Introduction to DNA Flashcards Preview

MCBG > Introduction to DNA > Flashcards

Flashcards in Introduction to DNA Deck (26):
1

What is heterochromatin and what does it look like under an electron microscope?

Densely packed form of chromatin
Looks darker

2

What is euchromatin and what does it look like under an electron microscope?

Lightly packed form of chromatin
Looks lighter

3

What is the shape of DNA?

Right handed double helix

4

What is a gene?

A section of DNA that codes for a protein

5

How do you fit 2 metres of DNA into a 6 micrometre cell nucleus?

DNA is wrapped around histones to form a nucleosome
30nm of nucleosomes is a solenoid

6

What is the human genome?

The entire DNA sequence of a human
22 and 2 sex chromosomes

7

What are the two nucleic acids?

DNA and RNA

8

What is a polynucleotide?

Linear polymer of nucleotides
E.g. DNA and RNA

9

What is a nucleoside?

Sugar and base

10

What is a nucleotide?

Sugar, base and phosphate

11

Which is the difference between ribose and deoxyribose?

Ribose has two OH on carbon 2 and 3
Deoxyribose has a H and OH on carbons 2 and 3

12

What bond links together nucleotides?

Phosphodiester bonds

13

What bases are purine?

Adenine and guanine

14

What bases are pyrimidine?

Thymine, cytosine and uracil

15

What is at the 5' end of a DNA chain?

Phosphate

16

What is at the 3' end of DNA?

OH

17

What are the complementary base pair rules and how many hydrogen bonds form between them?

Adenine and thymine or uracil- 2
Guanine and cytosine- 3

18

How do DNA strands connect?

Complimentary and antiparallel

19

Which way of a DNA strand is left to right?

5' to 3'
By convention top strand is this direction

20

Where are cell cycle checkpoints?

Between G1 and S
Between G2 and mitosis

21

What is the name of DNA replication?

Semi-conservative

22

What enzyme catalyses DNA replication?

DNA polymerase

23

What happens in the initiation stage of DNA replication?

recognise origin of replication
primase kicks starts process as DNA polymerase can only extend the 3' end and shows where to start

24

What happens in the elongation stage of DNA replication?

Moving replication fork
Helicase unwinds double helix
DNA polymerase extends 3' end only
lagging strand uses fragments of DNA called ozkazaki fragments- use primers
RNA Primers are replaced with DNA
DNA ligaments joins the fragments

25

What happens in the termination stage of DNA replication?

When two facing replication forks meet DNA ligase joins final fragments

26

What is a chromatid?

When chromosomes are connected by the centromere, they are the two arms
If not connected by centromere a chromatid is a chromosome