CH16 final

Question 0

Define replication fork

Answer 0

At each end of replication bubble

Question 1

define origins of DNA replication

Answer 1

The replication of a chr begins at particular sites …

short stretches of DNA having specific sequence of nucleotides

Question 2

Define helicase

Answer 2

are enzymes tht untwist the dbl helix at the replication fork. separating the 2 parental strands and making them available as template strands.

Question 3

define okazaki fragments

Answer 3

the lagging strand is synthesized discontinuously, as a series of segments . these segments of the lagging strand are called okazaki fragments

Question 4

Define DNA polymerase

Answer 4

these enzymes catalyze the synthesis of new DNA by adding nucelotides to preexisting chains

Question 5

define DNA ligase

Answer 5

joins the sugar phosphate backbones of all the okazaki fragments into a continuous DNA strand

Question 6

Define leading strand

Answer 6

DNA polymerase III . this continuously adds nucleotides to the new complementary strand as a fork progresses . the DNA stand made by this is called the leading strand 5’ —> 3’ end tht is being made

Question 7

Define lagging strand

Answer 7

Is adding nucleotides towards the 5’ end.
this means primase primers the a 5’ end and DNA polymerase III synthesizes the okazaki fragment until it hits the next primer.
DNA polymerase I removes the primer and replaces it w/ nucleotides but the chain is not attached until DNA ligase connects the strand of nucleotides together

Question 8

Mismatch repair

Answer 8

other enzymes remove and replace incorrectly paired nucleotides tht have resulted from replication errors.

Question 9

excision repair

Answer 9

An area where there are damaged DNA it is cut out by nuclease and is filled in w/. new nucleotides

Question 10

describe how DNA becomes transcibed and translated into proteins tht run metabolism

Answer 10

Transcription- is the synthesis of RNA using info from DNA .

translation - is the synthesis of a polypeptide using info in the mRNA .

Question 11

mRNA

Answer 11

carries a genetic message from the DNA to the protein synthesizing machinery

Question 12

Triplet code

Answer 12

Genetic instructions for a polypeptide chain are written in the DNA as a series of nonoverlapping 3 nucelotide words

Question 13

codons

Answer 13

the mRNA nucleotides triplets are called codons

Question 14

reading frame

Answer 14

Reading the sequence of nucleotides triplets correctly

Question 15

Promoter

Answer 15

The DNA sequence where RNA polmerase attaches and initiates

AUG

Question 16

Transcription unit

Answer 16

The stretch of DNA downstream from the promoter tht is transcribed into an rna molecule

Question 17

Transcription factors

Answer 17

In ek a collection of proteins called “””” mediate the binding of RNA polymerase and the initiation of transcription

Question 18

RNA polymerase

Answer 18

Pries the 2 straands of DNA apart and joins together RNA nucleotides complementary to the DNA template strand

Question 19

Poly A tail

Answer 19

is attached to the 3’ end

Question 20

Introns

Answer 20

The noncoding segmetnts of nucleic acids tht lie between coding regions

Question 21

Exons

Answer 21

The are expressed usually by being translated into amino acid sequences

Question 22

Rybozymes

Answer 22

RNA molecules tht function as enzymes

Question 23

tRNA

Answer 23

the message is a series of codons along an mRNA molecule and the reanslator is called tRNA

Question 24

Anticodons

Answer 24

The paricular nucleotide triplet tht base paits to a specific mRNA codon