Cells are the basic units of life and come in two main types: prokaryotic and eukaryotic. Prokaryotic cells lack a nucleus while eukaryotic cells have a membrane-bound nucleus. Plant and animal cells also differ in that plant cells have a cell wall and chloroplasts, allowing them to perform photosynthesis, while animal cells do not. The organelles in cells such as the nucleus, mitochondria, chloroplasts, and vacuoles each have distinct structures and functions that allow the cell to carry out its basic processes.

1. cells – the basic
units of life

2.  A cell is the basic unit of
structure and function in
organisms hence basic unit of
life.
 Cells differ in size, shape and in
function.
 A cell made up of smaller
structures called organelles.

3. Two types of cells
Prokaryotic or Eukaryotic cells.
Only organisms of the domains Bacteria
and Archaea consist of prokaryotic cells –
cells without a membrane bound nucleus.
 Protists, fungi, animals and plants all
consist of eukaryotic cells – cell with a
membrane bound nucleus.

8. DIFFERENCES BETWEEN PLANT-
AND ANIMAL CELL
PLANT CELL ANIMAL CELL
CELL WALL CELL MEMBRANE
CHLOROPLAST NO CHLOROPLAST
BIG IN PLANTS SMALL IN ANIMALS
CAN PHOTOSYNTHESIZE CANNOT PHOTOSYNTHESIZE
MAKE THEIR FOOD DEPENDENT ON PLANTS IN
CASES OF FOOD

9. STRUCTURE AND FUNCTIONS OF THE
DIFFERENT ORGANELLS OF CELLS
Chapter 6 p. 98 – 131

10. CELL WALL
(ONLY IN PLANT CELLS)
 Porous
 Varies in thickness
 Consist of pectin (elasticity), cellulose fibrils held
together with non-cellulose substances (hardens
the cell when mature) and lignin (adds strength to
cell especially in woody plants)
 Cell wall is permeable and protects the inside of the
cell.
 Middle lamella (layer of adhesive substances) –
holds the cells together
 Plasmodesmata (pores) that connects the
cytoplasm of the connecting cells – selectively
permeable

11. CELL WALL WITH
PLASMODESMATA AND
INTERCELLULAR SPACES

12. CELL MEMBRANE/PLASMA-
(ANIMAL- AND PLANT CELLS)
 Consist of 2
phospholipid layers
and proteins in
between.
 The phospholipid
layers are part
hydrophillic and
part hydrophobic

13. NUCLEUS
 +/- 5µm, largest organelle in cell.
 Enclosed by a nucleomembrane
with nuclear pores. Function:
Protection and add to selective
permeability.
 Filled with nucleoplasma, a
nucleolus and chromatin. Function
of chromatin: carries genetic
material in the form of
chromosomes.
 Function of nucleolus: Produce r-
RNA

14. MITOCHONDRION
 Consist of 2 membranes: Outer –
and a highly convoluted inner
membrane- These folds are
called cristae – they increase
the surface area.
 Filled with matrix called stroma
that contains DNA and
ribosomes.
 Function: Produce energy in the
form of ATP by means of cellular
respiration

15. CHLOROPLAST
(PLANT CELL ONLY)
 Enclosed by a double
membrane
 Filled with stroma and
thylakoids filled with
chlorophyll arranged in
groups called grana.
 Ribosomes and starch grains
in stroma.
 Function: Photosynthesis

16. VACUOLE
(Large in plant-, small in animal-)
 Membranous sac
 Filled with cell sap.
 Causes turgor pressure in the
vacuole.
 Function: Stores various
substances, including waste.
 Helps with osmotic potential
of cell.

17. OTHER SMALLER ORGANELLES
Endoplasmic Reticulum – Transport
system in cell
Ribosomes – Protein synthesis
Golgi-apparatus – Make lysosomes and
acts as transport system.
Lysosomes – Intracellular digestion.
Plastids e.g.– Leucoplasts – Stores
starch
- Chromoplast – gives colour
to flowers and fruit.
* Centrioli – Mitosis in animal cells

18. PERMEABILITY OF THE CELL
MEMBRANE
The cell membrane has the ability
to regulate transport molecules
across its structure.
This function is essential to the
cell’s existence.
The fluid mosaic model helps to
explain how membranes regulate
the cell’s molecular traffic.

19. MICROSCOPYan instrument
Themicroscope is
designed to observe objects too small to
be seen with the naked eye.
 The human eye cannot distinguish objects
much smaller than 0.1mm.
The microscope act as an extension of the
eye, allowing one to see smaller objects.