Unit 3
Chapter 7
A View of the Cell
History of the Cell theory

Anton van
Leeuwenhoek’s
simple microscope
lead to greatly
improved
microscopes over
the next 200 years
Compound light microscopes
 With
light as its
energy source, it
uses a series of
lenses to
magnify up to
1500X
Electron microscope

Using a beam of electrons as its energy
source, it can magnify structures up to
500,000 X their actual size
(a pin head)
Cell Theory

1) All organisms are composed of one or
more cells

2) The cell is the basic unit of structure
and functions of living things

3) All cells come from preexisiting cells
Basic Cell Types
Prokaryotic
 Small, simple cells without membranebound organelles; i.e. bacteria

Eukaryotic
 Large, complex cells containing many
specialized organelles; i.e. plants, animals
& fungus

Plasma Membrane

A flexible boundary between the cell and
its environment maintains a balance of
nutrients, etc.
Selective permeability
 A process in which a membrane allows
some molecules to pass through while
keeping others out

Structure of the Plasma membrane
Phospholipids
 A double layer that creates water-soluble
outsides surrounding water insoluble
insides
 Transport Proteins
 Span the entire membrane to regulate
which molecules enter and which leave

Eukaryotic Cell Structures
Nucleus  cell control
Chromatin
 Strands of genetic
material (DNA) that
contains the directions
for making proteins
 Nucleolus
 A prominent body within
the nucleus, which
makes the ribosomes

Cytoplasmic Organelles
Endoplasmic reticulum
 Highly folded membranes
that is the site of cellular
chemical reactions
 Ribosomes
 Attached to the surface of
ER, they carry out the
function of protein
synthesis

Cytoplasmic Organelles
Golgi apparatus
 A flattened stack of
membranes that
packages proteins
into vesicles to be
secreted by the cell

Cytoplasmic Organelles
Vacuoles
 Membrane-bound
compartments for
temporary storage
of materials
 May be very large
in plant cells

Cytoplasmic Organelles
Lysosomes
 Small bodies filled with
digestive enzymes that
digest worn-out
organelles, food
particles, and even
engulfed bacteria
 Responsible for the
cell’s recycling of
materials

Cytoplasmic Organelles
Chloroplasts
 Containing the
green pigment,
chlorophyll, these
oval bodies
capture light
energy and turn it
into chemical
energy
(photosynthesis)

Cytoplasmic Organelles
Mitochondria
 Rod-shaped
organelle with
many inner folds,
which breaks down
sugar to release its
stored energy for
cell use
(cell respiration)

Cytoplasmic Organelles
Cytoskeleton
 Tiny rods and
filaments (called
microtubules) that
form a supporting
framework for the
cell and function in
cytoplasmic
streaming

Cytoplasmic Organelles
Centrioles
 Pairs of
microtubules that
play an important
role in cell division

Cytoplasmic Organelles
Cilia & Flagella
 External microtubules that aid the cell in
locomotion or feeding
