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44 terms

Chapter 10 Genetics CROC

DNA Structure & Analysis
STUDY
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What observation did Griffith make in his experiments with Streptococcus pneumoniae?
The mouse did not survive when injected with a mixture of live, avirulent (smooth) Streptococcus pneumoniae and heat‑killed, virulent Streptococcus pneumoniae.
What results did Avery, McLeod, and McCarty obtain in their experiments with virulent bacteria?
DNase destroyed the transforming activity.
Which enzyme makes DNA from an RNA template?
Reverse transcriptase
In forming a nucleotide, phosphorus is most often attached to the nucleoside at the C‑5′ position of the sugar.
True
Which of the following statements is true of thymine?
Thymine is the same as 5‑methyl uracil.
Watson and Crick used information from several individuals to construct their model of DNA. Whose X‑ray diffraction studies were critical to their work?
Rosalind Franklin
If a double‑stranded sample of DNA has a base composition of 20% guanine, which of the following statements is true?
The amount of thymine must equal 30%.
Which of the following statements does not describe Z‑DNA?
The strands are not antiparallel.
RNA differs from DNA in all of the following ways except by
The 5′-3′ orientation of the polynucleotide strand.
Of the following DNA strands in combination with their complementary strands (forming double helices), three undergo a hyperchromic shift with a Tm of about 42°C. Which one has a Tm of 52°C?
TCATGCGATC
Which technique can be used to identify the location of genes on a chromosome?
FISH
Which of the following statements about the Cot1⁄2 or half‑association value of DNA fragments is true?
Shorter DNA molecules would associate more quickly (smaller Cot1⁄2 values).
If Avery, MacLeod, and McCarty had determined that the transforming molecule was a protein, what experimental results would not have been observed?
Heat‑killed cultures treated with RNase would transform the R cells.
What conclusion could be drawn if Hershey and Chase had found only 35S in their bacterial cells?
Protein is the genetic material.

35S is radioactive sulfur. Sulfur is found only in protein, not in DNA
To which positions in the sugar of a deoxyribonucleotide can a phosphate be esterified?
C-3′ and C-5′
Which of the following statements best describes the structure of a DNA molecule?
DNA is composed of a sugar‑phosphate backbone with bases projecting toward the inside of the backbone.
If two DNA strands of identical length were analyzed, which of the following statements would be true of their Tm or melting temperature?
DNA with a low AT content would melt more slowly.
Which of the following statements about the difference between DNA and RNA is false?
RNA is usually much longer than DNA.
Why is it important for a retrovirus to carry its own reverse transcriptase protein instead of making it from its reverse transcriptase gene after it infects a cell?
The retrovirus must make DNA before it can use the cell's molecular machinery to make reverse transcriptase. Normal cells do not contain reverse transcriptase.
Guanine and adenine are purines found in DNA.
True
Which of the following statements about DNA structure is true?
The nucleic acid strands in a DNA molecule are oriented antiparallel to each other, meaning they run in opposite directions.
What is the complementary DNA sequence to 5′ ATGCTTGACTG 3′?
5′ CAGTCAAGCAT 3′
Genetic material must be able to:
Replicate, Store information, express information, and allow variation by mutation.
Nucelotides are composed of
nitrogenous base, pentose sugar, and phosphate group
Pyramiine bases C, T, & U have how many rings
Have one ring
Purines bases A & G have how many rings
Have two rings
How nucleotides linked?
Phosphodiester bond between the phosphate group at the C-5' positiong and the OH group on the C-3' position.
The amount of A is proportional to T & G is proportional to C but..
A+T does not equal G+C
What replaces thymine in RNA
Uracil
RNA only forms double stranded regions as they fold onto different
secondary structures
What are the 3 major classes of celluar RNAs?
rRNAs, mRNAs, and tRNAs
rRNAs are...
components of ribosomes for protein synthesis
mRNAs are...
the template for protein synthesis
tRNAs carry...
amino acids for protein synthesis.
Nucleic acid electrophoresis seperated
DNA & RNA fragments by size such that smaller fragments migrate through a gel at a faster rate than large fragments
DNA has net negative charge, moves
towards positive electrode in gel chamber
Application of known size standard enables...
quantification of DNA fragments of unknown size
molecular hybridization
DNA strands can be denatured by heat and then renatured to each other.
Complimentary strands renature,
the more similar, the more likely they hybridize.
If one strand is labeled...
can track its presence or absence and sometimes its abundance.
Fluorescent in situ hybridization (FISH)
used in identifying the chromosomal location of DNA of interest.
DNA serves as...
genetic material in bacteria and eukaryotes
Evidence from eukaryotes...
same material; expression of eukaryotic proteins in bacterial with eukaryotic genes.
RNA serves as gentic material in...
some viruses