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CHAPTER FOUR:
CELL STRUCTURE
AND FUNCTION
7.1 History of the Cell
Robert Hooke (1665) – Used compound scope to
examine thin cork slices. Coined the term
“cell” referring to the many little boxes.
Actually saw dead plant cells
 Anton van Leeuwenhoek (1673) – Use simple
scope (one lens), observed first living cells.
 Matthias Schleiden (1838) and Theodor Schwann
stated that all plants and animals (respectively)
are made up of cells .
 Rudolph Virchow (1855) – cells come only from
other cells.

The Cell Theory

All living things are made up of cells

Cells are the basic unit of structure and
function in all living things

Cells come from pre-existing cells
7.2 Introduction to Cells
Side
Length
Surface Area
Volume
Surface area to
Volume ratio
1mm
6mm2
1mm3
6 to 1
2mm
24mm2
8mm3
3 to 1
3mm
54mm2
27mm3
2 to 1
Cells vary by:
1. Size – Range from 2m (giraffe nerve cell from leg
to spine) to .2um (bacteria)
Limited by the ratio between outer surface area and
their volume.
As the surface area to volume ratio decreases, it
makes it difficult for nutrients and waste to get
around cell.
2. Shape – Structure is related to function
Red Blood Cells are biconcave disks
Nerve cells are electrical wires
Skin cells (Epithelial cells) are flat
White Blood cells creep along and squeeze
into all areas
3. Internal Organization –
 Organelles
– internal structures in
a cell, each with a specific function
All cells contain:
a. cell membrane – thin membrane,
porous to certain compounds
b. cytoplasm – gel-like substance where organelles,
ions, organic compounds are suspended in it
c. ribosomes – Protein factories in cells
d. DNA
Compare/Contrast
Types of cells
1. Prokaryotic cells
– cells that lack a nucleus and
membrane bound organelles
- two Groups: Bacteria and
Archaebacteria
- have a cell wall, cell
membrane, cytoplasm, DNA,
ribosomes
- enzymes and other
molecules are suspended in
cytoplasm
2. Eukaryotic Cells – contain a
membrane bound nucleus and
membrane bound organelles
- much more complex cell
- all cells other than bacteria
-includes these groups:
Protists, Fungus, Animals and
Plants
Nucleus
7.3 Cell Parts and Functions
 Three
main components:
nucleus
cell
membrane
cellular
organelles
Cell membrane
Cell Membrane
– separates the cell’s internal
environment from the external
environment.
- allows for the passage of some
substances based on size and
concentration
selectively
permeable
Phospholipid Bilayer
Of Cell Membrane
made up of a bilipid layer (lipid bilayer) –
two layers of phospholipids with proteins floating
through it; referred to as Fluid Mosaic Model


tails of phospholipids are hydrophobic while the
heads are hydrophilic – WHY???
Peripheral membrane proteins - do not penetrate
the hydrophobic core of the membrane; can be
easily removed without destroying the
membrane structure.
Integral membrane proteins - fully incorporated
into the membrane and are in contact with
both the inside and the outside of the cell;
some act as channels or tunnels for the
transport of substances, others have
Integral
carbohydrates attached to them – recognition
Peripheral protein
sites
protein
In the "fluid mosaic model" of
membrane structure, the membrane is
a fluid phospholipid bilayer in which
protein molecules are either partially or
wholly embedded. These layers easily
move around.
Cellular Organelles
Cytoplasm
- Made of gelatinous material
where nutrients and minerals
are carried in solution

Typical Animal Cell

Typical Plant Cell
Mitochondria
- powerhouse of the cells.
- where cellular respiration occurs =glucose is
broken down to release energy (in the form of
ATP) to the cell
- found in greater numbers in cells such as
muscle cells and liver cells; double membrane
with internal cristae (folds) to increase surface
area
Cristae
Double Membrane
Ribosomes

most numerous organelle,site of
protein synthesis (where proteins are
made)

not membrane bound therefore, they
are in prokaryotic cells.

made up of RNA and protein.

