Mr Dewhurst- Cellular control

Question 1

what is a codon

Answer 1

3 nucleotide bases on mRNA that codes for an amino acid

Question 2

what is meant by degenerate

Answer 2

more codons than amino acids so multiple combinations code for same amino acid

Question 3

what is meant by non-overlapping

Answer 3

code 3 bases at a time

Question 4

what’s meant by universal code

Answer 4

everyone has same amino acids so evidence we have common ancestor from start of life

Question 5

what happens when a stop codon is reached

Answer 5

produces shorter proteins as transcriptions stops

Question 6

what is a mutation

Answer 6

change in base sequence

Question 7

what is meant by substitution

Answer 7

one base is changed which might them change the amino acid meaning the 3D shape may change

Question 8

what is an example of a health condition caused by substitution

Answer 8

sickle cell anaemia- A swapped for T in gene of haemoglobin - red blood cell changes shape

Question 9

what is meant by nonsense substitution

Answer 9

base swapping causes stop codon which means protein is shorter and won’t function properly

Question 10

what is meant by missense substitution

Answer 10

amino acid changes which changes function and shape

Question 11

what is meant by silent substitution

Answer 11

change in base makes no difference to amino acid it has coded for

Question 12

what is the mutation of insertion

Answer 12

extra base added messing up whole sequence - pushes along one

Question 13

what is deletion

Answer 13

base removed which effects every codon after deletion

Question 14

what is the frame shift

Answer 14

caused by insertion and deletion- shifts back/forth causing every codon to change and the protein changes

Question 15

what is meant by the neutral effect of mutation

Answer 15

proteins function normally because protein is till synthesised and the phenotype is unchanged

Question 16

what is the harmful effect of mutation

Answer 16

protein is not synthesised or not functional- phenotype negatively effected

Question 17

what is the beneficial effect of mutation

Answer 17

slight change to amino acid - but change may be beneficial or protein may carry out desirable functions- rare

Question 18

what are 4 causes of mutation

Answer 18

radiation/ X-rays
chemical in cigarette smoke
chemicals in caffeine
UV light

Question 19

what are some health disorders caused by mutations

Answer 19

cystic fibrosis- deletion
cancer- protooncogenes changed- uncontrolled cell division
huntingtins

Question 20

what are transcription factors

Answer 20

proteins that move in from cytoplasm and bind with DNA to attatch RNA polymerases to DNA
mostly inactive and activated by hormones
some are only present at a certain stage of development

Question 21

what do transcription factors do

Answer 21

attatch to the promoter so RNA polymerase can bind and transcribe gene

Question 22

what happens when a transcription factor is bound to an inhibitor

Answer 22

stops transcription as prevents it binding to the promoter as it changes its shape

Question 23

what happens when oestrogen is bound to transcription factor

Answer 23

releases inhibitor so it can bind to promoter

Question 24

what is an operon

Answer 24

section of DNA that contains a cluster of genes transcribed together as well as control elements and regulatory gene

Question 25

what is the lac operon

Answer 25

in bacteria - E.coli only produces enzymes to respire ;lactose when it is present

Question 26

outline how the lac operon turns genes off

Answer 26

the regulatory gene codes for a repressor protein which attaches to the operator, blocking the promoter where RNA polymerase attaches so transcription cannot occur

Question 27

outline how lac operon turns genes on

Answer 27

when lactose is present it binds to the repressor changing its shape preventing it from binding to operator, this means that the RNA polymerase can bind to promoter and transcription can take place of structural genes that produce enzymes for lactose utilization