Practice Set 3

Question 1

Before the completion of the human genome project, it was generally estimated that
human DNA would contain up to 100,000 genes. We now know humans contain only
around 25,000 individual genes within our genomes. This “gene count” is so surprising
because:

Answer 1

All Answers Correct

A) simple roundworms have over 10,000 genes, so humans should have many more.

B) experimental analysis of mRNA diversity generated estimates of ~100,000 genes.

C) humans have a large genome size (3.3 ´ 109 base pairs).

D) the diverse types of tissue in humans require many thousands of genes.

Question 2

The splicesome functions to:

Answer 2

remove non-coding introns from transcribed RNAs.

Question 3

Template strand DNA and encoded RNA are:

Answer 3

complimentary of one another with antiparallel orientation.

Question 4

In what cellular compartment are introns removed from pre-mRNA to make mature
mRNA?

Answer 4

Nucleus

Question 5

If the DNA template 5’-ATGCATGC-3’ were transcribed to RNA, the RNA would read:

Answer 5

3’ UACGUACG 5’

Question 6

The splicesome includes both protein and a functional type of RNA known as:

Answer 6

small nuclear RNAs (snRNAs).

Question 7

The role of tRNA is:

Answer 7

to act as transporters bringing amino acids to the site of protein synthesis.

Question 8

In a chromosome, which of the following is true?

Answer 8

RNAs of different genes can be transcribed off either DNA strand, but always 5’ to 3’.

Question 9

Which of the following acts before the others?

Answer 9

RNA polymerase

Question 10

The -10 and -35 boxes found in most bacterial promoter elements were discovered by

Answer 10

comparing the DNA sequences in front of highly expressed genes and determining
nucleic acids that were common (consensus).

Question 11

A key characteristic of bacterial RNAs that is not observed with eukaryotic RNAs is
that:

Answer 11

transcription can occur in the same cellular region as translation.

Question 12

The carboxyl tail domain of RNA polymerase II plays a key role in:

Answer 12

all of the above.

Question 13

What is the function of the TATA binding protein?

Answer 13

Allows eukaryotic RNA polymerase II to bind to the promoter of genes

Question 14

In what cellular compartment are introns removed from pre-mRNA to make mature
mRNA?

Answer 14

Nucleus

Question 15

Which of the following constitutes the primary structure of a protein?

Answer 15

The linear sequence of amino acids in a polypeptide chain

Question 16

How many nucleotides would be expected for a gene coding for a protein with 300
amino acids?

Answer 16

900

Question 17

Two gametes, each carrying a mutant recessive allele for a different gene/enzyme in the
adenine biosynthetic pathway, come together to form a diploid embryo. The individual
derived from this embryo will display a:

Answer 17

wild-type phenotype, capable of synthesizing adenine.

Question 18

A biochemical pathway making flower pigments shows the following sequential color
conversions (each arrow represents an enzyme catalyzed step).
Colorless
→ yellow → blue → red
A B C
A plant is homozygous for mutations in enzyme “B,” inactivating the active site for this
enzyme. The resulting flowers will be:

Answer 18

yellow.

Question 19

The anticodon on the tRNA molecule:

Answer 19

binds to the mRNA in a complementary fashion.

Question 20

The ribosome is the primary site of

Answer 20

protein synthesis.