DNA Replication 3.3 U3 Flashcards
Prokaryote chromosomes vs Eukaryotes chromosomes?
Pro:
singular, circular
in cytoplasm
Eu:
multiple, linear
more
in nucleus
Euk vs Pro Chromosomes?
Pro:
singular, circular
in cytoplasm
Eu:
multiple, linear
more
in nucleus
Chromatin vs chromatid vs chromosome?
What is DNA coiled around and what does that form?
DNA is tightly coiled around histones, which form nucleosomes
What is X-Shape?
duplicated chromosome with supercoiled chromatin
What are the main roles of DNA?
Storing information:
Genetic info
Copying information:
Prior to division (during S phase) it has to be copied!
Transmitting information:
Genes are inherited from one gen to the next
What are the monomers of DNA
Nucleotides
What is the DNA structure?
Double-stranded
Double helix (linear in euk, circular in pro)
Monomers = nucleotides
5’ to 3’ directionality
5’ = phosphate end
3’ = OH end
Antiparallel
Hydrogen bonds between bases
What is Chargaffs Rule?
“Chargaff’s Rule”
# of A=T
# of C=G
# of purines = # of pyrimidines
What are the Base-Pairing Rules
Adenine with thymine (2 H bonds)
Guanine with cytosine (3 H bonds)
Describe the Contents of Nucleotides?
Monomers of DNA
Composed of three chemical groups:
5 Carbon Deoxyribose Sugar
Carbons are numbered for biochemical identification purposes
Phosphate
Attached to the 5’ deoxyribose carbon
1 of 4 Nitrogenous bases
Base Pairs?
A-T/U
G-C
What are Euk Telomere?
Eukaryotic DNA has ends
Prokaryotic doesn’t because it is stored as a circular chromosome.
These ends can be degraded over time, leading to gene loss.
Eukaryotes have “caps” of long nonsense DNA sequences called telomeres to protect against DNA degradation.
Many scientists speculate that telomere loss is associated with aging in eukaryotes.
What is the central dogma?
Describes the flow of information in a cell
DNA–>RNA–>Protein
Proteins carry out cell functions, which is expressed as a physical trait*.
What is Semi-Conservative Replication?
Each copy of the DNA will have one template (old) strand and one newly synthesized strand.
3 steps to DNA Replication?
Initiation, Elongation, Termination
What is Initiation in DNA Replication?
Topoisomerase (A) relaxes the supercoiled DNA near the origin of replication.
DNA Helicase (B) breaks the hydrogen bonds between the template strands.
Strands are kept from re-annealing (fancy word for binding) by single stranded binding proteins (C).
What is Elongation in DNA Replication?
Primase puts down RNA primers to help DNA polymerase actually bind to the template DNA Strand
DNA Polymerase binds and synthesizes the new strands from 5’ to 3’.
Replication on the leading template strand is continuous.
Replication on the lagging template strand is discontinuous
What is Termination in DNA Replication?
RNA primers are removed
DNA ligase fills in the gaps from the primer removal and between the Okazaki Fragments.
End result: Two Identical Copies of the DNA
