A1.2 Nucleic Acids

DNA

Stores genetic information

RNA

Creates proteins

Genes

Sequence of ATCG

Codon

Genes tell amino-acids a 3-letter code the sequence to form a protein

Virus

Unlivable without a cell of a living organism

Polymer

Large molecule made up of many monomers

Single; ATCG; Deoxyribose; Uracil; Protein Synthesis; Nucleus

Feature	DNA	RNA
Number of Strands	Double-stranded	???
Nitrogenous Bases	???	A, U, C, G
Sugar Type	???	Ribose
Base Unique to Type	Thymine (T)	???
Function	Genetic Storage	???
Location	???	Nucleus & Cytoplasm

DNA & RNA nucleotides

Phosphate group connected to the 5’ carbon of the sugar

Nitrogenous base connected to the 1’ carbon of the sugar

An OH group connected to the 3’ carbon of the sugar

Deoxyribose

H group is on the 2' carbon

Ribose

OH atom is on the 2' carbon

mRNA

Carries genetic messages

tRNA

Transfers amino acids

rRNA

Makes ribosomes, protein factories

ATP

Energy currency

Sugar-phosphate backbone

Structural framework for DNA/RNA

• Alternating sugar & phosphate

• Powerful phosphodiester bonds

• Holds nitrogenous bases together

Nucleotides

Connected by phosphodiester bonds

Phosphodiester

Type of covalent bond

• 3’ to 5’ of the next phosphate

Condensation

Water is released

Double-helix

Protects genetic information

RNA folding

Foldable into complex shapes

DNA structure

DNA’s double-helix

• Antiparallel

• Base pairs held by hydrogen bonds, easily split & replicated

2 hydrogen bonds

A -?- T

3 hydrogen bonds

C -?- G

Evolution

DNA sequence changes

3’, 5’—>3', 5’—>’3

Process	Product	How
Replication	Copies DNA	DNA polymerase adds nucleotides to the original DNA strands ??? carbon end
Transcription	Creates mRNA	RNA polymerase adds complementary nucleotides to 3’ carbon end of a DNA template, read ???
Translation	Makes polypeptide chains, folding into proteins	mRNA is read by ribosomes, read from ???

Nucleosome

DNA + Histones

1.65

DNA wraps X times around a histone octamer

Tightness

Influences what proteins get made

Chargaff’s Rule

DNA contains the exact same amount of A—T & C—G

Francis Crick & James Watson

Discovered…

• DNA double-helix

• DNA copying technique

• Complementary base pairing