1. Transcription & Translation
From DNA to Protein

2. DNA DNA is needed in each cell to make proteins.
Because DNA is so important, when a cell divides, it must pass on an exact
copy of the DNA to function correctly.
Process of DNA replication
DNA unzips – helicase enzyme
Free bases pair up with exposed bases
DNA rezips – 1 NEW strand -1 old strand

4. DNA makes protein

5. Transcription DNA making a copy of mRNA Happens in the nucleus
DNA unzips along a GENE
Free bases pair up with exposed bases
A-U C-G
When mRNA is complete, it detaches from DNA and DNA rezips
mRNA leaves the nucleus to go to the ribosome, carrying the DNA message
DNA is left in the nucleus SAFE

6. Message goes out to the ribosome
Transcription
Message goes out to the ribosome

7. Transcription

8. Genes & Codons
Each gene is composed of a specific sequence of nucleotides.
ACG CCA TGC TAC
Every three bases in this
sequence is called a codon.
The rRNA comes and reads
these codons

9. 3 Types of RNA
mRNA – message (the message from the nucleus to the ribosome)
rRNA – read (reads the mRNA)
tRNA – take (takes the amino acids to the growing protein)
Complementary to the mRNA
A – U C - G

10. Proteins Proteins are made of amino acids.
Each codon directs the cell to place a specific amino acid in a particular place as the protein is built.
For example, the codon CAA in DNA codes for the amino acid “valine”. If this codon was the third codon in a gene, valine would be the third amino acid in the protein.

11. mRNA codon chart
CCA
GUG
GUC
AUC
AAA
CGC
ACU

12. mRNA codon chart The mRNA!!! Which do you read for the amino acid?
DNA: ATC GTT ACG GCT ATA TCG TTA CGG
mRNA:
tRNA:
Amino
acids:
UAG
CAA
UGC
CGA
UAU
AGC
AAU
GCC
AUC
GUU
ACG
GCU
AUA
UCG
UUA
CGG
stop
glu
cys
arg
tyr
ser
asp
ala
Which do you read for the amino acid?
The mRNA!!!

13. Translation Making the protein Uses ALL 3 types of RNA
mRNA – is the MESSAGE
rRNA – READS the message – CODON by CODON
tRNA – TAKES the amino acids to the protein
Happens in the cytoplasm (at the ribosome)

15. DEMO – next class
Watch carefully and PAY ATTENTION!! You will be doing this shortly!!