Lecture 1 Flashcards
What does DNA compose of
Backbone made of sugar and phosphate groups.
Nitrogen containing bases that project from the backbone
DNA
What gets exposed on the 3’ end carbon
Hydroxyl group
DNA
What gets exposed on the 5’ end carbon
Phosphate group
What is anti parallel fashion
Two DNA strands line up in the opposite direction to each other
When antiparticle strands twist what does it make
Double helix
How is the DNA structure stabilised
Complementary base pairs
What base pairs bond to one another
Adenine - thymine
Guanine - cytosine
Wha does the parent or original strand do
Serve as a template
What happens in semi conservative replication
Parent strands seperate
Both used as a template for a new strand
Daughter molecules is made of one new and one old
What happens in conservative replication
Parent strand serves as a template for synthesis of a whole new one
What happens in dispersive replication
Parent strand is cut into sections
Daughter strand contains old DNA with new DNA
What does DNA polymerase do
Enzyme that catalysed DNA synthesis
What characteristic does the DNA polymerase have
It works in one direction
What end does DNA polymerase add nucleotides too
3’ end
How does replication start
Replication bubble
What direction does the replication bubble work
Both as it is bidirectional
What is the replication fork
Y shaped region where DNA is split into two seperate strands
What does helicase do
Catalyses the breaking of hydrogen bonds between the two DNA strands to seperate them
What do single strand DNA binding proteins do
Attach to the seperated strands to prevent them closing
What does topi isomerise do
Cuts and rejoins the DNA and relieves the tension in the helix
What does DNA polymerase require
Primer
What is a primase
RNA polymerase
What does RNA polymerase do
Synthesises a short RNA segment that acts as a primer
What polymerase adds nucleotides after the RNA primer
DNA polymerase 3
The two strands being used in replication what are they called
Leading strand
Continuous strand
Which strand is synthesised discontinuous lu
Lagging strand
When does the lagging strand start
Primase synthesises a short piece of RNA
What are the short continuous fragments
Okazaki fragments
What does DNA polymerase 1 do
Removes the RNA primer at the beginning of Okazaki fragments
What does DNA Ligase do
Joins the Okazaki fragments together
What is the replisome
Enzyme that is responsible for DNA synthesis aroud the replication fork
What is a telomere
Region at the end of a linear chromosome
Does not contain genes
After replication the lagging strand goes on a little longer than the template what happens to it
Gets degraded
What cells lack telomerase
Somatic cells
What does DNA polymerase 3 do
Proof read its work for any mismatched pairs
During infection what happens to the protein coat
The original parent virus is left behind as a ghost attachment to the exterior cell
