DNA replication

Question 1

what is ann unambiguous sequence ?

Answer 1

there is no ambiguity or shak where each base lies in the sequence
these are needed fo transcription and translation no room for uncertainty

Question 2

what is redundant or degenerate sequences ?

Answer 2

certain positions can be represented by multiple possible bases
two different nucleotides pairs could give thee same amino acid

this is used in coding for amino acids

Question 3

what is a codon ?

Answer 3

a set of three nuucleotides

Question 4

what is a commaless sequencee ?

Answer 4

genetic cod is read continuously with no gaps which is what happens in DNA there are no gaps

Question 5

what is non overlapping sequence ?

Answer 5

no nucleotides are shared between each codon

Question 6

what is universal code ?

Answer 6

genetic codee is conserveed throughout evolution

Question 7

what is the exception of universal code ?

Answer 7

mitochondria in humans

Question 8

what is redundant sequence ?

Answer 8

ensures that different codons can code for the same protein
for example there are 20 sets of codons that can code for the sam amino acid

Question 9

what is the wobbly hypothesis ?

Answer 9

allows for one tRNA to attach and to code for more than one set of codons

Question 10

why do we neeed less tRNA than odon sequences ?

Answer 10

du to thee wobbl hypothesis

Question 11

what ar the two amino acds that arre an exception to the reeduundant sequence theory ?

Answer 11

tryptophan
methioninie

Question 12

in what direectioinn does DNA synthesis happen in ?

Answer 12

in the 5 prime to 3 prime direction

Question 13

what is the difference between the leading strand and the lagging strand ?

Answer 13

the leading strand is made in the 5’ to 3’ direction and is mad in a continuous fashion and only requires one primer

the lagging strand is synthesized in the 3’ to 5’ direction and is made discontinuously in fragments called okazaki fragments each fragment needs its own RNA primer (( in the opposite direction off the replications fork )

Question 14

what enzyme unwinds the DNA strands from each other ?

Answer 14

DNA helicase which is assisted by SSBP
single strand binding proteins

Question 15

where does the origin of replication usually lie ?

Answer 15

in AT rich sequences

Question 16

what syndrome is associated with a lack of helicase ?

Answer 16

bloom syndrome

Question 17

what is the function off DNA topoisomerase and what is the difference between topoisomeras 1 and 2 ?

Answer 17

helps relax the supercoils avoids tangling of thee DNA strands
by cutting strands in the DNA

topoisomerase 1 : single strand breaks , no ATP needed
topoisomerase 2: double strand breaks , ATP needed

Question 18

what is DNA gyrase ?

Answer 18

a type of topoisomerase 2 that is specifically found in bacteria

Question 19

what drugs inhibit topoisomerase ?

Answer 19

etoposide teniposide
quinolones inhiibit top 2 in bacteria

Question 20

what is primase ?

Answer 20

enzyme that makes RNA primers
once the RNA polymerase is in place the DNA polymerase can attach and start adding nucleotides

Question 21

what is the difference between DNA polymerase 1 and 3 ?

Answer 21

both of these enzymes are only found in prokaryotes

1: degrades RNA primers

3: adds nuccleotides at thee 3’ end

Question 22

in what direction does synthesis happen with DNA polymerase and what direction does thee proof reading process happen in ?

Answer 22

synthesis happens in the 5’ to 3’ direction
proof reading happens in the 3’ to 5’ direction

Question 23

what is thee function of DNA ligase ?

Answer 23

binds thee okazaki fragments together with phosphodiester bonds

Question 24

what is telomerase ?

Answer 24

enzyme that helps maintain thee end of telomeres
telomeres get shorter with each replication so telomerase adds DNA to the end of these telomeres to avoid them gettingto short

Question 25

what is the DNA sequence added by telomerase ?

Answer 25

TTAGGG