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Structure and Function of
Cells
Why are Cell So Small?
• Most cells are too small to be seen
without a microscope. It would take
50 human cells to cover the dot on
this letter “i”.
• Cells take in food and get rid of
waste through their cell membrane.
• If cells grew larger they would need
more food and produce more waste.
• As the cells volume increases, its
surface area grows too
• However the cell’s volume grows faster
than the cells surface area.
• If a cell gets too large , the cell’s
surface area will not be large enough
to take in enough nutrients or pump
out enough waste.
• So the area of the cell’s surface compared with the cell’s volume– limits
the cell’s size.
Cell Size Continued
• A few cells are big.
• The yolk of a chicken egg is one big
cell.
• The egg can be this big because it
does not have to take in more
nutrients.
Organelles
• Organelles – structures
within a cell that
perform specific
functions.
• Each organelle has it’s
own name.
• Structure- the design
or shape of an
organelle.
• Function – the “job” of
the organelle in the
cell.
Two Types of Cells
Prokaryote
Eukaryote
• An organism that • An organism made up
consist of a single
of cells that have a
cell that does not
nucleus enclosed in a
have a nucleus.
membrane.
No Nucleus
Nucleus
Cell Wall
• Cell Wall –A rigid
structure that
surrounds the cell
membrane and provides
support to the cell.
• The cell wall of a plant
is a ridged yet flexible
structure that is made
of complex sugar called
cellulose.
• Plants, bacteria and
fungi all have cell
walls.
Cell Membrane
(Gate Keeper)
• Cell membrane –
protective barrier that
encloses the cell.
• The cell membrane
contains proteins, lipids
and phospholipids.
• The phosphorus layer is
outward facing and
hydrophilic or “water
loving.”
• The lipids layer is
inward facing and
hydrophobic or “water
fearing.”
Cytoplasm and Cytoskeleton
• Cytoplasm – Clear gel
like substance in a cell
that cushions and
protect the cell’s
organelles. The fluid
and most of the
organelles are
considered part of the
cytoplasm.
• Cytoskeleton – is a web
of proteins in the
cytoplasm.
Chloroplast (Solar Panels)
• Chloroplast are “green"
organelles that are
found in all plants and
some bacteria and
protist such as algae.
• Chloroplast are green
because they contain
chlorophyll. Chlorophyll
is a green pigment that
absorbs and traps the
energy of sunlight to
use in photosynthesis.
Chloroplast Under a Microscope
http://teachertube.com/viewVideo.php?video
_id=244847
Vacuole (Storage Tanks)
• In animal and fungal
cell, some vacuoles
act like lysosomes
because they store
digestive enzymes.
• In plant cells,
vacuoles are large
and centrally
located. These large
vacuoles store water
and support the cell.
Mitochondrion
(Power House/Generator)
• Mitochondria – are the
power source of the cell
where glucose (sugar) is
broken down.
• When glucose is smashed
inside the mitochondria,
large amounts of energy
in the form of ATP
(adenosine triphosphate)
is released.
Lysosome
(Waste Management)
• Lysosomes are
organelles that
contain digestive
enzymes.
• Lysosomes destroy
worn-out organelles,
gets rid of waste.
Nucleus
(Control Center/Brain)
• Nucleus- is found in
eukaryotic cells:
protist, fungi, plants
and animals
• Contains the cell’s
DNA or genetic
material.
• Controls all cell
activity.
• Nucleolus – is where
ribosomes are made.
DNA (Blueprint)
• DNA- deoxyribonucleic
acid
• DNA is found in the
nucleus
• Genetic material that
carries information
needed to make new
cells and new
organism.
4 Nitrogen Bases
Vesicles
•
Vesicles are
small cell
organelles that
are present in
cells. These
organelles are
small,
membrane
enclosed sacs
which store and
transport
substances to
and from one
cell to another
and from one
part of a cell
to another.
They are one
of the
important parts
of a cell.
Endoplasmic Reticulum
(Passageways / Delivery System)
• Endoplasmic Reticulum – The
ER are part of an internal
delivery system made of
tubes and passageways.
• Substances move from the
nucleus through the ER to
different places in the cell.
• Many chemical reactions
take place in the ER where
proteins, lipids, and other
materials are made.
Smooth Endoplasmic Reticulum – is smooth not covered
with ribosomes.
Rough Endoplasmic Reticulum – is covered with ribosomes
Golgi Body
(Postal Service)
• Golgi Body– packages
materials to be
transported throughout
of cell.
• Lipids and proteins
from the ER are
delivered to the Golgi
body. They are
packaged in pieces of
the Golgi membrane
called vesicles and are
sent where they are
needed in the cell.
Ribosomes (Protein Factories)
• Ribosomes are
organelles that make
proteins.
• Proteins are made of
amino acids.
• Amino Acids are 20
different organic
molecules that are
used to make protein.
Centrioles (Spindle Fiber)
• Cells have two small organelles
called centrioles which are a
little bundle of 9 tubes.
• Centrioles are seen during cell
division.
• During prophase, the centrioles
move to opposite ends of the
nucleus and a mitotic spindle of
threads (spindle fiber) begins to
appear. Those threads then
connect to the now apparent
chromosomes. During anaphase,
the chromosomes are split and
pulled towards each centriole.
Cell Song
• http://www.bing.com/videos/search?q=cell+rap+song+on+youtube&mid=EEA
648DCDF16FEE10F4CEEA648DCDF16FEE10F4C&view=detail&FORM=VIRE1
Cell Diagram- Class Assignment
• Cell Diagrams
• Draw separate
diagrams of a plant,
animal and bacteria
cell.
• Label each structure
or part of the cell.
• Write a brief
description of the
function of each part
of the cell.