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Hey Larry, I
think I lost an
electron.
Are you sure?
I’m positive.
Chapter 4
Cell Structure and
Function
The Cell Theory
Cells – basic units of structure
and function in living things
Early scientists that led to the
cell theory
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Anton van Leeuwenhoek (1600s) – given credit for
developing the 1st mini microscope, looked at pond water
and made detailed drawings
Robert Hooke – coined the term “cell” when he looked at
slices of cork and dead plant cells
Robert Brown (1833) – observed a dark structure near the
center of the cell (we now know this is the nucleus)
Matthias Schleiden (1838) – stated all plants are made of
cells
Theodor Schwann (1839) – discovered all animals are made
of cells
Rudolph Virchow (1855) - stated all cells come from the
division of preexisting cells
Cell Theory
 All living things are composed of cells.
 Cells are the basic units of structure and
function in living things.
 All cells come from preexisting cells.
Cell Structure
Identify and give the function of the
three basic structures of most cells.
Distinguish between prokaryotes and
eukaryotes.
Size of cells
 Most cells are 5 to 50 micrometers in
diameter
 Humans have
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#?
#?
#?
#?
cells
red blood cells
brain cells
cells per cm2 of skin
Size of cells
 Most cells are 5 to 50 micrometers in
diameter
 Humans have
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100 trillion cells
#? red blood cells
#? brain cells
#? cells per cm2 of skin
Size of cells
 Most cells are 5 to 50 micrometers in
diameter
 Humans have




100 trillion cells
20 trillion red blood cells
#? brain cells
#? cells per cm2 of skin
Size of cells
 Most cells are 5 to 50 micrometers in
diameter
 Humans have




100 trillion cells
20 trillion red blood cells
30 billion brain cells
#? cells per cm2 of skin
Size of cells
 Most cells are 5 to 50 micrometers in
diameter
 Humans have




