MCBG 3 Flashcards
How many purines can be found in a stretch of 100bp double stranded DNA
100 purines. 2 strands each nucleotide will have one purine
What is chromatin
A material that forms chromosomes in eukaryotes
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
What’s a nucleoside? Nucleotide
Nuceloside = base and sugar Nucleotide = phosphate base and sugar
What’s a exonuclease?
A protein that cleaves nucleotides fro, the end of the DNA chain
What’s a endonuclease?
An ezyme that cleaves a polynucleotidee by cleaving the chain at any point except the ends
In DNA polymerase what is the function of the exonuclease domain?
To act as a proof reader and cleave incorrectly assembled chains.
What demos DNA polymerase do?
It catalyses the formation of new DNA strands?
What are the three phases of interphase?
G1
Synthesis. DNA replication
G2
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
How are chromosomes grouped?
In order of size. There are 9 groups A-G
What happens in prophase?
DNA condenses into chromosomes
Nucleolus decondenses
Centrosomes spindles start to form
Prometaphase?
Nuclear spindles connect to chromosomes
No nuclear membrane
Metaphase?
Chromosomes line up on the equator (metaphase plate)
Polar spindle fibres
This is a random alignment
Anaphase?
Centromeres divide
Spindles contract
Sister chromatids instantly become chromosomes