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Biochemistry > Genetic Code , Mutations And Translation > Flashcards

Genetic Code , Mutations And Translation Flashcards

1
Q

name the stop codons

A

UAA- u are away

UGA- u go away

UAG- u are gone

also called nonsense codons

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2
Q

start codon

A

AUG

codes for methionine

(formyl methionine in prokaryotes)

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3
Q

code is degenerate

A

more than one codon can code for same a.a.

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4
Q

all a.a. except _________ have more than one codon

A

methionine

tryptophan

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5
Q

code is universal means

A

the code is same in all organism

except mitochondria

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6
Q

types of point mutations

A

involve only one base pair

TRANSITION-one purine-pyrimidine with another purine - pyrimidine

TRANSVERSION-one purine-pyrimidine with another pyrimidine- purine

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7
Q

silent mutation

A

new codon specifies same a.a. so no effect on protein

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8
Q

missense mutation

A

new codon specifies new a.a.

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9
Q

unequal crossover during meiosis 1 can result in which type of mutation

A

large segment deletion

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10
Q

eg of large segment deletion

A

alpha thalessemia-ch 16

cru-di-chat -ch 5

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11
Q

features of cru di chat

A

mental retardation

microcephaly

wide set eyes

kitten like cry

large segment deletion in ch 5

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12
Q

types of mutation in beta thalessemia

A

mutation in splice sites

gene deletions

mutations that slow transcriptional process

translational defect-nonsense / missense

(so there can be any)

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13
Q

trinucleotide repeat disorder in translated region

A

huntington

spinobulbar muscular atropy

(both are polyglutamine disorder)

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14
Q

trinucleotide repeat disorder in UTRs

A

myotonic dystrophy

fragile x

friedrich ataxia

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15
Q

energy requirement for a.a-t Rna synthesis

A

2 high enegy bonds from an ATP

this energy is then used for peptide synthisis also.

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16
Q

initiator tRNA in pro/eukaryotes carry which a.a.

A

pro-formly methionine

eukar-methionine

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17
Q

which are the 2 important binding sites on ribosome

A

P- binding site for growing peptide chaib

A- bind tRNA carring a.a.

A is ahead of P

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18
Q

each cycle of elongation uses how much energy

A

4 high energy bonds

2 from ATP during a.a. activation to charge tRNA , 2 from GTP

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19
Q

steps of translation

A

initiation
elongation
termination

20
Q

eEF-2 inhibited by

A

ADP ribosylation of eEF-2(eukaryotic) by diphtheria and pseudomonas toxin.

21
Q

grey baby syndrome

A

occur when chloramphenicol given to newborn especially premature

insufficient glucuronyl transferase activity which is needed for excrtion of the drug

22
Q

proteins translated on free ribosomes include

A

cytoplasmic proteins

mitochondrial proteins

23
Q

proteins translated on ribosomes ass with RER include

A

secreted proteins

proteins inserted into cell memb

lysosomal enzymes

24
Q

fxn of chaperones

A

specialized class of proteins whose fxn is to assist in protein folding

25
Q

ubiquitin and proteasome

A

ubiquitins form covalent bond with misfolded proteins which can be easily recognised by proteasome for degradation.

also play role in displaying Ag via MHCI

26
Q

role of N terminal hydrophobic single

A

translation of this sequence makes the translation occuring on free ribosome to occur in RER by poistioning the ribosome on RER.

used for protein:
secreted out
part of cell memb
lysosomes

27
Q

N-glycosylation

A

addition of sugar to N of asparagine residues

occurs in RER and golgi both

eg transferrin

28
Q

O- glycosylation

A

addition of sugar to OH’ group of serine and threonine.

occurs only in golgi(posttranslational modification)

eg:heparin

N glycosylation-both in RER and golgi

29
Q

both O and N glycosylation occurs in?

A

LDL receptor

30
Q

how are the lysozymes synthesised directed to the lysosomes.

A

phosphotransferse in the golgi adds phosphate to the mannose located in N -linked oligosaccharide chain.

this PHOSPHORYLATION is a critical event which removes tgem from secretion pathway and directs thrm to lysosomes.

31
Q

defect in I cell ds

A

defective phosphorylation of mannose.

lysosomal enz are released into the ECS(default pathway of golgi)

inclusion bodies accumulate in the cell(undigested substances in lysosomes because of lack of enz)

32
Q

hydroxyproline is an a.a. unique to

A

collagen

33
Q

primary structure of collagen is made up of which repeating tripeptide

A

Gly-X-Y-Gly-X-Y…

X-lysine
Y-proline

34
Q

role of vitC in collagen synthesis

A

needed by prolyl and lysyl hydoxylases which are responsible for hydoxylation of selected prolines and lysines.

35
Q

collagen synthsisi

A

prepro-alpha chains

pro-alpha chains

procollagen/triple helical structure via 3 pro-alpha chains.

procollagen secreted.

collagen / tropocollagen:propeptides cleaved from ends.

form fibrils by crosslinking

further cross link to collagen fibres.

36
Q

role of lysyl oxidase in collagen syn

A

this enz is used to assemble collagen molecules into fibrils by helping in cross linking

37
Q

type 4 collagen found in

A

Basement memb

38
Q

defect in type 4/BM leads to

A

goodpasture syndrome

alport ds

epidermolysis bullosa

39
Q

collagen in cartilage

A

2

40
Q

location of diff types of collagen

A

I–:
bone, skin , tendon

II–:
cartilage , vitreous

III–:
blood vs, granulation tissue

IV–:
BM

41
Q

collagen changes in wound repair

A

initially typeIII (thin, pliable)in granulation tissue

then typeI (high tensile strength)in scar

42
Q

Cu is required in which enz of collagen formation

A

lysyl oxidase

43
Q

what is the cause of weak collagen i menkes disease

A

Ehler Danlos syndrome type IX

deficiet cross linking secondry to functional Copper deficiency.

44
Q

kinky hair syndrome refers to

A

menkes disease

45
Q

cause of menkes ds

A

mutation in ATP7A which encodes an ATP- dependent Cu efflux protein in intestine

Cu can be absorbed into the mucosal cell but cannot be transported into blood.

all Cu requiring enz ll be affected.

Biochemistry (12 decks)

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