

Chromosomes are made up of DNA.

DNA = __________________________

GENE- Segment of DNA made up of individual nucleotides

THINK OF THE COOKBOOK ANALOGY

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Genetics - the study of how genes work to determine characteristics and to resolve how genetic information gets passed from parent to offspring.

The 23 pairs of chromosomes in the cell are jumbled and tangled in the nucleus.

So they need to be studied in a more organized form.

Karyotype - is an image of all the chromosomes in one nucleus that have been matched up into their respective homologous pairs.

What is different about each pair?

Idea of homologous chromosomes

- One copy from mother and one from father

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- The 23rd pair of chromosomes, are the X and the Y chromosomes, which determine the sex of the individual.

XX = female

XY = male.

The sex chromosomes

Amniocentesis-A prenatal test done to look at the karyotype of an

unborn child.

The Role of Proteins

- DNA sequence codes for a protein.

RECALL THIS BIO 30 PEOPLE!

- Every protein has a unique shape and function.

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Example of a protein = insulin a hormone

· Other examples of proteins are cell membrane proteins.

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§ The following are the major types of proteins and their roles.

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Making More Chromosomes

1) Mitosis- Happens in body cells (somatic cells) or

autosomal cells (ex. skin cells)

- Asexual reproduction

- All cells are diploid (2n)

- Parent AND Daughter Cells are identical

MIT

OSI

S

Video

2 ) Meiosis- Occurs in gametes or sex cells (ex. egg & sperm/pollen)

- Sexual Reproduction

- Reduction Division

- Crossing over which leads to...

- Variation and Unique Products

- Parent is diploid (2n) and Products are haploid (n)

Video

MEI

OSI

S

Fertilization· Male gamete + Female gamete = Full Organism

With Sexual Reproduction there can be variation!

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Selective Breeding - choosing individuals with useful characteristics to produce a more desirable plant or animal stock.

Early Ideas of Inheritance

1. Theory of preformation - the idea that all body parts were formed at the beginning of development and simply grow from a very tiny full-formed body to a larger body.

(However, there was confusion whether the pre-formed body was found in the egg or the sperm)

2. Charles Darwin - published his theory of evolution - where organisms best suited to their environment survived to pass on their characteristics of their offspring (natural selection).

3. Mendel - first person to study the inheritance of characteristics, and became the Father of Genetics.

- Cross-pollinated pea plants

- Self-pollination experiments

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Mendel's Conclusions

1. Inheritance is determined by "factors".

2. Individuals inherit one "factor" from each parent.

3. Factors are inherited independently.

4. Some factors are more powerful than others.

4. Francis Galton - Case Study

http://www.abheritage.ca/abpolitics/people/influ_eugenics.html

Father of Eugenics

Eugenics in Alberta...

Section 2.2 Inheritance

Aquired traits - (ex. scar) come from the environment and are not passed on to offspring.

Inherited traits - (ex. height) are the result of our genes.Aquired Inherited

Gene control - one allele or more?

A form of a gene.

Gene Terminology

1. Dominant vs. Recessive

2. Homozygous vs. Heterozgous(Carrier)

3. Geneotype vs. Phenotype

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BbB bbrown blue

B

B

b

B bbrown

Punnett SquareB

What fraction of kids will have brown eyes?

What fraction will have blue eyes?

Genotype PhenotypeBbB bbrown blue

b

B

b

B bbrown

Punnett Squareb

What fraction of kids will have brown eyes?

What fraction will have blue eyes?

Genotype Phenotype

BbB bbrown blue

b

B

B bbrown

Punnett Squareb

B

What fraction of kids will have brown eyes?

What fraction will have blue eyes?

Genotype Phenotype

c

C

c

Momma Mouse is black. That means she has at least one C.Poppa Mouse is albino. That means he is homozygous- cc

When we see the babies, we will know if momma is heterozygous (Cc) or homozygous (CC). How?

?

