Exam #2
What molecule indirectly provides energy for translation
ATP
Which is false when comparing DNA and RNA?
Both are composed of the same types of nucleotides
Which relationship about nucleotide composition in DNA is correct?
C+A=G+T
Which of the following is not an accurate description of a checkpoint that controls the progression of the cell cycle?
Cytokinesis involves the formation if cleavage furrow to separate cells
Which molecule is responsible for separating double-stranded DNA into single strands?
DNA helicase
Which is not a critical factor for DNA replication of the leading strand?
DNA ligase
During DNA replication, proteins that are important for separating the DNA strands and allowing movement of the replication fork include each of these except
DNA polymerase
Which produces short sequences of RNA which allows polymerase to synthesize a new strand of DNA?
DNA primase
A strand of DNA is composed of nucleotide bases, sulfate groups, and sugars
False
If there is 28% adenine then there must be 28% cytosine for the DNA composition of a particular organism
False
Leigh syndrome is a human disease that is characterized by mental impairment and progressive loss of movement abilities. People with Leigh syndrome have a mutation in one of several genes that encode the proteins needed for the electron transport chain. What effect would these mutations have on the function of the cell?
Fewer ATP molecules would be produced by ATP synthase than usual
Which statement about tRNA is FALSE?
Functional tRNAs have been spliced by splicesomes
Which statement accurately describes transcription by RNA polymerase?
It is possible for one RNA polymerase to transcribe one strand of DNA in the 5' to 3' direction and another RNA polymerase to transcribe the complementary strand of DNA in the 5' to 3' direction, producing two different transcripts
Which statement about DNA replication is incorrect?
It is powered by hydrolysis of ATP
When does the small ribosomal subunit bind to the transitional complex in eukaryotic cells?
It is the first component to bind to the mRNA
Why must the life cycle of sexually reproducing species alternate between haploid and diploid stages?
Meiosis must occur at some point in the life cycle to prevent a doubling of chromosomes in each generation
The following mRNA transcript would result in which polypeptide sequence? 5' ACU UUC ACU AUG UUU UUA UCC UCC ACU CCU UGA 3'
Met-Phe-Leu-Ser-Ser-Thr-Pro
Which of the following statements about the structure or composition of DNA is false?
The amount of thymine closely approximates that of guanine within a particular organism
If a DNA template strand has a sequence of 3' TACAATGTAGCC 5', the RNA produced from it will be which sequence?
5' AUGUUACAUCGG 3'
The process by which haploid cells are produced from diploid cells is called
meiosis
Beginning with the simplest level of structure, which order of organization of genetic material is correct?
nucleotide, double helix, strand, chromosome, genome
The building blocks of DNA are
nucleotides
Bacteria are grown in ^15 N (heavy) medium and then transferred to ^14 N (light) medium and are allowed to replicate for 2 generations. The DNA is subsequently isolated and centrifuged in a CsCl2 gradient to yield what type of gradient bands?
one light and one half-heavy band
The amino acids of a growing polypeptide chain are held together by what kind of bond during the elongation stage of translation?
peptide
The nucleotides within DNA are composed of a
phosphate group, deoxyribose sugar, nitrogenous base
In a single stand of DNA, nucleotides are connected by what type of bond?
phosphodiester
In a eukaryotic cell, the direct product of transcription is
pre-mRNA
Transcription begins near a site in the DNA called the
promoter
What is NOT involved in translation?
protein polymerase
Because more than one codon can specify the same amino acid, the genetic code is said to be
redundant
Which of the following are used by the cell to recognize the stop codon and terminate translation?
release factors
What is not a protein involved in DNA replication?
replication fork
Which is involved in replicating the lagging stand of DNA but is not involved in leading stand DNA replication?
ribosome
The mechanism of DNA replication is
semiconservative
What serves as the "translator" or intermediary between an mRNA codon and an amino acid (ie, what interacts with the mRNA and brings the amino acid to the ribosome)?
tRNA
Which statement about the 5' cap and mRNA processing is TRUE?
the addition of a 5' cap to mRNA occurs while the pre-mRNA is being made
When considering the complexity of genetic material, two strands of DNA are twisted to form a double helix
true
Which statement about RNA processing in eukaryotes is INCORRECT?
The excision of introns from pre-mRNA is the only modification required to produce a mature mRNA
What is the function of the poly A tail?
The poly A tail increases mRNA stability in eukaryotes by protecting it from hydrolysis, catalyzed by a protease, in the cytosol
Which statement about the mRNA start codon is INCORRECT?
