1. Translation
Packet #11
Chapter #8

2. Introduction Translation
The actual process of protein synthesis where the mRNA, made during transcription, is utilized along with ribosomes.

3. RNA Utilized During Translation
Review, And Types, of RNA

4. Types of RNA Continued…
tRNA
Transfer RNA
Transports amino acid molecules to the ribosome
Class of small RNA molecules that bear/carry specific amino acids to the ribsome during translation
What are the building blocks of proteins?
Amino Acids
The amino acids will be used to create a protein chain
rRNA
Ribosomal RNA
RNA found within the ribosomes used during translation.
Two sizes
30S
Large ribosome (subunit)
15S
Small ribosome (subunit)
Types of RNA
mRNA
snRNA
tRNA
rRNA

5. Types of RNA Continued…
mRNA
Messenger RNA
An RNA molecule transcribed from the DNA of a gene
Proteins are translated from mRNA by the help of RIBOSOMES
Carries the GENETIC CODE, from DNA, used to create proteins
Types of RNA
mRNA
snRNA
tRNA
rRNA

6. The Ribosomes

7. Ribosomes Ribosome The large subunit has three sites
Acts as the site of protein synthesis in the cell
There are two sized ribosomes used during translation
Large
30S
Small
15S
The large subunit has three sites
Attachment Site (A site)
Polypeptide Site (P site)
Exit Site (E site)

8. mRNA & The Genetic Code

9. Introduction mRNA carries the genetic code in the form of codons.
A codon is a group of three nucleotides that provide information necessary for a single, specific amino acid.

10. List of Codons & Amino Acids

11. tRNA and the Genetic Code

12. The Role of tRNA
Recall that the role of tRNA is carry individual amino acids to the location where the polypeptide chain is growing.
Hence, it must have something to match the codon found on the mRNA.
This is called the anticodon
A nucleotide triplet, found on tRNA, that aligns with a particular codon in the mRNA.
However, it MUST be noted that the codon is the one that indicates what the amino acid will be.

13. Steps of Translation

14. Peptide Bond Formation
Introduction
There are five basic steps during the process of translation.
Initiation
Peptide Bond formation
Elongation
Translocation
Termination
Initiation
Peptide Bond Formation
Elongation
Translocation
Termination

15. Initiation Ribosome binds to the mRNA
Small subunit binds to mRNA
Initiator tRNA binds at start codon
Start codon = AUG
tRNA carries anti-codon UAC
Initiator tRNA carries amino acid MET
Ribosome binds to mRNA
Large subunit binds to mRNA
Initiator tRNA will be located at the P site of large subunit

16. Peptide Bond Formation
Ribosome (rRNA) catalyzes the formation of a peptide bond between the new amino acid and the carboxyl end of the growing polypeptide

17. Elongation
Elongation occurs when the incoming amino acid binds to the polypeptide chain through the formation of a peptide bond.

18. Translocation The ribosomes move allowing the tRNA’s to switch sites
tRNA in the A (addition) site is translocated to the P (polypeptide) site
tRNA in the E (exit site) leaves the ribsome
mRNA shifts position
New tRNA with anticodon enters the A site

19. Termination Release factor (a protein) binds at stop codon
There are THREE stop codons
UUA
UGA
UAG
Polypeptide chain released from tRNA
tRNA released from P site
Ribosomes released from mRNA.

20. Special Note
As the polypeptide chain is being completed, attaches and enters into another organelle known as the endoplasmic reticulum.
Hence creating what is known as the rough endoplasmic reticulum.

21. The Danger of Mutations

22. Introduction
Mutations occur when a nucleotide base, or nucleotide bases, has either been changed, inserted or deleted within a gene.

23. Gene Mutations
When the base sequence of a molecule of DNA is altered, the sequence of nucleotides for the mRNA will also be altered.
This results in a change in the amino acid sequence for the polypeptide change and hence changes a protein/enzyme.
Mutation in gene
Change in mRNA
Change in the polypeptide sequence
Change in the structure of a protein/enzyme
Results in a severe consequence for the human body.

24. Types of Mutations

25. Types of Mutations Point Mutation
Change a single nucleotide of a gene.

26. Types of Mutations Frameshift Mutation
Addition or deletion of one or more nucleotides.
Results in a change in the improper grouping of nucleotides in subsequent codons.

27. Types of Mutations Missense Mutation Nonsense Mutation
The most common type of mutation where the new codon still codes for AN amino acid (not necessarily the same amino acid)
Nonsense Mutation
A mutation that changes an amino acid codon to an amino acid codon that is a stop codon--usually resulting in a shorter, and non-functional form, of a protein

28. Genetic Disorders Resulting From Mutations

29. Genetic Disorders Frameshift Mutations Huntington Disease
Dominant allele disorder that results in death by the age of 40
Cystic Fibrosis
Autosomal recessive disorder that results in excess excretion of lung mucous
Hemophilia
X-linked recessive disorder that results in the inability to clot blood

30. Genetic Disorders II Point Mutation Skin Cancer
Proliferation genes have nucleotide bases thymine changed into uracil.
UV light rays that enter skin cells.
This results in the proliferation genes being constantly turned on

31. Review

32. Review I Translation Process Mutations Initiation
Peptide Bond Formation
Elongation
Translocation
Termination
Mutation in gene
Change in mRNA
Change in the polypeptide sequence
Change in the structure of a protein/enzyme
Results in a severe consequence for the human body.

33. Review II
Types of Mutations
Point
Frameshift
Nonsense
Missense