Genotype Phenotype

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Sometimes genes have more than two alleles or the inheritance is Non-Mendelian.

Ex. Height

Ex. Coat color of rabbits

Blood type - is controlled by more than one gene and there are 3 possible alleles of the blood-type gene represented by the letters A, B and O.

BLOOD TYPE POSTER!

See PAGE 99

STOP BIO 30!!

What is the difference?

February 16, 2015

· A and B alleles produce a modified surface protein on the red blood cells that give the cell its unique phenotype as shown by the antigen on the surface.

· A and B are both dominant over the O type, but are not dominant over each other. They share dominance and are said to exhibit codominance, where both are expressed at the same time. This results in the phenotype AB.

· The O allele is recessive and does not produce a modified protein on the surface, does not produce an antigen, and can be masked by A and B alleles. To express the O type, an individual must be homozygous for the O allele.

· Thus, these 3 alleles can produce 4 phenotypes

Question: What geneotype(s) and phenotype(s) could the offspring of the following parents be?

Parent #1 Parent #2

- Sex is determined by these chromosomes as well.

- 50% chance of having a girl or boy every time there is conception.

Recall that usually every person has 2 sex chromosomes...So...

Video...What if this doesn't happen?

- Traits that are controlled by gene(s) found on either the X or Y chromosome.

- Different than autosomal inheritance which is due to genes on the other 22 chromosomes.

Sex-Linked Inheritance (X-Linked or Y-Linked Traits)

February 16, 2015

To make predictions, you still use a Punnett Square!

Traits that are dominant and recessive are still represented as upper and lower case letters, however, the sex-linked trait is represented as a superscript, with an upper and lower case superscript to represent dominant and recessive sex-linked traits.

Ex. color-blindness is an X chromosome, sex-linked trait (XN or Xn ). It is not carried by the Y chromosome.

A complete genotype for a color-blind man is XnY and a full vision male is XNY

A complete genotype for a color-blind female is XnXn and a full vision female is XNXn.

Question: If a man with hairy ears, a Y-linked trait, has children with a woman without hairy ears, what is the percentage probability that their sons will have hairy ears?

Section 2.3 - DNA - DEMO pg. 106 DNA - a double helix - like a staircase

- made from chemical units called nucleotides, consisting of a phosphate molecule, a sugar called a deoxyribose, and one of four nitrogen-base molecules.

Page 107

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Backbone = phosphate and the sugar parts

Rungs = The nitrogen bases

adeninecytosinethymineguanine.

The nitrogenous bases are attached together with hydrogen bonds.

Nitrogen bases bind with their complementary base pair.

A-T and C-G

% of A will always = % of T

% of C will always = % of G

DNA strand = ACTGTTAAC

Complement =

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How can this genetic code be packaged? DNA ReplicationIf we want an EXACT copy of DNA which cell process do we need?

February 16, 2015

1 - the DNA strand unwinds

2 - the bonds between the bases are broken

3 - the strands separate like a zipper being unzipped

4 - free-floating nucleotides in the nucleus attach to the complementary bases of the nucleotides exposed along the halves of the unzipped DNA strands.

5- this process produces 2 new DNA molecules, each with one strand of the original DNA and one newly created strand.

6 - the newly paired strands then coil back into the double helix form.

The Genetic Code (See DATABOOK)

DNA --> Protein

DNA: ACCTTGGGCACA

- We get there by looking at the DNA triplet codes!

Made up of what subunit?

Amino Acids

Let's Build the Protein

Look Out Bio 30...What's different?

TAB

LEWatch Out Biology 30 Students!!! We don't talk about mRNA in this class --- the table is DNA to Amino Acid!

STOPThe Versatility of Proteins

Proteins are molecules comprised of sequences of one or more amino acids in a variety of sizes and shapes and the protein molecule that performs important bodily functions.

An example is a hemoglobin protein molecule.

The Human Genome Project is complete -- However the shapes are now to be worked out!

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Let's Try One!

