Genetics Exam test questions and answers
graded A+
1. What must genes do? 1. Store info for cell function
2. Replicate
3. Mutate/change a little
2. Griffith Experiment 1928, Isolated two strands of streptococcus
pneumoniae:
virulent S strain and avirulent R strain; discovered
trans- forming principle (DNA) that caused live S
cells in dead mice who were exposed to live R cells
+ heat-killed S cells
3. Avery, Mcloed, McCarty 1944, Mixed S cell extract with deoxyribonuclease
Experi- ment
(de- stroys DNA), ribonuclease (destroys RNA), and
protease (destroys proteins); discovered that the
mouse only sur- vives with deoxyribonuclease
because it kills the DNA; it was clear that the only
part necessary to kill the mouse was the DNA of S
cells
4. Hershey-Chase Experiment 1951, Used radioactive isotopes of phosophorus
and sul-
fur to discover that the genetic material of the
bacterio- phage was DNA, not protein; proteins
contain almost no P and DNA contains no S;
therefore used as markers to later check bacteria
5. Chargaff Analyzed DNA from many species. Found that
[A=T] and [G=C] aka [pyrimidines=purines].
Found that ratio of (A+T)/(G+C) varied within
organisms but same within a species
6. X-ray diffraction The targeting of a beam of monochromatic x-rays
on a sample so that the radiation is scattered. This
1/
31
,Genetics Exam test questions and answers
graded A+
technique indicates how the atoms or molecules
are arranged in a given crystal. Used by Rosalind
Franklin to make images of the helical pattern of DNA
- dittraction pattern was 3.4 nm,
0.34 nm, and 2.0 nm - gave this information to
Watson
2/
31
, Genetics Exam test questions and answers
graded A+
7. DNA structure Antiparallel strands. A-T,G-C = binded by Hydrogen
bonds. Strands have phosphate sugar
backbone
8. How does DNA store info for cell Information is stored in the nucleotide
sequence
function?
9. How does DNA replicate? It uses a "semi-conservative" single-stranded
template to
synthesize the other strand
10. How does DNA change or It changes a letter in the nucleotide sequence
mu- tate?
(nucleotide change); there are 3x10^9 base pairs
in the humane genome so because of this large
size, mutations are bound to occur
11. Meselson and Stahl Proved that DNA replicates in a semiconservative
fash-
ion, confirming Watson and Crick's hypothesis.
Cultured bacteria in a medium containing heavy
nitrogen (15N) and then a medium containing
light nitrogen (14N); after extracting the DNA, they
demonstrated that the replicated DNA consisted of
one heavy strand and one light strand (new DNA
synthesizes with light nitrogen every time which is
why the left band gets thicker with every generation
3/
31
, Genetics Exam test questions and answers
graded A+
and the intermediate size DNA band gets smaller)
12. Why doesn't the It was disproven after 1 round of replication
conservative model of DNA
replication work?
4/
31
graded A+
1. What must genes do? 1. Store info for cell function
2. Replicate
3. Mutate/change a little
2. Griffith Experiment 1928, Isolated two strands of streptococcus
pneumoniae:
virulent S strain and avirulent R strain; discovered
trans- forming principle (DNA) that caused live S
cells in dead mice who were exposed to live R cells
+ heat-killed S cells
3. Avery, Mcloed, McCarty 1944, Mixed S cell extract with deoxyribonuclease
Experi- ment
(de- stroys DNA), ribonuclease (destroys RNA), and
protease (destroys proteins); discovered that the
mouse only sur- vives with deoxyribonuclease
because it kills the DNA; it was clear that the only
part necessary to kill the mouse was the DNA of S
cells
4. Hershey-Chase Experiment 1951, Used radioactive isotopes of phosophorus
and sul-
fur to discover that the genetic material of the
bacterio- phage was DNA, not protein; proteins
contain almost no P and DNA contains no S;
therefore used as markers to later check bacteria
5. Chargaff Analyzed DNA from many species. Found that
[A=T] and [G=C] aka [pyrimidines=purines].
Found that ratio of (A+T)/(G+C) varied within
organisms but same within a species
6. X-ray diffraction The targeting of a beam of monochromatic x-rays
on a sample so that the radiation is scattered. This
1/
31
,Genetics Exam test questions and answers
graded A+
technique indicates how the atoms or molecules
are arranged in a given crystal. Used by Rosalind
Franklin to make images of the helical pattern of DNA
- dittraction pattern was 3.4 nm,
0.34 nm, and 2.0 nm - gave this information to
Watson
2/
31
, Genetics Exam test questions and answers
graded A+
7. DNA structure Antiparallel strands. A-T,G-C = binded by Hydrogen
bonds. Strands have phosphate sugar
backbone
8. How does DNA store info for cell Information is stored in the nucleotide
sequence
function?
9. How does DNA replicate? It uses a "semi-conservative" single-stranded
template to
synthesize the other strand
10. How does DNA change or It changes a letter in the nucleotide sequence
mu- tate?
(nucleotide change); there are 3x10^9 base pairs
in the humane genome so because of this large
size, mutations are bound to occur
11. Meselson and Stahl Proved that DNA replicates in a semiconservative
fash-
ion, confirming Watson and Crick's hypothesis.
Cultured bacteria in a medium containing heavy
nitrogen (15N) and then a medium containing
light nitrogen (14N); after extracting the DNA, they
demonstrated that the replicated DNA consisted of
one heavy strand and one light strand (new DNA
synthesizes with light nitrogen every time which is
why the left band gets thicker with every generation
3/
31
, Genetics Exam test questions and answers
graded A+
and the intermediate size DNA band gets smaller)
12. Why doesn't the It was disproven after 1 round of replication
conservative model of DNA
replication work?
4/
31
