Chapter 15 Flashcards
one gene, ___ polypeptide
one
All enzymes are ___, but not all ___ are enzymes
proteins
What is an amino acid structure?
NH2-CHR-COOH
Define polar bonds.
covalent bond that shares electrons unequally
How are amino acids linked?
covalently by peptide bonds
What is are the phases of the protein structure?
Describe them.
primary:
- amino acid sequence
secondary:
- alpha helix or beta-pleated sheet
- peptide linkage and h-bonds
tertiary:
- polypeptide
- h-bonding, ionic bonding, s-s bonding (N-C), hydrophobic effect
quaternary (doesn’t always occur):
- protein
- polypeptide bonding
What are the types of stop codons?
- UAA
- UAG
- UGA
What is the wobble effect?
3rd nucleotide of the codon can vary
- due to degeneracy of the genetic code
What is the name for the AUG codon?
- E. coli:
- Eukaryotes:
- N-formylmethionine
- methionine
What is tRNA charging?
the attachment of a tRNA to its appropriate amino acid
- to the 3’ OH
- ATP is required
Initiation: (translation)
What is the order of bind?
- small ribosomal subunit to tRNA
- initiation factors (proteins)
- larger ribosomal subunit
How is translation/initiation different between E. coli and Eukaryotes?
E. coli:
- mRNA binds to sm subunit
- tRNA has N-formylmethionine
Eukaryote:
- mRNA is not directly involved
- start codons can be anywhere
- there can be more than 1 poly-cistronic mRNA
- tRNA has methionine
- GTP is used
Initiation: (translation)
Methionine is on the beginning of protein. What is this region call?
amino terminus (N-terminus)
Which direction is the protein formed?
n-terminus –> c-terminus
(amino) –> (carboxyl)
Elongation:
the Ribosomal small and large subunits share three sites to bind and interact with tRNA. What are they?
E: exit
P: peptidyl
A: aminoacyl
During transcription, does the mRNA move or remain bound to the tRNA?
Does the ribosome move?
mRNA remains bound to the tRNA, only the ribosome moves
Transcription/Elongation:
The binding of new tRNA to the A site require what type of energy?
GTP
How many base pairs does the ribosome move?
3 (1 codon)
Transcription/Elongation:
When the ribosome moves, where does the amino acid of the tRNA, originally from the P site, transfer to?
to the amino acid on the new tRNA in the A site
- energy from amino acid-tRNA bond
Transcription/Elongation:
What happens to the tRNA without an amino acid?
moves to the E site and diffuses away
Transcription/Termination:
Are the stop codons bound to RNA? If not, what are they bound to?
- no
- release factors (proteins)
Transcription:
How is elongation completed?
What energy type is used during this process?
- the peptide is cleaved off of the last tRNA
- whole complex falls apart
- GTP
Transcription/Termination:
What is the end of the peptide that was cleaved off of the last tRNA called?
carboxy terminus (C-terminus)
What are polyribosomes?
each mRNA may be used by many ribosomes at once
Transcription/Termination:
What aids in the folding of peptide?
What is removed during this process?
- chaperone molecules
- methionine
Transcription/Termination:
What is usually cleaved off of the polypeptide?
- longer sections at either ends
- signal peptides
- internal sections
Transcription/Termination:
What may be chemically modified?
amino acids
Transcription/Termination:
Is glycosylation rare in E. coli or animals?
What is it?
- E. coli
- attachment of s-s-s groups to proteins that are secreted/held on the outer surface of the cell membrane
