Download Unit 2: Cells

Unit 2: Cells
Chapter 3: Cells, The
Basic Units of Life
Lesson 3.1: The Diversity of Cells
The Diversity of Cells
Most cells are so small they can not be
seen by the naked eye.
 How did scientists find cell’s?


CELL: the smallest unit that can perform
all the processes necessary for life.
Cells and the Cell Theory
Robert Hooke was the first person to
describe cells (1665)
 He “discovered” cells by accident
 He was looking at a thing piece of cork
under a microscope
 The cork looked like it was made of “little
rooms” he called cells

THE CELL THEORY
1. All organisms are made of one or more
cells
 2. The cell is the basic unit of all living
things.
 3. All cells come from existing cells.

Cell Size – most cells are too small to
be seen without a microscope
(name one exception)
Why Are Cells So Small???
 Cells take in and get rid of wastes through
their outer surface.
 As a cell gets larger, it needs more food
and produces more waste.
 So, more materials pass through the outer
surface.

Surface area-to-volume ratio:
…is the ratio of the cell’s outer surface are
to the cell’s volume.
 = surface area
volume

Parts of a Cell: All cells have the
following parts in common
CELL MEMBRANE: a protective layer
that covers the cell’s surface and acts as a
barrier. It separates the cells contents from
its environment, and controls what goes
into and out of the cell
 CYTOPLASM: jell fluid in the cell
 All organelles “float” in the cytoplasm

ORGANELLES: structures that
perform specific functions within
the cell. (see pg 74)
1. Nucleus
 2. Ribosome
 3. Endoplasmic Reticulum
 4. Mitochondria
 5. Chloroplast
 6. Golgi Complex
 7. Vacuole
 8 Lysosome

Prokaryotic Cells: BACTERIA
AND ARCHEA

Prokaryotes are single-celled organisms
that do not have a nucleus or membrane
covered organelles
BACTERIA
The most common PROKAYOTES
 The smallest cells known
 Do not have a nucleus
 Have DNA – it is a long, circular strand
 Have no membrane covered organelles
 Have a cell membrane just inside the cell
wall
 See pg 64

ARCHEA – similar to bacteria
But can live in places no other organisms
can live – in extreme conditions
 Some times called extremophiles
 Heat-loving
 Salt-loving
 Methane-making
 See pg. 65

EUKARYOTIC CELLS –
all other cells (ex. You & me & a tree)
Largest cells – but most still microscopic
 About 10x larger than bacteria cells
 Have a nucleus
 DNA in nucleus
 Membrane covered organelles
 Some unicellular, most are multicellular

HW DUE TUES 11/22
Read Chapter 3 Lesson 2 “Eukaryotic
Cell”
 Make a chart in your notebook listing the
organelles and their function, and if it is
found in plant cells, animal cells, or both.
 Include the 8 organelles in the chart on pg
74 and Cell Wall, Cytoplasm, Cell
Membrane
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