Cellular Control

Question 1

Mutation

Answer 1

Random change to the structure or quantity of DNA
-gene or chromosome mutation

Question 2

gene mutation

Answer 2

Change to one or more bases
-change to order of bases
-can happen during DNA replication

Question 3

Chromosome mutation

Answer 3

Polyploidy- change in whole set
Non disjunction- when homologous pairs don’t separate

Question 4

Chemicals as mutagens

Answer 4

Tar in tobacco smoke

Question 5

Point mutations

Answer 5

Substitution of one base pair

Question 6

Indel mutations

Answer 6

One or more nucleotides are inserted of deleted
cause frame shift
code for different amino acids

Question 7

Nonsense

Answer 7

Result in STOP codon
Polypeptide chain becomes truncated

Question 8

Missense

Answer 8

Different amino acid formed
-altering shape
-prevents it carrying out its function
will change all polypeptide sequence

Question 9

Silent

Answer 9

No effect as code may still code for same amino acid
-polypeptide still carries out normal function

Question 10

Lac operon

Answer 10

length of DNA made from structural genes and control sites
Structural gene –> codes for protein
Control sites -> operator and promoter region of DNA

Question 11

how can mRNA be modified post translation

Answer 11

Activation of proteins like adrenaline
when adrenaline is activated it causes the synthesis of cAMP from ATP
causes further enzyme reactions which activates the protein

Question 12

how can mRNA be modified after transcription

Answer 12

introns spliced out
primary mRNA modified to mature mRNA
to prepare for translation

Question 13

promotor region

Answer 13

binding site for RNA polymerase

Question 14

operator region

Answer 14

repressor protein binds to prevent RNA from binding to transcribe genes

Question 15

beta galactosidase (Z)

Answer 15

hydrolyses lactose into galactose and glucose

Question 16

lactose permease (Y)

Answer 16

protein that becomes embedded in e coli membrane
helps transport more lactose into cell

Question 17

regulatory gene (I)

Answer 17

produces the mRNA
can limit mRNA production to stop transcription / translation of genes

Question 18

if lactose present

Answer 18

mRNA produced
Repressor protein made
lactose binds to repressor protein
forms an inducer repressor complex
therefore moves away from operator region
RNA polymerase CAN bind
Z&Y turned on

Question 19

if no lactose

Answer 19

mRNA transcribed at ribosome (makes repressor)
repressor protein binds to operator region (covering P)
RNA polymerase CANNOT bind to promotor
Z&Y turned off

Question 20

Transcription factors

Answer 20

In eukaryotic cells
proteins or short RNA which bind to promotor regions of DNA
AID or INHIBIT the attachment of RNA polymerase

Question 21

exons

Answer 21

coding regions

Question 22

introns

Answer 22

non-coding regions
can be spliced out
mutations in introns do not make a difference

Question 23

Homeobox genes

Answer 23

genes whose activity switches a whole set of other genes on or off
controls an organisms body plan
code for production of transcription factors
(regulatory gene) in animals plants and fungi
CAN BE FATAL

Question 24

homeobox acting as tumor suppressor cells

Answer 24

they prevent cells from dividing too rapidly

Question 25

mutations in hox group

Answer 25

limb malformation

Question 26

mutations in pax

Answer 26

eye deformations

Question 27

what do homeobox genes do

Answer 27

make sure body plan is correct as mutations in this could be lethal if head grows in the wrong place the organism cannot function properly Very important Been very little change in homeobox genes

Question 28

Apoptosis

Answer 28

programmed cell death also helps body plan as cells can be killed off to form body parts eg tadpoles tail is removed through apoptosis to form frog can keep cell division constant and can prevent cancers forming

Question 29

Process of apoptosis

Answer 29

Enzyme breaks cytoskeleton Cytoplasm become dense with tightly packed organelles Cell surface membrane changes (blebs form) Chromatin condenses, nuclear envelope breaks (DNA breaks into fragments Cell breaks into vesicles digested by phagocycotic cells

Question 30

how is development caused by homeobox genes

Answer 30

They code for transcription factors that activate genes when needed for development of body plan in eg zygote Their sequences are similar in plants and animals

Question 31

how is development caused by mitosis

Answer 31

Primary mechanism of growth genes regulating growth respond to stimuli internal or external to control growth

Question 32

how is gene expression regulated at transcription level

Answer 32

Transcription factors these are genes that can either inhibit or initiate transcription of genes so that only certain parts of DNA are expressed

Question 33

how is gene expression regulated at post transcriptional level

Answer 33

introns spliced out produce mature mRNA ready for translation