1. Topic: DNA Transcription and Translation
Aim: How are proteins made from DNA?

2. DNA RNA Amino Acids(Proteins)
DNA contains the genetic information to
make amino acids
Amino acids combine to make proteins
These proteins determine the physical traits
of an organism and control cellular functions.
Proteins do everything,
and DNA gets all the
credit!
Think of them as tiny minions
who do all the work

3. RNA vs DNA RNA: ribonucleic acid Carries out protein synthesis
Differences from DNA:
different sugar (ribose)
single strand
different base
no thymine
URACIL instead

4. DNA and Protein Synthesis

5. 3 Types of RNA:
Messenger RNA: (mRNA) carries nucleotide sequence from nucleus to ribosome
Transfer RNA: (tRNA) picks up amino acid in cytoplasm and carries them to ribosome
Ribosomal RNA: (rRNA)found in ribosome, joins mRNA and tRNA; forms protein

6. Steps of Transcription
Transcription- process that makes mRNA from DNA
DNA unzips into 2 separate strands A. DNA Helicase is the enzyme that breaks H-bond
2. Free floating RNA NITROGEN BASES in the nucleus pair up w/unzipped DNA NITROGEN BASES:
A. Cytosine(C) pairs with Guanine(G)
* (G) with (C)
B. Uracil(U) pairs with Adenine(A)
* (A) with (U)
C. Thymine (T) pairs with Adenine (A)
***remember (T) is only with DNA

7. 3. After all the pairing is done:
a single strand of RNA has been produced.
4. Genetic code from DNA is transferred to mRNA
5. The code obtained from DNA lets the mRNA know which amino acids to pick up:
code is a set of nitrogen bases = Codon

8. Transcription Adenine (DNA and RNA) Cystosine (DNA and RNA)
Guanine(DNA and RNA)
Thymine (DNA only)
Uracil (RNA only)
RNA polymerase
DNA
RNA

9. DNA G A T T A C A C U A A U G U mRNA
DNA RNA
Practice making mRNA using the DNA template
DNA
G A T T A C A
Remember:
RNA does not have
T(Thymine); it’s replaced by
U(Uracil)
C U A A U G U
mRNA

10. Transcription Practice
Transcript the following segment of DNA into RNA
DNA: A U G T T T A G A C A T G G C
RNA:

11. Translation
Conversion of RNA into amino acid sequence that makes a protein
The mRNA leaves the nucleus and enters the cytoplasm
Ribosomes attach to mRNA
tRNA (carrying anti-codon) picks up the correct amino acids and carries them to the mRNA strand forming the protein
Ex:
tRNA carries GAU (anti-codon)& looks for CUA on mRNA

12. DNA and Protein Synthesis
Codon: three bases code for a specific protein:
ex: AAA = Lysine
The codons code for 20 amino acids
Just like the alphabet has 26 letters to make all
the words we know, the 20 amino acids make
all the different proteins found in living
organisms
The codons are the template for protein synthesis,
which takes place on the ribosomes (rRNA) in the
cytoplasm

13. Translation: changing mRNA into Amino Acids (Proteins)
Amino acids are linked together in the same
order as the codons , creating a protein chain
Just like linking letters to make words, linking
amino acids makes proteins
mRNA
CUA AUG UGC
Leucine methionine
Amino Acid
Amino Acid
Amino Acid

14. DNA and Protein Synthesis - Summary

16. Translation mRNA tRNA mRNA Nucleus Lysine Phenylalanine Methionine
Ribosome
mRNA
Start codon

17. Translation (continued)
Growing polypeptide chain
Ribosome
tRNA
Lysine
tRNA
mRNA
mRNA
Ribosome
Translation direction

18. Summary of transcription and translation
DNA
Stage mRNA is transcribed from a DNA template. 1
mRNA
RNA polymerase
Amino acid
TRANSLATION
Stage Each amino acid attaches to its proper tRNA with the help of a specific enzyme and ATP. 2
Enzyme
tRNA
Initiator
tRNA
Anticodon
Stage Initiation of polypeptide synthesis 3
Large ribosomal subunit
The mRNA, the first tRNA, and the ribosomal subunits come together.
Start Codon
Small ribosomal subunit
mRNA
Figure 10.15

19. New peptide bond forming
Growing
polypeptide
Stage Elongation 4
A succession of tRNAs add their amino acids to the polypeptide chain as the mRNA is moved through the ribosome, one codon at a time.
Codons
mRNA
Polypeptide
Stage Termination 5
The ribosome recognizes a stop codon. The poly-peptide is terminated and released.
Stop
Codon
Figure (continued)

20. Lesson Summary Transcription: changing DNA into RNA
How to change DNA into RNA?
Answer: Just follow Chargaff’s Rule:
A always pair with T
C always pair with G
However, RNA does not have T(Thymine), it has U(Uracil)

21. Translation: changing mRNA into amino acids (proteins)
How to change mRNA into amino acids? Answer: Step 1: remember, 3 bases equal 1 codon Step 2: look at the universal amino acids chart to translate into the correct amino acids.