Question

1. which of the following statements is true?

a. ribosomes read mrna from the 5 to the 3 end and synthesize the nascent (growing) protein chain from the carboxyl to the amino terminus.
b. ribosomes read mrna from the 3 to the 5 end and synthesize the nascent protein chain from the amino to the carboxyl terminus.
c. ribosomes read mrna from the 5 to the 3 end and synthesize the nascent protein chain from the amino to the carboxyl terminus.
d. ribosomes read mrna from the 3 to the 5 end and synthesize the nascent protein chain from the carboxyl to the amino terminus.
e. ribosomes read dna from the 5 to the 3 end and synthesize the nascent rna chain from the 3 to the 5 end.

1. the following are needed for a eukaryotic chromosome to be replicated and segregated in mitosis

a. telomeres.
b. origin of dna replication.
c. centromere.
d. all of the above are required.
e. both a and b are required.

1. in the genetic code there are

a. more trnas than codons.
b. more different nucleotides than codons.
c. more codons than amino acids.
d. the same number of codons and amino acids
e. fewer codons that amino acids.

1. what kind of bond is typified by the sharing of electrons?

a. ionic bond
b. polar covalent bond
c. h - bond
d. nonpolar covalent bond
e. both b and d are correct answers.

1. which of the following enzymes catalyze the attachment of an amino acid to trna in the formation of aminoacyl trna?

a. rna polymerase
b. aminoacyl trna synthetase
c. helicase
d. amino peptidase
e. kinase

1. promoters ____ and ____.

a. bind transcription factors, specify which strand of dna to transcribe
b. bind rna polymerases, specify which strand of dna to translate
c. specify the site at which translation begins, determine the length of new polypeptide
d. bind to stop codons, determine the length of new polypeptide
e. bind to dna, specify which strand of dna to transcribe

1. which of the following is a list of pyrimidines?

a. uracil, adenine, cytosine
b. uracil, guanine, cytosine
c. thymine, adenine, cytosine
d. thymine, uracil, cytosine
e. thymine, guanine, uracil

Explanation:

• Question 40: Ribosomes read mRNA in the 5' to 3' direction and synthesize the protein chain from the amino - to the carboxyl - terminus. Option c is correct.
• Question 41: Telomeres, origin of DNA replication, and centromere are all required for a eukaryotic chromosome to be replicated and segregated in mitosis. Option d is correct.
• Question 42: There are 64 codons and 20 standard amino acids. So there are more codons than amino acids. Option c is correct.
• Question 43: Polar covalent bonds and non - polar covalent bonds involve sharing of electrons. Option e is correct.
• Question 44: Aminoacyl tRNA synthetase catalyzes the attachment of an amino acid to tRNA to form aminoacyl tRNA. Option b is correct.
• Question 45: Promoters bind to DNA and specify which strand of DNA to transcribe. Option e is correct.
• Question 46: Pyrimidines include thymine, uracil, and cytosine. Option d is correct.

Answer:

• Question 40: c. Ribosomes read mRNA from the 5' to the 3' end and synthesize the nascent protein chain from the amino to the carboxyl terminus.
• Question 41: d. All of the above are required.
• Question 42: c. more codons than amino acids.
• Question 43: e. Both b and d are correct answers.
• Question 44: b. aminoacyl tRNA synthetase
• Question 45: e. bind to DNA, specify which strand of DNA to transcribe
• Question 46: d. thymine, uracil, cytosine