ACTTGGGCCTATAGCTAG

What are the amino acids coded for by this DNA Sequence?

Let's Try Another!

Start Codon-Leucine-Phenylanine-Lysine-Glycine-Tryptophan-Stop Codon

What is the DNA sequence that coded for this chain of amino acids? What would happen if......

DNA = ACCTTTCGG

became... ACCTTACGG??????

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Section 2.4 - Mutations and Genetic Diseases

Mutation - heritable change in the sequence of nitrogen bases along a DNA molecule and this affects the proteins produced.

Causes = spontaneous/natural or energy radiation or chemicals.

Can be passed on if they occur in the gametes!

Not passed on if they occur in the somatic cells.

Factors that Increase Mutations.· A mutagen is any environmental influence that causes the

likelihood of mutations.· A carcinogen is any environmental influence or agent that

causes cancer.

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Types of Mutations:1. Point Mutations - one nucleotide accidentally gets substituted

for another nucleotide.

Ex.

2. Frameshift Mutation - where there is a deletion of addition of a nucleotide.

Ex.

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What could be the results? A mutation in a gamete could result in a GENETIC DISEASE.

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Patterns of Genetic Disease Inheritance

If the disease is caused by a mutated recessive allele then two copies of the recessive allele (homozygous recessive) must be inherited to develop the disease.

In this case a heterozygous person would be a carrier - could be advantageous -- ex. carrier for sickle cell anemia.

If the disease is caused by a mutated dominant allele then one copy of the dominant allele (heterozygous dominant or homozygous dominant) need be inherited.

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Beneficial Mutations:· Can lead to evolution because sometimes a mutation creates an

advantage for an individual s survival.

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Resistance in Bacteria

Beneficial to the bacteria!

Not so great for the humans!

Transformation - free DNA is incorporated into a bacterial cell.

Plasmid - a self-replicating piece of DNA that can be transferred

Super Bug

Pedigree Charts

· A pedigree chart is a set of standard symbols used as a tool for geneticists to trace a particular trait.

· See DATABOOK for all of the symbols!

· This is how we can trace genetic traits back through families!

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· What  is  the  sex  (gender)  of  the  oldest  child?· What  is  the  gender  of  the  youngest  child?· In  what  order  are  the  children  arranged,  from  left  to  right?· What  must  be  the  genotype  of  person  I  –  2?

The following questions pertain to the inheritance of the earlobe trait in humans that is thought to be controlled by a single gene. There are two general earlobe shapes, free lobes and attached

lobes.

Section 2.5 - Genetic Technologies· Used to identify, treat, and prevent hereditary

diseases, to develop new medicines, to solve crimes, to identify individuals, and even to re-design new organisms.

February 16, 2015

DNA Fingerprinting

Video

Jellyfish produce a protein that enables them to glow in certain light. Scientists are able to locate this gene and using a virus they have inserted this gene into the DNA of a mouse. This process is called transgenics. When the mouse embryo develops, each cell carries the gene to glow and as a result the mouse has become a genetically modified organism through transgenics and will glow.

Gene Modification

This process has been used for:

· Creating new food, medicines, etc.

· Creating new crops that are more resistant to pesticides.

· Producing a human gene that is capable of producing insulin required by diabetics.

· Producing organs in animals with the necessary antigens to make the organs more compatible for human transplant.

February 16, 2015

Recombinant DNA

Genes from a healthy human that produces insulin can be cut from the DNA using enzymes. This segment of DNA is spliced into a plasmid removed from bacteria. The DNA from the combination of the two organisms is now called recombinant DNA. This new strain of bacteria produces insulin that can be given to people who need insulin.

Recombinant DNA - Combination of 2 types of DNA

BIO 30 -- SCISSORS & GLUE = Restriction Enzymes & Ligase!

Gene Therapy

Genetic diseases are difficult to cure because they are caused by defective copies of an allele present in every cell of the person’s body.

Perhaps a cure could come from injecting functioning genes to replace the defective genes.