CELLS CELL THEORY

Cell theory: Cell theory is revision from year 8 and 10 Read 2.1 Heinemann-history of cell theory Points to note: remember Van Leeuwenhoek, Robert hook, cork, little boxes, microscopes etc Write out the cell theory below after your own reading and notes: Cells are the basic functional and structural unit of living organisms All organisms are made up of cells and the products of cells All cells come from preexisting cells The cell is the smallest living organizational unit All cells are basically the same chemical composition All energy flow (metabolism & biochemistry) of life occurs within cells

Cell Organelles Cell Membrane: Holds cell together Controls what passes in and out of the cell Referred to as selectively permeable- won’t let all molecules through depending on size and etc. Nucleus: Control centre of the cell Controls all processes the cell does Contains threadlike bodies- chromatin granules important in cell division During division chromatin appears as chromosomes

Cytoplasm All the contents of a cell within the plasma/cell membrane. The semifluid medium between the nucleus and the plasma membrane is called cytosol. (cytoplasm) Controlled by the nucleus Various functions occur here Functions are controlled by different organelles Lots of chemical reactions occur in the cytoplasm – This is called metabolism  

Organelles in the Cytoplasm Mitochondria: Through the process of cellular respiration it produces energy Small Granules: Glycogen in animals Starch in plants. Plastids: These are small bodies in a cell which contain a chemical substance Eg: Chloroplast is a plastid that contains the chemical chlorophyll

Endoplasmic Reticulum: It is a transport system for the cell but it also makes lipids Processes carbohydrates Detoxifies substances such as poisons and alcohol Can be rough – contains ribosomes (Rough Endoplasmic Reticulum) RER It can be smooth – No ribosomes (Smooth Endoplasmic Reticulum) SER Carries proteins from the nucleus to a Golgi Complex Ribosomes THESE ARE SMALL ORGANELLES RESPONSIBLE FOR THE MANUFACTURE OF PROTEINS IN THE CELL.

Golgi Body The function of the Golgi Body is to sort, chemically alter, and package important molecules

Plant Organelles Plants also have cell membranes, ribosomes, mitochondria and endoplasmic reticulum. Only Plant Cells  Chloroplast: Membrane bound organelle, it is the site of photosynthesis and ATP production in autotrophic plant cells Cell Wall: Cellulose layer that surrounds the plasma membrane of plant cells. Because it is very porous the cell wall permeable to molecules and ions that can pass through the plasma membrane through diffusion.  

PLANT ORGANELLES CONT: Vacuole Is a membrane bound, fluid filled sac inside plant and animal cells.   Large Vacuole Is a membrane bound, fluid filled sac inside plant and animals cells. Occupies much of the volume of a plant cell. Amyloplast (Starch Grain) A membrane bound organelle containing concentric layers of starch (amylopectin).  READ AND NOTE PAGE 21: Cilia and Flagella