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Flashcards in Chapter 13 Deck (27)
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1
Q

Chargaffs rules

How many hydrogen bonds form between base pairs

A
  1. DNA base composition varies between species
  2. Percentage of A=T and C=G

2 bonds with AT
3 bonds with CG

2
Q

Origin of replication

A

Site of start of replication; short stretches of DNA that have specific sequence of nucleotides. PROTEINS RECOGNIZE THE SEQUENCE AND ATTACH AND START

3
Q

Helicase

A

Enzyme that untwist the double helix at replication fork, separating the two strands

4
Q

SSBP

A

Bind to unpaired DNA strands, keeping them from re-pairing

5
Q

Topoisomerase

A

A protein that breaks, swivels and rejoins DNA strands to relive stress.

6
Q

Primase

A

An enzyme that joins RNA nucleotides to make a primer during DNA replication using the parental DNA strands as a template.

7
Q

DNA polymerase

A

Catalyze the synthesis of new DNA by adding nucleotides at the 3’ end of a pre existing strand

8
Q

Leading strand

Lagging strand

A

The new complementary strand synthesized continuously towards replication fork in 5’-3’ direction.

A disdcontinually synthesized DNA strand the elongates by means of Okazaki fragments in 5’-3’ away from replication fork.

9
Q

Okazaki fragments

A

Segments of 100-200 nucleotides long on lagging strand

10
Q

DNA ligase

A

A linking enzyme essential for DNA replication; catalyze the covalent bonding of the 3’ end of one DNA fragment to the 5’ end of another.

11
Q

Besides building what else does polymerase do?

A

Proof reads each nucleotide, if it’s wrong polymerase adds the correct one.

12
Q

Mismatch repair

A

Enzymes that remove and replace

13
Q

Nuclease

A

Enzyme that cuts DNA or RNA, either remaining one or a few bases or hydrolyzing DNA or RNA completely into its component nucleotides.

14
Q

Nucleotide excision repair

A

A repair system that removes and then correctly replaces a damaged segment of DNA using the undamaged strand as a guide.

15
Q

Telomeres

A

Repetitive DNA at the end of a euk. Chromosome. These protect the genes from being eroded during successive rounds of replication.

16
Q

Nucleoid

A

A non-membrane- enclosed region Im a prok. Cell where its chromosomes are located.

17
Q

Heterochromatin

A

Eukaryotic chromatin that remains highly compacted during interphase and is generally not transcribed.

18
Q

Euchromatin

A

Less condensed form of Euk. Chromatin that is available for transcription.

19
Q

Histones

A

Small protein with a high proportion of positively charges amino acids that binds to the negatively charged DNA.

20
Q

Nucleosome

A

Basic unit of DNA packing

21
Q

Plasmids

A

Small circular DNA molecules that are replicated separately.

22
Q

Gene cloning

A

Production of multiple copies of a gene

23
Q

Polymerase chain reaction

A

Technique used for amplifying DNA in Vito by incubating it with specific primers, a heat resistant DNA polymerase and nucleotides.

24
Q

DNA sequencing

A

Determining the order of nucleotide bases in a gene or fragment.

25
Q

In bacteria where does the replication fork go

A

From both directions until it meets

26
Q

How many origins of replication do eukaryotic chromosomes have?

A

Hundreds

27
Q

Telomerase

A

Enzyme responsible for maintain of the length of telomeres by addition of guanine repetitive sequences