Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

23 Cards in this Set

  • Front
  • Back
What are the two major steps of DNA replication?
1. DNA is locally denatured(or unwound) to separate the two template strands in order to prepare them for base pairing.

2. New nucleotides are attached by covalent bonding to each growing strand. The sequence of the new strand is determined by the original strand.
What are the two ends to our DNA molecule?
3'-ends in -OH
5'-ends in a phosphate
Origin of replication
a sequence of nucleotides that the replication complex can attach to in order to start replication. (mostly A and T because it's easier to break the double bonds)
Replication complex
contains molecules that aid in DNA replication such as:DNA helicase, single strand binding proteins, DNA polymerase, DNA ligase.
DNA helicase
splits open the DNA by separating the nitrogen-containing bases by using hydrolysis which eliminates the hydrogen bonds.
Single Strand binding proteins
bind to the individual strands and prevent them from twisting/recoiling
Difference between the leading and lagging strand
the nucleotide strands are anti-parallel
-during replication we read the template 3' --> 5'
-we created the new strand 5' --> 3'
lagging strand
the strand where replication occurs in fragments and replication moves opposite direction of helicase
leading strand
replication occurs continuously in the same direction the helicase moves.
Step One (replication) on leading
Primase attaches to the 3' end of the template and creates a primer.
What is primase?
a sequence of RNA nucleotides typically about 10-15 nucleotides long.
Step two of replication (leading)
DNA polymerase III can now jump on the leading strand at the primer and begins making the new DNA strands by adding nucleotides.
Step 3 of replication (leading)
When DNA polymerase III hits another primer or comes to the end of the DNA template it falls off.
Step 4 of replication (leading)
DNA polymerase I joins the primer, cuts it out, adds DNA in its place.
Step 5 of replication (leading)
DNA ligase travels down the strand sticking any fragments together.
Replication step six (leading)
Template and new strand coil together to form 1 new DNA molecule.
Replication step one (lagging)
primase adds primer to exposed template strand, polymerase III adds new DNA nucleotides
Replication step two (lagging)
-helicase continues to unwind exposing nucleotides in front of the primer
-now a new primase joins the template, adds another primer
-poly 3 joins the primer and adds new nucleotides
-poly 3 falls off when it hits primer
Replication step three (lagging)
These form okasaki fragments. primer, and DNA nucleotides on new strands
-polymerase I joins the DNA, cuts off the RNA and adds DNA nucleotides
-ligase glues the fragments together to get 1 continuous strand.
Proofreading and repair
all 3 DNA polymerases have the ability to proofread the DNA sequence and make repairs.
How does it work?
DNA polymerases will remove the error and replace with a new nucleotide. Ligase will glue it in place.
Mismatch repair
occurs when there are mismatched bases
DNA polymerase goes in, removes the wrong base and adds the correct one
Excision repair
occurs when enzymes discover that 1 or more of the nucleotides are damaged.
excise repair proteins cut out the damaged nucleotide and a few adjacent nucleotides.
polymerase (I+II) replace the gaps with nucleotides. Ligase glues it together.