Question

Easy questions, 30 min timed assignment, please answer ASAP thanks.

The amino acid least likely to be involved in nucleophilic a. Alanine. b. Asparagine. 1. and/or electrophilic enzyme catalysis is e. All are equally likely c. Aspartate. d. Arginine Fibrous proteins, such as collagen, have which one of the following properties? a. b. c. d. e. 2. highly soluble in water their hydrophilic residues are directed into the interior of the protein exhibits enzymatic activity serve structural roles in the cell monomeric 3. The carbon skeleton that is the precursor for serine is: a. glyceraldehyde-3-phosphate c.glycerol-3-phosphate none of the above d. glyoxalate 4. The high fidelity of DNA replication is due to all of the following EXCEPT a. b. c. d. e. production and subsequent removal of an RNA primer. Watson& Crick base pairing. proofreading by DNA polymerase. DNA ligase activity. mismatch repair. 5. Enzyme cascades are often activated by signal molecules. What advantage does activating a casca have over direct action by the signal molecule? a. Amplification. b. Fine tuning of regulatory effects. c. Coordinated response among multiple systems. d. All of these Two amino acids frequently found a. tyrosine and tryptophan b. serine and threonine c. 6. in B turns as well as collagen are d. glutamine and proline e. leucine and isoleucine glycine and proline 7. A single base change in mRNA: a. could have no effect at all on the resultant protein. b. could stop protein synthesis altogether. c. could cause an amino acid replacement in the resultant protein. d. could affect the three-dimensional structure of the resultant protein. e. any one or all of the above are possible. Amino acids that are classified as glucogenic can be used as a carbon source for fatty acids biosynthesis a. True b. False

Answer 1

1. (a). Alanine is a non-polar amino acid and is therefore less likely to participate in nucleophilic or electrophilic enzyme catalysis.

2. (d). Fibrous proteins have structural functions in the cell, for example, collagen is one of the most abundant proteins found in the human body and is a major component of the extracellular matrix that supports cells and give them structure.

3. (b). Biosynthesis of serine starts with 3-phosphoglycerate which is then oxidized to form 3-phosphohydroxypyruvate.

4.(a). All of the options seem to have an effect on fidelity of DNA replication. One option cannot be pinpointed since much research is still going on in the topic, however option (a) is the most suitable answer to the question out of all given options

5.(d). A direct pathway is used when you want a rapid response to the signal. But a cascade pathway has all the advantages as mentioned in the options.

6.(c). Glycine and proline are two frequently found amino acids in collagen.

7.(e) . All of the statements given are true since protein synthesis depends on the codon translated and if any of the bases in the codon is changed, it can have ant effect from stopping the translation process (if mutated triplet is now a stop codon) to changing the protein synthesized(which can further result in change of the 3-D structure of the polypeptide).

8.(b) . Ketogenic amino acids are more suited to be used as carbon sources for amino-acid synthesis compared to glucogenic amino acids.