BIOL-3333 Genetics-Ch. 6
RNA often forms double-stranded structures. When RNA is double -stranded, the base-pairing rules are slightly modified when compared to those seen in DNA. Match the case on the left with the base it would pair with on the right. If one of the bases isn't found in RNA, indicate that using the appropriate label on the right 1. A 2. U 3. G 4. C 5. T a. C b. U c. G d. A e. Isn't found in RNA
1. b 2. d 3. a 4. c 5. e
When was the structure of the DNA double-helix discovered?
1953
If a double stranded molecule of DNA is 20% Guanine, what is the percentage of thymine in the molecule?
30%
Based on x-ray images we know that a single turn of the DNA double-helix measures
34 angstroms
What is attached to the 1' carbon of the deoxyribose in a nucleotide?
A nitrogenous base
What are the three parts of a nucleotide?
A pentose sugar, a nitrogenous base, and at least one phosphate group.
For viruses that have single-stranded DNA chromosomes, how is the DNA utilized once it is inside the host cell?
A second strand of DNA is synthesized on the single-stranded template.
The AT/GC base pairing rule requires that purines (A and G) always base-pair with the pyrimidines (T AND C). Why is this?
Pairing a purine with a pyrimidine ensures a consistent diameter of the helix.
What is the name for the type of bond connecting two sugar molecules via a phosphate group in the backbone of DNA?
Phosphodiester bond
Which feature of Streptococcus pneumoniae promotes a virulent infection by protecting the bacterial cell against the host's immune system?
Polysaccharide capsule
Which biological entities were used in the experiments of Hershey and Chase (1952)?
T2 virus and Escherichia coli
Chargaff found that double-stranded DNA contains approximately a 1:1 ratio of adenine and thymine, and approximately a 1:1 ratio of cytosine and guanine. What did James Watson conclude from this observation?
That adenine in one strand of DNA binds to thymine in the other strand and that cytosine in one strand of DNA binds to guanine in the other strand.
What features of DNA molecules were deduced by analyzing Franklin and Wilkins' X-ray images?
The diameter of the molecule is roughly twice the width of a single nucleotide and the DNA molecule is spiral shaped.
What makes DNA negatively charged?
The negative charge on each phosphate in the sugar-phosphate backbone.
How did Hershey and Chase discriminate between DNA and protein in their experiments to show that DNA was genetic material of bacteriophage T2?
They labeled the DNA with radioactive phosphorous and the protein with radioactive sulfur.
Griffith (1928) discovered a process where a molecule from one type of bacteria could change the characteristics of another type of bacteria receiving the molecule; he named this process __________________.
Transformation
The experiments of Avery, MacLeod, McCarty were trying to determine the __________ in the experiments by Frederick Griffith.
Transforming substance
The structure of DNA that Crick and Watson proposed has _____________ strands of DNA that are wrapped around each other to form a helix. The DNA bases of each strand of DNA point towards the central axis of the molecule and are held together by __________________ bonds.
Two, hydrogen
Although DNA is usually found as a double stranded molecule, it must be __________________ to provide single-stranded regions for replication and transcription.
Unwound
For processes such as replication and transcription, double-stranded DNA must be
Unwound into single-stranded regions.
What is the main technological advancement that contributed to Crick and Watson working out the structure of the DNA double-helix?
X-ray diffraction
If Streptococcus pneumoniae bacteriaposses capsules, then colonies of the bacteria will have a _________________ appearance while colonies of bacteria that lack a capsule will appear ________________________.
smooth; rough
What are the types of base incorporate into DNA?
Guanine, Adenine, Thymine, Cytosine
Match the carbon number of deoxyribose with the structure attached to it. A. 1' B. 5' C. 3' 1. Phosphate group 2. Nitrogenous base 3. Hydroxyl group
A. 2 B. 1 C. 3
Which of the following describes a nucleotide? A. Nucleoside with an attached phosphate group B. Nucleoside where the base is a pyrimidine C. Nucleoside with a deoxyribose sugar. D. Nucleoside where the base if a purine.
A. Nucleoside with an attached phosphate group.
In order to determine its chemical composition, Avery, MacLeod, and McCarty subjected purified extracts of the transforming principle to a variety of enzymes. Which enzyme destroyed the activity of the transforming principle?
