Warm-up

What do you think a mutation is?

What can cause a mutation?

Feb. 26, 2013Topic: mutations

Objective

SWBAT explain what a genetic mutation is, list the types of mutations and explain if they are good or bad and why.

Today

Introduction to mutationsDefine

Explain the types of mutations

Activity: Mutation by Analogy

Up and Coming………….

Unit Test: Tues. March 5

DNA structure and Function

RNA structure and Function

Protein Synthesis

Mutations

Mutations

I. A mutation is a sudden change in the structure or amount of genetic material.

+ =

II. Chromosomal Mutation – Abnormal change in the structure in all or part of a chromosome or in the number of chromosomes

How to visualize/determine a chromosomal mutation

Karyotyping – examining a person’s genetic make-upA. A cell undergoing mitosis is

photographedB. Amniocentesis –

withdrawing amniotic fluid and cells of a fetus to test for disease

C. Arranged by size and location of the centromere.

Replicated chromosomes In metaphase of mitosis

Paired with homolog, arranged by size, shape

Female

A. Changes in chromosome structure (most cells die if this happens)1. Translocation – transfer of

part of a chromosome to a non-homologous

chromosomeNORMAL CHROMOSOME

TRANSLOCATION

A B C D E F G

A B C D E F G X Y Z

a. Burkitt’s lymphoma – cancer of the immune system.

A child with Burkitt’s Lymphoma(tumors of lymphocytes)

2. Inversion – A piece of the chromosome is rotated

NORMAL CHROMOSOME

INVERSION

A B C D E F G

A B E D C F G

Inversion of human andchimp DNA of chromosome #5

3. Addition – A piece of the chromosome breaks off

and attaches to the homologous chromosome

NORMAL CHROMOSOME

ADDITION

A B C A B C D E F G

A B C D E F G

4. Deletion – A piece of the chromosome breaks off

NORMAL CHROMOSOME

DELETION

A B C F G

A B C D E F G

a. Cri-du-chat syndrome – loss of part of chromosome #5.

A child with Cri-du-chat syndrome.Symptoms are stomach, intestinal, and heart problems as

well as mental retardation.

B. Nondisjunction – addition or loss of a whole chromosome1. Occurs during meiosis2. Trisomy 21 – extra

chromosome #21 is Down’s Syndrome.

3. Klinefelter Syndrome - XXY sex chromosomes

A male with a fewFeminine features

4. Turner Syndrome - only one X sex chromosome

A female with prepubescent features, cannot have children

C. Polyploidy – some multiple of the normal chromosome number1. Happens during mitosis or

meiosis2. Results in 3n, 4n, even 5n3. Plants and fruits grow larger

than normal4. This can be beneficial to

farmers and plant breeders

*Strawberries….remember the DNA

*Animals can not have polyploidy and survive!

III. Gene mutations – changes in the sequence of DNA or RNA strandsA. Point mutations – only one nucleotide has been changed

1. Adding or deleting one nucleotide changes

all the codons after the point in the sequence

normal DNA TAC CCG TAT AUG GGC AUA Met Gly Iso

mutation TAC ACC GTA T (addition) AUG UGG CAU A Met Try His -

Mutation TAC CGT AT (deletion) AUG GCA UA Met Ala -

2. One base is substituted for another in DNA

changes the mRNA sequence and the protein that is formed

normal DNA TAC CCG TAT AUG GGC AUA Met Gly Iso

Substitution TAC CGG TAT AUG GCC AUA Met Ala Iso

A. Sickle cell anemia is caused by a change in one base pair and red

blood cells are deformed. (substitution)

The impact of the change, addition, or deletion of one letterin a sentence composed of three-letter words.

THE CAT SAW THE DOG

Change of one letter Gain or loss of one letter

THE BAT SAW THE DOG THE CAT SAW TED OG

Deletion

Missense --> THE CAT SAW THE HOG THE ATS AWT HED OG <-- Nonsense

THE CAB SAW THE DOG

THE CAT SAW SHE DOG THE CAT SAW THE ZDO GDupl ication

Missense --> THE CAT SAD THE DOG THE CMA TSA WTH EDO G <-- Nonsense

THE CAT SAW THE DOC

What would happen to your DNA code if just one letter was repeated or missing?

A mutation

3. Silent mutation- sometimes a mutation still codes for the same amino acid. It does not affect the organism.

normal DNA TAC CCG TAT AUG GGC AUA Met Gly Iso

Substitution TAC CCC TAT AUG GGG AUA Met Gly Iso

4. Nonsense mutation-nucleotide changed results in a stop codon causing translation to stop prematurely

normal DNA TAC CCG TAT AUG GGC AUA Met Gly Iso

addition TAC ATC CCT AT AUG UAG GGA UA Met Stop - -

Mutations in what cells do what?

1. Mutations in a single body cell may cause the

cell to die

2. Mutations in sex cells – pass along the mutation

to the offspring

Advantages to mutations

• Sources of new base sequences• A force for natural selection (survival of the fittest, passing on traits

that help an organism survive)

• Add to genetic diversity

Activity

• Mutation by Analogy…….begin

and complete for HW