Put your HW in the HW folder. What do all of the following have in

common?

Genetic ChangesChapter 11.3

MUTATIONMUTATION defined as a change in the DNA sequence can be caused by errors in replication,

transcription, cell division, or by external agents

Mutations Reproductive cells

Will be passed down to offspring Embryo may not survive Offspring might be sterile

Body cells Impair cell function Cancer Premature aging

Point Mutation: Single base alteration

What do you see happening?

Sickle cell anemia

Frameshift Mutation A type of point mutation: single base is added or deleted from DNA

How is this different than a point mutation? How is it similar?

Frameshift cont’d If groups of 3 (or multiples of 3) bases is

added or deleted, it will only affect a few amino acids (1 per codon)

If 1, 2, 4 (any non-multiple of 3) is deleted, ALL amino acids will be different from the mutation onward. Causes a change in the reading frame

Cystic fibrosis – affects the lungs, liver, pancreas, small intestine, reproductive organs, and the skin

Chromosomal mutations When there are changes in the chromosome, it

is considered a chromosomal mutation. Part of a chromosome is broken off and lost There are 4 kinds of chromosomal mutations:

Deletions, Insertions, Inversions, Translocations

Break and rejoin incorrectly Nondisjunction

Deletion: Section is lost from a chromosome

Insertion: Section of 1 chromosome is added to another

Inversion: segment of chromosome reverses itself

For each #, what is different between the chromosome on the left to the one on the right?

Translocation: Sections of 2 different chromosomes are swapped

Nondisjunction

Results in a change in the chromosome # in the daughter cells

Polyploidy

Polyploidy in strawberries

Wild type Commercially propagated varieties

Each cell is 1n Each cell is 8n 8 copies of each chromosome!

Polyploidy in Dianthus

More examples: Consider a normal chromosome with genes in alphabetical

order: a b c d e f g h i 1. Deletion: part of the chromosome has been removed: a b c g h

i 2. Dupliction(Insertion): part of the chromosome is duplicated:

a b c d e f d e f g h i3. Inversion: part of the chromosome has been re-inserted in

reverse order: a b c f e d g h i

More examples cont.4. translocation: parts of two non-homologous

chromosomes are joined:

If one normal chromosome is a b c d e f g h i and the other chromosome is u v w x y z,

then a translocation between them would be

a b c d e f x y z and u v w g h i.

Causes of Mutations random, mistake in base pairing mutagens (ex. radiation, chemicals, high

temperature)

Radiation contains energy that can damage or break

apart DNA breaking and reforming of DNA can result in

deletions may convert one base into another or fuse two

bases together

Chemical mutagens include asbestos, benzene, and formaldehyde usually cause substitution mutations

Sources of formaldehyde

DNA repair “Proofreading” is performed by enzymes like

DNA ligase. Such repair mechanisms work very

efficiently, although they are not perfect. Thus, it is still best to avoid situations that

would expose us to mutagens.

HW for 3/13 Due tomorrow:

Worksheet on DNA/RNA and mutations Field trip permission slip and $5

Due Friday: Ch.12 Index Cards

Problem-Solving Lab 11-3 (p. 299) In your groups, answer questions 1-4 on a

blank sheet of paper with everyone’s name on it.

Group with the most correct answers gets 2 bonus points for the day.

You have 7 min – starting now!