Quiz on DNA & RNA
• Actual link to quiz in case hyperlink doesn’t
work:
• http://www.biologyjunction.com/qz_DNA.html
PROTEIN SYNTHESIS
• Genes: small sections of DNA
– Controls production of proteins
– Nucleotide: base unit for strand of DNA (made
of sugar, phosphate and nitrogenous base
PROTEIN SYNTHESIS
• Proteins are used to build cells and control
chemical reactions so they do most of the work
– Ex: breaking down glucose in cellular respiration,
digesting food, making spindle fibers in mitosis
PROTEIN SYNTHESIS
• Proteins are polymers of amino acids
– Amino acid chains are call polypeptides
• Nucleotides in each gene has info for
assembling string of amino acids that make
up a single protein
PROTEIN SYNTHESIS
• Enzymes control all chemical reactions of
organisms
• DNA has instructions for making proteins,
therefore, DNA controls cells
– Provides workers with instructions
• Workers for protein synthesis take
instructions, the workers are RNA
Replication Fork Annimation
• http://highered.mcgrawhill.com/olcweb/cgi/pluginpop.cgi?it=swf::
535::535::/sites/dl/free/0072437316/120076
/micro04.swf::DNA Replication Fork
PROTEIN SYNTHESIS
• RNA:
– Nucleic acid
– DNA = double helix (zipper);
– RNA = single helix (one side of zipper)
PROTEIN SYNTHESIS
• RNA: workers for protein synthesis
– Take instructions for how proteins are
assembled
– RNA assembles protein
PROTEIN SYNTHESIS
3 Types of RNA that build proteins:
1. Messenger RNA (mRNA)
2. Ribosomal RNA (rRNA)
3. Transfer RNA (tRNA)
PROTEIN SYNTHESIS
1. Messenger RNA (mRNA):
•
•
•
Brings instructions from DNA to cytoplasm
In cytoplasm, moves to ribosome
The ribosome is made up of ribosomal RNA
(rRNA)
PROTEIN SYNTHESIS
2. Ribosomal RNA (rRNA):
–
–
–
Makes up ribosome
Binds to mRNA
Uses instructions to assemble amino acids in
correct order
PROTEIN SYNTHESIS
3. Transfer RNA (tRNA):
•
•
the “supplier”
Delivers amino acids to ribosome to be
assembled into a protein
Click image to view movie
PROTEIN SYNTHESIS
• Transcription:
– In nucleus, enzymes make an “RNA copy” of piece
of DNA strand
– Result: formation of 1 RNA molecule (1/2 zipper)
Click image to view movie
PROTEIN SYNTHESIS
PROTEIN SYNTHESIS
• Genetic Code:
– Genetic message of info for building protein
– Proteins contain chains of amino acids
• Language of proteins = alphabet of amino acids
– In DNA, nitrogen bases are: A T C G
– In RNA, nitrogen bases are: A U C G
PROTEIN SYNTHESIS
PROTEIN SYNTHESIS
• Genetic Code:
– Codon: group of three bases in mRNA
– All organisms use same genetic code
PROTEIN SYNTHESIS
• Translation:
– Converting info in sequence of mRNA bases
into sequence of amino acids in protein
– Takes place at ribosomes in cytoplasm
PROTEIN SYNTHESIS
• Translation: From mRNA to Protein
– mRNA made in nucleus travels to cytoplasm
– In cytoplasm, ribosome attaches to strand of
mRNA like clothespin clamped onto clothesline
PROTEIN SYNTHESIS
• Function of tRNA
– Transfers RNA to ribosomes
– Each tRNA attaches to one type of amino acid
PROTEIN SYNTHESIS
• Function of tRNA:
– Pairs with mRNA codon, two molecules join
together
– Ribosome slides along mRNA to next codon
– Chain of amino acids is formed until a “stop”
codon is reached on mRNA strand
PROTEIN SYNTHESIS
PROTEIN SYNTHESIS
•
5 Steps of Translation:
1. Ribosome attaches to mRNA strand; tRNA
approaches ribosome
2. AUG codon signals “start” of protein synthesis
3. New tRNA molecule attaches to ribosome; amino
acids on tRNA molecules join
4. Ribosome slides along mRNA to next codon; new
tRNA carrying amino acid attaches to ribosome
and mRNA
5. Chain of amino acids is formed until “stop” codon
DNAi animation of protein
synthesis process from beginning
(Watson & Crick) to end
• http://www.dnai.org/a/index.html
Annimations
• http://www.biostudio.com/demo_freeman_p
rotein_synthesis.htm
• http://www.wisconline.com/objects/index_tj.asp?objID=AP
1302
• http://www.lewport.wnyric.org/JWANAM
AKER/animations/Protein%20Synthesis%2
0-%20long.html