Cells: The Basic Unit of Life Cells are the basic units of organisms Cells can only be observed under microscope Two basic types of cells: Plant Cell Animal Cell On the following slides, all structures are found in both plant and animal cells unless stated otherwise. 1

Cell Biology Animations

Plant Cell Cell wall Made of cellulose which forms very thin fibres Strong and rigid In plant cells only

Plant Cell Cell wall A dead layer Freely permeable Protect and support the interior of the cell. Give shape to the cell A dead layer Freely permeable

Plant Cell Cell membrane Lies immediately against the cell wall Made of protein and lipid Selectively permeable

Plant Cell Cell membrane Can control the movement of materials into and out of the cell A living layer Found in plant & animal cells

Plant Cell Cytoplasm Jelly-like substance enclosed by cell membrane Provide a medium for chemical reactions to take place

Plant Cell Cytoplasm Found in all cells Contains organelles and granules : e.g. chloroplast e.g. mitochondrion

Organelles very small size – some can only be observed under electron microscope All organelles have specific functions Found in the cytoplasm

Plant Cell Chloroplast Only in plant cells. Contain the green pigment chlorophyll Chlorophyll traps light energy, to make food by photosynthesis

Plant Cell Chloroplast Contain starch grains (products of photosynthesis)

Plant Cell Mitochondrion ( mitochondria ) Rod shape For cellular respiration (provides energy for the cell)

Plant Cell Mitochondrion ( mitochondria ) Active cells ( eg. sperms, liver cells) have more mitochondria

Plant Cell Non-living granules Starch granules Oil droplets Crystals of insoluble wastes

Plant Cell Vacuole large central vacuole Contains cell sap a solution of chemicals (sugars, proteins, mineral salts, wastes, pigments) Larger in plant cells than animal cells

Plant Cell Nucleus Control the normal activities of the cell Bounded by a nuclear membrane Contains the genetic material (DNA). DNA is organized into threadlike structures called chromosomes.

Nucleolus Nuclear Pore Contains the information for the production of proteins in the cell. Not bound by a membrane Nuclear Pore Allows large molecules to move in and out of the nucleus

Different kinds of plant cells Onion Epidermal Cells Root Hair Cell root hair Guard Cells Cellular World - YouTube

Animal cell No cell wall or chloroplasts Stores glycogen granules and oil droplets in the cytoplasm

Animal Cell Endoplasmic Reticulum (E.R.) Found in plant & animal cells Transport of materials in cell Rough and smooth types Rough E.R. has ribosomes attached to the outside.

Endoplasmic Reticulum mitochondrion

Animal Cell Ribosomes Found in plant & animal cells. Sites of protein synthesis. Found on rough E.R. or in the cytoplasm.

Animal Cell Golgi Bodies Found in plant & animal cells. Serve as storage, packaging and processing centres for products released by the cell. Animal Cell rleasedout 24

Animal Cell Microtubules “Skeleton” of the cell. Found in plant & animal cells. Gives cells shape and support. Found in centrioles, cilia, & flagella. Composed of Tubulin.

Animal Cell Lysosomes Small saclike structures that contain digestive enzymes. Found in most animal and some plant cells.

Rough E.R.

Different kinds of animal cells white blood cell red blood cell cheek cells sperm nerve cell muscle cell Amoeba Paramecium Journey Into a Cell - YouTube

Similarities between plant cells and animal cells Both have a cell membrane surrounding the cytoplasm. Both have a nucleus. Both contain mitochondria, golgi bodies, E.R. , ribosomes and microtubules.

Differences between plant cells and animal cells Relatively smaller in size Relatively larger in size Irregular shape Regular shape No cell wall Cell wall present

Differences between plant cells and animal cells Vacuole small or absent Large central vacuole No Chloroplasts Chloroplasts Present Nucleus at the centre Nucleus near cell wall