Cellular Control

Question 1

gene mutation

Answer 1

random change to genetic material

during DNA replication before division

Question 2

somatic mutation

Answer 2

during mitotic division so not passed to offspring

Question 3

point mutation

3 types?

Answer 3

1 base pair replaces another

silent, missense, nonsense

Question 4

silent mutation

Answer 4

triplet still codes for same amino acid

Question 5

missense

Answer 5

change to base triplet changes amino acid sequence (primary), so change tertiary so can’t function

Question 6

nonsense

Answer 6

becomes termination triplet

truncated protein not function

Question 7

indel mutation

Answer 7

nucleotides inserted/deleted from DNA

may cause frameshift which is when different groups of 3 form and all subsequent triplets are altered

Question 8

number of __________ increases _________ across generations

if________ then = disease

Answer 8

CAG triplets
at meiosis
above critical number

Question 9

transcription factors

how does it work?

Answer 9

protein/short non-coding RNA that combines with specific site on DNA to inhibit/activate transcription of gene
regulate gene expression

bind to specific promoter regions so aid/stop RNA polymerase

Question 10

post-transcriptional gene regulation

Answer 10

introns (non-coding) and exons (coding) transcribed to primary mRNA
edited to remove RNA introns, exons joined (endonuclease)
some introns encode proteins/become non-coding RNA involved in gene regulation

Question 11

post-translational gene regulation

Answer 11

activation of proteins by phosphorylation

signalling molecule activates transmembrane protein
which activates G protein
which activates adenyl cyclase
which catalyses ATP to cAMP
which activates PKA (protein kinase A)
which catalyses phosphorylation of protein and hydrolysis of ATP
activates enzymes in cytoplasm

PKA may phosphorylate another protein (CREB) which enters nucleus and acts as transcription factor

Question 12

operon

Answer 12

group of genes that function as single transcription unit

in prokaryotes

Question 13

lac O
lac Z
lac Y
P
I
Lac I

Answer 13

operator region
code for B-galactosidase
code for lactose permease
promoter region
codes for repressor protein (Lac I)

Question 14

E.coli normally metabolises ________.

if only ______ is present then what occurs?

Answer 14

glucose
lactose

lactose binds to lac I
can't bind to lac O
RNA polymerase binds to P
lac Z and lac Y transcribed
enzymes for lactose metabolism (B-galactosidase and lactose permease) produced

Question 15

lactose permease

Answer 15

allows lactose to enter cell

Question 16

B-galactosidase

Answer 16

hydrolyse lactose to glucose and galactose

Question 17

homeobox sequence (6)

Answer 17

180 base pairs involved in regulating patterns of anatomical development
in animals, plants, fungi
make up homeobox genes
encodes 60 amino acid homeodomain sequence within a protein
base sequences very similar and regulate development and differentiation
conserved - remain in all descendent species throughout evolutionary history

Question 18

homeodomain sequence

Answer 18

bind to DNA and regulate transcription of adjacent genes
homeo-domain containing proteins are transcription factors and fold to H-T-H (2 alpha helices connect by turn)
part of it recognises TAAT sequence of enhancer region from gene to be transcribed, enhancer region (initiates/enhances transcription)

Question 19

Hox genes

Answer 19

subset of homeobox genes
only in animals
formation of anatomical features in correct locations

Question 20

What do Hox genes do?

and extra info about them (4)

Answer 20

regulate embryo development along anterior-posterior axis

arranged in clusters, 4 if 4-limbed
expressed in order along axis-sequential and temporal order
encode homeodomain proteins that act as transcription factors
regulated by gap genes and pair-rule genes (these genes regulated by maternal mRNA from egg cytoplasm)

Question 21

mitosis regulated by ______________

Answer 21

homeobox and Hox genes

Question 22

_______ constant?

Answer 22

cell divides limited times before dies

Question 23

Apoptosis

and how?

Answer 23

programmed cell death

enzymes break down cytoskeleton
cytoplasm dense with tightly packed organelles
protrusions from membrane(blebs)
chromatin condense, nuclear envelope breaks, DNA breaks
cell breaks to vesicles, ingested by phagocytes

Question 24

What induces apoptosis?

Answer 24

nitric acid makes inner mitochondrial membrane more permeable to H ions to interrupt proton gradient and proteins into cytoplasm bind to apoptosis inhibitor

Question 25

good things about apoptosis

Answer 25

prevents cell proliferation without hydrolytic enzymes
removes bad T-lymphocytes
limb development