Protein SynthesisFrom Codes/genes to Proteins/machines

Central Dogma- DNARNAProtein

It explains how genetic information flows

Can you break the code???

8 5 12 12 15      3 12 1 19 19 

Making Proteins

Protein Synthesis Process of making

proteins Two part process

1. Transcription

2. Translation

Remember Reading DNA?

The four chemical bases in DNA (A, T, C, G) create a code/gene

Ribosomes “read” this DNA code/gene to make proteins. Where are ribosomes

located? Where is DNA located?

Nucleus Problem

Nucleus not permeable to DNA DNA is a large to fit out of

pore Double stranded = wide

How do we get the code/gene to the ribosomes to make proteins? Copy code into a smaller

molecule RNA (ribonucleic acid)

DNA BOTH RNA

RNA vs DNA• What is the difference?

• Compare and contrast DNA to RNA

Two Types of Nucleic AcidsDeoxyribonucleic Acid DNA Double Stranded Nucleotide sugar =

Deoxyribose Bases = A, T, G, C

Ribonucleic Acid

RNA Single Stranded

Smaller

Nucleotide sugar = Ribose

Bases = A, U, G, C

The Tail of Two RNA’s

Two RNA types needed for Protein synthesis

mRNA messenger RNA

tRNA Transfer RNA

Step 1: Transcription Process of making messenger RNA (mRNA) from DNA Exactly like Replication (with one small difference)

Use base paring rules C pair with G G pair with C T pairs with A

BUT A pairs with U (uracil)

Which enzyme is used to add nucleotides??

Protein synthesis

Modifications of Mrna before it can leave nucleus

Add5’ cap- protects mRNA and allows it to leave nucleus/find a ribosome

Poly (A) tail-They are added to: protect mRNA and allow it to leave nucleus/find a

ribosome

Introns (non-coding sequences between exons) are removed and exons (amino acid coding sequences) are spliced together

mRNA Function

Take gene from nucleus to ribosome Disposable copies(often

thoughsands) of VERY important information

Tells Ribosome how to build protein.

Transcription Practice (DNA to mRNA)

Open DNA: A T G C C G T T A A C G A G T C T

mRNA copy: U

Cheat SheetA = UT = AC = G G =C

Step 2: Translation

What does it mean to Translate something? Change from one language to another

Biology Translation To go from the language of DNA (A, T,

C, G, and U) to the language of protein (amino acids) Amino acids are the building blocks of

proteins

Translation Involves ribosome, mRNA and tRNA (transfer RNA)

Ribosome reads mRNA on codon (3 bases) at a time

tRNA matches with codon on mRNA Brings amino acid with

Ribosome takes amino acid from tRNA and links it to growing protein

Translation summary mRNA read by ribosome in

groups of 3 bases called CODONS Ex: AUG = Start making

protein Ex: UGA = Stop making

protein Codon on mRNA match Codon on

tRNA Codon tells ribosome what

amino acid to attach to protein

Decoding mRNA

Humans use decoder Codon wheel

Codon chart

Reading Codon Wheel Using 3 base Codon

Start at center of the wheel Find the first nitrogen base in codon Sets what ¼ of circle you will work in

Move to the next ring of circle Find second nitrogen base Sets what ¼ of the remaining circle you are in

Move to the last ring Find third nitrogen base Arrive at your amino acid

Finding Amino acid for Codon GAG

Reading Codon Chart Using 3 base Codon

Start at left side Find the first nitrogen base in codon Sets what row you are using

Move to the top of chart Find second nitrogen base Sets what column you are using

Find where column and row meet This is the box you are working in

Find matching Codon in this box

Find the amino acid for the codon CGU

CYUTranscribe this DNA to mRNATranslate the mRNA to amino acids

DNA T A C G G C A T C

mRNA

Amino Acid