The start codon is usually GGA
The term N-terminus refers to the presence of what functional group at one of the ends of the polypeptide?
amino group
What enzyme catalyzes the attachment of amino acids to tRNA molecules?
aminoacyl-tRNA synthase
Consider a diploid species where n=5. If an individual of this species was found to have 11 chromosomes, it would be categorized as
aneuploid
You prepare the first ever karyotype of an endangered species of frog. Upon examination you find that all the chromosomes are meta metacentric. This is going to make it difficult to identify
both p and q arms of the chromosomes
Which of the following is not a part of the mitotic spindle apparatus in plants?
centrioles
The formation of the bivalent during meiosis
contributes to the genetic diversity of a species
Eukaryotic ribosomes most often function in the
cytosol
The process of transcription and translation are collectively known as
gene expression
Which feature of DNA represents the highest (or most complex) level of structure?
genome
Which purine base forms 3 hydrogen bonds when binding its complementary nucleotide base?
guanine
The major way that meiosis II differs from mitosis is that
in meiosis II, the cells are haploid
Intervening sequences that are transcribed, but not translated into protein are called
introns
Which statement about RNA polymerase in bacteria is INCORRECT?
it catalyzes the addition of nucleotides to the 5' end of a growing RNA strand
Which molecule catalyzes covalent bond formation between fragments of DNA?
ligase
The actions of DNA helicase and DNA topoisomerase both promote the unwinding and uncoiling of DNA
True
Which of the following statements about the cell cycle is correct?
When the S phase of the cell cycle is finished, a cell has twice as much DNA as it did during the G1 phase
Without the work of Rosalind Franklin, Watson and Crick would not have known
Which nucleotides could pair together, how many strands of DNA made up the molecule, the shape of the molecule, and the width of the molecule
During crossing over in meiosis. an unequal exchange of genetic material occurs. This would most likely produce
a deficiency in one homologoue and a duplication in the other homologue
An mRNA sequence is 5' AUG GGC ACU CAU ACU UAA 3'. How many distinct aminoacyl-tRNA synthetases are required to translate the mRNA sequence?
4
What protein synthesizes messenger RNA in eukaryotes?
RNA polymerase II
Which is not a result of DNA polymerase III function?
Removal of RNA primers
Place the following events of mitosis in the correct order
Sister chromatids begin to condense, Nuclear membrane breaks up, sister chromatids align on the metaphase plate, sister chromatids separate, cleavage furrow forms
Which of the following statements is false concerning sister chromatids?
Sister chromatids separate during anaphase I of meiosis
DNA polymerase can be described as an enzyme that
adds nucleotides to the 3' end of a growing DNA strand
All of these nucleotide bases are pyrimidines except?
adenine
A unit of DNA sequence that is transcribed into RNA and ultimately results in the formation of a functional protein product is called a
gene
Which part of a gene contains the information that specifies an amino acid sequence?
transcribed region
The process that produces mRNA from DNA is called
transcription
What protein communicates to RNA polymerase to begin to transcribe genes?
transcription factors
Consider an organism whose diploid karyotype shows it to have a total of 60 chromosomes. How many chromosomes would be contained in the sperm of this organism?
30
How many replication forks are there at an origin of replication?
2
A DNA specimen that contains 30% guanine has ______ thymine
20%
Humans have ___ pairs of autosomes
22
Humans have ___ pairs of chromosomes
23
How many nucleotides make up a single codon?
3
Which statement describes a reason ribosomal genes are useful for comparing evolutionary relationships among organisms?
All organisms possess these genes and they can be compared with each other
What process enables a single gene to encode two or more polypeptides that are different in their amino acid sequence?
Alternative splicing (exon shuffling)
What was one of the pieces of evidence most critical to the discovery of DNA structure?
An X-ray diffraction pattern suggesting double helix shape
Which statement about DNA is false?
One chromosome is made up of many DNA molecules
Bacteria are grown in ^15 N (heavy) medium and then transferred to ^14 N (light) medium and are allowed to replicate for 1 generation. The DNA is subsequently isolated and centrifuged in a CsCl2 gradient to yield what type of gradient bands?
One half-heavy (between light and heavy) band
Why is there a need to produce Okazaki fragments on the lagging strand but not on the leading strand of DNA?
The two parental strands of DNA are anti parallel and DNA polymerase makes DNA in the 5' to 3' direction only
DNA is a double helix structure whose strands are held together by hydrogen bonds with A to T and C to G base pairing
True
At the end of meiosis I
the cells are haploid and the homologous pairs are in separate cells
Cytogenetics is
the field of genetics that involves the microscopic examination of chromosomes and cell division
In a haploid dominant species
the multicellular organism is haploid, and only the zygote is diploid
Which of these proteins is not matched with the correct function?
topoisomerase -> separates double-stranded DNA into single strands