EBIO 2070 Exam 2 CU Boulder
questions and answers(graded
A+)
Describe the roles and modes of action of the following components of the
translation apparatus: tRNA, aminoacyl-tRNA synthetase, small ribosomal
subunit, large ribosomal subunit, release factor. - answer tRNA: Contain an
attachment site for a specific amino acid and an anticodon that is
complimentary and antiparallel to one of the codons for that amino acid
aminoacyl-tRNA synthetase: Attaches an amino acid to its tRNA to form a
"Charged" tRNA
small ribosomal subunit: The small subunit to the ribosome attaches to
the 5' cap and "scans" for a start codon in the proper sequence
large ribosomal subunit: Associates with the small subunit spanning the
start codon
release factor: Recognize the stop codon and a water molecule causes the
release of the polypeptide from the tRNA.
Roles of ribosomes in the translation apparatus - answer *Recognize start
codon
*Stabilize tRNA-mRNA interactions
*Pepidyl transferase activity (acts as ribozymes)
*Move along mRNA in 5' to 3' direction
The mRNA moves in the ribosome in what direction - answer 5' to 3'
,Describe the processing of microRNAs and the mechanisms by which they
inhibit translation - answer In Animals, microRNAs bind to the 3'UTR of
multiple mRNA targets with partial pairing. Binding of microRNAs to mRNA
targets can inhibit translation by multiple mechanisms (cutting mRNA into
two segments, loss of poly-A tail causing degradation, blocking initiation
of translation and more)
Why do Eucaryotes have nucleosomes, splicing of introns, 5' caps, Polly A
tails, and microRNAs?
A) they allow a more complex regulation of gene expression
B) they represent very little cost to the organism and therefor are difficult
to eliminate through natural selection
C) they represent a defense against parasitic nucleic acids ( viruses and
transposable elements) - answer A
What does it mean that DNA replication is a semiconservative process? -
answer DNA is semiconservative because each of the Double Helix's being
formed has one old strand and one new strand.
Identify the roles and activities of the major proteins involved in DNA
replication in E.Coli - answer 1. initiator protein bind to the ORIGIN OF
REPLICATION
2. DNA HELICASE unwinds DNA
3. SINGLE-STRAND-BINDING PROTEINS bind to separate strands so they
don't come back together
4. GYRASE (a TOPOISOMERASE) relaxes DNA supercoiling
, 5. DNA PRIMASE synthesizes a short RNA PRIMER
6. DNA POLYMERASE adds nucleotides to the 3' end of the RNA primer
leading strand - answer the new complementary DNA strand synthesized
continuously along the template strand toward the replication fork in the
mandatory 5' to 3' direction
lagging strand - answer A discontinuously synthesized DNA strand that
elongates by means of Okazaki fragments, each synthesized in a 5' to 3'
direction away from the replication fork.
Haploid - answer (1n) having one set of chromosomes (egg and sperm)
Diploid - answer (2n) having two sets of chromosomes from each parent
Homologous chromosomes - answer Contain the same genes
Genome - answer the complete compliment of genetic information (DNA)
in a haploid chromosome set
Stages of Mitosis: Interphase - answer 2n, 2c Replication is going on in
this step
Stages of Mitosis: Prophase - answer 2n, 4c There are 4 sister chromatids
together forming two chromosomes
Stages of Mitosis: Metaphase - answer 2n, 4c The two chromosomes line
up horizontally
Stages of Mitosis: Anaphase - answer 4n, 4c The four sister chromatids
separate from each other making four chromosomes
questions and answers(graded
A+)
Describe the roles and modes of action of the following components of the
translation apparatus: tRNA, aminoacyl-tRNA synthetase, small ribosomal
subunit, large ribosomal subunit, release factor. - answer tRNA: Contain an
attachment site for a specific amino acid and an anticodon that is
complimentary and antiparallel to one of the codons for that amino acid
aminoacyl-tRNA synthetase: Attaches an amino acid to its tRNA to form a
"Charged" tRNA
small ribosomal subunit: The small subunit to the ribosome attaches to
the 5' cap and "scans" for a start codon in the proper sequence
large ribosomal subunit: Associates with the small subunit spanning the
start codon
release factor: Recognize the stop codon and a water molecule causes the
release of the polypeptide from the tRNA.
Roles of ribosomes in the translation apparatus - answer *Recognize start
codon
*Stabilize tRNA-mRNA interactions
*Pepidyl transferase activity (acts as ribozymes)
*Move along mRNA in 5' to 3' direction
The mRNA moves in the ribosome in what direction - answer 5' to 3'
,Describe the processing of microRNAs and the mechanisms by which they
inhibit translation - answer In Animals, microRNAs bind to the 3'UTR of
multiple mRNA targets with partial pairing. Binding of microRNAs to mRNA
targets can inhibit translation by multiple mechanisms (cutting mRNA into
two segments, loss of poly-A tail causing degradation, blocking initiation
of translation and more)
Why do Eucaryotes have nucleosomes, splicing of introns, 5' caps, Polly A
tails, and microRNAs?
A) they allow a more complex regulation of gene expression
B) they represent very little cost to the organism and therefor are difficult
to eliminate through natural selection
C) they represent a defense against parasitic nucleic acids ( viruses and
transposable elements) - answer A
What does it mean that DNA replication is a semiconservative process? -
answer DNA is semiconservative because each of the Double Helix's being
formed has one old strand and one new strand.
Identify the roles and activities of the major proteins involved in DNA
replication in E.Coli - answer 1. initiator protein bind to the ORIGIN OF
REPLICATION
2. DNA HELICASE unwinds DNA
3. SINGLE-STRAND-BINDING PROTEINS bind to separate strands so they
don't come back together
4. GYRASE (a TOPOISOMERASE) relaxes DNA supercoiling
, 5. DNA PRIMASE synthesizes a short RNA PRIMER
6. DNA POLYMERASE adds nucleotides to the 3' end of the RNA primer
leading strand - answer the new complementary DNA strand synthesized
continuously along the template strand toward the replication fork in the
mandatory 5' to 3' direction
lagging strand - answer A discontinuously synthesized DNA strand that
elongates by means of Okazaki fragments, each synthesized in a 5' to 3'
direction away from the replication fork.
Haploid - answer (1n) having one set of chromosomes (egg and sperm)
Diploid - answer (2n) having two sets of chromosomes from each parent
Homologous chromosomes - answer Contain the same genes
Genome - answer the complete compliment of genetic information (DNA)
in a haploid chromosome set
Stages of Mitosis: Interphase - answer 2n, 2c Replication is going on in
this step
Stages of Mitosis: Prophase - answer 2n, 4c There are 4 sister chromatids
together forming two chromosomes
Stages of Mitosis: Metaphase - answer 2n, 4c The two chromosomes line
up horizontally
Stages of Mitosis: Anaphase - answer 4n, 4c The four sister chromatids
separate from each other making four chromosomes
