Download RNA and protein synthesis

RNA REVIEW
–single stranded nucleotide chain
–ribose sugar
–G-C and A-U
–Uracil instead of Thymine
–Different types:
–mRNA, tRNA, rRNA
Types of RNA more details
o Ribosomal
or rRNA: combines
with proteins to make ribosomes.
o Messenger
or mRNA: Carries
instructions for protein synthesis
from nucleus to ribosomes in the
cytoplasm
oTransfer or tRNA: Carries amino
acids to the ribosome and matches
them to the coded mRNA message.
Proteins (polypeptides) are large polymers that are made
from monomers called amino acids.
Hundreds of amino acids linked together by peptide bonds
and fold into a specific shape to make up a protein.
There are 20 different types of amino acids.
Different order of amino acids = different protein!
The types of proteins an organism possesses depend upon the
sequence of nucleotides in DNA
REVIEW FUNCTION OF PROTEINS
Most structurally & functionally diverse group of
biomolecules!
Function - involved in almost EVERYTHING!
1. Metabolism – enzymes: biological catalysts!
2. Structure – hair, skin, nails (keratin, collagen)
3. Transport (cell membrane channels & pumps, hemoglobin –transports
oxygen in blood)
4. Defense (immune system – antibodies)
5. Regulation- hormones (insulin, HGH, cell cycle )
6. Motion - muscle fibers (actin & myosin)
7. Communication – protein receptors in cellmembrane send and
receive chemical signals (nerve cells)
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From gene to protein
nucleus
cytoplasm
transcription
DNA
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translation
mRNA
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protein
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ribosome
trait
THE CENTRAL DOGMA
Protein synthesis occurs in two major parts transcription
and translation.
1. Transcription: Process where DNA serves as a
template to produce complementary mRNA
2. Translation: Process in
which mRNA is used to link amino acids together to
synthesize proteins. Involves tRNA and rRNA
DNA
 mRNA  Protein
transcription
translation
Transcription “writing”
• Making mRNA from DNA
• Occurs in the nucleus
– transcribed DNA strand = template strand
– Enzyme is RNA polymerase
DRAW ME! - TRANSCRIPTION
The code of life
• Code for ALL life!
• Code is redundant
– several codons
for each amino
acid

Start codon


AUG
Stop codons

UGA, UAA, UAG
Part 2: Translation – “Turn into
Proteins”
1. Takes place in the cytoplasm.
2. mRNA finds a ribosome that is
floating in the cytoplasm or attached to
the rough ER.
3. Ribosomes are the site of
translation.
Translation Cont’d
4. A sequence of three mRNA nucleotides is called
a codon.
5. One codon codes for one amino acid.
6. tRNA molecules enter the ribosome carrying
the correct amino acid. The tRNA has an
anticodon that matches the codon on the mRNA.
7. Amino acids are linked together to form a
protein!
DRAW ME! - TRANSLATION
ribosome
cytoplasm