Cell Structure
& Function
http://koning.ecsu.ctstateu.edu/cell/cell.html
1600s
• Galileo is credited for building the first
microscope in 1625.
• Robert Hooke in 1665 looked at a thin
slice of cork under the microscope and
saw a honeycomb structure made up of
small compartments he called cells
• Anton van Leeuwenhoek in 1670,
improved the quality of the microscope
lenses and became the first person to see
living cells.
Cell Theory
• All living things are made up of cells.
• Cells are the smallest working units of all
living things.
• All cells come from preexisting cells
through cell division.
Definition of Cell
A cell is the smallest unit that is
capable of performing life
functions.
MRS NERG
Examples of Cells
Amoeba proteus
Plant Stem
Bacteria
Red Blood Cell
Nerve Cell
Cell Structure
• All Cells have:
– an outermost plasma membrane
– genetic material in the form of DNA
– cytoplasm with ribosomes
Two Types of Cells
•Prokaryotic- are cells that do not have a
true nucleus or most other cell
organelles
•Eukaryotic- are cells that contain a nucleus
and organelles, and are
enclosed by a plasma membrane
Prokaryotic
• Do not have
structures
surrounded by
membranes
• Few internal
structures
• One-celled
organisms, like
Bacteria
http://library.thinkquest.org/C004535/prokaryotic_cells.html
Eukaryotic
• Contain organelles surrounded by membranes
Plant Animal
http://library.thinkquest.org/C004535/eukaryotic_cells.html
“Typical” Animal Cell
http://web.jjay.cuny.edu/~acarpi/NSC/images/cell.gif
“Typical” Plant Cell
http://waynesword.palomar.edu/images/plant3.gif
Cell Parts
Organelles
tiny cellular structure that performs specific functions within a
cell
Surrounding the Cell
Cell Membrane
• This is a partially
permeable membrane
separating the cell from
the environment it is
made up of lipid and
protein, it controls
movement of
substances in and out,
its strong but flexible.
http://library.thinkquest.org/12413/structures.html
Cell Wall
• This is a rigid layer
surrounding the cell
made of cellulose, it
gives the plant its
shape and prevents it
from bursting
• fully permeable.
http://library.thinkquest.org/12413/structures.html
Inside the Cell
Cytoplasm
• This is a jelly like substance, its made of
mostly water (70%) and protein.
• Metabolic reactions occur in it.
Vacuoles
• This is a large room in
the center of the cell,
it stores sugars and
salts and controls
movement of water in
and out of the cell.
• Animals have much
smaller membrane
bound spaces called
vesicles
Vacuoles are membrane sacs that are generally larger
than vesicles.
Examples:
Food vacuole - formed when protists bring food
into the cell by endocytosis
Contractile vacuole – collect and pump excess
water out of some freshwater protists
Central vacuole
Chloroplast
• They are sacs
which contain
chlorophyll which
is a green
pigment that
traps sunlight for
photosynthesis.
• has starch grain
as product of
photosynthesis
Nucleus
• This determines how the cell behaves and
it contains chromosomes made of strings
of DNA which also determines which
proteins the cell should make.
Nucleolus
• Inside nucleus
• Contains RNA to build
proteins
http://library.thinkquest.org/12413/structures.html
Difference between DNA and RNA
Nuclear Membrane
• Surrounds nucleus
• Made of two layers
• Openings allow
material to enter and
leave nucleus
http://library.thinkquest.org/12413/structures.html
Chromosomes
• In nucleus
• Made of DNA
• Contain instructions
for traits &
characteristics
http://library.thinkquest.org/12413/structures.html
Mitochondria
• Powerhouse of the cell
• Produces energy through
chemical reactions –
breaking down fats &
carbohydrates
• Controls level of water and
other materials in cell
• Recycles and decomposes
proteins, fats, and
carbohydrates
Ribosomes
• Each cell contains
thousands
• Make proteins
• Found on ribosomes
& floating throughout
the cell
• Can be found in all
types of cells
Endoplasmic Reticulum
• Moves materials around
in cell
• Smooth type: lacks
ribosomes
• Rough type (pictured):
ribosomes embedded in
surface
http://library.thinkquest.org/12413/structures.html
Mitochondria
• Function – synthesis of ATP
– 3 major pathways involved in ATP
production
1. Glycolysis
2. Krebs Cycle
3. Electron transport chain (ETC)
Golgi Bodies
• Protein 'packaging
plant'
• Move materials within
the cell
• Move materials out of
the cell
http://library.thinkquest.org/12413/structures.html
Golgi Apparatus
• Golgi Apparatus
– Stack of flattened membrane sacs
• Function Golgi apparatus
– Completes the processing substances
received from the ER
– Sorts, tags and packages fully processed
proteins and lipids in vesicles
Lysosome
• Digestive 'plant' for
proteins, fats, and
carbohydrates
• Transports undigested
material to cell
membrane for removal
• Cell breaks down if
lysosome explodes
http://library.thinkquest.org/12413/structures.html
Specialised Cells:
Red Blood Cells:
Red blood cells are
found in the blood of
animals, its function is
to transport oxygen from
the lungs to all the body
cells, and carbon
dioxide from the body
cells to the lungs.
They are adapted by four ways:
•They have a biconcave disc shape that
gives it a large surface area to carry more
oxygen.
•They contain a chemical called hemoglobin
that combines with oxygen and carbon
dioxide.
•They have no nucleus to carry more oxygen
and CO2
•They are tiny enough to squeeze through
capillaries.
• Muscle Cells
They are cells found in muscles in animals,
they contract and relax together to move
the organisms.
Their function is to contract to support
and move the body.
They are adapted by two ways, First, is that
they are made of contractile filament to
help in contraction. Second is it contains
lots of mitochondria to supply the cell with
energy.
contractile filament
Ciliated Cells:
•Ciliated cells are present in the trachea and
bronchi of our respiratory system.
•Their function is to use their cilia to move the
mucus up the trachea to the throat. The
mucus traps bacteria and dust particles.
When it reaches the throat, mucus is
swallowed to the stomach where the acid kills
the bacteria.
Root Hair Cells:
•These are cells situated in the roots of plants.
They contain no chloroplasts.
•Their function is to absorb water and minerals
from the soil. And to anchor the plant in the soil.
•They are adapted by 3 ways. One, they have an
extension that increases the surface area for more
water intake. Two, they have a large number of
mitochondria for respiration to become more
active. Three a concentrated vacuole to help
absorbing water by osmosis.
Cells and Organisms
• Tissues
group of cells with
similar structures,
working together to
perform a shared
function
• Organ- a structure
made up of a group
of tissues, working
together to perform
specific function
• Organ System- a group of organs with
related functions, working together to
perform body function
Calculating Magnification
Unit of length (International
System)
Unit Equivalent
1 meter (m) = 1000 mm
1 millimeter (mm) = 1000 micrometers
1 micrometer (μm) = 1000 nanometer
1 nanometer = 1000 picometer
Biological Drawing
• Drawing must be significantly larger than the
photograph
• Diagram must have a clean, clear, unbroken
lines
• All visible structures are clearly shown
• NO SHADING or COLOUR is used
