DNA Structure and replication

Question 1

Central dogma

Answer 1

DNA-transcription-RNA-translation-protein

Question 2

Chromosome Theory of inheritance

Answer 2

chromosomes carry genetic material across generations
- though to contain proteins and nucleic acids

Question 3

what did two strains of Pneumococcus that Frederick Griffith use tell us?

Answer 3

A single gene mutation change can convert an S strain to R strain of the same antigenic type
- Smooth cause fatal pneumonia in mice
- Rough was not fatal

Question 4

Discovery of transformation

Answer 4

Non-virulent IIR were transformed into virulent III S cells

Question 5

Griffiths proposal

Answer 5

• the transformation factor as the molecule transformed the RII into SIII
• The transforming factor carried hereditary information
• ## Described as transformation

Question 6

What is the transforming principle

Answer 6

DNA

Question 7

Transformation

Answer 7

Taking up naked exogenous (outside) DNA
- is a genetic event (transferred into generations)
- variation is broad

Question 8

bacteriophages(phages)

Answer 8

Viruses that infect bacteria
- DNA is responsible for pages infection of bacteria cells

Question 9

T2 phages anatomy

Answer 9

• have protein shell
• tail segment (attaches to host cell-bacteria wall)
• head that contains DNA

Question 10

T2 and E. Coli experiment

Answer 10

• T2: 50% protein, 50% DNA
• infections is initiated by T2 tail fibers
• New viruses are produced inside bacterial cell

Question 11

What is the genetic material in T2

Answer 11

DNA not protein

Question 12

nucleoside phosphate (mono, di, tri)

Answer 12

• triphosphates are most significant
  1. precursor molecules molecule for nucleic acids synthesis in the cell
  2. adenosine- and guanosine triphos (ATP,STP) are essential in cell bioenergetics

Question 13

three properties of genetic code

Answer 13

• must replicate
• must encode information
• must be able to change (mutable)

Question 14

What are the three forms of DNA

Answer 14

A-form and B-form (most common), Z-form

Question 15

Complementarity

Answer 15

Specific of A with T, and G with C - dues to specific chemical affinity between nitrogenous bases

Question 16

Chargaff’s rules

Answer 16

• amount of adenine is proportional to thymine and amount of guanine is proportional to amount f cytosine
• The sum of purines equal the sum of pyrimidines
• sum of (G+C) does not necessarily equal the sum of (A+T)

Question 17

Issues for DNA replication

Answer 17

1. unwinding of the helix
2. reducing increased coiling generated during unwinding
3. synthesis of a primer for initiation
4. discontinuous synthesis of the second strand
5. removal of the RNA primers
6. joining of the gap filling DNA to the adjacent strand
7. proofreading

Question 18

Basics of DNA replication

Answer 18

• SEMICONSERVATIVE
• BI-DIRECTIONAL
• MAIN SYNTHESIS – POLYMERASE III
• DIRECTION 5’ – 3’
• START AT POINT(S) OF ORIGIN

Question 19

basics of DNA replication steps

Answer 19

1. Unwinding and stabilizing DNA double helix
2. Initiation of DNA synthesis, synthesis of RNA primers
3. Continuous DNA synthesis – leading strand
4. Discontinuous DNA synthesis – lagging strand
5. Proofreading and correction of errors

Question 20

Semiconservative DNA replication

Answer 20

each daughter duplex contains one parental and one daughter strand (go back and look at pictures on slide 38)

Question 21

Conservative DNA replication

Answer 21

one daughter duplex contains both parental strands and the other contains both daughter strands (go back and look at pictures on slide 38)

Question 22

Dispersive DNA replication

Answer 22

(go back and look at pictures on slide 38)