1. PROTEIN SYNTHESIS

2. Protein Synthesis The production of polypeptide chains (proteins)
Two phases: Transcription & Translation

3. DNA  RNA  Protein Eukaryotic Cell DNA Pre-mRNA mRNA Ribosome Protein
Nuclear
membrane
Transcription
RNA Processing
Translation
DNA
Pre-mRNA
mRNA
Ribosome
Protein
Eukaryotic Cell

5. Structure of RNA
Like DNA, RNA is a polymer of nucleotides. In an RNA nucleotide, the sugar ribose is attached to a phosphate molecule and to a base, either G, U, A, or C. Notice that in RNA, the base uracil replaces thymine as one of the pyrimidine bases. RNA is single-stranded, whereas DNA is double-stranded.

6. Genes & Proteins Proteins are made of amino acids 20 total amino acids
Amino acids chains are called polypeptides

7. Two Parts of Protein Synthesis
Transcription: DNA makes a copy of mRNA
Translation: mRNA makes a chain of amino acids (protein)

8. Genetic Code Each three-letter unit on mRNA is called a codon
The fact that the genetic code is about universal in living things suggests that the code dates back to the first organisms on earth and that all living things are related.

9. Notice that in this chart, each of the codons (white rectangles) is composed of three letters representing the first base, second base, and third base. For example, find the rectangle where C for the first base and A for the second base intersect. You will see that U, C, A, or G can be the third base. CAU and CAC are codons for histidine; CAA and CAG are codons for glutamine.

10. Transcription Translation
Transcription occurs when DNA acts as a template for mRNA synthesis. Translation occurs when the sequence of the mRNA codons determines the sequence of amino acids in a protein.
Translation

11. Transcription (DNA RNA)
During transcription in the nucleus, a segment of DNA unwinds and unzips
RNA polymerase joins the RNA nucleotides so that the codons in mRNA are complementary to the DNA

12. During transcription, complementary RNA is made from a DNA template
During transcription, complementary RNA is made from a DNA template. A portion of DNA unwinds and unzips at the point of attachment of RNA polymerase. A strand of mRNA is produced when complementary bases join in the order dictated by the sequence of bases in DNA. Transcription occurs in the nucleus, and the mRNA passes out of the nucleus to enter the cytoplasm.

13. RNA Processing in the nucleus
Pre-mRNA has introns (garbage) & exons (code)
Cut introns out
intron
exon
exon
intron
splicesome
exon

14. Messenger RNA (mRNA) Primary structure of a protein A U G C aa1 aa2
start
codon
codon 2
codon 3
codon 4
codon 5
codon 6
codon 7
codon 1
methionine
glycine
serine
isoleucine
alanine
stop
codon
protein
Primary structure of a protein
aa1
aa2
aa3
aa4
aa5
aa6

15. Transfer RNA (tRNA) Transports amino acids to the mRNA
Have anticodons that are complementary to mRNA codons

16. Ribosomes
Large
subunit P
Site A
Site
mRNA A U G C
Small subunit

17. Translation (RNA Protein)
Happens in the ribosome
Three steps:
1. initiation: start codon (AUG)
2. elongation: amino acids linked
3. termination: stop codon
Let’s Make a Protein !