may be free floating in cytoplasm or
attached on endoplasmic reticulum
Endoplasmic Reticulum
– channels or passageways in the
cell; two types of ER:
1 – Rough with ribosomes
attached for the production
and distribution of proteins
2 – Smooth – Synthesis of
steroids in gland cells, Ca++
regulation in muscle cells
1
2
3
4
5
6
7
8 - 10
Nucleus
Nuclear Envelope
Rough endoplasmic reticulum
(RER)
Smooth endoplasmic reticulum
SER)
Ribosome on the rough ER
Proteins that are transported
Transport vesicle
Golgi apparatus
Golgi Apparatus (Bodies)
o
stack of smooth flat sacs
o
processing, packaging and secreting
organelle of the cell
o
much like a processing & exporting plant
Work in close association with ER
Lysosomes



single membrane sacs; are the cells' garbage
disposal system
breakdown worn out organelles such as
mitochondria and produce hydrolytic
enzymes to that degrade DNA, proteins,
lipids and carbohydrates
responsible for the un-webbing of hands of
fetus while developing in utero
Cytoskeleton
- network of protein strands that provide support and mobility of
organelles in cytoplasm
Two components of cytoskeleton
- microfilaments – made of actin (protein threads); involved with
cellular movement and muscle contractions
- microtubules – larger structures; involved in cell division, make
up flagella and cilia, also make up spindle fibers that assist in
chromosome migration during cell division
Cilia and Flagella

extensions from cell membrane

assist in movement

cilia - when short and multiple numbers.

covering of Paramecium, lining of respiratory tract and
nasal passages.

flagella- long and usually only 1 to a few; sperm cells,
Euglena; used for propulsion
Nucleus





only in Eukaryotic cells
stores hereditary information in DNA
surrounded by a double nuclear envelope;
nuclear pores perforate membrane
chromatin - strands of a combination of DNA
and protein within nucleus; these will later
become chromosomes.
nucleolus (1 or more) produces ribosomes
7.4 Plant Cells
Are eukaryotic and have
most of the same
organelles as animal cells
except:
1.Cell walls

made up of cellulose
and pectin (glue
between walls)

gives cells rigidity,
protection & support.

is also porous
2.
Vacuoles
- store enzymes, food, water and wastes
- huge water vacuole in plant cells
- gives plant cell “turgor” (full of water and fully
supported) – 90% of cells may be water
- some contain metabolic wastes which may be
toxic to other organisms (poison ivy)
3. Plastids
- double membrane, DNA containing to store
starch, fats or pigments such as chlorophyll
- chloroplast – where photosynthesis occurs;
made up of stacks called thylakoids, where
energy conversion occurs
- leucoplast - store starch
Typical Animal Cell
1. _______________
2. _______________
3. _______________ (Dots)
4. _______________
5. _______________
6. _______________
7. _______________
8. _______________
9. _______________
10._______________
11._______________
12._______________
13._______________
Typical Plant
Cell
Cheek Cells
Elodea
Onion Cells
Potato Cells
Organelle
Function
Plant
Cells
Animal
Cells
Mitochondria
Site of cellular respiration - transfer of energy - Folds called
Cristae
Yes
Yes
Ribosomes
Site of Protein synthesis
Yes
Yes
Endoplasmic Reticulum
Rough - Protein packaging & transport site
Smooth - Sythesis of lipids
Yes
Yes
Golgi Apparatus
Processing & packaging center for cell secretions
Few
Many
Lysosomes
Produce hydrolytic enzymes
Few
Many
Cytoskeleton
Network of protein filaments - keep cell's shape and for
movement
Yes
Yes
Microfilaments &
microtubules
Support, movement and cell division
Yes
Yes
Cilia & Flagella
Cell movement & circulation Cilia - many & short, Flagella 1or 2 & long
Yes
Yes
Nucleolus
Production of ribosomes
Yes
Yes
Nucleus
Contains DNA, synthesizes RNA & Ribosomes
Yes
Yes
Chromatin
DNA & protein - genetic information
Yes
Yes
Cell Wall
Outmost layer of plant cell - support & protection Made of
cellulose & pectin glue between walls
Yes
No
Vacuole
Stores enzymes, wastes, water & food Large water in plants
- support
Yes, large
water vacuole
Many
Plastid
Stores food and pigments - Chloroplasts (photosynthesis) &
leucoplasts (stores starch)
Yes
No
Centrioles
Microtubules that function during cell division
No
Yes
Cell Membrane
Selectively permeable - made of a bilipid layer & proteins
Yes
Yes