Name: _______________________

NOTES Gene Mutations

What is a gene mutation?

These mutations are actually quite ________________ (they happen all the time).

Mutagens

________________

________________

Mutagens are factors that cause _____________________ to happen. The more mutagens you are exposed to, the greater the odds of generating mutations that may be _________________ to you.

How gene mutations work- Gene mutations are changes in the order of the A,G,C and T bases that make up a gene

Original DNA Sequence: AAT TAC CCT TTT AAA ACT TAC CAT

Addition: AAT TAC ACC TTT TAA AAC TTT ACC AT

Deletion: AAT TAC CTT TTA AAA CTA CCA T

Substitution: AAT TAC TCT TTT GAA ACT TAC AAT

The Effects of Gene Mutations

Positive Mutation

A mutation that BENEFITS the individual who has it.

Examples:

Negative Mutation

A mutation that is HARMFUL to the individual who has it.

Examples:

Neutral Mutation

A mutation that does not affect the individual. Most mutations are of this type.

Examples:

Chromosomal Mutations – refer to text pgs 194 -195

Occur during Meiosis when _________________________________ are created.

Often involve sections of single chromosomes

Types:

A.____________________________________

B.____________________________________

C.____________________________________

D.____________________________________

Ex. Fruit flies- moving chromosome sections can result in fruit flies with legs attached where the antennae should be or other deformaties.

Unlike gene mutations, chromosome mutations can result in _____________ changes in the organism. (minor or major)

Because many genes are affected instead of just a few ______________.

Most chromosome mutations are _____________passed on to the offspring. (not or are)

Chromosome mutations usually cause organisms to_____________ before they can reproduce.

Whole Chromosome Mutations- Occur when an _________ chromosome is present in the sperm or egg cell or a chromosome is___________.

- In humans each cell should have _____ pairs of homologous chromosomes. Each chromosome in a pair carries the same ______, located in similar locations. Homologous chromosomes are also similar in _______.

Syndrome: a disease or disorder with a specific group of symptoms that occur together

Example of Whole Chromosome Mutation

· Down Syndrome caused by a whole chromosome mutation where an ____________________________________ chromosome is present in cells. Individuals with this syndrome are shorter, have __________________ facial features, prone to heart defects and diseases such as Alzheimer’s and leukemia.

Karyotypes - Refer to text page 196/197.

We can capture what chromosomes look like to discover chromosome mutations by:

· Extracting DNA from cells in ________________________ of mitosis

· Enlarging a picture of the chromosomes from the cell

· Homologous Chromosomes are identified and paired by comparing ___________, ___________________ _______________ and ___________________ ___________________

Read p. 197, 6-1B Analyzing a Karyotype and write the answers down BELOW

What to Do!

1. Examine the karyotype of Edwards Syndrome in textbook pg. 197!

2. Count total # of Chromosomes:_________& total # of Chromosome pairs:_____________

3. Determine if the individual is a male or a female?___________________

What did you find out?

1. Describe the chromosome error found:_______________________________________

2. a. Would Karyotyping identify a gene mutation? Yes or No

b. Why or why not?_____________________________________________________________

To Do!

· Handout on Identifying Gene Mutations - (insertion, deletion, or substitution)

· Complete questions: Understanding Cells, the Nucleus, the role of DNA, Genes and Proteins and Mutations for marks! Due next class!

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