Bio chap 4

Question 1

peptide bonds

Answer 1

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

Question 2

polypeptide (protein)

Answer 2

a polymer of amino acids connected by peptide bonds

Question 3

chaperones

Answer 3

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

Question 4

Denatured

Answer 4

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

Question 5

Primary Structure

Answer 5

the sequence of amino acids in a protein, determines how a protein folds

Question 6

secondary structure

Answer 6

interactions between stretches of amino acids in a protein—result from hydrogen bonding in the polypeptide backbone

Question 7

tertiary structure

Answer 7

overall three dimensional shape….

the ability to carry out functions solely depends on shape

Question 8

localized folding

Answer 8

hydrogen bonds can form between the carbonyl group

Question 9

Which one of the following interactions is not a stabilizing force at the tertiary level of protein organization?

Answer 9

hydrogen bonding between a carbonyl oxygen of one peptide bond and an amide hydrogen of a nearby peptide bond

Question 10

A cooperative effect often occurs in multi-subunit proteins, leading to improved function of the subunits when bound to each other.

Answer 10

true

Question 11

Which one of the following statements about amino acids is incorrect?

Answer 11

The bridge between cysteines that connects parts of a protein is a stable, but non-covalent interaction.

Question 12

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?

Answer 12

precursors of tRNAs bound to nucleotides, and not amino acids

Question 13

Alpha helices are coils with how many amino acids per complete turn?

Answer 13

3.6

Question 14

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?

Answer 14

Statement 1) is true; statement 2) is false.

Question 15

Folding domains typically range in length from __________ amino acids.

Answer 15

25 to 100 or more

Question 16

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?

Answer 16

glutamic acid

Question 17

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?

Answer 17

The initiation complex would fail to form properly, and translation would not occur.

Question 18

Secondary structures are stabilized by which type of interaction?

Answer 18

hydrogen bonding

Question 19

All changes in gene sequence are mutations, but not all mutations decrease or increase in frequency over time.

Answer 19

true

Question 20

Which one of the following statements about translation in eukaryotes is incorrect?

Answer 20

A single processed mRNA can possess multiple protein coding regions.

Question 21

The bond between two amino acids is referred to as a(n) _____ bond.

Answer 21

peptide

Question 22

A consecutive sequence of codons following a start codon is called a _______.

Answer 22

reading frame

Question 23

False statements regarding glycine

Answer 23

• 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.

Question 24

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?

Answer 24

Rossman Folds

Question 25

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

Answer 25

a messenger RNA

Question 26

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

Answer 26

true

Question 27

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

Answer 27

operon

Question 28

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

Answer 28

60S

Question 29

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?

Answer 29

No, most amino acid sequences cannot produce functional proteins.

Question 30

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?

Answer 30

3′-UCCUCCA-5’

Question 31

Imagine that you have a unit of hemoglobin, a protein that is present in the aqueous environment of the human bloodstream. What type of folding domain does hemoglobin likely possess?

Answer 31

globin fold

Question 32

Which one of the following types of proteins interacts directly with a stop codon?

Answer 32

release factor

Question 33

Which of the following is not a possible function of a protein-folding domain

Answer 33

transfer of an amino acid to a ribosome

Question 34

Scientists often utilize compounds resembling nucleic acids called “morpholinos,” which can effectively prevent translation of any part of an mRNA of interest. Which of the following statements is most likely true regarding morpholinos?

Answer 34

Morpholinos are complementary to the target mRNA sequence and bind to the region upstream of the initiation codon.

Question 35

Which of the following statements is true regarding the development of pyrimethamine resistance in malaria parasites?

Answer 35

Full resistance to pyrimethamine is the result of four mutations that arose one at a time and together affected an enzyme present in malaria-causing parasites.

Question 36

Which of the following processes occur in the cytoplasm of eukaryotic cells?

Answer 36

translation only

Question 37

Imagine that a scientist is able to travel back in time to when the first proteins appeared. What would she not observe?

Answer 37

Proteins would be long compared to proteins today and would possess several folding domains

Question 38

Which of the following represent possible functions for a protein folding domain (choose all that are applicable)?

Answer 38

catalysis

ligand binding