AP Biology

Protein SynthesisPart 1

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Aminogroup

Carboxylgroup

carbon

Peptide Bonding

George Beadle & Edward Tatum

DNA vs. RNA

Prokaryote vs. EukaryoteTranscription & Translation

Protein Synthesis

5 Carbon Sugar Important Parts(The open bond at the 3’ carbon.)

Marshall Nirenberg

Amino Acid codon chart

Reading Frames

Initiation“Build the factory”

Elongation of the mRNA

Termination

Post Transcription Modification

Spliceosomes

AP Biology

Protein SynthesisPart 2

Peptide Bonding

2’ structure

3’ Structure

Translation by the Ribosome

Transfer RNA (tRNA)

Transfer RNA in 3D

Amino Acid Codon Chart

Anti-codon matches the codon

Connecting tRNA with Amino Acid

Ribosome Structure

Initiation“Build the factory”

Elongation of the peptide & Translocation

Peptide Bonding Upclose

Termination of translation

3’ T A C C A G C C G G T A A T A G G G A C C A T T 5’ DNA TEMPLATE

5’ A U G G U C G G C C A U U A U C C C U G G U A A 3’ mRNA

METH VAL

GLY HIST TYR PRO

TRP

____

____ ___

___

3’ U A C C A G C C G G U A A U A G G G A C C A U U 5’ ANTI – CODON Sequence

Does the DNA Sequence (Million Dollar Blueprint) look like the Anti-codonSequence? Remember, this is how the ribosome “knew” the Amino Acid wasCorrect.

PROTEIN

Polyribosomes

ChaperoninProtein will stay in the cell

RER & SRPProtein will leave the cell

The BIG Picture

AP Biology

Protein SynthesisPart 3

RNA plays multiple roles in the cell: Type of RNA Functions

Messenger RNA (mRNA)

Carries information specifying amino acid sequences of proteins from DNA to ribosomes

Transfer RNA (tRNA)

Serves as adapter molecule in protein synthesis; translates mRNA codons into amino acids

Ribosomal RNA (rRNA)

Plays catalytic (ribozyme) roles and structural roles in ribosomes

Type of RNA Functions

Primary transcript

Serves as a precursor to mRNA, rRNA, or tRNA, before being processed by splicing or cleavage

Small nuclear RNA (snRNA)

Plays structural and catalytic roles in spliceosomes

SRP RNA Is a component of the the signal-recognition particle (SRP)

Type of RNA Functions

Small nucleolar RNA (snoRNA)

Aids in processing pre-rRNA transcripts for ribosome subunit formation in the nucleolus

Small interfering RNA (siRNA) and microRNA (miRNA)

Are involved in regulation of gene expression

Transcription & TranslationProkaryote vs. Eukaryote

Codon Chart, Yet again

Point Mutation(A single point is changed)

Reading Frame Mutations(Everything behind is changed)

Somatic vs. gametes(Who is affected?)

AP Biology

Eukaryotic Genome Control Mechanisms for Gene expression

Chromatin vs. Chromosomes appearance within the cell.

Histone Proteins and Supercoiling

DNA double helix

Histonetails

His-tones

Linker DNA(“string”)

Nucleosome(“bead”)

10 nm

2 nm

Histone H1

Nucleosomes (10-nm fiber)

Supercoiling of Chromatin

Euchromatin vs. Heterochromatin(The dark spots are the hetero)

DNA Control stages in Protein Synthesis

Signal

NUCLEUS

DNA

RNA

Chromatin

Gene availablefor transcription

Gene

Exon

Intro

Transcription

Primary transcript

RNA processing

Cap

Tail

mRNA in nucleus

Transport to cytoplasm

CYTOPLASM

mRNA in cytoplasm

Translation

Degradationof mRNA

Polypeptide

CleavageChemical modificationTransport to cellular

destination

Degradation of protein

Active protein

Degraded protein

Methylation

.

Histonetails

Amino acidsavailablefor chemicalmodification

DNAdouble helix

Histone tails protrude outward from a nucleosome

Acetylation of histone tails promotes loose chromatinstructure that permits transcription

Unacetylated histones Acetylated histones

“Build the factory”

Enhancers

Distal controlelement Activators

Enhancer

DNA

DNA-bendingprotein

TATAbox

PromoterGene

Generaltranscriptionfactors

Group ofmediator proteins

RNApolymerase II

RNApolymerase II

RNA synthesisTranscriptionInitiation complex

Notice the different nucleotide control

sequences(red vs, pink)

Controlelements

Enhancer Promoter

Albumingene

Crystallingene

Availableactivators

Availableactivators

Albumingene notexpressed

Albumingeneexpressed

Liver cell Lens cell

Crystallin genenot expressed Crystallin gene

expressed

Liver cellnucleus

Lens cellnucleus

miRNA &siRNA

Dicer

Hydrogenbond

Proteincomplex

miRNATarget mRNA

Degradation of mRNA

OR

Blockage of translation

Control of exons

How many As on the tail?

“Build the factory”

ChaperoninProtein will stay in the cell

RERProtein will leave the cell

Proteosomes

Protein tobe degraded

Ubiquitinatedprotein

Proteasome

Protein entering aproteasome

Protein fragments(peptides)

Proteasomeand ubiquitinto be recycled

Ubiquitin