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!!)Transcription Animation
Protein Synthesis Animation TeacherTube Videos –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 animation of mutually exclusive exons»Spicing Animation from NobelPrize.org Click on: Schematic animation of mutually exclusive exons» Before the mRNA leaves the nucleus, the introns are removed, and the exons are spliced together. How Spliceosomes Process RNA
TRANSLATION mRNA (genetic language) needs to be translated into protein language VCAC: Molecular Processes: Translation: The MovieVCAC: Molecular Processes: Translation: The Movie
TRANSLATION Coding from mRNA to making protein Animations (click here for translation animation)Animations Transcribe and Translate a Gene (good activity)Transcribe and Translate a Gene
The mRNA travels out of the nucleus through nuclear pores to a ribosome in the cytoplasm The mRNA binds to a ribosome The mRNA binds to a ribosome Ribosome translates codons (use chart ) Ribosome translates codons (use chart )
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?
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: TranslationProtein Synthesis 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______?
Nice Animations of Protein Synthesis Shows Nucleus to Protein ☺ Protein Synthesis Animation Protein Synthesis Animation Protein Synthesis - Learning Activity - Flash Player Installation Protein Synthesis - Learning Activity - Flash Player Installation
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…
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 chromosome to a different chromosome
Frameshift Animation Quiz 5 - Addition and Deletion MutationsAnimation Quiz 5 - Addition and Deletion Mutations
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 RepressorAnimation Quiz - The Tryptophan Repressor
LAC OPERON (start making lactase) The lac Operon ANIMATIONThe lac Operon (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 MovieVCAC: 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
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 the bacterium’s cell wall, releasing new bacteriophage particles that can 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 Bacterial chromosome Lytic Cycle The Lytic Cycle Go to Section:
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 Bacterial chromosome 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