ch. 10 - chemical nature of a gene

what four general characteristics must genetic material possess?

1. must contain complex information

2. be able to replicate

3. must encode phenotype (to code for traits)

4. have ability to vary

how does RNA nucleotide differ from a DNA nucleotide?

RNA - OH on 2’ carbon atom; more reactive + less stable than DNA

DNA - only H on 2’ carbon atom; one less O

identify the three parts of a DNA nucleotide

1. deoxyribose sugar

2. phosphate group

3. nitrogenous base

how does a purine differ from a pyrimidine?

purine (A,G): two fused rings, 9 membered

• pair w/ pyrimidine via h-bonds

pyrimidine (C, U, T): one ring, 6 membered

what purines + pyrimidines are found in DNA and RNA?

DNA: C-G, A-T

RNA: C-G, A-U

describe the central dogma

(replicate) DNA —- (transcribe into) RNA —- (translate into) Proteins

describe different chemical bonds found in DNA?

phosphodiester - connect nucleotides

• joins 5’-phosphate group of one nucleotide to 3’-OH of the next

H-bonds - link bases on opposite strands

stacking interactions - adjacent bases align so rings are parallel + stack on top of one another; stabilize DNA molecule

what is DNA methylation?

methyl groups (CH3) are added by specific enzymes to certain positions on nitrogenous bases

in eukaryotic cells -

• methylated sequences: low levels of transcriptions

• un-methylated sequences: actively transcribe