Gene Regulation and Mutations

Can the letters of any word be rearranged to form another word in English? Give examples. If you rearranged the letters at random, is it likely that you would form another English word? Explain your answer. If the protein “building blocks” that create cells were rearranged at random, do you think that a useful change in the cell would result? Explain your answer.

A. Gene Regulation 1. DNA contains a lot of instructions to make many different proteins. a. Not every protein is needed at all times.

2. GENE REGULATION is an organism’s ability to control which genes are transcribed when, in response to need/ environment.

Thinking question: Does GENE REGULATION occur in both PROKARYOTES and EUKARYOTES? Thinking question: Do you think the process is different?

a. GENE REGULATION occurs differently in PROKARYOTES and EUKARYOTES a. GENE REGULATION occurs differently in PROKARYOTES and EUKARYOTES. An example includes physical changes observed during a growth spurt in humans.

1. Occasionally, an error occurs during DNA REPLICATION. B. Mutations 1. Occasionally, an error occurs during DNA REPLICATION. a. Most errors are repaired by the cell. THINKING QUESTION: Which enzyme repairs errors during DNA REPLICATION?

2. A permanent change in a cell’s DNA sequence is called a MUTATION. a 2. A permanent change in a cell’s DNA sequence is called a MUTATION. a. MUTATIONS can range from changing a single base pair to the addition or removal of entire sections of DNA.

b. MUTATIONS can cause different effects in an organism, from no impact to illness to death.

C. Mutation Types 1. POINT MUTATIONS are changes in a single base pair. a. A SUBSTITUTION is a POINT MUTATION where one base replaces another.

2. SUBSTITUTIONS can impact AMINO ACIDS (A. A. ) in three ways: a 2. SUBSTITUTIONS can impact AMINO ACIDS (A.A.) in three ways: a. MISSENSE – the original A.A. is changed to another (ACU Thr  AAU Asn).

b. SILENT – the A. A. is not changed (ACU Thr  ACC Thr). c b. SILENT – the A.A. is not changed (ACU Thr  ACC Thr). c. NONSENSE – the A.A. is changed to a STOP CODON (UGC Cys  UGA Stop).

3. FRAME SHIFT MUTATIONS disrupt the groups of three bases by adding or removing a NUCLEOTIDE. a. INSERTIONS add one. b. DELETIONS remove one.

4. Other MUTATIONS involve changes of larger portions of DNA. a 4. Other MUTATIONS involve changes of larger portions of DNA. a. Ex: An entire extra copy of CHROMOSOME 21 results in Down Syndrome.

b. INVERSIONS flip a sequence of bases in place.

Let’s Practice Mutations This is the original DNA sequence: ATG CGA CGT GAA TTC GAT CAG ATG CGA CGT GAT ATT CGA TCA G What type of mutation is this? INSERTION!

Let’s Practice Mutations This is the original DNA sequence: ATG CGA CGT GAA TTC GAT CAG ATG CGA CGT GAA TTC GCT CAG What type of mutation is this? SUBSTITUTION!

Let’s Practice Mutations This is the original DNA sequence: ATG CGA CGT GAA TTC GAT CAG ATG TGC AGC GAA TTC GAT CAG What type of mutation is this? INVERSION!

DELETION! This is the original DNA sequence: ATG CGA CGT GAA TTC GAT CAG ATG CGA CGT GAA TCG ATC AG What type of mutation is this? DELETION!

D. Mutation Causes 1. Random MUTATIONS during DNA REPLICATION are rare, and usually repaired by DNA POLYMERASE. a. Most are caused by MUTAGENS – substances in the organism’s environment that change DNA sequences.

2. MUTAGENS include things like chemicals, radiation, and cigarette smoke.

3. MUTATIONS in body cells may affect the organism, but may not pass on to offspring. Sperm/egg cell MUTATIONS are passed on. a. NOT all MUTATIONS are harmful. They create diversity and can help organisms survive.

MISSENSE mutation changes the amino acid. POINT MUTATIONS Substitution- one base replaces another Describes the change in DNA Describes change in AA MISSENSE mutation changes the amino acid. SILENT mutation does not change amino acid. NONSENSE mutation changes A.A. to stop codon.

INSERTIONS add an extra base. DELETIONS remove a base. FRAME SHIFT MUTATIONS These typically affect EVERY amino acid after the place where the mutation occurred. INSERTIONS add an extra base. DELETIONS remove a base.

https://www.youtube.com/watch?v=GieZ3pk9YVo