1. Cells

2. Cells The basic unit of life Microscopic Organelles Two types
Structures within cells that perform different functions but work together
Two types
Animal cells
Plant cells

3. Animal Cell

4. Plant Cell

5. Organelles in Animal Cells
Cell membrane
Made of proteins and lipids
Thin, partially permeable
Controls exchange of substances in cell
Protects organelles
Cytoplasm
Made of water and dissolved substances
Present throughout the cell
Provides nutrients, glycogen granules
Site of chemical reactions
Nucleus
Controls cell activities
Contains genetic material or DNA in chromosomes

6. Organelles in Animal Cells
Mitochondrion
Pleated membrane to increase surface area
Contains respiratory enzymes
Produces energy through respiration
Vacuole
Fluid-filled membranes
Small, temporary with no fixed shape
Exchange of water, minerals and stores
substances including waste
Endoplasmic Reticulum
Several membranes
Make fats and proteins
Contain ribosomes that make proteins

7. Organelles in Plant Cells Only
Plant cells contain all the organelles that Animal cells contain in addition to these:
Cell wall
Freely permeable
Made of cellulose
Outside cell membrane
Give shape and protects cell
Chloroplast
Contain green chlorophyll and enzymes
Site of photosynthesis

8. Organelles in Plant Cells Only
Starch grains
Stores carbohydrates
Vacuole
Large, permanent with fixed shape
Contains cell sap
Supports cell when turgid
Stores cell waste
Cytoplasm
A thin layer

9. Specialization Unicellular organisms made of one cell
Independent of other cells
One cell carries out functions
Multicellular organisms made of many cells
Each cell does a different job
All work together and depend on each other

10. Specialization Division of Labour Allows organism to increase in size
Higher productivity and efficiency
Develop special features to carry out specific functions
Different functions can be performed at the same time

11. Similar or identical cells that perform a specific function are arranged in groups to form tissues
Cell Tissues

12. Several different kinds of tissues are grouped to form an organ
Tissue Organ

13. Organs form larger functional units called systems
Organ System

14. Systems are grouped to form an organism
System Organism

15. Bacteria Unicellular Microscopic Release toxins Not all harmful
Cause diseases
Tuberculosis
Typhoid
Cholera

16. Viruses Unicellular (smaller than bacteria)
Need other organisms to live
Reproduce only inside living cells
Enter body through openings
Attach to then enter host cell
Use the host cell to copy itself
New viruses destroy and leave the host cell and attack new host cells
All are harmful and cause diseases
Common cold
Influenza
AIDS
Measles

17. Fungi Very small (yeast) or large (mushrooms)
Do not cause many diseases
Athlelte’s foot
Ringworm

19. Fungi cell

20. Cells of the human body

22. Reactions in Cells

23. Osmosis
Movement of water particles from an area of high water concentration to an area of low water concentration across a selectively permeable membrane.

24. Diffusion
Movement of molecules from a region of high concentration to a low concentration
In gases and liquids
Can occur across thin, permeable membranes
End- products of digestion diffuse from gut into blood
Carbon dioxide and Oxygen diffuse between blood and alveoli
Between blood and cells
Characteristics of surfaces for efficient diffusion
Thin
Concentration gradient
Moist
Large surface area to volume ratio

25. Importance of Diffusion and Osmosis
To bring useful substances to organelles for reactions to take place
Glucose and Oxygen in Respiration
Removal of waste products
Carbon dioxide from respiration, urea
These are secreted out of the cell
Small vessicles transport substances
Hormones are transported this way

26. Active Transport
Transport of molecules across a membrane from a region of lower concentration to a region of higher concentration, using energy.
Allows cells to take up extra substances already present in its cytoplasm .e.g liver and glucose
Allows cell to remove extra substances present in the cytoplasm.