bio questions

The anticodon of a particular tRNA molecule is __________.

complementary to the corresponding mRNA codon

In eukaryotic cells, transcription CANNOT begin until __________.

several transcription factors have bound to the promoter

Which of the following mutations would likely be most dangerous to a cell?

Deletion of one nucleotide

Which of the following is NOT true of a codon? It may code for the same amino acid as another codon. It is the basic unit of the genetic code. It extends from one end of a tRNA molecule. It never codes for more than one amino acid.

It extends from one end of a tRNA molecule.

which of the following molecules are produced by transcription?

Messenger RNA Ribozymes

The average length of a transcription unit along a eukaryotic DNA molecule is about 27,000 nucleotide pairs, whereas an averaged-sized protein is about 400 amino acids long. What is the best explanation for this fact?

Most eukaryotic genes and their RNA transcripts have long noncoding stretches of nucleotides that are not translated

Which of the following molecules is/are produced by translation? Include molecules that are subject to further modification after initial synthesis.

RNA polymerase Aminoacyl-tRNA synthetase

Which of the following mutations would be MOST likely to have a harmful effect on an organism? a single nucleotide insertion downstream of, and close to, the start of the coding sequence a single nucleotide deletion near the end of the coding sequence a single nucleotide deletion in the middle of an intron a deletion of three nucleotides near the middle of a gene

a single nucleotide insertion downstream of, and close to, the start of the coding sequence

Which of the following is a (are) normal feature(s) of eukaryotic mRNA? 5′ cap poly-A tail 5′ UTR 3′ UTR all of the above

all

The nontemplate strand of a portion of a gene reads 5′ ACTGGTTCA. What will be the sequence of the resulting transcript for this portion? 5′ UGACCAAGU 5′ ACUGGUUCA 5′ UGAACCAGU 5′ ACUUGGUCA

b

When a mutation caused by a nucleotide pair substitution occurs in a protein coding region, which of the following effects can not occur? silent frameshift missense nonsense All are possible.

b

Which of the following is the best example of gene expression? A frog adapts to variation in its environmental temperature. Mouse fur color results from pigment formed by gene-encoded enzymes. DNA is replicated during the S phase of the cell cycle. The percent of A versus a alleles in a population is altered by natural selection. Mutation alters the sequence of a region of DNA.

b

In which group(s) of organisms would you expect to see polyribosomes? prokaryotes eukaryotes both neither

both

How many amino acyl tRNA synthetases should there be? 64 61 20 3

c

What kind of molecules are transcription factors? DNA RNA proteins lipids

c

During a normal translation cycle, where would you expect to find a polypeptide on a ribosome? on a tRNA attached to the E site on a tRNA attached to the P site on a tRNA attached to the A site alternating between tRNAs attached to the P site and tRNAs attached to the A site

d

Where does RNA polymerase begin transcribing a gene into mRNA? It looks for the AUG start codon. It starts at one end of the chromosome. Transfer RNA acts to translate the message to RNA polymerase. The ribosome directs it to the correct portion of the DNA molecule. It starts after a certain nucleotide sequence called a promoter.

d

Which component is NOT directly involved in translation? Which component is NOT directly involved in translation? GTP tRNA DNA ribosomes

dna

When a mutation caused by a nucleotide pair insertion occurs in a protein coding region, which of the following effects can not occur? silent frameshift missense nonsense All are possible.

silent

A codon consists of __________ bases and specifies which __________ will be inserted into the polypeptide chain. four ... fatty acid two ... nucleotide four ... amino acid three ... amino acid three ... nucleotide

three ... amino acid