BS 161 Chapter 3 questions with verified answers
5' cap Ans✓✓✓ The modification of the 5′ end of the primary transcript by the
addition of a special nucleotide (7-methylguanosine) attached in an unusual
chemical linkage (the cap is linked to the RNA transcript by a triphosphate bridge
between the 5′ carbons of both ribose sugars).
essential for translation because in eukaryotes the ribosome recognizes an mRNA
by its 5′ cap. Without the cap, the ribosome would not attach the mRNA and
translation would not occur.
helps stabilize the RNA transcript
A cell that is deficient in ribosomes is unable to complete what process?
Choice A., transcription
Choice B., translation
Choice C., replication
Choice D., transformation Ans✓✓✓ tranformation
A segment of one strand of a double-stranded DNA molecule has the sequence 5′-
ACTTTCAGCGAT-3′. What is the sequence of an RNA molecule synthesized from
this DNA template? Ans✓✓✓ The RNA transcript has the sequence:
5′-AUCGCUGAAAGU-3′.
A single unit of heredity that contains the information for an individual protein is
referred to as a... Ans✓✓✓ gene!
,A template strand of DNA is read in the _____ direction in order to direct
synthesis of RNA in the _____ direction.
3'-5'; 5'-3'
5'-3'; 3'-5'
5'-3'; 5'-3'
3'-5'; 3'-5' Ans✓✓✓ 3'-5'; 5'-3'
A transcribed region of DNA has a 5' to 3' sequence TTCATGGCGAC. The 5' to 3'
sequence of an RNA transcribed from this DNA would be 5'_______3'. Ans✓✓✓
GUCGCCAUGAA
All nucleic acids are synthesized by addition of nucleotides to the __ end.
Ans✓✓✓ All nucleic acids are synthesized by addition of nucleotides to the 3′
end. That is, they grow in a 5′-to-3′ direction, also described simply as the 3′
direction.
alternative splicing Ans✓✓✓ A process in which primary transcripts from the
same gene can be spliced in different ways to yield different mRNAs and therefore
different protein products.
More than 80% of human genes are alternatively spliced.
In most cases, the alternatively spliced forms differ in whether a particular exon is
or is not removed from the primary transcript along with its flanking introns.
,An intron is:
a polypeptide that is clipped out of a larger protein post-translationally.
part of an intact, mature mRNA that leaves the nucleus.
an RNA sequence that is removed during the processing of an RNA molecule in
the nucleus.
a type of transfer RNA.
part of an RNA transcript that is not present in the DNA template. Ans✓✓✓ an
RNA sequence that is removed during the processing of an RNA molecule in the
nucleus
An RNA transcript is synthesized in which direction?
3' to 5'
N terminus to C terminus
5' to 3'
5' to 5'
C terminus to N terminus Ans✓✓✓ 5' to 3'
, As we will see, it is the ______________ of DNA that accounts for differences in
genes. Ans✓✓✓ As we will see, it is the order of individual subunits (bases) of
DNA that accounts for differences in genes.
Base stacking Ans✓✓✓ Stabilizing hydrophobic interactions between bases in the
same strand of DNA.
Occurs because the nonpolar, flat surfaces of the bases tend to group together
away from water molecules, and hence stack on top of one another as tightly as
possible.
Central dogma figure Ans✓✓✓
chemical differences b/w RNA and DNA Ans✓✓✓ First, the sugar in RNA is ribose,
which carries a hydroxyl group on the 2′ carbon (highlighted in pink in Fig. 3.13a).
Hydroxyls are reactive functional groups, so the additional hydroxyl group on
ribose in part explains why RNA is a less stable molecule than DNA.
Second, the base uracil in RNA replaces thymine in DNA (Fig. 3.13b). The groups
that participate in hydrogen bonding (highlighted in pink in Fig. 3.13b) are
identical so that uracil pairs with adenine (U-A) just as thymine pairs with adenine
(T-A).
Third, while the 5′ end of a DNA strand is typically a monophosphate, the 5′ end
of an RNA molecule is typically a triphosphate.
chromatin Ans✓✓✓ A complex of DNA, RNA, and proteins that gives
chromosomes their structure; chromatin fibers are either 30 nm in diameter or, in
a relaxed state, 10 nm.
