day7 protein synthesis · 2019. 2. 25. · day7_protein synthesis author: wai created date:...

PROTEIN SYNTHESIS2/21/19

DO NOW▸What are 3 differences between DNA and

RNA?

▸What is the central dogma of molecular biology?

AGENDA▸ Transcription

▸ Translation

▸ Summary

PROTEIN SYNTHESISCORNELL NOTES TITLE (PAGE 105)

PROTEIN SYNTHESIS▸ Process of assembling proteins using the

information encoded in DNA

PROTEIN SYNTHESISThe Steps of How to Make Proteins

Genetic info only flows from:

DNAà RNA à Protein

DNA RNA PROTEIN

!8

Protein Synthesis

1. Transcription

2. Translation

Transcriptioncomes from the word transcribe.

To transcribe something means to copy it in another way.

Hint: Court transcriber

DNA RNA PROTEIN

DNA à RNA = Transcription

Transcription

TRANSCRIPTION▸ Genetic information is passed from DNA in

the nucleus to mRNA

▸ Transcription: DNA -> RNA

But why do we need to make a new copy?

*DNA always stays in the nucleus!

*Ribosomes, the protein-making machines, are in the cytoplasm!

Nucleus


TRANSCRIPTION STEPS▸ RNA Polymerase (enzyme) unwinds DNA and makes

a matching mRNA

▸ T->A, A->U

▸ pre-mRNA: introns (“useless” code) + exons (codes for gene)

▸ Introns get spliced out, so the final mRNA has exons only

▸ mRNA leaves the nucleus out into the cytoplasm, to a ribosome.

Step 1: RNA Polymerase (enzyme) unwinds DNA.

T A T A

TA TA

A G C T C G A A C G G A

TCCGTTCGAGCT

A G

C

TC G A A C G G

A

TC

CGTTCGAG

CT

3’ 5’

5’ 3’

RNA polymerase


Step 2: RNA Polymerase also makes a matching messenger RNA (mRNA).

T A T A

TA TA

A G

C

TC G A A C G G

A

TC

CGTTCGAG

CT

3’ 5’

5’ 3’

UCCGUUCGAGCRNA polymerase

mRNA

Note:

It matches A to U (uracil)

instead of T (thymine)!!


* There are useless DNA codes called INTRONS that get spliced out. The pieces that are left, called EXONS, form the actual mRNA.

Pre-mRNA:UCCGGAG UAACAG U GG A

intron intron

exonexon exon

GAG UAA

mRNA:

UCCG C

Exons are expressed!


Step 3: mRNA leaves the nucleus out into the cytoplasm, to a ribosome.

T A T A

TA TA

A G

C

TC G A A C G G

A3’ 5’

5’ 3’

UCCGUUCGAGC

mRNA

TC

CGTTCGAG

CT

A G C T C G A A C G G A

TCCGTTCGAGCT


Translationcomes from the word translate.

To translate something means to change it into another language.

translationHey, what’s up?

What do you want to eat?

Hola, que tal?

Que quieres comer?

DNA RNA PROTEIN

Translation

RNAà Protein = Translation

TRANSLATION▸ Genetic information is passed from RNA to

make proteins in the ribosomes

▸ Translation: RNA -> protein

But why do we need to translate RNA?

RNA

A,U,G,C (nucleotides)

Pro, met, ser, val, leu, met…

(amino acids)

PROTEIN


!22

NUCLEOTIDES AND AMINO ACIDS ARE COMPLETELY

DIFFERENT MOLECULES!!!

TRANSLATION STEPS▸1. Ribosome reads every 3 nucleotides,

called CODONS (1 codon = 3 nucleotides)

▸Ribosomes starts translating when it reads the codon “AUG.”

▸2. Transfer RNA (tRNA) brings an amino acid for each codon.

▸ tRNA has an anticodon that matches the codon

*tRNA has an ANTICODON that matches the codon on the mRNA.

amino acid attachment site

U A C

anticodon

TRANSLATION STEPS▸ 3. Amino acids connect to make a Protein!

▸ 4. Ribosome stops translating at a STOP codon (UAA , UAG , or UGA ).

Step 1. Ribosome (rRNA) reads every 3 nucleotides, called CODONS.

(1 codon = 3 nucleotides)

ribosome

C GUU CG A GC UU C C A G U G U U A A


mRNA

Step 2. It starts translating when it reads the codon “AUG.”

ribosome


START

C GUU CG A GC UU C C A G U G U U A AmRNA

Step 3. Transfer RNA (tRNA) brings an amino acid for each codon.

ribosome

START

tRNARNAà Protein = Translation


Step 4. Amino acids connect to make a Protein!

ribosome

tRNA

met



ribosome

met


STARTC GUU CG A GC UU C C A G U G U U A A

mRNA

ribosome

met

tRNA

pro



mRNA

ribosome

met pro



mRNA

ribosome

met pro

tRNA

ser



mRNA

ribosome

met pro ser



mRNA

ribosome

met pro ser

tRNA

gly



mRNA

ribosome

met pro ser gly

STOP

5. Ribosome stops translating at a STOP codon (UAA , UAG , or UGA ).



mRNA

ribosome

met pro ser gly

STOP


START

5. Ribosome stops translating at a STOP codon (UAA , UAG , or UGA ).


A protein is made!met pro gly val

STOP



mRNA

What happens to the protein, after it is made?

• It travels in the Rough Endoplasmic Reticulum (E.R.) (Hallways)

• Then gets packaged & delivered in Golgi Apparatus (Office Aides)

VIDEO

▸ https://www.youtube.com/watch?v=oefAI2x2CQM

▸

-VIDEO SHEET-SUMMARY

-TRANSCRIPTION AND TRANSLATION: ANALOGY STORY - PART 4 ONLY

ILLUSTRATIVE SUMMARY

ILLUSTRATIVE SUMMARY▸ At least 4 colors

▸Must LABEL

▸Must include ALL terms

▸ If you’re doing a diagram or flow chart, you must EXPLAIN the flow chart

day7 protein synthesis · 2019. 2. 25. · day7_protein synthesis author: wai created date:...

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