Levels of Organization
Organism
Organelles
Organ System
Cells
Organ
Tissues
Cells
A
cell is the smallest unit that is
capable of performing all 8 life
functions.
 MRS
C GREN
Cells
 The
size & shape of a cell relates
to its function.
 Two
main types
of cells:
Prokaryotic
2. Eukaryotic
1.
Prokaryotic Cells
 Cells
that lack a cell nucleus, or
any other membrane-bound
organelles.
 Chromosome
is a
simple DNA chain
with the ends joined
to form a circle.
Prokaryotic Cells
 Most
are unicellular, but some
prokaryotes are multicellular.
 E.g . bacteria, blue-green algae
Eukaryotic Cells
 Higher
organisms whose cells are
arranged into complex structures
enclosed within membranes.
 The
chromosome is a length of DNA
folded. It is wound around proteins.
 E.g.
Animals, plants,
fungi and protists.
Organelles
 No
plant or animal cells are alike
but they do share some common
organelles.
Features
Function
Uni
Location
Animal
Organelle
Plant
In your Notes....
Cell Membrane
 All
cells are separated from their
environment by a cell membrane.
 For
cells with cell
walls, the membrane
is inside the cell wall.
Cell Membrane
 Consists
of two layers
of lipids (lipid bilayer).
 One
lipid includes a
hydrophilic (waterloving) head and
hydrophobic (waterhating) tails.
Lipid
Lipid Bi-layer
Cell
Membrane
Semi-Permeable Membrane
 Proteins
in the membrane allow
nutrients, oxygen, and water into the
cell and waste products out of the
cell.
 These
proteins
also limit other
molecules from
entering or
leaving the cell.
Protein Gate
Lipid
Lipid
Cytoplasm
 Cytoplasm
is the semi-fluid
solution found inside the cells.
 It
contains dissolved substances,
enzymes and all other cell
organelles.
Cytoskeleton
 Scaffolding-like
structure made of
protein found in cytoplasm.
 Helps
the cell
maintain or change
its shape.
Nucleus
 Usually
the largest organelle the
nucleus
contains genetic material
Nucleus
that directs all cell activities.
Pores
 Separated from the
Nuclear
rest
of theMembrane
cell by a
nuclear membrane.
Nucleolus
Nucleus
 Made
up of
three parts:
1. Nuclear envelope – a double
membrane covering that controls
the entry and exit of the large
molecules and particles that need to
go in and out.
Nucleus
2.
Genetic Material – In a resting cell
the DNA is unravelled (chromatin)
and too small to be seen.
When a cell is about
to divide the DNA
coils, thickens and
can be seen
(chromosomes).
Nucleus
3.
Nucleolus – The main function of
the nucleolus is the production and
assembly of ribosome components
(RNA, proteins).
Endoplasmic Reticulum (ER)
 Continuous
with the cell membrane
and the nuclear envelope.
 The
ER is a series of membranes and
connecting tubes that provide a
work surface for chemical reactions
as well as a passageway for moving
materials around the cell.
Endoplasmic Reticulum (ER)
 There
1.
2.
are two types or ER:
Smooth ER
Rough ER (ribosomes attached)
Ribosomes
 Found
either bound to the ER or
free floating within the
cytoplasm.
 Site
where
proteins are
made (protein
synthesis).
Ribosomes
 Free
ribosomes
make proteins to
be used in the
cell.
 The
ribosomes bound to the ER
make proteins to be secreted by
the cell.
Golgi Bodies/Apparatus
A
series of
flattened sacs
found in the
cytoplasm.
 The
primary function is to process
and package the macromolecules
such as proteins and lipids that are
synthesized by the cell.
Lysosomes
 Tough,
membranous
bags containing
digestive
enzymes.
 They
digest excess or worn-out
organelles, food particles, and
engulfed viruses or bacteria.
Vacuoles
 Vacuoles
are membrane-bound
compartments that can serve a
variety of storage functions.
 They
often
contain water,
food or wastes.
Vacuoles
Video
 In
animal cells food vacuoles engulf
food where it is digested by the
lysosome's enzymes.
 In
plants it acts as a storage, a fluid
skeleton and it also hold colour and
poisons.
 In
unicellular organisms contractile
vacuoles pump water out of the cells.
Contractile Vacuoles
 These
specialized vacuoles pump
excess water out of a cell and is
found prominently in freshwater
protists.
Mitochondria
 Converts
energy
from food into a
form that a cell
can use, called
ATP.
 It
is the site of aerobic respiration. A
cell with a large energy requirement
will have lots of mitochondria.
Mitochondria
 It
has its own circular DNA, ribosomes
and transfer RNA and protein making
machinery.
 In the matrix the
krebs cycle takes
place.
 The
electron
transport chain
takes place in the
cristae.
Cell Wall
 Found
in plant cells, algae and
most bacteria.
 Made
of cellulose to
provide strength and
shape.
Chloroplasts
 Found
in the cytoplasm of plants.
 Function
is to manufacture
glucose through photosynthesis.
 Contains
the green pigment
chlorophyll.
Chloroplasts
 Made
of thylakoid discs arranged
in stacks called grana.
Centrioles
 Found
in all animal cells and most
unicellular organisms.
 During
cell
division, the
centriole pair
extends to form
spindles to move
chromosomes
apart.
Cilia and Flagella
 Found
in some animal cells and
unicellular organisms.
 Both
are cellular projections and are
almost identical in structure,
although cilia are shorter and often
more numerous.
 Many
cells that line surfaces within
our bodies are ciliated.
Cilia and Flagella
 Both
are often
associated with
movement.
Eyes Spots
 Photoreceptive
organelle found in
green algae and other unicellular
photosynthetic organisms.

It allows the cells to
sense light direction and
intensity and respond to
it by swimming either
towards or away from
the light.
Eye Spots
 This
helps the cells in finding an
environment with optimal light
conditions for photosynthesis.
 Eyespots
are the
simplest and
most common
"eyes" found in
nature.
Cilia and Flagella