Unit 2 H=Chap. 4

In 1665, the English scientist ROBERT HOOKE, used a microscope to examine a thin slice of cork. He described it as consisting of “great many little boxes”. It reminded him of the small rooms in which monks lived… CELLS!

All living things are composed of one or more cells Cells are the basic units of structure and function in all living things. ALL cells come from preexisting cells.

1. SHAPE - Diversity of form reflects a diversity of function

2. SIZE – visible with unaided eye, microscopic, etc.

MOST CELLS ARE SMALL FOR 2 REASONS 1. A SMALL CELL HAS MORE SURFACE AREA THAN A LARGE CELL FOR A GIVEN VOLUME OF CYTOPLASM 2. THE CELL'S NUCLEUS (THE BRAIN) CAN ONLY CONTROL A CERTAIN AMOUNT OF LIVING, ACTIVE CYTOPLASM

3. INTERNAL ORGANIZATION: Organelles, Eukaryotes and prokaryotes

EQ= What are membranes and what purpose do they serve? Give an example of one.

1. THE PLASMA MEMBRANE (Present in ALL cell types) Functions: Regulates what enters/leaves the cell Separates internal environment from the external environment Composed of a lipid bilayer (Fat) Selectively-permeable membrane

2. THE CELL WALL (Plant cells ONLY) Surrounds the cell membrane Helps to protect and support the cell

The fluid-filled area BETWEEN the NUCLEUS & the CELL MEMBRANE…fluid & organelles “cyto” = cell “plasm” = fluid Cytosol = cell fluid only 3. THE CYTOPLASM

4. THE NUCLEUS (Eukaryotic cells) Control center of the cell Contains DNA Double Layer Membrane called the NUCLEAR ENVELOPE covered with many small pores The NUCLEOLUS synthesizes (makes) ribosomes, which are important in making proteins for the cell

Chromatin: nuclear DNA (long fibers known as chromosomes) Nuclear Envelope: Double membrane Nuclear Pore: Regulate flow of materials in and out of cell Nucleolus: Ribosome synthesis Nucleoplasm: Fluid of the nucleus

Extension of the nuclear membrane regions with ribosomes = ROUGH ER (transport ribosomes) regions w/o ribosomes = SMOOTH ER (lipid synthesis)

Sites of protein synthesis 2 sub-unit

The function of the Golgi Apparatus is to sort, chemically alter, and package important molecules. (UPS guy!)

Powerhouse of the cell… (generates fuel for cell’s activities) Sites of cellular respiration

Responsible for intracellular digestion. Lysosomes are membranous sacs of acidic enzymes. (Rare in plant cells)

Detoxify harmful substances that enter the body.

Stores extra material for the cell. Nutrients, water, etc. The “garage”

All CELLS HAVE DIFFERENT SHAPES AND ARE CAPABLE OF SOME TYPE OF MOVEMENT. HELPS SUPPORT CELL STRUCTURE AND DRIVE CELL MOVEMENT.

a.Cilia – short hair- like extensions on the cell that aid in cell movement b.Flagella – long hair-like extension on a cell that helps the cell propel