Genetics Lesson 8-11
reconstituted TMV particles by mixing coat proteins of on strain of TMV with RNA from another strain and determining which strain led to a subsequent phenotype
An experiment was performed by Frankel-Conrat and workers to demonstrate that TMV uses RNA rather than DNA for its genetic material. What did they do?
treat extracts of type IIIS with different enzymes to look for loss of transforming factor
How is it demonstrated that DNA is the "transforming principle"?
peptide
A ____________ is composed of two or more amino acids.
throughout the cell cycle, in S phase
Bacteria synthesize DNA __________ and eukaryotes synthesize DNA __________.
proofreading
Because of __________, the error rates in DNA replication are as low as one error per 10,000 to 100,000 nucleotides.
labeled phosphorous
By labeling T2 phage with radioactive isotopes, Hershey and Chase were able to tell that DNA was the genetic material when __________ was found in the cells of test organisms.
are DNA sequences that are interchangeable between chromosomes in S. cerevisiae.
Centromeres in Saccharomyces cerevisiae:
he mutated DNA with a single nucleotide insertion and then continued to mutate the DNA until 3 total nucleotides were added, this restored frame
Crick used suppressor mutations to demonstrate the triplet nature of the genetic code. How did he do this?
both ii and iv are correct
DNA polymerase I functions as a(n): i. construction enzyme. ii. mutation enzyme. iii. repair enzyme. iv. enzyme to remove the RNA primer and replace it with DNA.
It provides the nucleotide sequence that is used to make a complementary, antiparallel strand during replication.
DNA polymerase I requires two different components of DNA, primer and template. What functions does the template component form?
has 146 nucleotide pairs of DNA wrapped around the octamer of histones.
Each nucleosome:
Protoplasts
Hershey and Chase found a significant amount of protein injected into the host cells with the DNA. To eliminate this problem, scientists can now infect __________ with pure phage.
they have now compared thousands of nucleotide sequences to the amino acid sequence of the polypeptide
How did scientists confirm in vitro assignment of codons to each amino acid?
Shine-Dalgarno sequence
How do prokaryotes identify where to start translating an mRNA?
autonomously replicating sequences.
In Saccharomyces cerevisiae, short regions of DNA have been found that act as origins of replication. These are called:
2 and 3 are correct
In eukaryotes, there are three different polymerases. What is their main difference? 1. they identify different types of introns 2. they transcribe different types of RNA 3. sensitivity to alpha-Amanatin
mRNA is translated as it is being synthesized.
In prokaryotes, which of the following is true?
Information flows from RNA to RNA to protein.
In some viruses, the central dogma of biology is altered. Which of the following is an example of this alteration?
must be precisely spliced out in order to be translated to produce the correct polypeptide. c. are spliced out of the DNA.
Introns:
labeled DNA with heavy nitrogen and then looked to see the density of the DNA after one round of replication.
Messelson and Stahl first analyzed bacterial replication to determine the mechanism of replication. They:
degenerate/ redundant
More than one codon can specify each amino acid in the genetic code. The genetic code is __________.
double ring bases, single ring bases
Purines have _______ and Pyrimidines have ______.
the same as the non-template strand, except using U instead of T.
RNA is:
Ribonucleoside monophosphates are used.
RNA synthesis occurs in a manner similar to DNA synthesis during replication except which of the following is different in RNA synthesis?
labeled DNA with thymidine and analyzed the structure during subsequent rounds of replication.
Taylor and colleagues studied replication in Vicia faba to demonstrate that replication is semiconservative on plants as well. These scientists:
contains an RNA template for telomere synthesis.
Telomerase:
folded genome
The _________ is the functional state of a bacterial chromosome.
Viroids do not have a protein coat.
The difference between RNA viruses and viroids is:
both 3 and 4 are correct
The genetic code is ordered. What does this mean? 1. all of the amino acids are coded for 2. all amino acids have four codons 3. many base substitutions at the third position do not change the amino acid coded for 4. amino acids with similar chemical properties often only differ by one base
semiconservative
The mechanism of DNA replication where each of the complementary strands from the parental double helix is conserved is termed:
gene expression
The phenotypic function of genetic material is:
linear chain of amino acids
The primary structure of a polypeptide is the:
nucleotide sequences, amino acids, unstable
The process of gene expression is defined as information stored in __________ is translated into ________ through ________ intermediates called mRNA.
complementarity
The property of _________ of the DNA double helix makes DNA uniquely suited to store and transmit genetic information from one generation to the next,
rRNA
There are 5 types of RNAs. Which type is a structural and catalytic component of the ribosome?
a left-handed structure.
