Lecture 36 Flashcards
(28 cards)
What is a point mutation?
A genetic mutation whereby a single nucleotide (or very few nucleotides) has been inserted, deleted or substituted of an incorrect base compared to the original DNA sequence
What is a missense mutation?
Similar to a point mutation where a single nucleotide changes the codon and codes for a different amino acid
What is a nonsense mutation?
Similar to missense and point mutation. It is where a codon is changed to a terminating/STOP codon
What is a insertion mutation?
It is when one or more nucleotides are added to a DNA sequence.
What is a deletion mutation?
Where part of the DNA sequence is lost. Causes a shift to a different sequence.
What is a frameshift mutation?
Caused by either a insertion or deletion mutation. This leads to shift in the codon sequence.
What is a mutation in protein structure?
Mutations in blood such as the switch of glutamate to valine which causes sickle cell anemia
What is HD?
Huntington’s disease that is the breakdown of nerve cells
What causes HD?
A dysregulation of the huntingtin gene. Normal individuals have 10-25 repeats of CAG coding for glutamine while those affected have 37-80 repeats.
How do antibiotics work?
They work better because they stop the translation in prokaryotes.
How does a erythromycin work?
Erythromycin binds to ribosome at 23S RNA. Resistance to this antibiotic occurs because specific adenine is methylated and inhibits the interaction
How do antibiotics target prokaryotes and not eukaryotes?
Both have different ribosomes that are targeted
How is translation in eukaryotes?
The same as prokaryotes just 12 IF, met is not formyl, no Shine-Delgarno, and Poly A Tail in intiation
How does translation initiation happen in eukaryotes?
- ribosome binds to 5’ cap
- eIF5b and eIF2 bind to GTP and carry tRNA
- moves to START codon and looks for Kozak sequence for initiation
4.recruit large subunit 60s to turn 80s - GTP hydrolyze and come off
Can coupling of transcription and translation happen?
Yes. This happens in e coli. and happens in the cytoplasm because there is no nucleus. This would not happen in eukaryotes(us) because both transcription and translation happen in different places.
What happens in the final stage of protein synthesis when it is released?
It can start to fold and have covalent modification. Folding just means tertiary structure. This is aided by chaperones and happens when 30 AA emerge from the ribosome
What do the chaperones do?
They aid the folding and make sure that it folds correctly. Also called heat shock proteins
Why are they called heat shock proteins?
Because they are expressed in high rates in cells exposed to heat.
How many heat shock proteins are there?
There are many but the most common are HSP 60 and HSP 70
What does HSP 70 do?
It has high affinity for unfolded proteins and ATP
What happens to ATP during HSP 70?
It is hydrolyzed causing a conformational change and enclosing polypeptide in an unfolded state. ADP is changed for ATP and releases polypep. and allows folding
What are some covalent modifications that can happen during the final stages of protein synthesis?
- disulfide bond formation
- hydrox. of AA
- complexing with carbs and lipids
- proteolytic cleavage(formyl is removed)
What happens to proteins that are destined to be outside(secreted)?
Usually synthesized on ribosomes studded to the RER.
What happens to protein destined to be in the cytoplasm, nuclei, mito, or chloro?
Usually synthetized in free ribosomes in cytoplasm
