Protein SynthesisFrom DNA to protein

And viruses

And bacteria

Central Dogma• You Tube Protein Synthesis (2:51)• DNA Transcription and Protein Assembly (3:02) From DNA to

proteins

• FROM GENOTYPE TO

PHENOTYPE (From DNA to proteins)

Beadle and Tatum

REMEMBER US?

George Beadle and Edward Tatum during the late 1930s and early 1940s • Using Neurospora crassa bread mold

determined "one gene one enzyme hypothesis"

Protein Synthesis Overview get “Central Dogma” and “Protein Synthesis” Worksheets

• DNA Replication, Transcription, Translation Youtube (8 mins)

Learn these Terms

• Transcription = DNA → mRNA

• Translation = mRNA → protein

Three Bases Lingo

• DNA Triplet ATC

• mRNA Codon UAG

tRNA Anti-codon AUC

The 3 RNA’s

• mRNA – messenger RNA – codes from DNA in the nucleus to take the genetic code to the ribosome in the cytoplasm

• tRNA – transfer RNA – brings a specific amino acid to the ribosome

• rRNA –ribosomal RNA – plus protein makes up a ribosome

Transcription: DNA to mRNA

• DNA never leaves the nucleus• It codes to mRNA to take the

message outside the nucleus• TRANSCRIPTION YOUTUBE (1:53)

RNA polymerase(RNAP)

• The enzymes that

makes RNA from the

DNA template

DNA

RNARNAP

Not all RNA nucleotides make the cut:

Introns and Exons• Primary mRNA = exons +

introns• INTRONS = discarded, noncoding

region of mRNA• EXONS = the coding regions, spliced

together RNA are called also = Mature mRNA

• RNA Splicing Youtube (1:38)

SPLICING RNA

Mature mRNA

Or Primary RNA

SPLICING ANIMATIONsnRNP’s Spliceosome

Seriously detailed splicing youtube (1:39)

McGraw-Hill How Splicesosomes Process RNA

• Before the mRNA leaves the nucleus, the introns are removed, and the exons are spliced together.

Exons leave the nucleus

Mature mRNA leaves

Transcription Initiation Control

Transcription Promotors• DNA sequences at start site (recognize

TATA BOX)

• RNA polymerase and accessory proteins (transcription factors) bind to the promoter to initiate production of an mRNA transcription.

TATA

Transcription Terminator• mRNA is cut free from DNA

The mRNA travels out of the nucleus through nuclear pores to a ribosome in

the cytoplasm

The mRNA binds to a ribosome

Ribosome translates codons (use chart)

TRANSLATION

• mRNA (genetic language) needs to be translated into protein language (chain of amino acids)

• Translation Youtube (2:06)

TRANSLATION

• Coding from mRNA to making protein (at the ribosome)

• DNA Translation Youtube (2:06)

tRNA

• transports amino acids to ribosomes

• There is a specific amino acid for each tRNA

Job of tRNA

• Complements the codon of mRNA and picks up the appropriate amino acid

ANIMATION:Animation of Translation

Note the A P E sitesCentral Dogma youtube (3:03)

• A site – Amino acid is dropped off

• P site – Polypeptide builds

• E site – tRNA exits (after giving its amino acid to building polypeptide chain)

APE sites of Ribosome youtube (1:31)

A P E Sites at the Ribosome

Translocation: movement of

tRNA across the ribosome

Notice AUG codon means “start” building a new protein. UAA,

UAG, UGA mean “stop’ building the protein.

There are 20 Amino Acids• These 20 are shared by all living

organisms• What does CAC code for?• histidine

Translation Initiation

• mRNA attaches to the ribosome (AUG –start codon)

Translation Elongation

tRNA brings amino acids to the ribosome

Translation Termination

mRNA reaches one of the STOP codons• Bond breaks the last tRNA and its amino

acid to release the polypeptide bond

Cooooool Protein Synthesis 3-D

• CENTRAL DOGMA (2:52)

All mRNA’s start with AUG, so all DNA genes start with______?

Answer

•Methionine

• THINK:

• What would happen if something caused the base sequence to change?

• What sorts of things could cause this?• Could the base changes be repaired?• Would those changes be passed on

to the individual’s offspring?

MUTATION:

A change in the base sequence of a gene resulting in a different base sequence and thus different amino acid sequence.

What causes mutations? MUTAGENS

Thalidomide baby…

• Mutagen =any source of mutation is a physical or chemical agent–EX: X-rays–UV light–cigarette components–Hazardous chemicals

Mutagens

Mutation Animations

• BBC - Education Scotland - Higher Bitesize Revision - Biology - Genetics and adaptation - Mutations: Revision 2

• EXPLAIN HOW EACH MUTATION IS DIFFERENT FROM THE ORIGINAL DNA SEQUENCE

Gene (point)mutations

SUBSTITUTION – Replace one base for another. Minimal effect

ADDITION – Adding a base

DELETION – removing a base

Addition/deletions cause a complete Frame Shift that affects the whole gene.

