Genetics Unit 11: Nucleic Acid Structure And Dna Replication

Front 1

Nucleic acid bases

Back 1

Purines: Adenine and guanine
Pyrimidines: cytosine, thyamine, uracil.

Front 2

Nucleosides

Back 2

Composed of a base and its conjugate sugar (ribose, deoxyribose). Bases are attached to the 1' position of the sugar ring.

Front 3

Nucleotides

Back 3

Base + Sugar + phosphates.

Front 4

B form DNA

Back 4

Is way DNA is usually found in living cells. Is a smooth, right handed helix.

Front 5

Single copy dna sequence

Back 5

60% of human genome. Made up of unique neocleotide sequences. Encode for proteins, reg. sequences, ect.

Front 6

Moderatley reiterated dna sequences

Back 6

30% of human genome. Genes that belong to gene families and and are usually organized in repeated arrays. Encode for histones and rRna.

Front 7

Highly reiterated DNA sequences

Back 7

5-10% of genome. Short dna sequences (5-500 neucleotides) repeated thousands of times.

Front 8

Semiconservative replication

Back 8

Each single stranded molecule used as a template for its compliment. Creates 2 double helixes each with one old and one new strand.

Front 9

Is DNA replication bi-directional?

Back 9

yes

Front 10

Replicon

Back 10

All DNA replicated from a given origin.

Front 11

DNA polymerase 1

Back 11

In addition to polymerase activity, can degrade DNA from either end. This means it can remove necleotides in front of it or go back and remove them (proof reading).

Front 12

DNA polymerase 3

Back 12

In addition to polymerase activity, can remove misincoorperated nucleotides behind it if the nucleotides are unpaired. DNA pol 3 is more processive than DNA pol 1 (aka can put on more nucleotides before it falls off. Is also more efficient b/c the binding to the DNA strand is the rate limiting step.

Front 13

Leading Strand in DNA synthesis

Back 13

DNA being polymerized towards the fork. Is continuous.

Front 14

Lagging strand

Back 14

DNA is polymerized away from the fork. Is done in short fragments called Okazaki fragments.

Front 15

DNA ligase

Back 15

Splices adjacent okazaki fragments together. Requires ATP

Front 16

Primase

Back 16

Adds 3' OH primer to initiate DNA synthesis. Lays down RNA in a primer independent fashion.

Front 17

Single strand DNA binding proteins

Back 17

Bind non-enzymatically to a single stranded DNA stabilizing the single strand form preventing it from going back to doublestranded.

Front 18

Helicases

Back 18

Bind single stranded DNA in front of fork and separate the strands in a ATP dependent reaction. Single strands then stabilized by single strand dna biding proteins.

Front 19

Topoisomerase

Back 19

Travel ahead of fork and untwist and unwind the supercoiled DNA and the duplex by breaking and reattaching covalent bonds.

Front 20

Gyrases

Back 20

Bacterial topoisomerases. Inhibited by antibacterial antiboitics nalidixic acid, coumermycin, and novobiocin.

Front 21

Topoisomerase I

Back 21

Catalyzes relaxation of supercoiled DNA. Makes one cut.

Front 22

Topoisomerase II

Back 22

Catalyzes relaxation of supercolied DNA but also canalyzes knotting and unknoting. Makes 2 cuts.

Front 23

Anti-parralell

Back 23

In the DNA double helix, one strand is 5' one side 3' other, the other strand is 3'one side 5' other.

Front 24

Primary, secondary, and tertiary structures of nucleic acids

Back 24

Primary = Base pair sequence
Secondary = double helix
Tertiary = supercoiling of double helix

Front 25

3 requirements for DNA polymerases

Back 25

1) Free 3' hydroxyl group
2) A single stranded DNA template
3) Deoxynucleotide triphosphates

Front 26

Nick Translation

Back 26

DNA polymerase removes the RNA primer sequence in the Okazaki strand, replacing it with DNA.

Front 27

Cisplatin

Back 27

Anti cancer drug. Forms platinum complexes within DNA which cross link adjacent bases of DNA. Cell tries to repair, when it cant repair, triggers apoptosis.