DNA (deoxyribonucleic acid)

I. Watson and CrickII. DNA Structure

A. Components of DNAB. Patterns of base pairing

III. DNA replicationA. Assembly of nucleotide

strandsB. Replication enzymes

IV. Organization of DNA in chromosomesWatson and Crick

Rosalind Franklin Maurice Wilkins

nucleotide

base

Linus Pauling

DNA structureII. DNA Structure

A. Monomers of DNA

B. Patterns of base pairing

Antiparallel

nucleotide

base

DNA structure

Who, among the following, was not a co-discoverer of thestructure of DNA? a. Linus Pauling b. Rosalind Franklinc. Maurice Wilkins d. Francis Crick

To what carbon of deoxyribose does adenine attach?a. 1’ b. 2’ c. 3’ d. 4’ e. 5’

To what carbon of deoxyribose does a new nucleotide attach?a. 1’ b. 2’ c. 3’ d. 4’ e. 5’

The two jobs of DNASelf replication and genetic code

III. DNA replicationA. Assembly of nucleotide

strandsB. Replication enzymes

Enzymes: DNA polymerases

After DNA rep, sister chromatids stay attached at centromere

Repair enzymes

III. DNA replication

IV. Organization of DNA in chromosomes

homologous

3 bases/ amino acid10,000 bases/ protein (1 gene)

3,000,000,000 base pairs/ genome

22,000 genes/ genome

Histone proteins

Human Genome Project

How many bases does it take to code for one amino acid?a. 1 b. 2 c. 3 d. 5

Approximately, how many genes in the human genome?a. 10, 000 b. 20, 000 c. 30, 000 d. 60, 000

What is the role of histone proteins?a. They neutralize the negative charges of DNAb. They allow DNA to coil up tightlyc. Both a and bd. Neither a or b

DNA sequences in the human genome

DNA fascinating fact

What are the most common elements of our DNA?a. Coding sequencesb. Regulatory sequencesc. Intronsd. Transposons

What are transposons?a. DNA segments between exonsb. Random repetitive DNAc. DNA coding sequencesd. DNA segments that make copies of themselves

I. Protein synthesisA. Transcription

- Amanita and RNA polymeraseB. Classes of RNA/ RNA versus DNAC. Translation

1. The genetic code2. Translation, the final steps

II. MutationsA. Types of mutationsB. Origins of mutations

III. Regulation of gene activityIV. Viruses

Protein synthesis

RNA versus DNA

RNA versus DNA

3 types of RNA

Overview of protein synthesis

Transcription: same language

Translation: different language

pp 191-198

Overview of protein synthesis

A. Transcription

No Thymine, instead RNA has Uracil

Puff

Introns and exons

Collagen gene has 50 introns

Osteogenesis imperfecta

SNURPS

Exon shuffling

Replication versus transcription

In replication, DNA unzips

In replication, DNA nucleotides are brought in

In replication, both sides of the helix are replicated

In replication, DNA polymerases do all the work

The ultimate purpose of replication is

DNA replication takes place in

DNA doesn’t leave the nucleus RNA is processed

Amanita and RNA polymerase

Messenger RNADNA: TAC CAT GAG ACT … ATC mRNA: AUG GUA CUC UGA …

UAG

Ribosomal RNA and ribosomes

Ribosomal RNA and ribosomes

Transfer RNA

Codons and anticodonsDNA: TAC CAT GAG ACT … ATC

mRNA: AUG GUA CUC UGA … UAGtRNA: UAC CAU GAG ACU … AUC

C. Translation1. The genetic code2. Translation, the final

steps

Codons wobble

Which RNA carries amino acids from a pool to the ribosome for assembly?

a. tRNA b. rRNA c. mRNA d. vRNA

How many coding codons are there?a. 20 b. 30 c. 61 d. 64

Which of the following is not a difference between RNA and DNA?a. The sugar is differentb. The nucleotides are differentc. The helix structure is differentd. The bond between phosphate and sugar is different

2. Translation, the final steps

2. Translation, the final steps

http://highered.mcgraw-hill.com/olc/dl/120077/micro06.swf

II. MutationsMutation = change in nucleotide sequence

Mutations can be: bad

neutralgood

Three examples of gene mutations1. Point mutation

2. Frameshift mutation

Most mutations are caused by errors in DNA replicationMutagens

Mutations in coding and non-coding regions

Selected againstDrift Selected for

Mutations in somatic and germ cells

3. Gene duplication

Point mutations ACT GAG TCATGA

Example: Sickle cell trait

TTC AGG

A and B blood types

Frameshift mutations (type of point mutation)

Insertion ACT GAG CAT

TGA

DeletionACT GAG CATTGA

A CT CGTA.. … …

_ TCG TA. … ..

O type blood

Gene duplication

Causes

1. Uneven crossing over

2. Replication slippage

Gene duplication

Entire genome duplicated3N

B. Origins of mutationsmutagens

Errors in DNA replication

viruses

Environmental insults

III. Viruses

HIV Flu

Cold Ebola

2. RNA virusesRetroviruses:Reverse transcription

Reverse transcriptase

A. Diversity1. DNA viruses

Small Pox

RNA DNA

Infect more cells

B. Viruses structure and function

protein coat

viral DNA or RNA

Living or non-living?

C. HIV1. Pandemic

C. HIV2. structure

• 2 strands of RNA

• 3 enzymes• Protein coat• Lipid membrane• HIV target cell?

• Helper T cells

• 9 genes

• Macrophages

2. infection cycle

HIV evolution and reverse transcriptase

HIV target?

CCR5

HIV resistance in humans

HIV replication

• infection and budding

• origin

polio virus

HIVSIV

The end