DNA: deoxyribonucleic acid

• Chemical compound that passes hereditary information from generation to generation

• Where is DNA found in Eukaryotic cells? (plant, animal, fungi, protist)?

Nucleotide• Building block of DNA

• 3 parts Nitrogen Base

Phosphate

5 carbon sugarDeoxyribose

Attached with covalent bonds

Four different nucleotides make up DNA

• Each has a different nitrogen base

Purines

2 ring nitrogen base structure

Pyrimidines

1 ring nitrogen base structure(uracil is only in RNA—not DNA)

Double Helix Structure• Ladder

– Sugar-phosphate are the sides

– Nitrogen bases attach across as the rungs

• A binds with T• G binds with C

– Attach with hydrogen bonds

• Two strands run antiparallel

DNA is organized into chromosomes

• Genome: All of the genetic material for a specific organism

• Gene: portion of DNA that carries information for a single protein

Central Theory of Molecular Biology

The process of replication creates new copies of DNA.

The process of transcription

creates an RNA using

DNA information.

The process of translation

creates a protein using

RNA information.

Replication

• DNA polymerase adds nucleotides

• Complementary base pairing

Semi-Conservative Replication• Each new molecule consists of one old

strand and one new strand

RNA

• Directs protein synthesis

• Not helical• Single stranded• 5 carbon sugar is

Ribose• 4 nucleotides

– Adenine– Guanine– Cytosine– Uracil

3 classes of RNA1. Messenger RNA (mRNA)

2. Transfer RNA (tRNA)

3. Ribosomal RNA (rRNA) Makes up ribosome

Carries protein building instructions

Transports amino acid

Transcription• One strand of DNA is

the template• Begins at promoter

• Enzyme: RNA polymerase

• Complementary base pairing

• Ends at terminator

RNA to protein• Occurs in cytoplasm on ribosomes• Ribosomes read mRNA bases in triplets called codons• 64 different codons• Code for 20 amino acids

– Most correspond to more than one codon

• Example: glutamate: GAA and GAG

Codons

• Start codon: AUG – Codes for methionine– First amino acid

• UAA, UAG and UGA are stop codons– Prevent further amino acid addition

Codon chart1st

base

2nd base3rd

baseU C A G

U

UUU Phe/F(Phenylalanine)

UCU

Ser/S(Serine)

UAU Tyr/T(Tyrosine)

UGU Cys/C(Cysteine)

U

UUC UCC UAC UGC C

UUA

Leu/L(Leucine)

UCA UAA Stop (Ochre) UGA Stop (Opal) A

UUG UCG UAG Stop (Amber) UGG Trp/W (Tryptophan) G

C

CUU CCU

Pro/P(Proline)

CAU His/H(Histidine)

CGU

Arg/R (Arginine)

U

CUC CCC CAC CGC C

CUA CCU CAA Gln/Q(Glutamine)

CGA A

CUG CCG CAG CGG G

A

AUUIle/I

(Isoleucine)

ACU

Thr/T(Threonine)

AAU Asn/N(Asparagine)

AGUSer/S (Serine)

U

AUC ACC AAC AGC C

AUA ACA AAALys/K

(Lysine)

AGAArg/R (Arginine)

A

AUG Met/M (Methionine) ACG AAG AGG G

G

GUU

Val/V(Valine)

GCU

Ala/A(Alanine)

GAU Asp/D(Aspartic acid)

GGU

Gly/G (Glycine)

U

GUC GCC GAC GGC C

GUA GCA GAA Glu/E(Glutamic acid)

GGA A

GUG GCG GAG GGG G

Key Nonpolar Polar Basic Acidic Stop codon

Translation

1. Initiation

2. Elongation

3. Termination

Today’s lab

• Extract DNA from strawberry• Add extraction buffer

– Made of shampoo and salt– Breaks open cells– Helps to separate DNA from protein

• Add ethanol – Precipitates out DNA

• Collect spool of DNA• Take home if you want to