Transcription & Translation

Transcription & Translation

Protein Synthesis

Biology 12

Central Dogma

In nucleus

Produced in nucleus Travels to cytoplasm

Produced in cytoplasm

Task

Complete the following table:

Transcription Translation

Location

Template

(What is read)

Purpose

Outcome (End result)

Definition: Transcription

Transcription

Nucleus Location

DNATemplate

(What is read)

To change DNA into a form that can make a protein

Purpose

Messenger RNA

(mRNA)

Outcome

(End result)

Definition: Translation

Translation

Location Cytoplasm (by ribosome)

Template

(What is read)mRNA

PurposeAmino acids assembled in particular

order to make a protein

Outcome

(End result)Protein (polypeptide)

Central Dogma

Task

Transcription & Translation Using pages 239/240

Make notes for EACH about: Initiation (how it starts) Elongation (how it is built) Termination (how it ends)

Transcription ‘to copy’

Initiation: RNA polymerase binds to DNA @ ‘promoter’

Elongation: RNA polymerase builds mRNA

From DNA 3’ end Uses complimentary base pairing

Remember: thymine (T) is replaced by uracil (U)

Transcription ‘to copy’

Termination: RNA polymerase reaches end of gene Stops transcribing

End Result: mRNA breaks away from DNA mRNA exits nucleus

Translation ‘new language’

Initiation: Ribosome binds to start codon

Elongation: Ribosome moves along mRNA

From mRNA 5’ end 3 nucleotides = codon = amino acid tRNA delivers proper amino acid

Turn to page 240!

Translation ‘new language’

Termination: Ribosome reaches stop codon Stops translating

End Result: Ribosome falls off mRNA Protein (polypeptide chain) is released

Start and Stop Codons

Start Codon: Begins translation

AUG (universal start codon) ALSO Codes for methionine (Met)

Sometimes GUG or UUG

Stop Codon: Ends translation

UGA, UAA, UAG

Page 240!

Transfer RNA (tRNA)

Delivers amino acid to ribosome

Reads mRNA codon Has a matching

‘anticodon’

One tRNA for each amino acid

Next amino acid to be added topolypeptide

Growingpolypeptide

mRNA

tRNA

The Whole

Picture

Figure 6 (pg 239)

Example

DNA template:

3’ TAC ACA CGG AAT GGG TAA AAA ACT 5’

Complimentary DNA Read from DNA template (start reading at 3’)

mRNA codon Read from DNA template (start reading at 3’)

tRNA anticodon Read from mRNA

Amino Acids (protein) Read from mRNA

United Nations Conference

Who’s who? Mr. Na

mRNA

Meri Boso ribosome

Flash cards tRNA

Translation protein

Task

A. # 2, 4 – 6, 9 – 11(page 241)

Omit “ribosomes” for #4

B. # 2(page 249)

C. # 3, 4 & 6(page 254)

DNA

rules!

Task A:#2 – Central Dogma

DNA makes RNA (mRNA) through transcription

RNA makes proteins through translation

#4 – RNA types

mRNA Messenger RNA End product of

transcription Takes message from

DNA into cytoplasm Used by ribosome to

make protein

tRNA Transfer RNA Delivers amino acid

to ribosome rRNA

Ribosomal RNA Helps form and

maintain ribosomes

#5 – DNA vs. RNA

DNA Sugar – deoxyribose Double stranded Base pair – thymine Stays in nucleus Can replicate itself Longer strands

RNA Sugar – ribose Single Stranded Base pair – uracil Can leave nucleus Cannot replicate

itself Shorter strands

#6 – Transcription/Translation

Transcription Purpose:

To make mRNA from DNA

Location: Nucleus

Translation Purpose:

To make a specific protein from mRNA

Location: Cytoplasm

(ribosome)

#9 – Stop vs. Start Codon

Start Codon mRNA code Tells ribosome to

begin translation Example:

AUG Also codes for

methionine And: UUG, GUG

Stop Codon mRNA code Stops translation of

that specific amino acid chain

Examples: UAA, UAG, UGA

#10 – Transcribe to mRNA

DNA:

GGA TCA GGT CCA GGC AAT

TTA GCA TGC CCC AA

*mRNA*:

CCU AGU CCA GGU CCG UUA

AAU CGU ACG GGG UU

#11 – Translate to Amino Acids

mRNA sequence divided into codons:

GGC AUG GGA CAU UAU UUU GCC CGU UGU GGU GGG GCG UGA

*Protein translation*:

Gly Met(start) Gly His Tyr Phe Ala

Arg Cys Gly Gly Ala (stop)

Task B:#2 – Transcribe to mRNA

DNA:

TAC TAC GGT AGG TAT A

*mRNA*:

AUG AUG CCA UCC AUA U

Task C:#3 – Anticodons

#4 – Change in 3rd Base May Not Result in Error

Why not? Amino acids have more than one codon

Example: proline Codons CCU, CCC, CCA, and CCG CC - always codes for proline Third base/nucleotide does not matter

#6 – Translate to Amino Acids

mRNA:

GGC CCA UAG AUG CCA CCG GGA AAA GAC UGA GCC CCG

*Protein translation*:

Met (start) Pro Pro Gly Lys Asp (stop)