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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



evolved proteins, protect slow folding or denatured proteins until they can attain their proper structures



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.



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?



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.



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.



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


Which one of the following is specific to the synthesis of only one type of protein?

a messenger RNA


Members of a protein family often contain the same folding domain.



A(n) ________ is a group of functionally related genes transcribed as a polycistronic mRNA from a single promoter to a single terminator.



Which one of the following ribosomal subunits has three different pieces of rRNA in it?



One of your friends has decided to make it his life's work to characterize all functional proteins, as he is convinced that all possible amino acid combinations can result in a protein. Is it possible to confirm his hypothesis in this way?

No, most amino acid sequences cannot produce functional proteins.


It is actually the 16S rRNA component of a 30S ribosomal subunit which is responsible for recognition of a Shine-Dalgarno sequence. Which one of the following sequences in the 16S rRNA would you predict is responsible for the interaction between a small subunit and mRNA?