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Flashcards in Nucleotides/DNA Structure Deck (34):
0

Nucleic Acids - components

Bases, sugars, phosphate groups

1

Purines

Adenine
Guanine

2

Prymidines

Cytosine
Thymine
Uracil

3

Nuclosides

Purine and Prymidine bases and pentose (ribose or deoxyribose)

4

Nulceotides

Phosphorylated nucleosides

5

Oligonuclotides

Short polymers of nucleotides

6

Ionic forces & DNA

Ionic forces also affect the stability and confirmation of double helix

7

DNA ligase - fxn

Forms phosphodiester bonds between free 5' and 3' ends of DNA

8

Active site of enzyme

contains substrate bindind site and the catalytic site

9

Nucleases - fxn

Hydrolyze phosphodiester bonds

10

Exonucleases - action

cleave the last nucleotide residue a either of the two terminals.

11

Endonucleases - action

cleave phosphodiester bonds in the interior

12

DNA confirmations

B, Z, A

13

Common cell DNA confrimation

B

14

Z -DNA

occurs within DNA sequences that control gene transcription

15

A-DNA

form taken by DNA-RNA hybrid during transcription

16

Topoisomerases - fxn

specific enzymes that regulate superhelices

17

Topoisomerases - types

Type I
Type II
Gyrases

18

Type I Topoisomerases

break only one DNA strand and alllow it to rotate about the other to relive the super coil. Also reseal the break that was created after supercoild relieved

19

Type II Topoisomerases

beak both DNA strands, relax the supercoil and then reseal the DNA.
REUIRES ATP

20

Gyrases

Topoisomerases that relive supercoiling generated by the unwinding of DNA

21

Topoisomerases - clinical function

Used as targets for antimicrobial and antineoplastic agents. They convert Topoisomerases into DNA-breaking agents by specifically interfering with DNA ligase activity of the topoisomerase.

22

Alternative DNA Confirmations

DNA Bending
Cruciforms
Triplex DNA
Quadruplex DNA

23

Cruciforms - def., fxn

regions of DNA in which interchain hydrogen bonds are disrupted and interchain bonds form
fxn in control of replication and transcription

24

Hoogsten pairing

pairing of bases occurs in different faces of bases than do Watson and crick pairing

25

Triplex DNA

Occurs in DNA w string of purine bases
Fxn in transcription control, initiation and termination of replication, exchanging telomeres stability
Third strand pairs with Hoogsten pairing

26

triple stranded DNA - clinical

associated with hereditary persistence f fetal hemoglobin

27

Quaduplex DNA

forms in immunoglobulin genes that undergo recombination
also occurs in teleomeres

28

Histones

Basic proteins in eukaryotic DNA
NOT in prokaryotic DNA, instead HU protiens

29

Chromatin

DNA with its associated proteins
During cell division, becomes condensed to chromosones

30

Chormosones - components

Condensed chromatin
Centromere
Telomere

31

Centromere

site of attachment of the chromosome to the mitotic spindle

32

Telomere

ends of chromosomes

33

Structural genes

DNA coding sequences that code for protein