Translation Flashcards
How much of the genome encodes for protein?
A very small percent
What is the basic structure of amino acids
Backbone (amino and carboxyl group) and R group
What kind of bonds joins amino acids
covalent peptide
What makes AAs different from each other
The R group
What is the AA equivalent to the 5’ end
Amino (N) terminus
What is the AA equivalent to the 3’ end
Carboxy terminus
How many levels of protei structure are there
4
How many levels of structure do all proteins have
3
What are the levels of protein structure in order
Primary
Secondary
Tertiary
Quaternary
Describe primary protein structure
AAs covalently linked via peptide bonds
Describe the secondary protein structure
H-bonding of the peptide backbone causes peptide chain to fold into patterns
Alpha helices and beta sheets
Describe tertiary protein structure
Secondary elements organized into 3D stable units
What mediates and stabilizes tertiary protein structure
ionic and disulfide bonds between the amino acid side chains
Connection between hydrophobic AAs and tertiary structure
Tertiary structure allows them to be shielded from the aqueous environment
What is the name for structural units within a protein
Domains
Can a protein have more than one domain
Yes. Each has a uniques function
Do all proteins have quaternary structure?
No
What makes up the quaternary structure of a protein
Protein subunits (polypeptide)
What is the other name for quaternary structure
Oligomer
What are the segments of mRNA that code for each amino acid called
Codons
How many bases are in a codon
3
What is the start codon
AUG (codes for methionine)
What determines the reading frame
The location of the start codon
What are the stages of translation
Initiation
Elongation
Termination
What direction does translation happen
5’-3’
What are the ‘main players’ in translation
Ribosome
transfer RNAs (tRNAs)
Ribosome-details
Large complex of protein and RNAs, 2 subunits
Moves along RNA and adds AAs
tRNA details
Bind to RNA and AAs
One end has an anti-codon that binds to complementary mRNA codon and the other carries the corresponding amino acid
What is an anticodon
Set of 3 nucleotides on a tRNA that bind to complementary mRNA codon
Spark notes of initiation
Ribosome, mRNA, initiator tRNA combine to form initiation complex
Moves along RNA until start codon is reached
Ribosome in initiation
Small subunit binds to mRNA 5’ cap
Once start codon is reached, large subunit joins
tRNA in initiation
Binds to 5’ cap
Spark notes of elongation
Polypeptide gets longer (surprise!)
Ribosome in elongation
Exposes (A site) codons to rRNA, which attaches appropriate AAs (P site)
Peptide bond form with polypeptide chain and ribsome continues along mRNA
Who recognizes stop codons
release factors (proteins)
How do release factors work
make an enzyme that adds H2O to last molecule on polypeptide chain–no peptide bond –> protein chan separated from tRNA
Why do proteins need chaperones
Because the environment is highly crowded and can be proteotoxic
Chaperones:
proteins and protein complexes that enable successful protein folding
How do chaperones work
Associate with proteins (usually hydrophobic sections) and suppress inappropriate reactions
What are the two types of chaperones
Hsp60s and Hsp70s
What are Hsp70s and how do they work
They are protein monomers. They bind to hydrophobic stretches
What are Hsp60s and how do they work
Protein complexes. Provide and protected environment for protein folding
Substitutions:
One base pair replaced with a different one
What are the types of substitutions
Nonsense and missense
Nonsense:
Stop codon coded for
Missense:
Different AA coded for
Insertion:
1 or more nucleotides added
Deletion:
1 or more nucleotides removed
What is a potential consequence of in-del mutations
Framshifts–triplet code is altered
Therapeutic uses of protein chaperones
Low molecular weight molecules act like chaperones
Types & functions of therapeutic chaperones
Chemical - nonspecific action (can work on many proteins)
Pharmacological - bind to specific proteins
How can therapeutics be used to overcome premature stop codons?
Engineered suppressor tRNA reads premature stop codon as an AA
What are the building blocks of proteins
Amino acids
