cellular control

Question 1

what is a mutation?

Answer 1

A change in the DNA which could result in the creation of a non functioning protein as it causes a change in the base sequence of DNA.

Question 3

What is a point mutation?

Answer 3

one base pair replaces another

Question 4

What is an indel mutation?

Answer 4

One or more nucleotides are inserted or deleted from a length of DNA

Question 5

what are the three types of point mutations?

Answer 5

silent, missense, nonsense

Question 6

what is a silent mutation?

Answer 6

A change to the base triplet where the triplet still codes for the same amino acids

Question 7

What is a missense mutation?

Answer 7

a change to the base triplet sequence that leads to a change in amino acid sequence and the tertiary structure which prevents a protein from carrying out its usual function

Question 8

What is a nonsense mutation?

Answer 8

alters base triplet so it becomes a stop triplet which ends in a truncated protein that doesn’t function

Question 9

What is a frame shift?

Answer 9

occurs as a result of insertions and deletions as if nucleotides base pairs are not inserted as triplets then all the triplets positioning is altered creating a frame shift which affect the primary structure of the protein

Question 10

what is an operon?

Answer 10

the term for a group of simultaneously controlled genes that are either all expressed or not

Question 11

where is the lac operon and what is its function?

Answer 11

usually found in coli and is a sequence of 3 genes that collectively aid with lactose digestion

Question 12

What is the favoured substrate fro bacteria?

Answer 12

Glucose is favoured as it requires less energy to digest glucose than lactose.

Question 13

What are the 3 genes within the lac operon and what do they do?

Answer 13

lacZ, lacY, lacA. They are involved in producing enzymes involved in lactose metabolism

Question 14

What happens when glucose is absent?

Answer 14

lactose binds to the repressor which changes its shape and prevents it from binding yo the operator therefore lactose metabolising enzymes can be produced.

Question 15

What is the process when glucose is present?

Answer 15

when glucose is present the repressor binds to the operator to prevent transcription and preventing the lactose metabolism enzymes being produced .

Question 16

What are transcription factors?

Answer 16

proteins or short non coding pieces of RNA which can bind to different base sequences on DNA to begin transcription in eukaryotic cells

Question 17

What are introns?

Answer 17

non coding regions

Question 18

What are exons?

Answer 18

coding regions

Question 19

How does cAMP activate enzymes to stimulate transcription?

Answer 19

1. a signalling molecule binds to a receptor on plasma membrane
2. activates a transmembrane protein which activates a g protein
3. activates cyclase enzymes
4. catalyses formation of molecules of cAMP from ATP
5. cAMP activates PKA
6. this causes phosphorylation of proteins which activates enzymes in the cytoplasm
7. proteins enter the nucleus and act as a transcription factor

Question 20

what are homeobox genes?

Answer 20

these are sequences of genes which create proteins that regulate the expression of genes involved in the formation of body plan

Question 21

what do how genes regulate?

Answer 21

mitosis and apoptosis

Question 22

What is the process of apoptosis?

Answer 22

1. enzyme breaks down cell cytoskeleton
2. cytoplasm becomes dense with tightly packed organelles
3. cell surface membrane changes and small protrusions called blebs form
4. chromatin condenses, nuclear envelope breaks and DNA breaks
5. cell breaks into vesicles that are ingested in phagocytic cells.