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GENE EXPRESSION Individuality & Mutations

DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

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Page 1: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

GENE

EXPRESSION Individuality & Mutations

Page 2: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

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

Can you list more examples of

proteins made? Enzymes, insulin, cell membrane, hair, muscles

Page 3: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

**THEREFORE, NOT ALL DNA IS

EXPRESSED (MADE INTO PROTEIN) IN EVERY CELL!**

Page 4: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

This video segment investigates why one

species of fruit fly has wing spots while

another genetically similar one does not.

As the video explains, although two

organisms may both possess the same

gene linked to a particular trait, this trait

may not be expressed unless the gene is

turned on

4

Turning genes on video (5 min):

http://www.teachersdomain.org/reso

urce/novat10.sci.life.evo.fruitfly/

Page 5: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

II. Review: Determining Sex Human Chromosomes

46 in a normal human cell!

Two types: a) Normal chromosomes: 44 in each BODY CELL; 22 in each

GAMETE (sex cell) b) Sex chromosomes: 2 in each BODY CELL; 1 in each

GAMETE (sex cell) MALE: X and Y FEMALE: X and X

Page 6: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Is this a

male or a

female??

Karyotype

Page 7: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Chances for having a boy or girl? 50% OF

COURSE…LET’S SEE!

X Y

X X

XX

XX XY

XY

Page 8: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

http://www.brainpop.com/science/cellularlifeandgenetics/geneticmutatio (2:33)ns

DNA fails to copy accurately

Page 9: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

III. Mutations: What happens when DNA goes wrong

A change in the genetic material which effect 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!!!!!!!!!!

When do mutations occur?

During replication (meiosis / mitosis) and protein synthesis

Page 10: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Mutations caused by Mutagenic Agents:

1. Radiation

x- rays, UV, radioactive substances

2. Chemicals

formaldehyde, benzene, asbestos fibers, nicotine

Page 11: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

A. Chromosomal Mutations Change in number of chromosomes or structure

Ex: normal human body cell = 46 Human Karyotype Arrangement of a male

Page 12: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Types of Chromosomal Mutations 1. Deletion

A portion of a chromosome is taken

away form a chromosome

2. Duplication

A portion of one chromosome

breaks off and is attached to its

homologous chromosome giving it

an extra copy

3. Inversion

A portion of a chromosome breaks

off and then becomes reattached to

the same chromosome in an

inverted (upside down) fashion

4. Translocation

transfer of one section of a

chromosome

Page 13: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Genetic Disorders Relating to

chromosomal mutations

Down Syndrome

Due to nondisjunction

failure of homologous

chromosomes to

separate during

meiosis

An extra

chromosome 21

Page 14: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Klinefelter Syndrome

• XXY abnormal sexual development and infertility

Page 15: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

B. 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

DNA MUTATION VIDEO

http://www.bing.com/videos/search?q=mutation+videos&FORM=VIRE6#v

iew=detail&mid=0F73B8E85CE1098084470F73B8E85CE109808447

Page 16: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

A. POINT MUTATION: affects 1 nucelotide (base)

Example: CTC on DNA makes mRNA = GAG codes for

GLUTAMINE If T changed to A, would have GUG which codes for VALINE

Wrong AMINO ACID is coded for which means, wrong

PROTEIN is made

Types of Gene Mutations

Page 17: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

B. FRAME-SHIFT: A base is deleted or added

Example: TCA-TTT on DNA;

mRNA = AGU-AAA on codes for Serine + Lysine

If the T is deleted in the DNA, the mRNA would now

read GUA-AA

rRNA will CODE “GUA” first which is for Valine

1. Similar if a base is added

2. Wrong AMINO ACID is coded for = wrong PROTEIN is

made OR Translation will abruptly STOP

Page 18: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Disorders from Gene Mutations

Sickle cell anemia – Sickle shaped

cells get caught in capillaries (can’t

transport oxygen sufficiently)

Cystic Fibrosis- affects recessive allele

mutating the CFTR gene

Normal red

blood cells (top)

and sickle cells

(bottom)

Page 19: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

IV. Environmental Expression

Some genes are “turned on” under certain environmental conditions.

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 black absorbs the heat,

helping little bunny rabbit to stay warm

Page 20: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

• 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

V. The Human Genome

Page 21: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Class and/or Homework:

Topic 3 RB pages 50-52

Read these pages and answer questions 23-31 on loose leaf paper

Page 22: DNA and Individuality · an extra copy 3. Inversion A portion of a chromosome breaks off and then becomes reattached to the same chromosome in an inverted (upside down) fashion 4

Topic 3 RB pgs 50-52

23) 4

24)a gene mutation is a change in the instructions of the gene. The nitrogenous bases forms the code instructions, so changing this sequence would alter the amino acid/protein

25) 3

26) 2

27) 4

28) 1

29) 1

30) 4

31) 1