There are several alternate forms of double helical DNA. The Z DNA form is:
at the 5′ end of the tRNA, there is a relaxed base pairing
There is wobble in the codon-tRNA interaction. What does wobble mean in this context?
amino acyl tRNA synthetases
What enzyme covalently bonds the correct amino acid to the tRNA?
rRNA
Which type of splicing occurs by autocatalytic splicing?
mRNA
Which type of splicing occurs by the activity of the spliceosome?
an enzymatic process by which an RNA sequence is changed to give a modified polypeptide sequence after translation
What is RNA editing?
both 2 and 3 are correct
What is a DNA renaturation experiment? 1. when DNA is bound to RNA to study transcription 2. single stranded genomic DNA is cooled so that hydrogen bonds to its complementary sequence 3. a type of experiment that can quantitate different classes of repetitive DNA 4. when DNA is subjected to X-ray diffraction
the complete replication apparatus moving along the DNA molecule at a replication fork
What is a replisome?
RNA polymerase stalls at a hairpin loop while it is transcribing an A-rich sequence.
What is a step of rho independent termination?
it binds to a STOP codon in the A site to disassociate the ribosome
What is an RF?
a combination of the replisome and the primosome in prokaryotic DNA replication
What is rolling circle replication?
break the hydrogen bonds between complementary strands
What is the function of DNA helicase in DNA replication in prokaryotes?
synthesize a free 3′ OH for DNA polymerase to use
What is the function of DNA primase in DNA replication in prokaryotes?
binds to helicase and contributes to the birection replication fork
What is the function of DnaC?
maintain DNA in a single stranded state before replication
What is the function of SSV in DNA replication in prokaryotes?
to condense the bacterial genome so it will fit into the cell
What is the function of negative supercoiling bacteria?
regulating gene expression
What is the function of nonhistone chromosomal proteins in human chromosomes?
alleviate supercoiling ahead of the replication fork
What is the function of topoisomerase in DNA replication in prokaryotes?
tRNA
What type of splicing occurs by precise endonucleolytic cleavage and ligation?
nuclein
When first discovered, J.F Miescher called the acidic substance that had high levels of nitrogen and phosphorous in cells:
the nucleolus
Where is rRNA transcribed in eukaryotes?
DNA polymerase III
Which DNA polymerase is the true DNA replicase responsible for the semiconservative replication of DNA in E. coli?
DNA ligase
Which enzyme covalently bonds a 3′-OH to a 5′ phosphorous in DNA, such as when DNA is nicked or to link Okazaki fragments together?
IF3
Which initiation factor in prokaryotes controls the ability of the 30S subunit of the ribosome to begin the initiation process?
Watson and Crick
Who deduced that the structure of DNA is a double helix?
Variable intron splicing can lead to variability in polypeptide sequence.
Which of the following is TRUE about introns?
Transcription occurs after FACT removes histone H2A and H2B.
Which of the following is TRUE about transcription in eukaryotes?
The DNA stays hydrogen bonded to itself.
Which of the following is not a step-in transcriptional initiation?
50% of the bases are purines
Which of the following is true about double stranded DNA?
the large subunit is where the catalytic activity occurs
Which of the following is true about ribosome structure?
-histones are synthesized during S phase for chromatin packaging -the cell must duplicate the nucleosome structure on the chromosome after replication -nucleosomes are dissembled right before replicating a section of DNA -eukaryotes have many more DNA polymerases than prokaryotes do
Which of the following is true of eukaryotic DNA replication?
3′ tail
Which of the following modifications to eukaryotic mRNA helps to protect the 3′ end from degradation?
5′ cap
Which of the following modifications to eukaryotic mRNA signals to the ribosome where to begin translation?
sigma factor
Which of the following subunits plays no role in chain elongation
Okazaki fragments
Which of the following would you find only on the lagging strand of DNA?
50S
Which ribosomal subunit has the catalytic function for polypeptide biosynthesis?
P
Which site in the large ribosomal subunit is where the aminoacyl-tRNA is loaded during initiation?
initiation
Which stage of transcription in eukaryotes requires transcription factors?
he performed a series of experiments that demonstrated that frame was restored when three insertions were added
Why did Crick postulate that there must be three nucleotides per codon?
some segments of the chromosomes such as centromeres and telomeres are more difficult to sequence
Why is it common to find gaps in DNA sequences of chromosomes?
2 and 3 are correct
Why is the reading frame of an mRNA important? 1. it tells the ribosome how fast to translate 2. it is the series of nucleotide triplets that are read during translation 3. if the reading frame is incorrect, the amino acid sequence will not be correct
supercoils
___________ allows DNA to be collapsed into a tight structure.