Module 2 Flow of Genetic Information in the Cell Flashcards
The Flow of Genetic Information or also known as _________
Central Dogma of Life/Biology
What happens to RNA during cell division?
synthesized in interphase then gets distributed in daughter cells
Where is RNA stored in a cell?
nucleus, cytoplasm and mitochondria
types of RNA (8)
- mRNA
- tRNA
- rRNA
- snRNA
- snoRNA
- miRNA
- siRNA
- IncRNA
type of RNA that encodes proteins
mRNA
type of RNA that acts as adaptor between mRNA and amino acids
tRNA
type of RNA that forms the ribosome
rRNA
type of RNA that functions in various nuclear process (e.g splicing)
snRNA
type of RNA that facilitates chemical modification of RNAs
snoRNA
type of RNA that regulates gene expression (2)
miRNA
IncRNA
type of RNA that silences gene expression
siRNA
3 proposed Models of Replication
- semiconservative (pd + pd) -> (dd + pd)
- conservative (pp + dd) -> (pp + pp)
- dispersive (mekus2) (pd + pd) -> (pd + pd)
demonstrated semiconservative replication
Meselson and Stahl (1958)
Meselson and Stahl Experiment
centrifuged bacteria cultured in medium containing nitrogen
summary of DNA replication
- ________ unwind the parental double helix
- ________ stabilize the unwound parental DNA
- The leading strand is synthesized continuously in the _______ direction by ________
- The lagging strand is synthesized discontinuously. ______ synthesizes a short _______, which is extended by ___________ to form an ________.
- After the RNA primer is replaced by DNA, ________ joins the Okazaki fragment to the strand.
- Helicase
- Single-strand binding proteins
- 5’ -> 3’ , DNA polymerase
- Primase synthesizes short RNA primer, which is extended by DNA polymerase to form an Okazaki fragment.
- DNA ligase
DNA polymerase and function
1 - repair
2 - cleans up Okazaki fragments
3 - main polymerase
Enzyme that prevents tangling upstream from the replication fork
gyrase or topoisomerase
why is RNA primer needed?
DNA polymerase 3 (enzyme that builds new DNA strand) can only add nucleotides to existing strands of DNA
Replacement of RNA primer by DNA is done by ________.
DNA polymerase I
Enzymes do make mistakes at a rate of about _____________. In humans, with our 6 billion base pairs in
each diploid cell, that would amount to about __________ every time a cell divides!
1 per every 100,000 nucleotides
120,000 mistakes
Explain the three (3) main steps in DNA replication.
initiation
elongation
termination
the enzyme that is responsible for the polymerization of nucleotides to nucleic acid during the elongation phase of DNA replication
DNA polymerase
________ is the first DNA polymerase was discovered by ______- in _____ for which he received the 1959 Nobel Prize in Chemistry.
DNA polymerase I
Arthur Kornberg
E.coli
DNA pol 1 has 3 enzymatic activies
- polymerization (5’ -> 3’)
- exonuclease (3’ -> 5’) - proofreading
- exonuclease (5’ -> 3’) - edit out sections of damaged DNA
discovered DNA pol II and III
Thomas Kornberg son of Arthur Kornberg
DNA Pol III is highly “______” while DNA pol I is “____”
processive
distributive
Fidelity of DNA replication can be traced to three distinct activities:
- accurate selection of nucleotides
- immediate proofreading
- post-replicative mismatch pair
Types of DNA Damage or Lesion
- loss of amino group (deamination): C - > U
- mismatches
- breaks in the backbone
- crosslinks
is a frequent cause of breaks in backbones, but some chemicals produce breaks as wells
ionization radiation
two types of crosslinks
intrastrand - same DNA strand
interstrand - opposite DNA strand
DNA damaging agents (5)
- DNA replication stress
- ionizing radiation
- UV light
- oxygen radicals
- polyaromatic hydrocarbon
repairs base mismatch (insertion/deletion)
mismatch repairre
repairs ssDNA breaks
base-excision repair
repairs intrastrand crosslinks
nucleotide-excision repair
repairs interstrand crosslink
dsDNA break repair
Each time a cell divides, the telomeres get _____.
shorter
When telomeres get too short, the cell can no longer divide; it becomes _______ or it dies
inactive or “senescent”
associated with aging, cancer, and a higher risk of death.
telomere shortening
some factors of aging (4)
- telomere shortening
- chronological age - risk factors increase overtime
- oxidative stress - oxidants damage DNA, proteins, lipids
- glycation - glucose sugar bind and inhibits DNA, proteins, lipids
DNA to protein:
- When a gene is switched on, ________ attaches to the start of the gene. It moves along the DNA making a strand of ______. This process is called ________.
- ________ is the removing and adding sections of RNA.
- mRNA moves out of the nucleus out to the ______.
- ______ binds to mRNA and reads the code in mRNA to produce a chain made up of _____.
- ______ carry the amino acids to the ribosome
- RNA polymerase, mRNA, Transcription
- RNA splicing
- cytoplasm
- ribosome, amino acids
- tRNA
_______ repeats that bind a set or proteins called _______and protect the DNA by forming a closed telomere ‘cap’
TTTAGGG
shelterin
- enzymes that lengthens telomeres
- prevents progressive shortening of lagging strand
telomerase
- are unique DNA segments that contain multiple short repeated sequences
- AT-rich stretch
replication origin
control the initiation of DNA replication by directing assembly of the repeat on machinery to specific sites on the DNA chromosome
Origin-binding proteins