5' cap Ans✓✓✓ The modification of the 5′ end of the primary transcript by the
addition of a special nucleotide (7-methylguanosine) attached in an unusual
chemical linkage (the cap is linked to the RNA transcript by a triphosphate bridge
between the 5′ carbons of both ribose sugars).
essential for translation because in eukaryotes the ribosome recognizes an mRNA
by its 5′ cap. Without the cap, the ribosome would not attach the mRNA and
translation would not occur.
helps stabilize the RNA transcript
A cell that is deficient in ribosomes is unable to complete what process?
Choice A., transcription
Choice B., translation
Choice C., replication
Choice D., transformation Ans✓✓✓ tranformation
A segment of one strand of a double-stranded DNA molecule has the sequence 5′-
ACTTTCAGCGAT-3′. What is the sequence of an RNA molecule synthesized from
this DNA template? Ans✓✓✓ The RNA transcript has the sequence:
5′-AUCGCUGAAAGU-3′.
A single unit of heredity that contains the information for an individual protein is
referred to as a... Ans✓✓✓ gene!
,A template strand of DNA is read in the _____ direction in order to direct
synthesis of RNA in the _____ direction.
3'-5'; 5'-3'
5'-3'; 3'-5'
5'-3'; 5'-3'
3'-5'; 3'-5' Ans✓✓✓ 3'-5'; 5'-3'
A transcribed region of DNA has a 5' to 3' sequence TTCATGGCGAC. The 5' to 3'
sequence of an RNA transcribed from this DNA would be 5'_______3'. Ans✓✓✓
GUCGCCAUGAA
All nucleic acids are synthesized by addition of nucleotides to the __ end.
Ans✓✓✓ All nucleic acids are synthesized by addition of nucleotides to the 3′
end. That is, they grow in a 5′-to-3′ direction, also described simply as the 3′
direction.
alternative splicing Ans✓✓✓ A process in which primary transcripts from the
same gene can be spliced in different ways to yield different mRNAs and therefore
different protein products.
More than 80% of human genes are alternatively spliced.
In most cases, the alternatively spliced forms differ in whether a particular exon is
or is not removed from the primary transcript along with its flanking introns.
,An intron is:
a polypeptide that is clipped out of a larger protein post-translationally.
part of an intact, mature mRNA that leaves the nucleus.
an RNA sequence that is removed during the processing of an RNA molecule in
the nucleus.
a type of transfer RNA.
part of an RNA transcript that is not present in the DNA template. Ans✓✓✓ an
RNA sequence that is removed during the processing of an RNA molecule in the
nucleus
An RNA transcript is synthesized in which direction?
3' to 5'
N terminus to C terminus
5' to 3'
5' to 5'
C terminus to N terminus Ans✓✓✓ 5' to 3'
, As we will see, it is the ______________ of DNA that accounts for differences in
genes. Ans✓✓✓ As we will see, it is the order of individual subunits (bases) of
DNA that accounts for differences in genes.
Base stacking Ans✓✓✓ Stabilizing hydrophobic interactions between bases in the
same strand of DNA.
Occurs because the nonpolar, flat surfaces of the bases tend to group together
away from water molecules, and hence stack on top of one another as tightly as
possible.
Central dogma figure Ans✓✓✓
chemical differences b/w RNA and DNA Ans✓✓✓ First, the sugar in RNA is ribose,
which carries a hydroxyl group on the 2′ carbon (highlighted in pink in Fig. 3.13a).
Hydroxyls are reactive functional groups, so the additional hydroxyl group on
ribose in part explains why RNA is a less stable molecule than DNA.
Second, the base uracil in RNA replaces thymine in DNA (Fig. 3.13b). The groups
that participate in hydrogen bonding (highlighted in pink in Fig. 3.13b) are
identical so that uracil pairs with adenine (U-A) just as thymine pairs with adenine
(T-A).
Third, while the 5′ end of a DNA strand is typically a monophosphate, the 5′ end
of an RNA molecule is typically a triphosphate.
chromatin Ans✓✓✓ A complex of DNA, RNA, and proteins that gives
chromosomes their structure; chromatin fibers are either 30 nm in diameter or, in
a relaxed state, 10 nm.
