1. Please turn in your homework
Today you will need:
Your science notebook
Scissors
Glue
Something to write with
Please turn in your homework

2. Protein Synthesis Consists of 2 main steps Step 1: Transcription
Step 2: Translation

3. Central Dogma Proteins DNA RNA Transcription Translation Step 1 Step 2
Occurs at the Ribosome
Occurs in the Nucleus

4. Transcription
Step 1
DNA
RNA
Occurs in the Nucleus

5. RNA is different from DNA in 3 ways
What is RNA?
RNA is different from DNA in 3 ways

6. The sugar is Ribose instead of deoxyribose

7. RNA is Single stranded instead of double stranded

8. G C C G T A A U Thymine is replaced by Uracil Let’s make an RNA strand
How to code DNA into mRNA
In RNA
There is no Thymine
Adanine bonds to Uracil
A – U G C C G
Uracil
Adenine T A
Let’s make an RNA strand
DNA A T G C
mRNA A U U A C G U G

9. 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
C10L10C12

10. Step 2 of protein synthesis
TRANSLATION

12. During translation, the nitrogen bases of mRNA tell the cell which amino acids (building blocks of proteins) are needed to build a protein (polypeptide).

13. mRNA bases are read in groups of 3 called codons
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

14. example: UCU, UCC, UCA, and UCG all code for the amino acid
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.

15. Lets practice
mRNA
AUG
UGA
CCU
Amino Acid
mRNA
GCG
GAU
UGC
Amino Acid

16. AUG START Methionine U C A G Second Base of Codon First Base of Codon
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
C10L10C12

17. Lets practice mRNA AUG UGA CCU Amino Acid mRNA GCG GAU UGC Amino Acid
Met
(Start)
Stop
Pro
mRNA
GCG
GAU
UGC
Amino Acid
Asp
Cys
Ala
C10L10C12

18. Translation
During translation the mRNA strand synthesized during transcription will be used to make a protein.

19. How is a protein (polypeptide) made?
The mRNA leaves the nucleus and attaches to a ribosome
C10L10C12

20. How is a protein (polypeptide) made?
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.
C10L10C12

21. How is a protein (polypeptide) made?
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).
C10L10C12

22. C10L10C12