Protein Synthesis From DNA to protein And viruses.
-
Upload
isabela-beste -
Category
Documents
-
view
223 -
download
6
Transcript of Protein Synthesis From DNA to protein And viruses.
Protein Synthesis
From DNA to protein
And viruses
BIG PICTURE
• Processing of Gene Information - Prokaryotes versus Eukaryotes
• Transcription and Translation
Beadle and Tatum
George Beadle and Edward Tatum during the late 1930s
and early 1940s
• Using Neurospora crassa bread mold determined "one gene one enzyme hypothesis"
•has since been modified to "one gene one polypeptide"
Protein Synthesis Overview
Learn these Terms
• Transcription = DNA → mRNA
• Translation = mRNA → protein
Three Bases Lingo
• DNA Triplet ATC
• mRNA Codon UAG
tRNA Anti-codon AUC
Three Bases Lingo
• DNA original template
• mRNA codes from DNA, takes to cytoplasm
tRNA brings amino acid to ribosomes
rRNA structure of ribosome
Transcription
• DNA never leaves the nucleus
• It codes to mRNA to take the message outside the nucleus
• What do you see?
• Transcription Animation (HOT!!)
Protein Synthesis Animation
TeacherTube Videos –Protein Synthesis (good and to the point)
TeacherTube Videos - DNA to Protein
Introns and Exons
• Primary mRNA = exons + introns
• INTRONS (noncoding region of mRNA) are discarded
• The coding regions, spliced together RNA are called EXONS. = Mature mRNA
SPLICING ANIMATION
• Spicing Animation from NobelPrize.org Click on: Schematic animationof mutually exclusive exons»
• Before the mRNA leaves the nucleus, the introns are removed, and the exons are spliced together.
• How Spliceosomes Process RNA
Intron and Exon Summary
TRANSLATION
• mRNA (genetic language) needs to be translated into protein language
• VCAC: Molecular Processes: Translation: The Movie
TRANSLATION
• Coding from mRNA to making protein
• Animations (click here for translation animation)
• Transcribe and Translate a Gene (good activity)
The mRNA travels out of the nucleus through nuclear pores to a ribosome in
the cytoplasm
The mRNA The mRNA binds to a binds to a ribosome ribosome Ribosome Ribosome translates translates codons (use codons (use chartchart))
Translation
•Ribosome “reads” each codon (3 bases) on the mRNA.
• The mRNA “chart” is consulted and the correct amino acid is determined.
•What amino acids are being requested?
ANSWER
AGC =cysteine
UGA =STOP
CCU=proline
AGC =serine
GGA=glycine
CAA=glutamine
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
•A tRNA with the anticodon complementary to the codon is sent to pick up the requested amino acid and bring it to the ribosome.
tRNA’s hang out in the cytoplasm. Think of them as trucks that transport amino acids from where they float around in the cytoplasm, to the ribosome. Think of the anticodon as the license plate on the tRNAthat matches the mRNA codon.
APE slots on the ribosome
• The ribosome attaches to the mRNA and provides a slot (A) for the tRNA to slide into so it can match the mRNA.
Note the P and A site
• Protein Synthesis: Translation
• A site – Amino acid is dropped off
• P site – Polypeptide builds
• E site-polypeptide exits
There are 20 Amino Acids
• These 20 are shared by all living organisms
Notice AUG codon means “start” building a new protein. UAA,
UAG, UGA mean “stop’ building the protein.
All mRNA’s start with AUG, so all DNA genes start with______?
Answer
•Methionine
Nice Animations of Protein Synthesis
• Shows Nucleus to Protein
• ☺Protein Synthesis Animation
Prot PPt s s Pei he i L r ea i g P t v tP P c i il s Pl P r PstPF a h aea
ll t oa i
• 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
Examples of mutagens?
Thalidomide baby…
GOOD OR BAD?
Mutagen =any source of mutation is a physical or
chemical agent–EX: X-rays–UV light–cigarette components–Hazardous chemicals
Mutation Lingo
• Mutation = any change in the genetic material (nucleotide sequence of DNA)
Gene (point)mutations
SUBSTITUTION – Replace one base for another. Minimal effect
ADDITION – Adding a base
DELETION – removing a base
•Frameshift mutations =change every amino acid that follows the point of mutation
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
Frameshift
• Animation Quiz 5 - Addition and Deletion Mutations
Translocation
Mutation Animations
• What change do you notice?
Translocation 9 and 22
Name the mutation
• Animation Quiz 1
• (Not for the faint of heart) Human Mutants: Mutant Human Organs : Video : Discovery Channel Channel
Also could have substitution
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:_______________________
AAGGTTCGGAGT (DNA)
type of mutation Amino acids
AACGTTCGGAGT:____________________Substitution (C for the G)
AAGGTCTCGGAGT:____________________Insertion (the C)
AAGGTTCGAGT:_______________________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
NEWS FLASH!!!!
• Not every gene in your body is translated into polypeptides all the time.
OPERON
• A cluster of genes under the control of a promoter (beginning of gene)
Promoter
• a nucleotide sequence that enables a gene to be transcribed
Operator
• a segment of DNA that a repressor or activator binds to
Lac Operon (promoter and repressor)
• Animation Quiz - The Tryptophan Repressor
LAC OPERON (start making lactase)
• The lac Operon ANIMATION
• (If lactose is present, the repressor attaches to it. The genes to break down the lactose (lactase) can be made.)
• PICK ME VCAC: Molecular Processes: Lac Operon: The Movie
HOX Genes
• Hox genes are defined by a DNA sequence known as the homeobox, which is a sequence of 180 nucleotides
HOX GENES
• “Body Plan Genes”
HOX GENES: TELL THE BODY WHERE TO PUT THE PARTS
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