Introduction to DNA Flashcards
What is the structure of DNA?
right handed double helix
antiparallel strands
What is the smallest unit of packaged DNA?
nucleosome
How many chromosomes in the human genome?
24
What is in a nucleoside?
sugar and base
What is in a nucleoetide?
sugar, base and phosphate group
What are the two pentose sugars? What is the difference between the two? In which molecules are they found?
ribose (RNA) or 2-deoxyribose (DNA)
ribose 2C OH group
2-deoxyribose 2C H only
Name the two purine bases
adenine
guanine
Name the pyrimidine bases
cytosine
thymine
uracil
What type of bonds are nucleotides joined by?
phosphodiester bond
How many H bonds between G and C
3
How many H bonds between A and T and A and U
2
What occurs in G1?
cell content replication
What occurs in S-phase?
DNA replication
What occurs in G2?
double check and repair
What occurs in M phase?
cell division
What enzyme separates the DNA strands?
DNA helicase
What enzyme creates the new DNA strand?
DNA polymerase
What enzyme joins the DNA fragments?
DNA ligase
Why is a kickstart by primase required?
DNA polymerase can only extend from 3’ end
What are the fragments in the lagging strand called?
OZKAZAKI
What does primase do and why?
produce short sequence of RNA that acts as a primer to kickstart transcription by DNA polymerase
They are later removed
What does the exonuclease domain of DNA polymerase do?
part of proofreading function
cleaves phosphodiester bonds from end
What does the endonuclease domain of DNA polymerase do?
part of proof reading function
cleave phosphodiester bonds from middle
