DNA Replication & The Cell Cycle Flashcards
What does DNA stand for?
Deoxyribonucleic Acid
What is the function of DNA?
The sequence of nucleotides in DNA determines the amino acid sequence that makes up proteins.
What is some history of DNA?
Rosalind Franklin determined the structure of DNA with the help of x-ray diffraction. Later, Watson and Crick built a 3D model of DNA using Franklin’s x-ray diffraction.
What is the structure of DNA?
It is a double helix with two nucleotide chains in the shape of a twisted ladder. (the sides of the ladder are phosphate and sugar and the rungs are nitrogen bases)
Is DNA parallel or antiparallel?
Antiparallel, sides in opposite directions.
What are hydrogen bonds role in DNA?
Hydrogen bonds hold nucleotide chains together (loosely)
What is complementary base pairing?
The percentage of adenine will approximately equal the percentage of thymine (same for cytosine and guanine)
What are pyrimidines and purines?
pyrimidines are single-ringed while purines are double-ringed (purines bond with pyrimidines)
What does RNA stand for?
Ribonucleic Acid
Describe RNA.
Single stranded, uracil instead of thymine, ribose instead of deoxyribose, 3 types (rRNA, tRNA, and mRNA)
What is the binding of enzymes called in DNA replication?
Replisome (combo of DNA and enzymes)
How does bonding work in DNA replication?
Enzymes bond to DNA at replication origins (many on each DNA) usually a lot of A-T bonds because they are easier to break than C-G bonds.
Why doesn’t the sugar-phosphate backbone break like the nitrogen bases?
They are held together by strong covalent bonds.
What is the first step in DNA replication?
Helicase unwinds the helix (unzips)
What is the second step in DNA replication? (After helicase unwinds the helix)
Strand stabilizing proteins keep the DNA unwound.
What is the third step in DNA replication? (After strand stabilizing proteins keep the DNA unwound)
DNA polymerase only moves in the 3’ to 5’ direction as it synthesizes the new strand continuously.
What is the fourth step in DNA replication? (After DNA polymerase only moves in the 3’ to 5’ direction as it synthesizes the new strand continuously)
Primase makes RNA primer so DNA polymerase can attach and discontinuously synthesize a copy in short pieces call Okazaki fragments.
What is the fifth step in DNA replication? (After primase makes RNA primer so DNA polymerase can attach and discontinuously synthesize a copy in short pieces call Okazaki fragments)
RNA primer is replaced by DNA polymerase. Ligase joins the Okazaki fragments forming a long strand of DNA.
What strand does primer add RNA primer to?
Leading strand
How does DNA polymerase add new nucleotides?
in the 5’ to 3’ direction on leading strand and in discontinuous fashion to lagging strand.
What does DNA polymerase replace primers with?
DNA bases
What does DNA ligase do?
Seals holes of Okazaki fragments
Describe DNA replication.
semi-conservative and happens in multiple “bubbles”
What is DNA repair?
Errors, mutation can cause birth defects, cancer, or diseases
what is DNA repair’s defense?
DNA polymerase proof reads its own work and removes and replaces errors