Question

QUESTION 13 What chemical group is at the end of an amino acid chain corresponding to the 3' end of the mRNA molecule? A. Peptide bond B.5 phosphate group C.3" hydroxyl group D. Amino (N-terminus) E. Carboxyl (C-terminus) QUESTION 14 Which of the following is true regarding pre-mRNA modifications/processing? O A. Alternative splicing allows for increased complexity and synthesis of protein isomers OB. The 5' cap is added after RNA polymerase dissociates from the gene OC. The poly A tail is necessary for recognition by the small ribosomal subunit OD. The 5' cap is necessary for recognition by the small ribosomal subunit E. A and D

Answer 1

QUESTION 13-

E. Carboxyl (C-terminus) - The C-terminus is the end of an amino acid chain (protein or polypeptide), terminated by a free carboxyl group (-COOH). and mRNA codons are read from 5' to 3' , and they specify the order of amino acids in a protein from N-terminus (methionine) to C-terminus.

QUESTION 14-

D. 5' cap is necessary for recognition by the small ribosomal subunit- the cap plays a role in the ribosomal recognition of messenger RNA during translation into a protein which attributed to protein factors that bind specifically to the cap structure: the cap-binding complex (CBC) in the nucleus and eIF4E in the cytoplasm.

A. The open reading frame (ORF) encodes the polypeptides: N-met-asp-phe-C: since start codon AUG codes for met , GAC codes for asp and UUC codes for phe then stop codon UGA comes and chain terminates.

QUESTION 15-

B. AUG/release factor- translation initiates when ribosomes recognises the 1st AUG start codon codes for metheonine.Termination happens when a stop codon in the mRNA (UAA, UAG, or UGA) enters the A site. Stop codons are recognized by proteins called release factors.

A. Phasphodiester/peptide-

Nucleotides are linked together by the formation of a phosphodiester bond which is formed between the 3' -OH group of one sugar molecule, and the 5' phosphate group on the adjacent sugar molecule. This results in a loss of a molecule of water, making this a condensation reaction, also called a dehydration synthesis.

The bond that holds together the two amino acids is a peptide bond, It occurs when the carboxylic group of one molecule reacts with the amino group of the other molecule, linking the two molecules and releasing a water molecule.

QUESTION 27-

D. Quartenary- The quaternary structure of a hemoglobin molecule includes four tertiary structure protein chains, Most of the amino acids in hemoglobin form alpha helices, and these helices are connected by short non-helical segments.. Individually, each alpha helix is a secondary polypeptide structure made of amino acid chains. The amino acids are in turn the primary structure of hemoglobin.