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Flashcards in MCBG 3 Deck (35):
1

How many purines can be found in a stretch of 100bp double stranded DNA

100 purines. 2 strands each nucleotide will have one purine

2

What is chromatin

A material that forms chromosomes in eukaryotes

3

How is DNA packaged ?

DNA DNA is wrapped around histones to form nucleosomes
These are then coiled into units call SOLENOIDS
Solenoids are then coiled into solenoid loops
Chromatin
Chromatin loops
Condensed chromatin loops
Chromosomes

4

What's a nucleoside? Nucleotide

Nuceloside = base and sugar
Nucleotide = phosphate base and sugar

5

What's a exonuclease?

A protein that cleaves nucleotides fro, the end of the DNA chain

6

What's a endonuclease?

An ezyme that cleaves a polynucleotidee by cleaving the chain at any point except the ends

7

In DNA polymerase what is the function of the exonuclease domain?

To act as a proof reader and cleave incorrectly assembled chains.

8

What demos DNA polymerase do?

It catalyses the formation of new DNA strands?

9

What are the three phases of interphase?

G1
Synthesis. DNA replication
G2

10

How are the arms of a chromosome labeled?

Top or small arm is P for petit

The longer arm is Q because is comes after P

11

How are chromosomes grouped?

In order of size. There are 9 groups A-G

12

What happens in prophase?

DNA condenses into chromosomes
Nucleolus decondenses
Centrosomes spindles start to form

13

Prometaphase?

Nuclear spindles connect to chromosomes
No nuclear membrane

14

Metaphase?

Chromosomes line up on the equator (metaphase plate)
Polar spindle fibres

This is a random alignment

15

Anaphase?

Centromeres divide
Spindles contract
Sister chromatids instantly become chromosomes

16

Telophase?

Nuclear membrane formation
Cleavage of cell begins
Decondensing of DNA
Spindles disappear

17

What happens in cytokinesis?

Cytoplasm divides

Parent cell becomes 2 daughter cells with identical genetic information

18

Do sister chromatids always have identical dna in mitosis?

Yes!

19

Non-sister chromatids have the same DNA?

Yes

20

Meiosis.
How many daughter cells are produced?
What's the genetic material like?

4 genetically different daughter cells
Haploid

21

In meiosis when does crossing over occur?

Prophase 1

22

What happens in prometaphase in meiosis?

Nothing. There is no prometaphase. Bazinga

23

In meiosis what lines up at the metaphase plate?

A tetra. Two chromosomes with 4 chromatids

24

How does meiosis generate genetic diversity?

Random assortment of chromosomes. at the start of meiosis you have two chromosomes (4 chromatids). One chromosome is from your mother and then the other from your father.

Crossing over

25

What's the cell pre meiosis called in a male?
What has this specialised from?
What is the name of the haploid cell
And these develope into mature?

Primary spermatocyte
Spermatogonium
Spermatids
Mature sperm

26

How long does spermatogenesis occur?

~60 days

27

What's the cell pre meiosis called in a female?
What has this specialised from?
What is the name of the haploid cell
And these develope into mature?

Primary oocyte
Oogonium
Ovum + three polar bodies
Mature ovum

28

Length of oogenesis?

12-50 years

29

What's a telomere?

Repetitive nucleotide sequence at the end of chromosomes

30

TTAGGG What does this code for?

Telomeres. This sequence is repeated 2500 time

31

What's the "equator" called?

Metaphase plate

32

How is genetic diversity obtained in meiosis? 2

Randomly alignment (assortment) of chromosomes (metaphase I)
Crossing over (prophase 1)

33

What's slippage in DNA mutation?

An extra base is added and it loops out

34

DNA mutation: how can slippage cause an addition of a base and sometimes a removal?

Depends on which strand? New strand slippage causes an addition of a base. If slippage occurs on a template strand then a nucleotide will be missed

35

What's the most dangerous type of DNA mutation?

Double stranded breaks. Hard to fix