Unit 5: The Central Dogma - DNA Structure & Replication Flashcards
What does DNA stand for?
Deoxyribonucleic Acid
What are the monomers of DNA?
Nucleotides
What are the three parts of nucleotides?
Phosphates, deoxyribose sugars, and nitrogen bases.
What are the four different nucleotides?
Guanine, Adenine, Cytosine, and Thymine.
Which nucleotides are purines?
Guanine and Adenine
What does it mean if a nucleotide is a purine?
The nucleotide has two rings.
Which nucleotides are pyramines?
Cytosine and Thymine
What does it mean if a nucleotide is a pyramine?
The nucleotide has one ring.
Why is DNA in the shape of a double-helix?
Pyramines always bond with purines.
Which nucleotide does Adenine bind to?
Thymine
Which nucleotide does Thymine bind to?
Adenine
Which nucleotide does Cytosine bind to?
Guanine
Which nucleotide does Guanine bind to?
Cytosine
In which phase does DNA replication take place?
The “S Phase” is where DNA replication takes place.
What does semi-conservative mean?
It means that the DNA is composed of one strand of parent DNA and one strand of newly synthesized DNA.
What are the six enzymes needed for DNA replication?
Helicase, Topoisomerase, Primase, DNA Polymerase, Exonuclease, and Ligase.
What does Helicase do?
It unzips the DNA, creating 2 single strands of DNA.
What does Topisomerase do?
It relaxes the coiled DNA.
What does Primase do?
It primes the DNA, creating a starting point for DNA polymerase.
What does DNA Polymerase do?
It is a builder, and synthesizes new strands of DNA by adding nucleotides.
What does Exonuclease do?
It cuts out RNA primers.
What does Ligase do?
It fills in the any holes and gaps, joining together DNA.
What are the seven steps of DNA replication?
Unzipping, Stabilizing, Priming, Building and Extending, Replacing, Gluing, and Proofreading.
What happens in “Unzipping”?
Helicase unzips the double-stranded DNA by breaking the hydrogen bonds between base pairs.
What happens in “Stablizing”?
Single stranded binding proteins attach to each strand of DNA, and Topisomerase uncoils the DNA, reliving tension.
What happens in “Priming”?
Primase attaches to the DNA, providing a starting point for DNA Polymerase.
What happens in “Building and Extending”?
DNA Polymerase builds a new DNA strand by adding new DNA nucleotides.
What direction is DNA built in?
DNA is built 5’ to 3’, which creates a leading and lagging strand.
What happens in “Replacing”?
RNA primers are removed by Exonuclease. DNA polymerase then replaces them with DNA nucleotides.
Why are there RNA primers on DNA molecules?
They are there so DNA polymerase knows where to go on the lagging strand.
What is an Okazaki fragment?
It is the space between each RNA primer.
What happens in “Gluing”?
Ligase glues the Okazaki fragments together.
What happens in “Proofreading”?
A type of DNA polymerase double-checks each DNA strand.
What type of group is the 3’ end? (Hydroxyl or Phosphate?)
Hydroxyl group
What type of group is the 5’ end? (Hydroxyl or Phosphate?)
Phosphate group
Single Stranded Binding Proteins
They attach to each strand of DNA and hold them back, preventing them from reattaching to each other.
DNA nucleotides
The basic building blocks of nucleic acids.
Leading strand
Synthesizes DNA at the average rate
Lagging strand
Takes a longer time, has a more complicated process to synthesize DNA.
RNA primers
Serves as a place for the Okazaki fragments to start.
What does Uracil replace in RNA?
Thymine
