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Flashcards in CH16 final Deck (25):
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define origins of DNA replication

The replication of a chr begins at particular sites ...
short stretches of DNA having specific sequence of nucleotides

1

Define replication fork

At each end of replication bubble

2

Define helicase

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

3

define okazaki fragments

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

4

Define DNA polymerase

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

5

define DNA ligase

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

6

Define leading strand

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

7

Define lagging strand

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

8

Mismatch repair

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

9

excision repair

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

10

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

Transcription- is the synthesis of RNA using info from DNA .
translation - is the synthesis of a polypeptide using info in the mRNA .

11

mRNA

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

12

Triplet code

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

13

codons

the mRNA nucleotides triplets are called codons

14

reading frame

Reading the sequence of nucleotides triplets correctly

15

Promoter

The DNA sequence where RNA polmerase attaches and initiates
AUG

16

Transcription unit

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

17

Transcription factors

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

18

RNA polymerase

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

19

Poly A tail

is attached to the 3' end

20

Introns

The noncoding segmetnts of nucleic acids tht lie between coding regions

21

Exons

The are expressed usually by being translated into amino acid sequences

22

Rybozymes

RNA molecules tht function as enzymes

23

tRNA

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

24

Anticodons

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