1. Review: DNA, Transcription & Translation

2. Structure DNA Code for proteins Double Stranded Helix
Can NOT leave nucleus
Made of Sugar (deoxyribose), Phosphate & nitrogen base
Thymine
Adenine
Guanine
Cytosine
RNA
Copy of the code for proteins
Transports code to Ribosome
Single Stranded
Can leave nucleus
Made of Sugar (ribose), Phosphate & nitrogen base
Uracil
Adenine
Guanine
Cytosine

3. Replication Two new strands of DNA Occurs in nucleus.
DNA makes a copy of itself.
Two new
strands of
DNA T A C G A T G C T A C G A T G C

4. Transcription mRNA molecule Occurs in nucleus.
DNA makes a mRNA copy of the code. T A C G A U G C A T G C
mRNA
molecule

5. Every 3 letters represents one amino acid or codon.
Translation
Occurs at Ribosome.
mRNA binds with tRNA to build an amino acid chain or protein.
Every 3 letters represents one amino acid or codon.
Example: GUU = Valine

6. Summary

7. 11.3 Section Summary 6.3 – pages 296 - 301
Mutations
Any change in DNA sequence is called a mutation.
Mutations can be caused by errors in replication, transcription, cell division, or by external agents.
11.3 Section Summary 6.3 – pages

8. Mutations Mutations can be harmful. Mutations can be beneficial.
Sickle cell anemia
Cystic fibrosis
Mutations can be beneficial.
Phenotypic (physical) changes
Flower color
Fur color

9. Mutations Mutations can occur in both types of cells:
Body cells (muscle, skin, brain, bone etc)
Gametes (Sex Cells – sperm or egg)
Sperm Cell & Egg Cell
Skin Cells

10. 11.3 Section Summary 6.3 – pages 296 - 301
Mutations in body cells
If a body cell’s DNA is changed, this mutation would not be passed on to offspring.
Damage to a gene may impair the function of the cell.
When that cell divides, the new cells also will have the same mutation.
This can result in the cells growing and dividing rapidly, producing cancer.
11.3 Section Summary 6.3 – pages

11. 11.3 Section Summary 6.3 – pages 296 - 301
Mutations in Gametes
Mutations that occur in the gametes or sex cells can be passed on to the offspring.
11.3 Section Summary 6.3 – pages

12. 11.3 Section Summary 6.3 – pages 296 - 301
Types of Mutations
A point mutation is a change in a single base pair in DNA.
THE DOG BIT THE CAT.
THE DOG BIT THE CAR.
A change in a single nitrogenous base can change the entire structure of a protein because a change in a single amino acid can affect the shape of the protein.
11.3 Section Summary 6.3 – pages

13. 11.3 Section Summary 6.3 – pages 296 - 301
An example of a point mutation, is sickle-cell disease.
Sickle-cell diseases cause the red blood cells to be deformed. The result is that they get stuck in the blood vessels, depriving tissues of oxygen, causing strokes, and blood clots.
11.3 Section Summary 6.3 – pages

14. What would happen if a single nitrogenous base (letter) is deleted?
Types of Mutations
What would happen if a single nitrogenous base (letter) is deleted?
THE DOG BIT THE CAT.
THD OGB ITT HEC AT.
A mutation in which a single base is added or deleted from DNA is called a frameshift mutation.

15. 11.3 Section Summary 6.3 – pages 296 - 301
Chromosomal Alterations
Sometimes during mitosis or meiosis chromosomes break and then rejoin incorrectly, or just a piece breaks off for good.
Structural changes in chromosomes are called chromosomal mutations.
Deletion- part is missing
Insertion- part breaks off and attaches in the wrong place
Inversion- part breaks off and attaches upside down
Translocation- breaks off and attaches to different chromosome
11.3 Section Summary 6.3 – pages

16. 11.3 Section Summary 6.3 – pages 296 - 301
Non-Disjunction
Occurs during meiosis, when chromosomes fail to separate properly.
Normal humans have:
46 chromosomes
22 pair of Autosomes
1 pair of Sex chromosomes
Non-Disjunction:
Too many chromosomes?
Too few?
47 or 45 chromosomes
11.3 Section Summary 6.3 – pages

17. Normal karyotype
Is this a male or female?

18. Down Syndrome
Also called Trisomy 21
3 chromosomes instead of 2

19. 11.3 Section Summary 6.3 – pages 296 - 301
Causes of Mutations
Some mutations seem to just happen, perhaps as a mistake in base pairing during DNA replication.
These mutations are said to be spontaneous.
However, many mutations are caused by factors in the environment, such as radiation, chemicals, and even high temperatures.
Ex: Chernobyl explosion
Any agent that can cause a change in DNA is called a mutagen.
11.3 Section Summary 6.3 – pages