3. • Proteins are composed of amino acids – there are 20
different amino acids
• Different proteins are made by combining these 20
amino acids in different combinations
4. • Proteins are manufactured in the ribosomes under the
strict control and order of DNA.
• The DNA language is made up of letters which are
ATGCATATGGAATCAG
• These letters forms Words
• ATC GCA GGA AUU AUG
• These words make sentences
•
6. DNA, Transcription and Protein Synthesis
• 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!
7. • Transcription is the Reading of the DNA and
Changing the code to mRNA.
• Translation is changing the mRNA into a trait by
Using tRNA to interpret the mRNA.
Transcription & Translation
8. • DNA has regions of coding and non-coding.
The regions of DNA that code for proteins or traits
are called EXONS, while the regions that do not code
for proteins are called INTRONS.
Introns & Exons
9. Making a Protein—Transcription
•First Step: Copying of genetic information from DNA to RNA
called Transcription
•Part of DNA temporarily unzips and is used as a template to
assemble complementary nucleotides into messenger RNA
(mRNA).
10. • Transcription occurs inside the nucleus in a two
step sequence of events.
– Pre-mRNA includes both introns and exons for the
gene.
– mRNA is only the coding portion (exons).
• Translation occurs in the cytoplasm at the
ribosomes.
– Reminder: The are three (3) types of RNA
• Messenager (mRNA)
• Transfer (tRNA)
• Ribsomal (rRNA)
Site of Transcription&Translation
11. Process of Transcription
Transcription- process that makes mRNA from DNA
1. 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)
12. 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 3
nitrogen bases = Codon
13. A U G G G C U U A A A G C A G U G C A C G U U
This is a molecule of messenger RNA.
It was made in the nucleus bytranscription from a
DNA molecule.
mRNA molecule
codon
Messenger RNA
14. A U G G G C U U A A A G C A G U G C A C G U U
A ribosome on the rough endoplasmic
reticulum attaches to the mRNA
molecule.
ribosome
Ribosome
15. A U G G G C U U A A A G C A G U G C A C G U U
It brings an amino acid to the first three
bases (codon) on the mRNA.
tRNA molecule
anticodon
U A C
A transfer RNA molecule arrives.
The three unpaired bases (anticodon)
on the tRNA link up with the codon.
Transfer RNA
16. A U G G G C U U A A A G C A G U G C A C G U U
Another tRNA molecule comes into
place, bringing a second amino acid.
U A C
C C G
Its anticodon links up with the second
codon on the mRNA.
Transfer RNA
17. A U G G G C U U A A A G C A G U G C A C G U U
A peptide bond forms between the
two amino acids.
Peptide bond
C C GU A C
Transfer RNA
18. A U G G G C U U A A A G C A G U G C A C G U U
The first tRNA molecule releases its amino
acid and moves off into the cytoplasm.
C C G
U A C
Transfer RNA
19. A U G G G C U U A A A G C A G U G C A C G U U
C C G
The ribosome moves along the mRNA to
the next codon.
Transfer RNA
20. A U G G G C U U A A A G C A G U G C A C G U U
Another tRNA molecule brings
the next amino acid into place.
C C G
A A U
21. A U G G G C U U A A A G C A G U G C A C G U U
A peptide bond joins the second
and third amino acids to form a
polypeptide chain.
C C G C C G
Polypeptide chain
22. A U G G G C U U A A A G C A G U G C A C G U U
The polypeptide chain gets longer.
G U C
A C G
The process continues.
This continues until a termination
(stop) codon is reached.
The polypeptide is then complete.
Termination (stop) codon
24. Use one of the codon charts on the next page to find the amino acid
sequence coded for by the following mRNA strands.
CAC/CCA/UGG/UGA
___________/___________/___________/____________
AUG/AAC/GAC/UAA
___________/___________/___________/____________
27. DNA and Mutations
Mutations are any changes that take place in DNA:
• Can be spontaneous or caused by mutagens
• ex: Chemicals, high temperatures, UV light,
radiation
• Can change the genetic code, and be replicated
when forming new body cells.
• In sex cells, can be passed on to offspring.
28. DNA and Mutations – Lets looks at different mutations
THE DOG BIT THE CAT
29. DNA and Mutations - Substitution
THE DOG BIT THE CAT
• Substitution - Replace just one letter:
THE DOG BIT THE CAR
30. DNA and Mutations - Deletion
THE DOG BIT THE CAT
Deletion: Delete just one letter (T):
THE DOG BIT HEC AT
