1. Topic 5 – When plans Change
DNA! ☺
DNA Rap

2. The chromosomes are found in the cell’s nucleus.
Chromosomes are made up of strands of DNA (genetic material)

3. Introduction
In grade 8 science you learned that the nucleus of a cell is the control center of the cell and contains the “genetic material”
What is this genetic material???

4. DNA: the secret of Life DNA – deoxyribonucleic acid
Structure of the DNA explains variation within and between species
DNA controls the structures and functions of cells
DNA is the genetic material
Chromosomes (composed of strands of DNA) are in a cell’s nucleus
Genes are sections of the DNA

5. The structure of DNA All -Teachers Give - Candy
They are in the shape of a coiled ladder (double helix)
The rungs of the ladder come in 4 different forms
Adenine (A)
Thymine (T)
Guanine (G)
Cytosine (C)
A forms chemical bonds to T
C bonds to G
All -Teachers Give - Candy

7. Complete the Sequence of DNAG

8. DNA STRUCTURE S C G S One Nucleotide P P S T A S P P
There are four kinds of nucleotides, each with a different nitrogen base G C A T
Adenine
Cytosine
Guanine
Thymine S A T S
DNA includes nucleotides, each made of a phosphate, sugar and a nitrogen base S
Sugar P
Phosphate

9. The DNA Genetic Code The sequence of base pairs in DNA forms a code.
It is like a blueprint that controls the production of proteins in the cell.
A section of DNA that codes for a specific protein is called a gene

10. Chromosomes The human body has 46 chromosomes
They are found in pairs, so really, each human cell has 23 pairs of chromosomes
Chromosomes are ESSENTIAL to cell divisions

11. Normal cell replacement
Multicellular organisms divide for growth and repair
The human body is VERY complex and made up of many different kinds of body cells (somatic cells)
Each kind of cell has a different life span
Different human cells (somatic cells) have different life spans.
Brain cells years
Red blood cells days
Stomach lining cells 2 days
Liver cells days
Intestine lining cells 3 days
Skin cells days

12. Cell Divisions
Before a cell divides, a copy of each chromosome is made
This is called mitosis
Mitosis is used for dividing all cells in the body except for the sex cells
This way, when a cell divides, each new cell gets a complete set of the chromosomes
* 1-9QB0 Mitosis

13. MITOSIS (dividing of Somatic Cells)
chromosomes

14. Somatic Mitosis 46 chromosomes DUPLICATES 92 chromosomes DIVIDES

15. PRACTICE
Draw mitosis of a pea plant that has 6 chromosomes

16. Sex Cells
Sex cells are the only cells in the human body that only have 23 chromosomes
Sperm and egg
Only when the sperm and the egg join together to form a zygote do they get a full set of chromosomes

17. Meiosis (sex cells) Meiosis is the process of forming the gametes
The only difference between meiosis and mitosis is cell division occurs TWO times
Why would division occur TWO times?
Because each sex cell only has 23 chromosomes

18. Meiosis The sperm and egg have met so there are 46 chromosomes
Chromosomes double
46 chromosomes randomly divide back into sex cells
Because it is random, that means there are 8.4 million different combinations of chromosomes – WOW!

19. MEIOSIS (Sex Cells) 46 chromosomes DUPLICATES 92 chromosomes DIVIDES

20. MITOSIS
MEIOSIS
-PRODUCES BODY CELLS (somatic) -OCCURS IN ALL LOCATIONS OF THE BODY -CHROMOSOME PAIRS REPLICATE BEFORE MITOSIS (DOUBLES-once) -ONE NUCLEAR DIVISION -TWO PRODUCTS (DAUGHTER CELLS) -RESULTS IN CELLS WITH SAME NUMBER OF CHROMOSOMES AS THE PARENT CELL
-PRODUCES THE GAMETES (SEX CELLS) -OCCURS ONLY IN THE GONADS (SEX CELLS) -CHROMOSOME PAIRS REPLICATE BEFORE MEIOSIS (DOUBLES-once) -TWO NUCLEAR DIVISIONS -FOUR CELLULAR PRODUCTS (TETRADS) -RESULT IN CELLS WITH HALF THE NUMBER OF CHROMSOMES AS THE PARENT CELL

21. Human Life Cycle Fertilization (46 Chromosomes)
Zygote (46 Chromosomes)
Egg – 23 Chromosomes
Sperm – 23 Chromosomes
Growth and Development
Growth and Development
Embryo

22. Technology and Variation
Moving pieces of DNA from one cell to another is called genetic engineering
This has allowed scientists to move desirable characteristics from one species to another
Does this biotechnology tamper with nature???

23. Examples: Genetically Engineered Foods
Aquaculture (fish farming) for fish production
Scientists have added genes for disease resistance as well as growth hormones.

24. A couple video clips- you be the judge
yUuiqIZ0
dQo

25. QUESTIONS
Draw out how mitosis and meiosis would work for the following organisms:
1. Pea Plant – 6 chromosomes
2. Ant– 2 chromosomes
3. Honey Bee – 32 chromosomes