What is the job of p53?

What does a cell need to build p53? Or any other protein?

The central dogma of biology is…

DNA RNA Protein

What do think this means?

Using the Information Stored in DNA to Build Proteins

• Genetic code is…

• Sequence of bases impt b/c…

• A gene is …

• Proteins are made on….

• How do we get the code for making proteins out of the nucleus and into the cytoplasm?

Protein Synthesis: Transcription and Translation

DNA vs

RNA

Transcription• Process by which the genetic code is copied

from DNA into messenger RNA

Transcription occurs in nucleus before translation

RNApolymerase

Newly made RNA

Direction oftranscription Template

strand of DNA

RNA nucleotides

Stages of Transcription

Initiation: RNA polymerase binds to a promoter, where the helix unwinds and transcription starts

Elongation: RNA nucleotides are added to the chain

Termination: RNA polymerase reaches a terminator sequence and detaches from the template

http://ramsey.schoolwires.com/114620810131521263/lib/114620810131521263/Transcription_2.mov

TerminatorDNA

DNA of gene

RNA polymerase

Initiation

PromoterDNA

1

Elongation2

Area shownin Figure 10.9A

Termination3

GrowingRNA

RNApolymerase

CompletedRNA

RNAtranscriptwith capand tail

Exons spliced together

Introns removed

TranscriptionAddition of cap and tail

Tail

DNA

mRNA

Cap

Exon Exon ExonIntron Intron

Coding sequenceNucleus

Cytoplasm

RNA Splicing

– Eukaryotic mRNA has non-coding sequences called introns, separating the coding regions called exons

– Eukaryotic mRNA undergoes processing before leaving the nucleus

– Cap added to 5’ end: single guanine nucleotide

– Tail added to 3’ end: Poly-A tail of 50–250 adenines

– RNA splicing: removal of introns and joining of exons to produce a continuous coding sequence

Copyright © 2009 Pearson Education, Inc.

10.8 The genetic code is the Rosetta stone of life

– Characteristics of the genetic code– Triplet: Three nucleotides specify one amino acid

– 61 codons correspond to amino acids

– AUG codes for methionine and signals the start of transcription

– 3 “stop” codons signal the end of translation

Copyright © 2009 Pearson Education, Inc.

Translation• Process of

decoding mRNA into a polypeptide sequence.

Translation

Codon to Amino Acid

Translation• Involves:

1. mRNA- carries codon

2. ribosome- rRNA, part of ribosome

3. tRNA- carries aa and anticodon

4. enzymes- help aa bond to tRNA

5. chemical energy, ATP

tRNAmolecules

Growingpolypeptide

Largesubunit

Smallsubunit

mRNA

tRNA-binding sites

Largesubunit

Smallsubunit

mRNAbinding site

Polypeptide

A site

1 Codon recognitionCodons

Aminoacid

Anticodon

P site

mRNA

Polypeptide

A site

1 Codon recognitionCodons

Aminoacid

Anticodon

P site

mRNA

2 Peptide bondformation

Polypeptide

A site

1 Codon recognitionCodons

Aminoacid

Anticodon

P site

mRNA

2 Peptide bondformation

3 Translocation

Newpeptidebond

Polypeptide

A site

1 Codon recognitionCodons

Aminoacid

Anticodon

P site

mRNA

2 Peptide bondformation

3 Translocation

Newpeptidebond

Stopcodon

mRNAmovement

Translation: Start

Translation: Elongation

Translation: Termination

Protein Synthesis

Protein Synthesis: Key Points

• DNA “directs” synthesis of proteins

• Proteins made on ribosomes

• Transcription:

- RNA polymerase unzips DNA

- occurs in nucleus

• Translation:

- occurs in cytoplasm

- mRNA(codon) and tRNA(anticodon)

• Genetic Code is UNIVERSAL!!!!!!!

DNARNAProtein

Proteins

• Composed of aa• Chain of aa called polypeptide• Peptide bonds hold aa together• 1 or more polypeptide chains can

link and fold together to form a 3-dimensional protein

• Proteins differ in number and sequence of aa

• Protein structure determines their function

Protein Folding and FunctionAs the amino acid chain grows, it folds into a three-dimensional (3-D) structure, which depends on both the chemical nature and order of the different amino acids. The 3-D structure determines the function of the protein. When there is a change in one or more amino acids, then the ability of the protein to function may be affected. The protein's function may be unchanged or it may become sluggish, hyperactive, or inactive.

Proteome: collection of all proteins in a species