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C10L10C12

2. RNA and Protein Synthesis
Chapter 11
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3. Protein Synthesis Transcription Translation
Consists of 2 main stages:
Transcription
Takes place in the nucleus.
Makes mRNA
Translation
Takes place in the ribosome.
Makes a protein (polypeptide)
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4. Central Dogma DNA RNA Proteins Transcription Occurs in the Nucleus
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5. Making mRNA from DNA
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6. Similar to DNA EXCEPT it differs in 3 ways :
The Sugar in RNA is ribose
instead of deoxyribose
RNA is single stranded (not double stranded like DNA)
RNA contains the nitrogen base Uracil
instead of Thymine
(but it’s still a pyrimadine)
Uracil
Adenine
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7. Types of RNA Messenger RNA (mRNA) Ribosomal RNA (rRNA)
There are 3 types of RNA:
Messenger RNA (mRNA)
Carry copies of instructions for the assembly of amino acids into proteins
Serve as “messengers” from DNA to the rest of the cell
Ribosomal RNA (rRNA)
Helps build ribosomes
Transfer RNA (tRNA)
Transfers the amino acid to the ribosome
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8. Central Dogma DNA RNA Proteins Transcription Translation
Occurs at the Ribosome
Occurs in the Nucleus
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9. Protein Synthesis
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10. C10L10C12

11. The Genetic Code Example: RNA Strand: U C G C A C G G U
During translation, the nitrogen bases of mRNA tell the cell which amino acids (building blocks of proteins) are needed to build a protein (polypeptide).
mRNA bases are read in groups of 3 called codons. Each codon codes for an amino acid.
Example:
RNA Strand: U C G C A C G G U
Reads as: UCG – CAC – GGU (3 codons)
Represents the amino acids:
Serine – Histidine – Glycine
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12. Amino Acids
There are only 20 different amino acids, but 64 different codon possibilities, so several codons might represent 1 amino acid.
example: UCU, UCC, UCA, and UCG all code for the amino acid SERINE
There is also one codon AUG that is called the START codon because it starts protein synthesis.
There are 3 stop codons that stop protein synthesis.
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13. Lets practice mRNA AUG UGA CCU Amino Acid mRNA GCG GAU UGC Amino Acid
mRNA
GCG
GAU
UGC
Amino Acid
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14. AUG START Methionine U C A G C10L10C12 Second Base of Codon
First Base of Codon U C A G
Third Base of Codon
UUU
Phenylalanine
phe
UCU
Serine
ser
UAU
Tyrosine
tyr
UGU
Cysteine
cys
UUC
UCC
UAC
UGC
UUA
Leucine
leu
UCA
UAA
STOP
UGA
UUG
UCG
UAG
UGG
Tryptophan
trp
CUU
CCU
Proline
pro
CAU
Histadine
his
CGU
Arginine
arg
CUC
CCC
CAC
CGC
CUA
CCA
CAA
Glutamine
gln
CGA
CUG
CCG
CAG
CGG
AUU
Isoleucine
ile
ACU
Threonine
thr
AAU
Asparagine
asn
AGU
AUC
ACC
AAC
AGC
AUA
ACA
AAA
Lysine
lys
AGA
AUG
Methionine
Met (start)
ACG
AAG
AGG
GUU
Valine
val
GCU
Alanine
ala
GAU
Aspartic Acid
asp
GGU
Glycine
gly
GUC
GCC
GAC
GGC
GUA
GCA
GAA
Glutamic Acid
glu
GGA
GUG
GCG
GAG
GGG
AUG
START
Methionine
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15. Lets practice mRNA AUG UGA CCU Amino Acid mRNA GCG GAU UGC Amino Acid
Met
(Start)
Stop
Pro
mRNA
GCG
GAU
UGC
Amino Acid
Ala
Asp
Cys
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16. Translation
During translation the mRNA strand synthesized during transcription will be used to make a protein.
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17. What happens during translation?
The mRNA leaves the nucleus and attaches to a ribosome
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18. What happens during translation?
Translation begins at the START codon (AUG) on the mRNA.
The codons in mRNA match anticodons in tRNA.
TRNA transfers amino acids to the ribosome when they are called for by the codons in mRNA.
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19. What happens during translation?
The ribosome moves down the mRNA strand, codon by codon, and each tRNA brings an amino acid that is added to the growing protein (polypeptide).
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