20.4 - MUTATIONS AND GENETIC VARIATION

Introduction

Let’s Read – page 687 paragraph one

What of this to do we agree with?

What don’t we agree with and why?

Mutations are changes in a sequence of DNA

They may be harmful, neutral or beneficial (there are incredibly few beneficial mutations)

Broad Types of Mutations

Point mutations – change a single base pair

Gene mutations – change the amino acid that was coded for – usually involve more than one base pair

Brief to Do:

Fill in the worksheet called “Types of Mutations”

The types and pictures can be found on page 687

The descriptions can be found on page 688

You have 20 minutes

Other Mutation Vocabulary

A frameshift mutation causes the reading frame of codons to change Result: completely different

amino acids are coded for How many base pairs need to

be inserted or deleted to cause a frameshift mutation?

Translocation is the movement of a group of base pairs from one part of the genome to another 2 pieces of DNA from different

chromosomes break and switch places

RESULT – ”fusion” proteins produced have altered function if any function at all

Some leukemia is associated with translocation

An inversion – a piece of chromosome has turned itself around RESULT : a gene may be

disrupted

Causes of Genetic Mutations A spontaneous mutation is caused

when the DNA is being replicated (ex. By DNA polymerase I)

Mutagenic agents can cause induced mutations

Examples of mutagenic agents are UV radiation,

cosmic rays, X-rays and some chemicals

To Do:

With a partner or on your own do the case study on page 689 called “Gene Mutations and Cancer”

Hand in your answers together #1-6

Part 2

Inferring Relationships from DNA Sequences As a class read page 690 and

691

Vocab Phylogeny – proposed evolutionary

history of a species or group of organisms SINEs – (short interspersed elements) –

repeated DNA sequences 300 bp long that alternate with lengths of DNA sequences found in the genome of higher organisms

LINEs – (long interspersed elements) - repeated DNA sequences 5000 - 70000 bp long that alternate with lengths of DNA sequences found in the genome of higher organisms

Any other notes?

Mitochonridial DNA (mtDNA) -

To Do:

Watch “Animals the Defy Evolution” Make any necessary flashcards

Next Day to do:

1) Protein Synthesis Review Wksht

2) p. 694 #1-73) p. 702 #1-7, 214) P. 705 #1-15 5) Go to the computer lab and do

“Science Gizmo” – RNA to Protein worksheet