1. BC Science 9 Text: Chapters 4, 5, 6
Reproduction
BC Science 9 Text:
Chapters 4, 5, 6

2. The Nucleus Controls the Functions of Life Section 4.1
CHAPTER 4
The Nucleus Controls the Functions of Life
Section 4.1

3. The Nucleus and DNA
We know that the nucleus is the control centre of the cell.
The nucleus directs every single activity that the cell carries out.
The nucleus tells the cell how to grow, how to make proteins, how to repair itself and when to divide.
Have you ever stopped and wondered how something so incredibly small can command so much power and authority over our lives?
Essential Questions
What is DNA?
What does DNA look like?
What is the role of DNA in the everyday function of your cells?
How does a cell produce proteins?

4. Cell Parts and Organelles
Cells are equipped with many structures that allow the cell to perform a variety of functions.
Animal Cell
See page 122

5. The Nucleus Structure: The dense dark part at the centre of the cell
Function:
The control centre of the cell.
Controls all of the cell’s activities.

6. DNA Function What is DNA?
The nucleus of every cell in your body contains DNA.
 Deoxyribonucleic Acid
DNA is the molecule that has the master set of instructions for:
how cells function
what cells they will become
how they will grow and divide
when they will die
DNA stores information/instructions on how to make PROTEINS.
See page 126

7. DNA Structure The Structure of DNA
DNA looks like a twisted ladder called a double helix.
Two strands wrap around each other in a spiral shape.

8. DNA Structure DNA is made up of 3 parts/components.
This whole structure is called a NUCLEOTIDE

9. DNA Structure
The sides of the DNA ladder are made of repeating sugar and phosphate molecules
The steps of the ladder are made of four nitrogen bases:
Adenine (A), Guanine (G), Cytosine (C), and Thymine (T)
The bases join in a specific way
A always joins with T
G always joins with C

10. DNA Structure
Mutation
See page 126

11. Chromosomes
Structure: DNA and associated proteins Chromatin = uncoiled Chromosomes = tightly coiled Function: The template for making all proteins

12. DNA in the Nucleus Most of the time DNA is in the form of chromatin
Chromatin coils tightly into X-shaped chromosomes
Every organism has a specific number of chromosomes
Human cells have 46 chromosomes
arranged in 23 pairs
The 23rd pair determines the sex
of an individual:
XX for females and XY for males
See pages

13. Genes Genes are small segments of DNA located on a chromosome
Genes store the information needed to produce proteins
Each chromosome can carry thousands of genes
All your body cells have the same genes, but only specific genes are “read” in each cell to produce specific proteins
Specialized proteins called enzymes and hormones carry out important specific functions in the body
See pages

14. Production of Proteins 3 min. video (a bit advanced)
Protein production in the cell involves several important steps:
The nucleus receives a chemical signal to make a specific protein.
The DNA message for the protein is copied into a small molecule called RNA.
RNA leaves the nucleus through a nuclear pore.
The RNA message is delivered to a ribosome, the ribosome makes the protein.
The manufactured protein enters the endoplasmic reticulum (ER).
A vesicle forms at the end of the ER, and carries the protein to the Golgi body.
The Golgi body repackages the protein for transport out of the cell.
A vesicle forms off the end of the Golgi body to carry the protein to the cell membrane.
The vesicle attaches to the cell membrane, and its protein contents are released out of the cell.
See page 131

15. Protein Production Can you follow these steps in Protein Synthesis?
1. Chemical Signal
2. Production of RNA
3. RNA leaves nucleus
4. Ribosome reads RNA to make protein
5. Protein to ER
6. Vesicle formed around protein
7. Golgi packages protein
8. Vesicle moves to membrane
9. Protein released
See pg. 131

16. Summary Can you… State what items are found the nucleus?
Explain why is DNA important?
Explain how DNA is structured?
Describe what a gene is?
Explain how proteins are produced?
Explain how DNA, genes, and proteins are related?