unit 2 h=chap. 4

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

cellSeparates internal environment

from the external environmentComposed of a lipid bilayer (Fat)Selectively-permeable membrane

The Fluid Mosaic Model

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 membran

e

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

CHLOROPLAST

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