PROTEIN SYNTHESISFrom DNA to RNA to

Proteins

Genes• Sections of DNA that controls

making of physical traits/proteins

Types of RNA• Messenger(mRNA)-

carries protein making instructions from DNA.

• Ribosomal RNA (rRNA)- Part of the ribosome-Makes proteins.

• Transfer RNA (tRNA)- transfers amino acids (building blocks of proteins) to the ribosome to make a protein.

DNA vs. RNA (differences)• RNA

– Sugar (Ribose)– Phosphate group– Nitrogenous Bases

•A•U=Uracil(Not “T”)

•G•C

• Single Stranded• Shorter

• DNA– Sugar

(Deoxyribose)– Phosphate Group– Nitogenous

Bases– A– T=Thymine– G– C

• _Double Stranded• Longer

Protein Synthesis Overview• 2 Main Processes

– Transcription-_DNA_ copied into mRNA (nucleus)

– Translation-mRNA made into proteins_ ________ (ribosomes in cytoplasm)

DNA

mRNA

Transcription!

Ribosome tRNA

Amino acid

Protein

Translation!!!!

• http://www.youtube.com/watch?v=ztPkv7wc3yU

• Transcription video

Transcription• 1. DNA is unzipped (by RNA polymerase-enzyme)

at a gene. “Promoter” initiates copying.• 2. ONE strand of the DNA template is transcribed

(copied) into mRNA using complimentary base pairing.

• 3. RNA polymerase reaches “termination Signal”/end of gene. Stops copying.

Simulation

• http://www.phschool.com/atschool/phbio/active_art/protein_synthesis/index.html

Transcribe the following DNA strands.• ATTCGACG

• UAAGCUGC

• TTACCAGC• AAUGGUCG

• TTAAAACG• AAUUUUGC

Codon• 3 consecutive nitrogen bases on

mRNA that specify 1 particular amino acid.

FLOW OF GENETIC INFO

Genetic Trait-Blue eyes

A

C

B

NUCLE

US

Translation Video

• http://www.youtube.com/watch?v=B6O6uRb1D38&feature=related

Translation -- The decoding of mRNA into a protein

Nuclear envelope

tRNA

Amino acid

Polypeptide chain

Cell membrane

Transcription/translation video

• http://www.youtube.com/watch?v=NJxobgkPEAo

TranslationDecode mRNA to

Proteins

Steps of Translation• 1. The mRNA strand is broken into

codons– (Codon- 3 bases that code for an amino

acids.)

Translation• 2.Ribosome reads the

codons and translates them into amino acids.

• How??– Uses the Genetic Code

–Match the first letter on the left

–Match the second letter on the top

– Match the third letter on the right

–Ex: codon AUG– Amino Acid:

Methionine

• What amino acid goes with the following codons:

• UGG-

• GAA-

• ACA-

• UAG-

• AGC-

• CAG-

Example

Translate and write polypeptide (amino acid) chain• DNA- AGGCGGAGGCGG• mRNA-UCCGCCUCCGCC• Amino Acid-Ser-ala-ser-ala

DNA STRAND (Transcribe, translate, amino acid)

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

• 3. rRNA sends for the tRNA to bring the correct amino acids.

• 4.The tRNA anticodons match up with the mRNA codons – Ex: mRNA CUG -codon– t RNA GAC -anticodon brings

the amino acid methionine attached to it.• 5.Amino acids are attached to each other

making a protein, until a STOP codon is reached

Translation continued• 6. Disassembly- Ribosome

complex falls apart. Polypeptide chain (protein) is released.

CYTOPLASM

• DNA: ACA TTG TAG CAT

• mRNA:

• AminoAcids:

• DNA: TTT TAC TGG CGC GTA

• mRNA:

• AminoAcids:

Protein shape video-honors only

• http://www.youtube.com/watch?v=lijQ3a8yUYQ

FLOW OF GENETIC INFO

Protein Paths (Protein Synthesis) (p.83)

• 1. Nucleus- DNA copied to RNA

• 2. Ribosomes- RNA attaches to ribosomes (on ER) for protein synthesis.

• 3. Protein leaves ER and goes to Golgi Apparatus

• 4. Proteins modified/packaged in Golgi

• 5. Vesicles release proteins out of cell through cell membrane

Which is the correct path of protein synthesis???

D

C

B

A

Protein Paths (Protein Synthesis) (p.83)

• 1. Nucleus- DNA copied to RNA

• 2. Ribosomes/Rough ER- Synthesize Proteins (send to Golgi)

• 3. Golgi Apparatus- modifies/packages/sends proteins

• 4. Cell Membrane- carries proteins from Golgi (in vesicles) to be released from cell

Path of Proteins-