Lecture + Quiz 1

Question 1

Which of the sexual life cycle has the hyphae from two compatible organisms grow towards each other to meet and form the zygosporangium?

Diploid-dominant
Haploid-recessive
Haploid-dominant
Alternation of generations

Answer 1

Haploid-dominant

Question 2

Road to Molecular Genetics (1866-1953)

Answer 2

1866: Mendel publishes work on heredity of peas
1944: Avery et al. show evidence of DNA as carrier of genetic info (not RNA)
1950: Chargaff’s rules of base pairing
1952: Franklin and Wilkins obtain x-ray diffraction images of DNA
1953: Watson and Crick determine + publish paper on structure of DNA double helix

Question 3

genetics

Answer 3

the scientific study of genes and heredity- how certain qualities or traits are passed from parents to offspring

Question 4

molecular genetics

Answer 4

the study of genetics on a molecular level

Question 5

Frederick Griffith’s transformation experiment (1928)

Answer 5

showed that harmless R strain bacteria could transform into deadly S strain bacteria when mixed with heat-killed S strain. This suggested that a “transforming principle” (later identified as DNA) could transfer genetic information = transformation

Question 6

Avery’s DNA Experiment

Answer 6

DNA (not RNA) is the (transforming agent) genetic material
- DNA = “transformation principle”

Question 7

Hershey-Chase Bacteriophage Experiment

Answer 7

DNA (not protein) is the genetic material

Question 8

Gierer & Schramm Tobacco Mosaic Virus Experiment

Answer 8

RNA (not protein) can be genetic material in viruses

Question 9

chargaff’s rule

Answer 9

A% = T%
G% = C%

Question 10

Nucleotide

Answer 10

monomers/units that make up DNA & RNA
1. Pentose (5-carbon) sugar
- DNA = deoxyribose
- RNA = ribose
2. Nitrogenous base
- purines = adenine, guanine
- pyrimidines = cytosine, thymine (DNA), uracil (RNA)
3. Phosphate group attached to 5’ carbon

Question 11

how and who established structural model of DNA?

Answer 11

• maurice wilkins and rosalind franklin (1952) were using x-ray diffraction to study molecular structure –> 1st pic of DNA molecule
• watson & crick’s (1953) double helix model of DNA

Question 12

features of DNA structure

Answer 12

1. two polynucleotide chains wound in right-handed (clockwise) double-helix
2. nucleotide chains are anti-parallel
   - 5’ –> 3’
   - 3’ –> 5’
3. sugar-phosphate backbones are on the outside of the double helix, and the bases are oriented towards the central axis
4. complementary base pairs from opposite strands are bound together by weak hydrogen bonds
   - A pairs w/ T (2 H-bonds_
   - G pairs w/ C (3 H-bonds)
5. base pairs are 3.4 A apart –> one complete turn of the helix = 36 A (10 bases/turn)
6. sugar-phosphate backbones not equally spaced = major and minor grooves