Bio chap 4 Flashcards
(38 cards)
peptide bonds
successive amino acids in proteins are connected by PEPTIDE BONDS. The carboxyl group (COOH) of one amino acid rx with the amino group (NH3) of the next acid in line.
**molecule of H20 is released R groups t in different direction
polypeptide (protein)
a polymer of amino acids connected by peptide bonds
chaperones
evolved proteins, protect slow folding or denatured proteins until they can attain their proper structures
Denatured
most proteins can be unfolded, by chemical treatment or high temp. Chemicals removed, heat removed, all is good again…
Mutant proteins containing an amino acid that prevents proper folding are often devoid of their functional activity
Primary Structure
the sequence of amino acids in a protein, determines how a protein folds
secondary structure
interactions between stretches of amino acids in a protein—result from hydrogen bonding in the polypeptide backbone
tertiary structure
overall three dimensional shape….
the ability to carry out functions solely depends on shape
localized folding
hydrogen bonds can form between the carbonyl group
Which one of the following interactions is not a stabilizing force at the tertiary level of protein organization?
hydrogen bonding between a carbonyl oxygen of one peptide bond and an amide hydrogen of a nearby peptide bond
A cooperative effect often occurs in multi-subunit proteins, leading to improved function of the subunits when bound to each other.
true
Which one of the following statements about amino acids is incorrect?
The bridge between cysteines that connects parts of a protein is a stable, but non-covalent interaction.
Imagine that a researcher was able to travel back in time, shortly after the appearance of the first RNAs on Earth. What would she find?
precursors of tRNAs bound to nucleotides, and not amino acids
Alpha helices are coils with how many amino acids per complete turn?
3.6
Consider the following two statements about protein structure:
1 - All polypeptides have tertiary structure.
2 - All proteins have quaternary structure.
Which of the two statements above is correct?
Statement 1) is true; statement 2) is false.
Folding domains typically range in length from __________ amino acids.
25 to 100 or more
You are studying a protein that you call Protein X. There is an aspartic acid at a key position in Protein X which is important in the folding and stabilization of that protein. If this aspartic acid is changed to a different amino acid, which one of the following amino acid substitutions is most likely to allow the protein to fold normally?
glutamic acid
Imagine that a primary RNA transcript from your favorite gene was processed incorrectly, such that it has no 5’ cap. What would be the result?
The initiation complex would fail to form properly, and translation would not occur.
Secondary structures are stabilized by which type of interaction?
hydrogen bonding
All changes in gene sequence are mutations, but not all mutations decrease or increase in frequency over time.
true
Which one of the following statements about translation in eukaryotes is incorrect?
A single processed mRNA can possess multiple protein coding regions.
The bond between two amino acids is referred to as a(n) _____ bond.
peptide
A consecutive sequence of codons following a start codon is called a _______.
reading frame
False statements regarding glycine
- Glycine is an asymmetric amino acid.
- Glycine is a large, polar amino acid.
- Glycine is a relatively “inflexible” amino acid.
- Glycine is similar to tyrosine in terms of structure and chemical properties.
In metabolic processes that generate energy from six-carbon sugars like glucose, a molecule called NAD is often attached to an enzyme carrying out one of the metabolic reactions. Which one of the following folding domains is most likely to be found in the region of one of these enzymes where association with NAD occurs?
Rossman Folds
