1. Cell Growth and Reproduction
Key Questions:
Why do cells grow and reproduce?
How do cells grow and reproduce?

2. 2.1 The Importance of Cell Division
Chapter #2
2.1 The Importance of Cell Division

3. Importance of Cell Division
Growth
to increase size of organism
Repair
replace damaged or old cells
Reproduction
primarily unicellular organisms

4. All Cells Undergo Cell Division

5. Cell Theory The cell is the basic unit of life
All organisms are composed of cells
Some are composed of only one cell (unicellular) E.g. bacteria
Some are composed of two or more cells (multicellular) E.g. turtles

6. 2.2 Cell Structures Involved In Cell Division

7. Cells There are 2 main types of cells
Animal cell
Plant cell
Within cells are smaller structures called organelles
Carry out functions to ensure cell survival

8. Animal Cell (pg.

9. Plant Cell (pg

10. Cell Structures Cell membrane Cell Wall (in Plant cells only)
Protective covering
Allows for certain materials to enter/exit the cell
Cell Wall (in Plant cells only)
is a tough rigid structure that surrounds the cell membrane
Gives a cell a boxlike shape.
helps to protect the plants and provides support for the growing plant

11. Cell Structures cont… Nucleus Nucleolus control center for the cell
surrounded by nuclear membrane
contains nucleolus & chromosomes
Nucleolus
site for production & assembly of ribosomes

12. Cell Structures cont… Chromosomes
each human cell has 23 pairs (46 total)
made up of deoxyribonucleic acid (DNA) and protein
DNA is a long molecule that looks like a twisted ladder
DNA directs cells activities

13. Cell Structures cont… Cytoplasm Microtubules Centrioles
contains all organelles in the cell
most activities occur here
Microtubules
movement and support for the cell
Centrioles
special microtubules involved in cell division in animal cells only

14. Cell Structures cont… Mitochondria
Produces energy for the cell through a process called cellular respiration
Cellular respiration occurs when chemical energy taken from the food we eat is converted to energy ourselves can use.
Glucose + Oxygen  Carbon dioxide + water + Energy

15. Cell Structures cont… Chloroplasts (in Plant cells only)
trap energy from the sun & change it into chemical energy which the plant can use through a process called photosynthesis.
Carbon dioxide + water + energy  glucose + Oxygen

16. Cell Structures cont… Endoplasmic Reticulum (ER) Ribosomes
series of tubes and flattened sacs used to
transport materials in cell
Rough ER
ribosomes attached
transports proteins
Smooth ER
contains no ribosomes
makes and transports fats
Ribosomes
make proteins
either free in cytoplasm or attached to endoplasmic reticulum (ER)

17. Cell Structures cont… Golgi Body Vacuole
sorts proteins and packages them into structures called vesicles.
vesicles carry proteins, nutrients, and water in and out of the cell.
Vacuole
Storage compartments that store wastes and nutrients.
PLANTS have a large central vacuole that stores WATER.

18. Cell Structures cont… Lysosome
Recycle and break down organelles when they wear out.
contain enzymes to break down food particles, cell wastes, and worn-out cell parts.

19. 2.3 From DNA to Proteins

20. DNA
Chromatin is the material inside the nucleus that contains DNA and proteins.
Each strand of chromatin contains one molecule of DNA.
Chromatin coils tightly into X-shaped chromosomes
Genes are small segments of DNA located on a chromosome
Genes store the information needed to produce proteins

21. Human cells have 46 chromosomes arranged in 23 pairs
The 23rd pair determines sex
XX for females
XY for males
Each chromosome can carry thousands of genes

22. DNA Structure
DNA is made of 2 strands of smaller molecules called nucleotides
Nucleotides consist of a sugar, a phosphate, and a nitrogenous base

23. Each nucleotide has one of 4 different bases:
adenine (A) cytosine (C) thymine (T) guanine (G)
A always pairs with T (A – T)
C always pairs with G (C – G).
These pairs are often referred to as base pairs.

25. The Genetic Code
The bases in DNA combine to form 3-letter words (E.g. GGC or TAC)
Each 3-letter word codes for the production of one of 20 different amino acids
Amino acids are the building blocks of proteins

26. From Genes to Proteins
DNA molecules in a chromosome are organized into genes.
RNA is a copy of the genetic information in the gene
RNA carries instructions for making proteins from genes in nucleus to ribosomes in cytoplasm

28. There are several steps to making a protein from DNA, AKA Protein Synthesis.
Nucleus receives a signal to make a specific protein.
The DNA message for a specific protein is copied into a small molecule called ribonucleic acid (RNA). The RNA has only one strand.

29. 3. RNA leaves through a nuclear pore
4. The RNA message is delivered to the ribosome, and the ribosome makes the protein.
5. The manufactured protein enters the ER.
6. A vesicle forms off the end of the ER and carries the protein to the Golgi body

30. 7. The Golgi body repackages the protein for transport out of the cell
7. The Golgi body repackages the protein for transport out of the cell. 8. A vesicle forms off the end of the Golgi body to carry the protein to the cell membrane. 9. The vesicle attaches to the cell membrane and its protein contents are released out of the cell

31. Genes and Variation
Genes are responsible for all the characteristics in a species
All members of the same species have the same number and types of genes (E.g. eye colour) but within a species we can have different versions of the same gene (E.g. blue vs brown)
Versions are called traits or alleles.

32. 2.5 Changes to a Cell’s DNA

33. Changes to a Cell’s DNA
Any change in the DNA of a cell is called a gene mutation.
a change in the order of bases (A,C,T,G) that make up the gene.
There are several types of gene mutation:
Deletion (base missing)
Addition (extra base added)
Substitution (one base substituted for another)

34. Mutagens are substances or factors that cause mutations
Environmental mutagens such as:
Mercury
cigarette smoke
X-ray and UV radiation
viruses
Correcting mutations is difficult, but new techniques such as gene therapy offer hope.

35. The CLONE!!!
Merricks Speech
Birthing scene

36. Effects of Mutations
Gene mutations may produce proteins that are beneficial or harmful to the organism, or may have no effect at all.
Beneficial (positive)
Neutral (no effect)
Harmful
(E.g. genetic diseases, cancer).

37. Beneficial Mutation (positive mutation)
There are millions of people infected with HIV and AIDS
still no known cure or vaccine
Some individuals have been found to be resistant to the AIDS virus
because they carry a mutated gene that produces instructions for a protein that can prevent HIV infection

38. Neutral Mutation A mutation that does not affect an organism.
Ex. The gene mutation that results in the white coat colour of the spirit bear, since it does not increase or decrease the bear’s survival rate.

39. Harmful Mutation (AKA negative mutation)
Causes genetic diseases, such as Cystic Fibrosis
CF is caused by a mutation in a gene which codes for a protein that helps move certain chemicals into & out of the cell.
So the shape of the protein changes which and it can no longer do its job which cause the many symptoms of CF.
May cause Cancer

40. Cancer: Characteristics
Cancer is a disease in which cells divide very rapidly and uncontrollably.
Cells accumulate in masses called tumours. There are 2 types.
Benign: stay in one place and don’t interfere with surrounding tissues
Ex. Warts
Malignant: invade surrounding tissues and interfere with normal functions
Visible because of enlarged nuclei.

41. Cancer cont…
When cancer cells spread from original location this is called metastasis.
Substances that cause cancer are called carcinogens.
E.g. pesticides, X-rays, some viruses, chemicals in tobacco.
Treatment methods include surgery, radiation, and chemotherapy.