Download From DNA to Protein - Stevenson High School

From DNA to Protein
DNA Review
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Nucleic acid
Double helix
Two strands of nucleotides
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Phosphate-sugar backbone
Nitrogenous base steps
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Adenine
Guanine
Cytosine
Thymine
Ribonucleic acid (RNA)
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Nucleic acid
Usually single strand of nucleotides
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Sugar-phosphate backbone
Nitrogenous bases
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Adenine
Guanine
Cytosine
Uracil
DNA/RNA Comparison
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Structure
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DNA: double helix
RNA: single strand
Sugars
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DNA: deoxyribose
RNA: ribose
Bases
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DNA: A, G, C and T
RNA: A, G, C, and U
Base-pairing rules
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DNA
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A=T
G=C
RNA
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A=U
G=C
Getting the info out…
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Where is DNA stored?
Getting the info out…
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Where is DNA stored?
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nucleus
Where are proteins synthesized?
Getting the info out…
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Where is DNA stored?
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Where are proteins synthesized?
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nucleus
Ribosomes in the cytoplasm
Problem?
Getting the info out…
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Where is DNA stored?
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Where are proteins synthesized?
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nucleus
Ribosomes in the cytoplasm
Problem?
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How does the cell get the info to the
workers?
RNA is the solution!
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3 types of RNA
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mRNA: messenger RNA
tRNA: transfer RNA
rRNA: ribosomal RNA
RNA helps build proteins
mRNA
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Single, uncoiled chain
Carries genetic information from
nucleus to cytoplasm
tRNA
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Single chain folded into
a hairpin
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~80 nucleotides long
Binds to specific amino
acids
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~ 45 varieties of tRNA
rRNA
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RNA folded into
globular form
Combines with
proteins to form
ribosomes
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Ribosomes build
proteins!
Transcription of RNA
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Copying genetic info from DNA into RNA
Begins at promoter (special DNA
segment)
Ends at termination signal
Assisted by RNA polymerase
Transcription
Adenine (DNA and RNA)
Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
Base pairing
DNA RNA
G ≡ C
C ≡ G
T = A
A = U
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RNA
polymerase
DNA
RNA
Importance of Proteins
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Proteins determine structure & function
of cell
Protein = polymer of amino acids
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Folded upon itself (globular)
3-D structure
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IMPORTANT for function
Genetic Code
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Genetic code = triplets of mRNA that
code for amino acids
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CODON = 3 nucleotide bases in row
ONLY 20 different amino acids
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64 possible triplets
START codon: AUG
STOP codons: UAA, UAG, UGA
Genetic Code
Translation
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RNA  protein
Process of assembling polypeptides
from mRNA info
Protein synthesis
1. mRNA is transcribed in nucleus and
leaves through nuclear pore
Protein synthesis
2. mRNA attaches to a ribosome
translation starts at start codon (AUG)
tRNA has anticodon
- complementary to
mRNA codon
Protein synthesis
3. Polypeptide
assembly line
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Insert video from Presentation – Protein
synthesis
Protein Synthesis
Protein Synthesis
nucleus
tRNA
ribosome
mRNA
anticodon
codon
mRNA