GENE

EXPRESSIONIndividuality & Mutations

Amoeba Sisters video

https://www.youtube.com/watch?v=GieZ

3pk9YVo

Complete video handout

http://www.amoebasisters.com/uploads/

2/1/9/0/21902384/video_recap_of_muta

tions_by_amoeba_sisters.pdf

https://www.youtube.com/watch?v=GieZ3pk9YVohttp://www.amoebasisters.com/uploads/2/1/9/0/21902384/video_recap_of_mutations_by_amoeba_sisters.pdf

I. Are all genes turned on in all cells?

The answer is NO!

Every body cell contains your DNA (genetic

make-up)

Cells “use” only genes specific for function

EX. Red blood cells use only genes that

make it carry oxygen

Other examples of proteins made

include Enzymes, insulin, cell membrane, hair, muscles

**THEREFORE, NOT ALL DNA IS EXPRESSED

(MADE INTO PROTEIN) IN EVERY CELL!**

III. Mutations: A change in the genetic material which effects the genetic

information and traits

Not all mutations are bad, some are beneficial Ultimate source of genetic variation (depends on

environment)

MUTATIONS MUST OCCUR IN SEX CELLS IN ORDER FOR THEM TO BE PASSED ON TO NEXT GENERATION!

Mutations occur during replication (meiosis / mitosis) andprotein synthesis

Mutagenic Agents that cause mutations:

1. Radiation

x- rays, UV, radioactive substances

2. Chemicals

formaldehyde, benzene, asbestos fibers, nicotine

A. Gene Mutations A random change in DNA sequence

**Review** What does DNA ultimately code for? Proteins!!!

Is construction of protein based on original DNA strand?

Yes! (b/c it is what codes for mRNA)

What would happen to the protein if

DNA sequence was changed?

Wrong protein made

Wrong shape of protein

This would make protein

unusable

A. POINT MUTATION:

o affects 1 single nucelotide (base)

o Types: Substitution, Insertion, and Deletion

Types of Gene Mutations

Substitution Insertion

Deletion

Frameshift Mutations

One or more bases are either

inserted or deleted

When this occurs it moves the

whole reading frame for the

ribosome over changing each

codon after the mutation

Wrong AMINO ACID is coded for = wrong PROTEIN

is made OR Translation will abruptly STOP

Disorders from Gene Mutations1) Sickle cell anemia – Sickle shaped cells get caught in capillaries

(can’t transport oxygen sufficiently)

2) Cystic Fibrosis- affects recessive allele on chromosome #7

mutating the CFTR gene effecting the lungs causing mucus build-up

Normal red blood cells

(left) Sickle cells (right)

Chromosomal Mutations

There are four types:

A. Deletion – a piece of a chromosome is completely lost

B. Duplication – a piece of a chromosome is repeated

C. Inversion – a piece of a chromosome swaps with another piece on the same chromosome, changing order

D. Translocation – a piece of one chromosome breaks off and attaches to a different non-homologous

chromosome

• Chromosomal mutations involves changing the number or structure of a chromosome which would affect many genes.

Chromosomal Mutation Related Disorders

1. Down Syndrome• Due to failure of

homologous chromosomes

to separate during meiosis

called NONDISJUNCTION

• An extra chromosome on #

21

2. Klinefelter Syndrome• XXY abnormal sexual

development and infertility

The adaptive value of a gene mutation is

dependent upon the nature of the mutation and

the type of environment with which the organism

interacts

The environment interacts with genes in the

development and expression of inherited traits

Some genes are “turned on” under certain

environmental conditions – this is referred to as

gene expression

III. Environmental Expression

EX. Himalayan Rabbit: Fur changes color due to TEMPERATURE change WARM = White fur (no pigment produced)

COLD = Black fur

Why does this make sense? Because a black color absorbs the heat, helping little

bunny rabbit to stay warm

Effect of Cold on Himalayan Hare Fur Color

The application of an ice pack

to a region of shaved hair

results in black hair

growing back instead of

the original white color.

• How do we know that traits and diseases are

genetically related?

• THE HUMAN GENOME PROJECT

• What is it? Project to identify the location of

30,000 genes

• Why do it? To identify the locations of genetic

diseases and possibly control and/or eliminate

them

• How far along are we? The map was completed

in 2004

The Human Genome Project Article Review

IV. The Human Genome

http://www.genome.gov/Pages/EducationKit/video/qt/3D.mov