Genetics Exam test questions and answers graded A+

Genetics Exam test questions and
answers graded A+
Characteristics of genetic material - ANS✅✅1. must contain complex information

2. must be able to replicate

3. must encode the phenotype

4. must have the capacity to be different in different species



Fred Griffith's transformation experiment - ANS✅✅Injected mice with strains of bacteria that
either affected them or didn't, when the two were combined the mouse died.

1) injected with rough strain = mouse lives

2) injected with smooth strain = mouse dies

3)injected with boiled smooth strain = mouse lives

4) injected with rough strain and boiled smooth strain = mouse dies



Avery, MacLeod, McCarty - ANS✅✅Determined that DNA was
Griffith's "Transforming Factor."

~Boiled smooth strain was split into 3 samples. When Dna was destroyed, the animal survived



Protease - ANS✅✅breaks down proteins



Rnase - ANS✅✅breaks down RNA



Dnase - ANS✅✅breaks down DNA



Hershey-Chase Experiment - ANS✅✅Used radioactive phosphorous and sulfur to label DNA and
protein respectively; infected bacteria passed on DNA; helped prove that DNA is genetic material not
proteins

~T2 Phage are grown in mediums containing the radioactive material



Chargaff's Rule - ANS✅✅A=T and G=C

,Rosalind Franklin - ANS✅✅Used X-ray diffraction to discovered:

1) the double-helical structure of DNA.

2)helix contains 10 nucleotides per turn

3) helix has a diameter of 20 angstroms (2nm)



Nucleotide - ANS✅✅A building block of DNA, consisting of a five-carbon sugar covalently bonded
to a nitrogenous base and a phosphate group.



Nucleoside - ANS✅✅nitrogenous base + sugar



James Watson and Francis Crick - ANS✅✅The scientists credited with building the first correct
model of the structure of DNA by using Franklin's X-rays. They discovered:

1) DNA is double stranded and runs antiparallel

2) Bonds between A-T and C-G hold the 2 strands together

3) complementary basing suggests a mechanism for replication



Pyrimidines - ANS✅✅Cytosine and Thymine

~has three rings



Purines - ANS✅✅Adenine and Guanine

~ two rings



Nucleotides are joined by - ANS✅✅phosphodiester linkages between the sugar of one nucleotide
and the phosphate of the next

~do NOT break in heat



C + G - ANS✅✅3 hydrogen bonds



A + T - ANS✅✅2 hydrogen bonds



B form DNA configuration - ANS✅✅the typical configuration in vivo---that proposed by Watson
and Crick

, ~RIGHT handed helix

~found in cells



A form DNA configuration - ANS✅✅under high salt concentrations, the helix gets a little more
compact

~RIGHT hand helix

~ exists when DNA is isolated



Z form DNA configuration - ANS✅✅seen in short DNA pieces with alternating purine/pyrimidine
bases

~LEFT handed helix



tRNA (transfer RNA) - ANS✅✅characterized by an anticodon, which binds the mRNA at the
ribosome, and the amino acid-carrying portion



nucleoside analogs - ANS✅✅mutagens that incorporate into DNA in place of a normal base;
causes mistakes in base pairing



Conservative DNA replication - ANS✅✅The original double strand serves as a new template for a
new DNA molecule



Dispersive DNA replication - ANS✅✅Both DNA molecules break down into fragment and serve as a
template for the new fragment

~Both copies of genome are composed of scattered pieces of old and new DNA



semi-conservative DNA replication - ANS✅✅The original strand unwinds and is used as a template
to generate a new strand



Messelson-Stahl Experiment - ANS✅✅Needed a way to distinguish the old from the new strand.
They used two isotopes of Nitrogen: 14N and 15N

1) Grow the bacteria in heavy 15N for many generations. This made the DNA HEAVY

2) Took a sample of those bacteria and switched the rest to 14N. Took additional samples over a few
cell cycles. New DNA contained 14N which was lighter