Mutation Lingo

• Mutation = any change in nucleotide sequence of DNA

• Reading frame = triplet grouping• Mutagenesis = creation of

mutations

More Mutation Lingo

• Nonsense mutation = change an amino acid into a STOP codon

• Missence mutation = change the amino acid coding

• Silent mutation = no change in protein product

Chromosome Mutations

Translocation•• Inversion• Segment of a same chromosome

is turned end to end

has moved one segment of a chromosome to a different chromosome

Translocation

Translocation 9 and 22

Cystic Fibrosis Deletion

Albinism is due to a mutation of the melanin pigment gene. A one base substitution results in only 1 amino acid being in error.

ALBINISM

AAGGTTCGGAGT (DNA)

type of mutation Amino acids

AACGTTCGGAGT:____________________

AAGGTCTCGGAGT:____________________

AAGGTTCGAGT:_______________________

ANSWER-

• Substitution (C for the G) • Insertion (the C)• Deletion (the G)

Chromosomal mutations

Affect the entire chromosome - often fatal.

Mutagens can cut up DNA into pieces.

When Repair mechanism reassembles them, they may be in the wrong order.

Oncogenes

Genes that when mutated result in cancer.

EXAMPLE: BRCA1 and BRCA2

Found to cause breast cancer on 81-kb region of human chromosome 17

Viral Infections

Viruses

• Nothing more than packaged genes• Simple tools for geneticists• HIV EBOLA

Bacteriophage Infection (SEM)

Bacteriohage Infection

Every virus has two stages

• a dormant, particulate, transmissible stage called the virion stage

• an active, intracellular stage called the infectious stage

Infectious Stage: Lytic Infection

1.attachment

2. Insertion of virus DNA

3. replication of virus components

4.packaging and assembly of new virions

5. exit from cell –”lysis” bursts

Bacteriophage enzyme lyses thebacterium’s cell wall, releasingnew bacteriophage particles thatcan attack other cells.

Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles

Bacteriophage takes over bacterium’s metabolism, causing synthesis of new bacteriophage proteins and nucleic acids

Bacteriophage injects DNA into bacterium

Bacteriophage attaches to bacterium’s cell wall

Bacteriophage

Bacteriophage DNA

Bacteriophage protein

Bacteriophage protein coat

Bacteriophage DNA

Bacterialchromosome

Lytic Cycle

The Lytic Cycle

Go to Section:

LYTIC INFECTION

•Lytic Infection Animation

Lysogenic Infection

• The viral DNA becomes integrated into the bacterial DNA after infection. It is replicated along with the host DNA when the host reproduces. The viral DNA is referred to as a prophage.

Bacteriophage proteins and nucleic acids assemble into complete bacteriophage particles

Bacteriophage enzyme lyses the bacterium’s cell wall, releasing new bacteriophage particles that can attack other cells

Bacteriophage DNA inserts itself into bacterial chromosome

Bacteriophage DNA (prophage) may replicate with bacterium for many generations

Bacteriophage DNA (prophage) can exit the bacterial chromosome

Bacteriophage DNA forms a circle

Bacteriophage DNA

Bacterialchromosome

Bacteriophage injects DNA into bacterium

Prophage

Lytic Cycle

Lysogenic Cycle

A Lysogenic Infection

Go to Section:

DIAGRAM COMPARISON

• Lytic and Lysogenic Infections

Virus Examples

• RNA instead of DNA: cold, flu, HIV, polio, measles, mumps

• DNA viruses: herpes. Chicken pox, hepatitis

• Herpes infections may flare up when under stress, a cold, or sunburn

Ebola Virus

• Causes hemorrhagic fever• Movie Outbreak

Hanta Virus

• Southwestern US mice carried it

cardiovascular collapse, respiratory failure, and death

HIV

• Has 2 copies of RNA• Is a retrovirus (RNA to DNA)• Carry enzyme reverse transcriptase

Aids infected cells

• HIV = Human Immunodeficiency Virus

• AIDS = Acquired Immune Deficiency Syndrome

F Factor

• Fertility factor• Allows one bacterium to carry genes to

another by conjugation

Sex pili

Bacterium Plasmid

• Circular DNA in bacteria• Extra genes, not essential for bacterial

survival

Transformation

• Uptake of DNA from another bacteria cell

Conjugation

• Physical union of two bacterial cells to transfer DNA

R Plasmid

• Contain genes that are resistant to many antibiotics

Transduction

• Some viruses move bacterial from one bacterial cell to another