Biochemistry: Mod 1

Biochemistry: Mod 1.• DNA = phosphate + deoxyribose sugar + A/T/C/G o Contains two strands. The strands are antiparallel (opposite each other). o 5’ → 3’ 3’ ← 5’ • RNA = phosphate + ribose sugar + A/U/C/G o Single strand, can fold back onto itself and form pairs between itself (stem‐loop). • Each nucleic acid is made up of polymers (many monomers) that are called nucleotides. o Nucleotides contain one or more phosphates, a five‐carbon sugar, and a nitrogen base. o Nucleotides are always made in the 5’ to 3’ direction. o 5 is always the beginning of the strand, 3 is the end where nucleotides are added. • DNA organization: DNA is wrapped around proteins called histones → nucleosome → chromatin fiber→ chromosomes • Steps to the central dogma: o Coding DNA → template DNA → mRNA → tRNA (amino acid) o DNA → transcribed to mRNA → translated to protein o Each step is complementary (opposite) to the previous step, but if you skip a step it will be identical to the previous step. o Example  1. Coding DNA strand 5’ AAA TTT GGG CCC 3’  2. Template DNA strand 3’ TTT AAA CCC GGG 5’  3. mRNA 5’ AAA UUU GGG CCC 3’  4. tRNA Lys Phe Gly Pro • Pairing: o DNA: A → T o RNA: A → U • DNA replication: o Because DNA is a double helix, one strand can be separated and serve as a template for synthesis of a new strand. o Semi‐conservative: each copy of DNA contains a template strand and a new strand. o Steps of replication: