Exam 4 practice test

Who formulated the one gene-one enzyme hypothesis?

Beadle and Tatum

Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of __________.

RNA

Which statement about gene expression is true

Each amino acid in a protein is coded for by three DNA bases

When RNA is being made, the RNA base __________ always pairs with the base __________ in DNA.

U….A

Generally speaking, how many genetic codes are there?

1

What mRNA codon would be made from the DNA triplet CGT?

GCA

The number of nucleotide bases "read" together on the mRNA to designate each amino acid is _____; this unit is called a(n) __________.

three…. codon

The codons AAA, CCC, GGG, and UUU specify the amino acids lysine, proline, glycine, and phenylalanine, respectively. What peptide sequence would be encoded by the sequence 5'-CCCAAATTTGGG-3'?

pro-lys-phe-gly

How many nucleotides are needed to code for a protein with 450 amino acids?

at least 1350

In many cases, more than one codon codes for the same amino acid. Because of this, we say that the code is __________.

redundant

Bacteria can transcribe and translate human genes to produce functional human proteins because __________.

the genetic code is nearly universal

In a eukaryotic cell, transcription takes place __________.

in the nucleus

Which describes the arrangement of genetic information in a DNA molecule?

The three-nucleotide words of a gene are arranged in a non-overlapping series on the DNA template strand.

At one point, as a cell carried out its day-to-day activities, the nucleotides GAT were paired with the nucleotides CUA. This pairing occurred __________.

during transcription

Which catalyzes the linkage between ribonucleotides to form RNA during gene expression?

RNA polymerase

One strand of a DNA molecule has the following sequence: 3'-AGTACAAACTATCCACCGTC-5'. In order for transcription to occur in that strand, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated.

promoter

During the transcription of a given portion of a DNA molecule___

mRNA is synthesized on only one of the chains

In transcription, ____

-only one of the DNA strands is used as the template

-the promoter region acts as an initial binding site for RNA polymerase

-the RNA nucleotides used are produced by the cell

True or false

In bacteria, proteins called transcription factors enhance the affinity of RNA polymerase to the promoter sites of genes (false)

In eukaryotes, which mechanism of gene regulation operates after transcription, but before translation of mRNA into protein?

RNA splicing

Which accurately describes the usual process of transcription for eukaryotic genes?

Exons are transcribed, but the RNA transcribed from introns does not leave the nucleus.

Which statement correctly describes mRNA processing

Introns are cut out of the primary transcript, and the resulting exons are spliced together.

A cell biologist found that two different proteins with largely different structures were translated from two different mRNAs. These mRNAs, however, were transcribed from the same template within the cell nucleus. Which mechanism bcould best account for this?

Exons from the same gene could be spliced in different ways to make different mRNAs.

The function of tRNA during protein synthesis is to __________.

deliver amino acids to their proper site

Which summary of protein synthesis is correct?

The mRNA is made on a DNA template, and then amino-acid-bearing tRNA’s bind to it through codon-anticodon pairing.

The bonds that hold tRNA molecules in the correct three dimensional shape are ___

hydrogen bonds

During translation in a eukaryotic cell __________.

polypeptides are synthesized at ribosomes, according to instructions carried by mRNA

The P site of a ribosome does what?

It holds the tRNA carrying the growing polypeptide chain.

The first amino acid inserted into a new polypeptide chain in eukaryotic cells is usually __________.

methionine

Which is a post-translational modification of a polypeptide?

cleavage of a polypeptide into two or more chains

During translation, amino acid chain elongation occurs until ___

the ribosome encounters a "stop" codon

Polysomes may be defined as __________.

groups of ribosomes

Cells are able to distinguish proteins destined for secretion or for segregation to specific intracellular compartments from those that will remain in the cytoplasm because __________.

some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER

What is the proper order of the following events in the expression of a eukaryotic gene?
1. translation
2. RNA processing
3. transcription
4. modification of protein

3, 2, 1, 4

The mRNA codons 5'-CAA-3' or 5'-CAG-3' are translated as the amino acid glutamine by __________.

the same tRNA with the anticodon 3'-GUU-5'

Which statement regarding the structure and function of tRNA is false?

Although each tRNA consists of a relatively short, single RNA strand, this single strand can achieve a three-dimensional structure by folding back upon itself and forming covalent bonds between complementary bases.

A geneticist found that a particular mutation had no effect on the polypeptide encoded by the gene. This mutation probably involved __________.

a silent or neutral mutation

A base-pair substitution mutation in a germ cell line is likely to have NO effect on phenotype if the substitution __________.

occurs in an intron

A virus infects a cell and randomly inserts many short segments of DNA containing a stop codon throughout an organism's chromosomes. This will probably cause __________

manufactured proteins to be short and defective

A point mutation in which a single base pair is inserted or deleted from DNA is called a(n) __________.

frame-shift mutation

Ultraviolet (UV) radiation is damaging to cells because it __________.

causes mutations in the DNA

Transcription factors are found in __________.

archaea and eukaryotes

When genes are expressed, they produce __________.

RNA molecules + polypeptides

What is a key difference in gene expression between eukaryotic and prokaryotic cells?

In prokaryotic cells, the mRNA transcript is immediately available as mRNA without processing.