Grade 10: Life Science

1. Life Science Grade 10
BY CHRIS SIHOKA AND KGOTSO SEROKA
KLMMETSE@GMAIL.COM/ 0793251325

2. Cell: basic unit of life

3. Key concepts
• Difference between animal cell and plant cell
• Where organelles are found and function.

4. Animal cell

5. Animal cell (microscopic view)

6. Plant cell

7. Plant cell (microscopic view)

9. Cell division

10. KEY CONCEPTS
 The cell cycle is divided into two main stages: interphase and the mitotic phase.
 During interphase cells grow in size and replicate their DNA
 Mitosis is the process by which cells distribute their replicated DNA to two daughter cells.
 The mitotic phase consists of five stages: prophase, metaphase, anaphase, telophase and cytokinesis.
 Mitosis is the means of reproduction in unicellular organisms that undergo asexual reproduction.
 Mitosis is required for growth and repair in multicellular organisms.
 Cancer is caused by carcinogens and is treated through surgery, radiation and chemotherapy.

11. Assignment: Due date: 21 May 2017
Names of the mitotic phases.
Draw simple descriptive diagrams showing the chromosome changes in mitotic
phases.
The difference between animal and plant cells in cytokinesis.
The purpose of mitosis.
 Causes and treatment of cancer.

13. CHROMOSOME
Long arms of chromosome.
Chromatid
Centromere
Short arms of chromosome

14. Interphase
 This stage is divided into three parts: G1, G2 and S phases.
 G1 phase:
occurs just after the two daughter cells have split and the cells have only one copy of
their DNA.
Cells in this stage synthesise proteins and increase in size.

15.  S phase:
Is the stage during which DNA replication occurs.
The cell makes an identical copy of each of its chromosomes.
Chromosomes are found inside the nucleus of the cell and consist of long
strands.
 DNA that contain the genetic information of the cell.

16. G2 phase:
 The cell will start to replicate its organelles in preparation for mitosis.

17. Mitotic Phase (M phase)
 The mitotic phase (M phase) is composed of two stages: mitosis and
cytokinesis.
 In mitosis; chromosomes in the cell nucleus separate into two
identical sets in two nuclei.
 Cytokinesis: the cytoplasm, organelles and cell membrane split into
two IDENTICAL cells.

18. Mitosis phases.
Prophase (P)
Metaphase (M)
Anaphase (A)
Telophase (T)

19. PROPHASE (P)
• Nuclear and nuclear membrane
disappears.
• Chromatids joins to form a chromosome
attached by a centromere.
• Centrioles move to opposite poles.
• Centrioles give rise to the spindle
fibres which form between the poles.

20. METAPHASE
• Chromosomes line up on the equator of the cell.
• The chromosomes appear in a straight line across the middle of the cell.
• Each chromosome is attached to the spindle fibres by its centromere.

21. ANAPHASE
• The chromatids are pulled to opposite poles of the cell by the shortening the spindle fibres.
• Chromatids are now called daughter chromosomes.

22. TELOPHASE
• Nuclear membrane reforms around the daughter chromosomes.

23. CYTOKINESIS
• Cytoplasm splitting into two.
• In a plant cell a cross wall is formed by the cell plate dividing the cytoplasm in two.

24. THE ROLE OF MITOSIS
Growth.
Repair damage.
Reproduction in some simple organisms.

25. QUESTION
Identify whether cell division is occurring in an animal cell or plant cell.
Give reasons for your answer. (2)

26. What happens when cell division go wrong?
CANCER!

27. TYPES OF CANCER
Breast cancer
Lung cancer
Oesophageal cancer
Leukaemia (blood cancer)
Melanoma (skin cancer)
Cancer can affect almost any tissue in the body. A list of
some common cancers includes:

28. TYPES OF CANCER CELLS
BENIGN TUMORS; tumours cannot spread
to other tissues.
Malignant tumors: they are able to invade
tissues and spread to other parts of the
body.

29. HOW DOES CANCER CELLS DIFFER WITH
NORMAL CELLS?
Cancer cells don’t listen to signals to stop growing.
Cancer cells grow new blood vessels
Cancer cells spread around the body:

30. CAUSES OF CANCER
Cancer is caused by agents called carcinogens. Carcinogens cause cancer by damaging
DNA which can no longer code for the important regulatory functions of the cell cycle.
CARCINOGENS SUCH AS:
 Cigarette smoke
 Radiation
 X-rays
 UV light
 food additives
 Several dangerous chemicals

31. PREVENTION OF CANCER
Avoid smoking.
Avoid alcohol.
Healthy diet.
Regular physical activity.
Sun protection.
Regular screenings.

32. TREATMENET OF CANCER
Radiation therapy.
Chemotherapy.
Surgery.
Traditional medicines.