Download Ch 2 - Cell Structure

Prokaryotes Vs.
Eukaryotes
There are 2 main types of cells:
 Prokaryotes: - have no membranebound nucleus or organelles
– Usually very small 0.0005 – 0.001mm

Eukaryotes: - have membrane-bound
nucleus and organelles
– Usually from 0.01 – 0.1mm
– Often complex
– Often specialised
Type
of cell
Animal Plant Fungus Protist Bacterium Virus
P Vs. E
Eukaryote
Prokaryote
Nucleus
Yes
No,
nuceloid
Organelles
Yes
No
Cell
Wall
Cell
Membrane
No
Yes
Yes
Some Yes
Yes
Not
living.
Must
invade
other
cells to
survive
not
really a
cell
type.
Cannot
live on
its
own.
Organelles




Organelles are structures within the
cell that are enclosed by a membrane
They can be described as
compartments within a cell
They carry out specific functions
Because they are enclosed by
membranes, organelles can maintain
conditions which are very different to
other parts of the cell
Nucleus




The nucleus contains the DNA
It is enclosed by membrane sometimes
called the nuclear envelope
This membrane has pores/spaces
through which certain substances
(such as mRNA) can pass in/out of
The DNA inside forms a template for
protein production
Nucleus

The nucleus controls the functioning of
the cell:
– Cell division
– Protein production
– Apoptosis (programmed cell-death)

Within the nucleus are many large
clumps which appear as dark spots
under the microscope. These are
nucleoli (nucleolus sing.)

The nucleoli are clumps of RNA
molecules
Nucleoli
Nuclear
Pores
Nuclear
Membrane
Ribosomes





Produce protein for the cell by using
DNA as a template
These are not membrane-bound  not
true organelles
All cells have them (even prokaroytes)
Cannot be seen without an electron
microscope or specialised staining
Made up of rRNA and other proteins
Endoplasmic reticulum
A
series of membrane-bound channels.
Its main function is transport of
substances within the cell.
There are 2 types:
– Rough (RER): has ribosomes on the surface,
found surrounding the nucleus
– Function is to produce proteins and modify
them for transportation
– Smooth (SER): - also found surrounding
nucleus, often joined to RER
– Function is to remove toxins/de-activate
them
Golgi Body



Also called Golgi complex or Golgi
apparatus
Consists of stacks of membranebound sacks
Functions to package and transport
proteins and lipids for export into
secretory vesicles which can pass out
of the cell membrane easily
Secretory vesicles
Chloroplasts






Produce energy for the cell
Contain chlorophyll in the grana
Chlorphylyll is an enzyme which traps the
energy from sunlight for use in sugar
productions (photosynthesis)
Chlorophyll is also a pigment which is
green in colour
Plant cells (and some fungi) contain
chloroplasts
These organelles are often large enough
to see with the light microscope and
contain small amounts of DNA
External
membrane
Inner membrane
Grana
Stroma
Mitochondria




Convert the energy obtained from food
(glucose) to a form that the cell can use
(ATP) using O2
This process is called cellular
respiration
Mitochondria also contain small
amounts of DNA
All cells except Monera have these
Vacuoles

The main functions of vacuoles
are to store substances such as
food in an environment which is
separate to the cytoplasm
– Eg food

Other specialised vacuoles store
substances which may pose
danger to the cell
Lysosomes, Peroxisomes


Lysosomes contain destructive
enzymes which can break down
damaged or old cell parts and
molecules
Peroxisomes contain enzymes which
break down hydrogen peroxide (H2O2)
which is a product of many
biochemical reactions and can be
highly toxic and damaging to cells
Cytoplasm

The fluid component of the cell

Also called the cytosol or cytogel


It contains dissolved minerals,
proteins, enzymes, sugars, salts, lipids
and the organelles
It provides the perfect environment for
chemical reactions
Cytoskeleton

This is an internal framework of
proteins which supply structure
and support to the cell and allow
movement of the cell and the
organelles within
Cell Membrane



Also called the Plasma Membrane
or Plasmalemma
Function is to control the
movement of substances into and
out of the cell
All cells have one!!
Cell Wall


Not found in animal cells
Plays an very important role in
structural support of the cell
 Prevents
the cells from bursting
due to water absorption

Found in bacteria, fungi, plants
and some protists
Animal Cell
Cell
Membrane
Mitochondrion
Endoplasmic
reticulum
Nucleus
Cytoplasm
Golgi body