An enzyme that degrades DNA
When two strands of DNA in a double helix run in opposite directions, one 5' to 3' and the other 3' to 5', what is this called?
Antiparallel
DNA can adopt two different conformations. Which is the most abundant conformation seen in living cells?
B DNA
Which of the statements below correctly describe the structure of a DNA double helix? A. Two strands of DNA are held together by phosphodiester bonds between bases on opposite strands B. DNA strands form a helical structure C. It contains one strand of DNA D. Bases on opposite strands are hydrogen bonded together E. The bases in the DNA molecule point outwards, away fro the central axis of the molecule.
B. and D.
There are two conformations of DNA: B DNA and Z DNA. What are the main structural features of B DNA?
Bases are aligned perpendicular to the central axis of the molecule and there are 10-base pairs per turn
In which locations can circular chromosomes be found?
Chloroplasts, Prokaryotic, Mitochondria, Papovaviruses
What are the names of the different types of nucleic acid?
DNA and RNA
Which types of macromolecules are present in the T2 bacteriophage?
DNA and protein
Order the steps of the experiment in which Hersey and Chase showed that DNA is genetic material of bacteriophage T2. Put the first step in their protocol at the top of the list, and the last step at the bottom of the list A. Centrifuged the blended E. coli/virus mixture B. Allowed time for infection of bacteria by virus C. Measured radioactive 32P or 35S in the pellet and the supernatant D. Sheared virus coats from cell walls of bacteria using a blender E. Incubated 35S-labeled bacteriophage or 32P-labeled bacteriophage with E. coli in separate flasks
E. B. D. A. C.
If you built a ball-and-stick model of the DNA double helix, where would you place the bases?
Facing each other inside the helix.
Individual strands of DNA are composed of building blocks called _________________.
Nucleotides
For Streptococcus pneumoniae, which for is vulnerable to elimination by the host's immune system because it lacks a protective polysaccharide-rich capsule?
R (rough) form
How can nucleotides found in RNA be discriminated from those found in DNA?
RNA nucleotides may contain uracil, RNA nucleotides don't contain thymine, RNA nucleotides contain ribose
Which characteristic of the DNA molecule is responsible for carrying genetic information?
Sequence of A, G, T, and C bases
Which proteins can bind to double-helical DNA by recognizing chemical differences based on spatial pattern of atoms in bases located within the major and minor grooves?
Sequence-specific DNA-binding proteins
How did Rosalind Franklin contribute to the discovery of the DNA double-helix structure?
She conducted the X-RAY diffraction experiments
when comparing the sizes of RNA molecules to DNA molecules found in nuclear chromosomes, RNA molecules will be _____________ than DNA molecules.
Smaller
Hershey and Chase (1952) conducted experiments to test whether DNA to protein was the genetic material, using a bacteria-infecting virus called a(n) _________________.
bacteriophage
Using the Feulgen reaction that tags DNA with a red stain, it was established that __________________ were the nuclear components that were composed of DNA
chromosomes
Because the two strands of a DNA molecule are _______________, if you know the base sequence of one strand, you know the base sequence of the other strand as well.
complimentary
When comparing the structural features of RNA with the structural features of DNA, DNA uses the sugar ________________ and RNA uses the sugar _______________.
deoxyribose, ribose
While the prokaryotic bacterial chromosome is made of ______________-stranded DNA, the chromosome of one of its infecting bacteriophages, M13, is composed of ______________-stranded DNA.
double; single
Chromosomes in the nuclei of eukaryotic cells are composed of ________________DNA, while bacterial cells have chromosomes which are made of _____________ DNA.
linear; circular
Friedrich Miescher (1869) isolated a weakly acidic material from the nuclei of white blood cells that he named __________________. The material contained mostly ______________ along with some contaminants.
nuclein, DNA
A sugar, such as deoxyribose, attached to a base but not to a phosphate group is called a __________________.
nucleoside
A DNA chain is a long polymer made of monomer subunits called _______________.
nucleotides
In their experiments to identify the nature of the genetic material, Hershey and Chase hypothesized that the genetic material from the ___________ would be injected into the ____________.
phage; bacterium
