Nucleic Acids
What 3 things make up a nucleotide?
Phosphate group, nitrogenous base, 5-Carbon sugar
What are all the parts of the replication fork?
DNA Pol I, II, III, helicase, SSBs, ligase, primase, gyrase
What phase of cell division takes the longest time?
G1
What happens during elongation?
RNA extends in 5' to 3'
What is the start codon in eukaryotes?
AUG (methionine)
What are purines and how many rings form the structure? What are pyrimidines and how many rings form the structure?
Purines: Adenine and Guanine, 2 rings
Pyrimidines: Cytosine, Thymine, Uracil, 1 ring
What is specific DNA Repair? Non-specific?
Specific targets a single kind of damage and only repairs that type. Non-specific targets multiple types of damage using a single mechsnism.
What happens during metaphase?
Chromosomes line up in the middle of the cell.
When do transcription and translation happen in prokaryotes?
at the same time
What are the 2 functional ends of tRNA
anticodon loop, acceptor stem
What does Adenine bond with? how many bonds does it form? What does Cytosine bond with? how many bonds?
Adenine bonds with thymine or uracil, 2 bonds. Cytosine bonds with Guanine, 3 bonds.
What are the leading and lagging strands?
Leading: synthesized continuously. Lagging: synthesized in short fragments called Okazaki fragments.
What happens during anaphase?
centromeres break down, Chromosomes move to opposite poles, poles move apart
How does termination happen?
the end is marked by a terminating sequence, one example is a hairpin Uracil loop
How does termination occur?
A stop codon enters the A site, then a releasing factor helps release the peptide from the ribosome
What kind of bonds bond nucleotides together? What kind of bonds bond complimentary base pairs?
Nucleotides: Phosphodiester (covalent).
Comp base pairs: Hydrogen
What is telomerase and what does it do?
an enzyme that helps maintain telomeres (protective caps as the end of chromosomes) from shortening
What happens during prophase?
chromosomes condense, the nuclear envelope breaks down, microtubules organize into mitotic spindle
What happens during initiation?
sigma subunit identifies the promoter, unwinding begins at -10, 2 common 6-base sequences occur at -35 and -10
What are the 3 steps of initiation?
1. Special initiator tRNA (carries N-formylmethionine) binds to the small ribosomal subunit 2. The 5’ end of the mRNA binds to the ribosome using a ribosome binding sequence (RBS) 3. The large ribosomal subunit is added. The initiator tRNA will be in the Psite.
What are the similarities and differences of DNA and RNA
DNA: it carries genetic info, remains in the nucleus, has a double helix structure, and contains deoxyribose and thymine. RNA: Involved in protein synthesis, Leaves the nucleus, Single-stranded, Ribose, Uracil. Both: Adenine, Guanine, and Cytosine.
What is different in Eukaryotic DNA Replication?
Linear molecules & multiple chromosomes, more initiation factors, more origins of replication (ORIs), telomerase, Different polymerases
What happens during telophase
Chromosomes decondense, Nuclear envelope reforms, mitotic spindle goes back to being microtubules.
What post-transcriptional modifications are made in eukaryotic cells?
5' cap protects from degradation and Participates in the initiation of translation. Poly A tail protects from degradation and is involved in the nuclear export process. Splicing removes introns
What are the 3 steps of elongation?
1. Next charged tRNA enters the A site assisted by an elongation factor (EF-Tu) 2. A peptide bond is formed between the amino acid in the P site and the amino acid in the A site 3. Translocation of the ribosome occurs and the process can continue. An accessory factor (EF-G) helps with this.