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

RNA polymerase Newly made RNA Direction of transcription 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 /lib/ /Transcription_2.mov

Terminator DNA DNA of gene RNA polymerase Initiation Promoter DNA 1 Elongation 2 Area shown in Figure 10.9A Termination 3 Growing RNA polymerase Completed RNA

transcript with cap and tail Exons spliced together Introns removed Transcription Addition of cap and tail Tail DNA mRNA Cap Exon Intron Coding sequence Nucleus 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

tRNA molecules Growing polypeptide Large subunit Small subunit mRNA

tRNA-binding sites Large subunit Small subunit mRNA binding site

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA 2 Peptide bond formation

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA 2 Peptide bond formation 3 Translocation New peptide bond

Polypeptide A site 1 Codon recognition Codons Amino acid Anticodon P site mRNA 2 Peptide bond formation 3 Translocation New peptide bond Stop codon mRNA movement

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!!!!!!! DNA  RNA  Protein

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 Function As 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