Genetic Material (Chap 2)

Question 1

def of genetic material

Answer 1

1- stable info on structure, function, development and reproduction.
2-replicate accurately
3-capable of change

Question 2

def of chromosome

Answer 2

• threadlike structure of nucleic acid and proteins

- found in the nuclei

Question 3

History and genetic material

Answer 3

• Griffith’s Transformations Exp 1928 (Streptococcus pneumonica) : transformation principle deduced from S and R strains together resulted in dead cells (transfer of infected material)
• Avery’s Transformation Exp 1930/1940 ( enzymes –> nucleases, RNase, DNase) : when enzyme eliminates DNa there is no transferring of Infectious to harmless
• Hershey+Chase exp (Bacteriophage) 1952: during replication if the isotope P is uptaken the progeny will show it but the same DNA function is expressed.

Question 4

Lytic vs Lysogenic

Answer 4

-Grow+reproduce
vs
-resting

Question 5

Composition + Structure of DNA and RNA

Answer 5

• monomer=nucleotide–> pentose sugar(deoxyribose or ribose) +nitrogenous base (Pyrimidine/u,t,c or pyrine/a,g) + phosphate group
• A=T or A=U (2-bonds) + G=(3 bonds)

Question 6

Nucleoside def

Answer 6

• a nucleotide without the phosphate group

Question 7

Polynucleotide def

Answer 7

• covalent bond b/n phosphate group + 3’ sugar

- uses phosphodiester bonds and dehydration

Question 8

DNA double helix

Answer 8

• base composition studies (Erwin Chargaff): purines match up with pyrimidine
• X-ray Diffraction studies (Rosalind Franklin + Maurice Wilkins) : there is ADNA (R-handed and found in low humidity with short and wide strand), BDNA (longer and liner and found in cells more and high humidity) and ZDNA( left handed and not common)
• Watson+Cricket model: 2 antiparallel righthanded polynucleotide with sugar phosphate backbone on the outside

Question 9

RNA Structure

Answer 9

• single stranded: tRNA, r”, m”, sn”, mi”

- double stranded = sim to DNA

Question 10

Organization of DNA in Chromo?

Answer 10

=genome

• Viral “ : any format
• Prokaryotic “: can be single, double or circular, with plasmids that DNA is supercoiled @ looped domaines that are controlled by topoisomeraese
• Eukaryotic “: nucleosome with histone core (H2A, H2B, H3, H4), in metaphase the karyotype is a complete set, link/anchore(H1) and c-value is the total # of haploid DNA

Question 11

Prokaryotic Chromosome states

Answer 11

• relaxed

- supercoiled

Question 12

Chromatin

Answer 12

• histone(packing )+ nonhistones( acidic protein +DNA repair + transcription+ replication + recombination)
• ‘bead-on-a-string’ are 10nm nucleosomes of chromatin fiber that are compact in a solenoid structure

Question 13

Euchromatin

Answer 13

• norm cycle of condensation
• DNA expressed
• devoid of replication sequence

Question 14

Heterchromatin

Answer 14

• condensed region
• replicate in S phase
• Constitutive Het: highly condensed (telomers @chromo end and centromers attached by spindels during Mit and mei) + Facultative Het: switched b/n euch and heterch( anactivated seg that can be in any position or stage)

Question 15

Telomeres segment types

Answer 15

• Simple: extreme end of DNA Chromo

- Associated : often repeated