LEC EXAM #3 CHP. 11

Question 1

Point mutation:

Answer 1

Insertion or deletion of 1 or 2 bases at DNA level-> causes shift/missence in amino acid at protein level

Question 2

Silent mutation:

Answer 2

Mutation that doesn’t effect amino acid but shifts AKA FRAMESHIFT MUTATION

Question 3

BEST and WORST place for mutation on DNA codon:

Answer 3

Best: 3rd pos.
Worst: 1st pos.

Question 4

BEST place for mutation:

Answer 4

In telomere or centromere because no genes

Question 5

Which mutation is worse? nonsense or missense

Answer 5

Nonsense because makes the protein nonfunctional

Question 6

Nonsense mutation example:

Answer 6

CCR5 DELTA 32- coreceptor HIV uses for entry -> HIV can’t enter cell-> HIV resistant

Question 7

NONSENSE mutation:

Answer 7

Causes early stop codon-> protein terminates early-> nonfunctional

Question 8

Ames test:

Answer 8

Test compounds to see if mutagenic/carcinogenic

Question 9

Revertants:

Answer 9

Mutagen compound that mutates strain from his- into his+ that grows on media lacking histidine

Question 10

How does Ames test work? (6)

Answer 10

1. Genetically modified strain of salmonella that no longer has a functional histidine gene
2. Add rat liver extract
3. Grow strain in media containing histidine
4. In another tube, add rat liver extract + mutagen
5. Plate on media that does not contain histidine
6. If able to grow on media lacking histine-> mutated his- to his+

Question 11

What did that compound do to make the revertants?

Answer 11

Caused mutations that causes it to move back to his+

Question 12

Compound is:

Answer 12

Mutagenic which makes it carcinogenic

Question 13

Conjugation:

Answer 13

Form of horizontal gene transfer that uses a pilus to transfer the plasmid

Question 14

Cell with plasmid:

Answer 14

F+ cell

Question 15

Cell without plasmid:

Answer 15

F- cell

Question 16

What allows transfer of plasmid DNA from F+ cell to the F- cell?

Answer 16

Pilus

Question 17

Result of transfer of plasmid DNA from F+ to F- cell?

Answer 17

2 new double stranded plasmids

Question 18

Operons:

Answer 18

Set of genes for a particular pathway that results in an enzyme

Question 19

In the absence of tryptophan:

Answer 19

the TRP repressor dissociates from the operator and RNA synthesis proceeds

Question 20

In the presence of tryptophan:

Answer 20

the TRP repressor binds the operator and RNA synthesis is blocked

Question 21

T or F

Repressor protein is always present inside the cell.

Answer 21

True

Question 22

What happens when TRP binds to the repressor?

Answer 22

Causes a conformational change in the repressor when it that allows it to bind to the operator

Question 23

Repressible operon:

Answer 23

Can be repressed/turned off if it comes in contact with TRP, but normally it’s always on until you turn it off

Question 24

Lac operon:

Answer 24

Inducible operon that stays turned OFF until coming in contact with lactose

Question 25

When lactose binds to repressor:

Answer 25

Conformational change which doesn’t allow it to bind to the operon

Question 26

Cyclic AMP is made from:

Answer 26

Low levels of glucose and high levels of lactose

Question 27

cAMP-clyclic AMP:

Answer 27

Works in the presence of low ATP and binds to CAP protein

Question 28

cAMP + cap complex:

Answer 28

Makes RNA polymerase bind to promoter when we’ve used up glucose in the presence of low ATP

Question 29

cAMP + cap complex is in ________ cells only:

Answer 29

Prokaryotic

Question 30

Missence mutation:

Answer 30

Results in an amino acid substitution (similar to nonsense mutation)

Question 31

UV light causes:

Answer 31

Covalent bonds between nitrogenous bases-> changes Thymine base to one big mass and therefore cannot bind

Question 32

X-rays cause:

Answer 32

Double strands to break

Question 33

In the absence of cAMP:

Answer 33

CAP does not bind the promotor-> transcription occurs at low rate

Question 34

In the presence of cAMP:

Answer 34

CAP binds to promotor and increases RNA polymerase activity

Question 35

In the presence of the cAMP-CAP complex:

Answer 35

Stimulates RNA polymerase activity and increases RNA synthesis unless repressor is bound to the operator-> RNA synthesis blocked

Question 36

INSULIN:

Answer 36

1. insert a gene of interest
2. find a suitable vector (bacteriophage or plasmid) using a restriction enzyme + ligase. Human gene (insulin) + plasmid (vector)= recombinant DNA
3. introduction of vector to host cell-> enters host cell-> genetically modified bacterial cell
4. add resistance gene and grow in media. allowing for GMB to express human insulin