Cell Structure and Organization

The concept of a cell

The cell is the basic unit of life.. All living things are made up of cells.  Cells are very small.
a. If an organism is made of only one cell, it is called unicellular.
b. If an organism is made of many cells, it is called multicellular.

The cell theory

To understand cells, scientists developed a theory about cells and their function.
a. All living things are made up of cells
b. All life processes occur in the cell
c. Cells are the basic unit of structure of living organisms
d. All cells are produced from other cells

Cell structure

There are two types of cells; prokaryotic cells and eukaryotic cells
a. Prokaryotic cells are bacteria cells.
b. Eukaryotic cells are plant and animal cells.

Parts of a cell

a. Plant cells and Animal cells are different.
b. Cell membrane is the thin layer of living tissue which surrounds the cell.  It controls the movement of substances in and out of the cell.  It is said to be selectively permeable because it will only let some substances in.
c. Cytoplasm is the liquid substance that fills the cell, which holds the organelles and allows chemical reactions to take place.  The cytoplasm is made mostly of water.
d. Nucleus is where genetic information is found.  This information is the instructions to make proteins.  This information is kept on chromosomes, which are passed down from the parents.
e. Mitochondria are organelles which perform cell respiration.  The release energy from food.
f. Vacuoles (in animal cell) are organelles filled with fluid which are used by cells for secretion, storage, and excretion.

g. Sap Vacuoles (in plant cells) are filled with sap fluid, which keeps the plant rigid and maintains cell shape
h. Cell Wall (in plant cell) is a strong covering around the cell made up of cellulose, which supports and gives shape to the plant cells.
i. Chloroplasts (in plant cells) are organelles which perform photosynthesis by making chlorophyll
Plant cells and Animal cells
Plant cells and Animal cells

Cell differentiation

 There are two types of organisms
a. Unicellular organisms which are only composed of one cell.  Examples are bacteria, amoeba, paramecium, and euglena.
b. Multicellular organisms which are composed of more than one cell.  Examples are fungi, plants, and animals.

Cell Structure
Cell Structure

Cell Structure
Cell Structure

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Major groups of living things

Digestive system in humans


Classification of Living Things