Basic Structure of a Cell
CELL THEORY
• All living things are
made of cells
• Cells are the basic
unit of structure and
function
• Cells come from the
reproduction of
existing cells (cell
division)
Two Main Types of
Eukaryotic Cells
Plant Cell
Animal Cell
Different kinds of animal cells
white blood cell
Amoeba
red blood cell
muscle cell
cheek cells
sperm
nerve cell
Paramecium
Examples of Animal Cells
Muscle cells
Cheek cells
Red blood cells
Cell or Plasma Membrane
(2,5)
• Composed of double layer of phospholipids
and proteins
• Surrounds outside of ALL cells
• Controls what enters or leaves the cell –
selectively permeable
Proteins
Cell
membrane
Protein
channel
Lipid bilayer
Cytoplasm
• Jelly-like
substance
• Found in ALL cells
• Contains
organelles
• Provides a place
for chemical
reactions to take
place
Nucleus
(12,15)
• Controls the activities
of the cell
• Contains DNA in
chromosomes
• Genes control cell
characteristics
Nuclear Envelope/Membrane
• Double membrane
surrounding nucleus
• Contains nuclear pores
for materials to enter
& leave nucleus
Nuclear
pores
Inside the Nucleus
(14,16)
The genetic material (DNA) is found
DNA is spread out
And appears as
CHROMATIN
in non-dividing cells
DNA is condensed &
wrapped around proteins
forming
as CHROMOSOMES
in dividing cells
Nucleolus
(13,14)
• Inside nucleus
• Makes
ribosomes
that make
proteins
Endoplasmic Reticulum - ER
• Connects to nuclear envelope & cell
membrane
• Functions in Synthesis of cell
products & Transport
Two kinds of ER ---ROUGH & SMOOTH
Rough Endoplasmic Reticulum
(Rough ER)
(11,11)
• Has ribosomes
on its surface
– Makes
membrane
proteins
– TRANSPORT
proteins out
of cell
Smooth Endoplasmic Reticulum
(7,1)
• Smooth ER lacks
ribosomes
– Makes membrane
lipids (steroids)
– Regulates calcium
(muscle cells)
– Detoxic
substances (Liver)
Ribosomes (10,10)
• Made of PROTEINS
• “Protein factories” for cell
• Join amino acids to make
proteins
• Process called protein synthesis

Ribosomes
Can be attached to
Rough ER
OR
Be free
(unattached)
in the
cytoplasm
Golgi Bodies
(8,12)
• Stacks of flattened
sacs (PANCAKES)
• Modify, sort, &
package molecules
for storage OR
transport out of cell
• Vesicles pinch off
the ends
CIS
TRANS
vesicle
Golgi Animation
Materials are transported from Rough ER
to Golgi to the cell membrane by VESICLES
Lysosomes
(3,7)
• Contain digestive
enzymes
• Break down food,
bacteria, and worn
out cell parts
Cytoskeleton
(5,6)
• Helps cell maintain
cell shape
• Also help move
organelles around
• Made of proteins
– Ex. Microfilaments
– Ex. Microtubules
Mitochondrion
(plural = mitochondria)
(4,3)
• “Powerhouse” of the cell
• Generate cellular energy
(ATP)
• Site of CELLULAR
RESPIRATION
• Has its own DNA
• What kind of cells would
have MORE
mitochondria?
What do mitochondria do?
“Power plant”
of the cell
Burns glucose to
release energy (ATP)
Stores energy as ATP
Cilia & Flagella
• Function in moving
cells and
movement of
particles across a
membrane
• Cilia -short and
many (spirit
fingers)
• Flagella - longer
and fewer (ex
sperm tail)
Cell Movement with Cilia
& Flagella
Cilia Moving Away Dust Particles from the
Lungs
Respiratory System
Centrioles (1)
• Found only in
animal cells
• Made of bundle of
microtubules
• Appear during cell
division
• Help to pull
chromosomes
apart
Centrioles & the Mitotic Spindle
Vacuoles (8)
• Storage of
wastes, water,
and nutrients
• Small or absent
in animal cells
• Plant cells have
a large Central
Vacuole
• No vacuoles in
bacterial cells
Plant Cell
Different kinds of plant cells
Onion Epidermal Cells
Guard Cells
root hair
Root Hair Cell
Examples of Plant cells
Guard Cells
Pollen
Xylem cells
Cell Wall (4)
• Supports and protects cell
• Found outside of the cell
membrane
• Found in plants, fungi, &
bacteria
• cellulose in plants
• peptidoglycan in
bacteria
• chitin in Fungi
Chloroplasts (9)
• Plant cells ONLY
• Contain chlorophyll
• Photosynthesis –
(energy from sunlight
makes food (glucose)
• Contains its own DNA
Differences between plant
cells and animal cells
Animal cells
Irregular shape
No cell wall
No chloroplast
Vacuole small or
absent
Glycogen as food
storage
Plant cells
Regular shape
Cell wall present
Have chloroplast
Large central
vacuole
Starch as food
storage
• http://www.youtube.com/watch?v=Yu21ShnKh
Hk&feature=related
Cell Types
• Cells can only be observed under
microscope
• Three Basic types of cells include:
Animal Cell
Plant Cell
Bacterial Cell
Number of Cells
Although ALL living things are made of
cells, organisms may be:
• Unicellular – composed of one cell
• Multicellular - composed of many cells
that may organize into tissues, etc.
Prokaryotes
• Cells that lack a
nucleus or membranebound organelles
– Nucleoid region
(center) contains
the DNA
– Single, circular
chromosome
• Surrounded by cell
membrane & cell wall
• Contain ribosomes
• E.x. bacteria
Eukaryotes
• Cells that HAVE a
nucleus and membranebound organelles
Contain 3 basic cell
structures:
• Nucleus
• Cell Membrane
• Cytoplasm with
organelles
• E.x. protists, fungi,
plants, and animals
CELL SIZE
Which Cell Type is
Larger?
Plant cell > _____________
Animal cell > ___________
bacteria
_________
Cell Size
Question:
Are the cells in an elephant
bigger, smaller, or about the
same size as those in a
mouse?
Factors Affecting Cell Size
• Surface area (plasma membrane
surface) is determined by
multiplying length times width (L x
W)
• Volume of a cell is determined by
multiplying length times width
times height (L x W x H)
• Therefore, Volume increases
FASTER than the surface area
Cell Size
• When the surface area is no
longer great enough to get rid of
all the wastes and to get in
enough food and water, then the
cell must divide
• Therefore, the cells of an
organism are close in size
Cell Size
Question:
Are the cells in an elephant
bigger, smaller, or about the
same size as those in a mouse?
About the same size, but …
The elephant has MANY MORE cells
than a mouse!