Genetic Code , Mutations And Translation

Question 1

name the stop codons

Answer 1

UAA- u are away

UGA- u go away

UAG- u are gone

also called nonsense codons

Question 2

start codon

Answer 2

AUG

codes for methionine

(formyl methionine in prokaryotes)

Question 3

code is degenerate

Answer 3

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

Question 4

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

Answer 4

methionine

tryptophan

Question 5

code is universal means

Answer 5

the code is same in all organism

except mitochondria

Question 6

types of point mutations

Answer 6

involve only one base pair

TRANSITION-one purine-pyrimidine with another purine - pyrimidine

TRANSVERSION-one purine-pyrimidine with another pyrimidine- purine

Question 7

silent mutation

Answer 7

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

Question 8

missense mutation

Answer 8

new codon specifies new a.a.

Question 9

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

Answer 9

large segment deletion

Question 10

eg of large segment deletion

Answer 10

alpha thalessemia-ch 16

cru-di-chat -ch 5

Question 11

features of cru di chat

Answer 11

mental retardation

microcephaly

wide set eyes

kitten like cry

large segment deletion in ch 5

Question 12

types of mutation in beta thalessemia

Answer 12

mutation in splice sites

gene deletions

mutations that slow transcriptional process

translational defect-nonsense / missense

(so there can be any)

Question 13

trinucleotide repeat disorder in translated region

Answer 13

huntington

spinobulbar muscular atropy

(both are polyglutamine disorder)

Question 14

trinucleotide repeat disorder in UTRs

Answer 14

myotonic dystrophy

fragile x

friedrich ataxia

Question 15

energy requirement for a.a-t Rna synthesis

Answer 15

2 high enegy bonds from an ATP

this energy is then used for peptide synthisis also.

Question 16

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

Answer 16

pro-formly methionine

eukar-methionine

Question 17

which are the 2 important binding sites on ribosome

Answer 17

P- binding site for growing peptide chaib

A- bind tRNA carring a.a.

A is ahead of P

Question 18

each cycle of elongation uses how much energy

Answer 18

4 high energy bonds

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

Question 19

steps of translation

Answer 19

initiation
elongation
termination

Question 20

eEF-2 inhibited by

Answer 20

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

Question 21

grey baby syndrome

Answer 21

occur when chloramphenicol given to newborn especially premature

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

Question 22

proteins translated on free ribosomes include

Answer 22

cytoplasmic proteins

mitochondrial proteins

Question 23

proteins translated on ribosomes ass with RER include

Answer 23

secreted proteins

proteins inserted into cell memb

lysosomal enzymes

Question 24

fxn of chaperones

Answer 24

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

Question 25

ubiquitin and proteasome

Answer 25

ubiquitins form covalent bond with misfolded proteins which can be easily recognised by proteasome for degradation. also play role in displaying Ag via MHCI

Question 26

role of N terminal hydrophobic single

Answer 26

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

Question 27

N-glycosylation

Answer 27

addition of sugar to N of asparagine residues occurs in RER and golgi both eg transferrin

Question 28

O- glycosylation

Answer 28

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

Question 29

both O and N glycosylation occurs in?

Answer 29

LDL receptor

Question 30

how are the lysozymes synthesised directed to the lysosomes.

Answer 30

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.

Question 31

defect in I cell ds

Answer 31

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)

Question 32

hydroxyproline is an a.a. unique to

Answer 32

collagen

Question 33

primary structure of collagen is made up of which repeating tripeptide

Answer 33

Gly-X-Y-Gly-X-Y... X-lysine Y-proline

Question 34

role of vitC in collagen synthesis

Answer 34

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

Question 35

collagen synthsisi

Answer 35

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.

Question 36

role of lysyl oxidase in collagen syn

Answer 36

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

Question 37

type 4 collagen found in

Answer 37

Basement memb

Question 38

defect in type 4/BM leads to

Answer 38

goodpasture syndrome alport ds epidermolysis bullosa

Question 39

collagen in cartilage

Answer 39

2

Question 40

location of diff types of collagen

Answer 40

I--: bone, skin , tendon II--: cartilage , vitreous III--: blood vs, granulation tissue IV--: BM

Question 41

collagen changes in wound repair

Answer 41

initially typeIII (thin, pliable)in granulation tissue then typeI (high tensile strength)in scar

Question 42

Cu is required in which enz of collagen formation

Answer 42

lysyl oxidase

Question 43

what is the cause of weak collagen i menkes disease

Answer 43

Ehler Danlos syndrome type IX deficiet cross linking secondry to functional Copper deficiency.

Question 44

kinky hair syndrome refers to

Answer 44

menkes disease

Question 45

cause of menkes ds

Answer 45

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.