100 trillion cells
20 trillion red blood cells
30 billion brain cells
155,000 cells per cm2 of skin
Size of cells
The ability of information to flow in and
out of cells limits their size
http://ed.ted.com/lessons/the-wackyhistory-of-cell-theory
Three structures common to most
cells
 Cell Membrane – outer boundary
 Nucleus – control center
 Cytoplasm – material between the cell
membrane and nucleus
 Note: Some books list plasma
membrane, cytoplasm,
chromosomes/DNA, & ribosomes
Cell/Plasma Membrane
Cell Membrane –
outer boundary
 Structure:
 Phospholipid bilayer
 hydrophilic heads, hydrophobic tails
 Contains lipids (bilayer), proteins (channels), and
carbohydrate chains (identification cards)
 Function:
 Regulates what enters and leaves the cell
 Semi-permeable membrane
 Protection and support
Cell Wall
Pectin
Cell Wall –
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Only in plants, algae, and some bacteria
Lies outside the cell membrane
Structure:
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surrounds the cell membrane
1st layer – contains pectin (gluey substance that helps
hold the cells together)
2nd layer – primary cell wall (made of cellulose)
3rd layer (in woody stems) – secondary cell wall
(composed of cellulose and lignin to make cellulose more
rigid)
Function:
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Helps to protect and support the cell
Very porous (water, oxygen, carbon dioxide, etc. can pass
through easily)
Gives rectangular shape to plant cells
Nucleus
Nucleus - control center
 2 categories of organisms
 Prokaryotes – organisms whose cells lack
nuclei (i.e. bacteria)
 Eukaryotes – organism whose cells contain
nuclei
Pro = before
Eu = true
karyon = kernel (nucleus)
Prokaryote vs. Eukaryote
Prokaryote vs. Eukaryote
2 Types of Cells
Prokaryotic
(Pro= before, karyon = kernel)
Eukaryotic
(Eu=true, karyon = kernel)
Found in 2 domains: Archaea and
Bacteria (*Kingdom
Monera:Archaebacteria/Eubacteria)
single celled
Found in Domain Eukarya (all other
Kingdoms): Animal, Plant, Fungi,
Protist
No true nucleus; lacks nuclear
envelope/membrane
True nucleus; bounded by nuclear
envelope/membrane
Genetic material found in nucleoid
region
Genetic material found within
nucleus
Called Prokaryotes
Called Eukaryotes
Evolved first – 3.5 billion years ago
and are very small 1-10um
Evolved 1.45 billion years ago and are
larger 10-100um
No membrane bound organelles –
ribosomes are only organelle
Contains cytoplasm with cystol and
membrane-bound organelles
Prokaryote vs. Eukaryote
Characteristic
Prokaryotic
Eukaryotic
Cell membrane
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Cytoplasm
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Genetic Material
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Nucleus
Organelles
Archaea
Bacteria
Plants, animals, fungi, & protists
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Only have ribosomes
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Nucleus - control center
Structure:
 NUCLEAR ENVELOPE – double membrane around the
nucleus that contains pores, allows molecules to move in
and out of the nucleus, and protects the nucleus
 NUCLEAR PORES – allows passage of materials into or out
of nucleus (RNA, ribosomes)
 NUCLEOLUS – a small, darkened region in the nucleus that
is made up of RNA and proteins, this is where ribosomes
are made
 CHROMOSOMES – large structures formed from DNA
that contain the genetic info
Function:
 Information center of the cell
 Contains DNA (chromatin vs. chromosomes)
 Directs cell activities
Nucleus - control center
Cytoplasm
 Material between the cell membrane
and the nucleus
 Contains the organelles of the cell
Who Am I?
Robert Hooke!
I stated all plants are made of cells
I stated all cells come from the division of
preexisting cells
I coined the term “cell” when he looked at
slices of cork and dead plant cells
I given credit for developing the 1st mini
microscope, looked at pond water and made
detailed drawings
I discovered all animals are made of cells
I observed a dark structure near the center
of the cell (we now know this is the nucleus)
Group Activity
 Each group will be assigned one organelle
 You must answer the following questions:
 What does it look like? (What is its structure?)
 What does it do? (What is its function?)
 Is it found in prokaryotic cells?
 Is it found in eukaryotic cells?
 In plants?
 In animals?
Group Activity
 Group
 Group
 Group
 Group
 Group
 Group
#1 – mitochondria
#2 – chloroplasts
#3 – ribosomes
#4 – endoplasmic reticulum
#5 – Golgi apparatus
#6 – lysosomes
Organelle Analogies
 Mitochondria and Chloroplasts: Power
Stations
 Ribosomes: Protein Factories
 Endoplasmic Reticulum & Golgi Apparatus:
Manufacturers and Shippers
 Lysosomes: Cleanup Crews
 Vacuoles and Plastids: Storage Tanks
 Cytoskeleton: Framework
Mitochondria
Mitochondria
Structure:
 Double membrane
 Cristae - inner folds, increase surface area
 Outer membrane for protection of cell
Function:
 “Powerhouse” of the cell
 Able to self-replicate ( # in cells with high
energy need)
 Converts sugars into energy for cells
Chloroplast
Chloroplast
Structure:
 Double membrane
 Elaborate structure inside
Function:
 Another power station
 Found in plant cells only
 Conversion of light energy (sun) into
chemical energy (glucose)
Ribosomes
Ribosomes
Structure:
Small ball-like structures
Found free-floating in
cytoplasm or attached to
rough endoplasmic
reticulum
Composed of RNA and
protein
Function:
Synthesis of proteins
(where proteins are made)
Endoplasmic Reticulum (ER)
Endoplasmic Reticulum
 Structure:
Network of flattened sacs
Can be rough (w/
ribosomes) or smooth (w/o)
 Function:
Transport materials within
or out of cell
Synthesis of
macromolecules
Rough - proteins, lipids,
carbs
Smooth - lipids
Golgi Apparatus
vesicle
Golgi Apparatus
Structure:
Flattened stacks of membranes
Vesicles attached to top and
bottom
Function:
Collection, modification, packaging
of proteins and other substances
Vesicles attach, deposit materials
GA modifies materials based on needs
Vesicles attach to membrane and
distribute modified substances
Lysosome
Lysosome
Structure:
Small, circular structures
Found only in animal cells
Contain digestive enzymes
Function:
Digestion of:
Worn out organelles
Debris
Large ingested particles
Lysosomes are responsible for your hands
not being webbed!!
Vacuole
Vacuole
Structure:
Large, central structure in plants
Many, small, circular structures in animal
cells
Filled with liquid
Function:
Storage of water, salts, proteins,
carbohydrates, waste products
Pressure system for plants, prevents wilting
Special case: contractile vacuole - prevents
excess water intake, leading to cell-bursting
Plastid
Plastid
Structure:
Differ based on type of plastid (chloroplast is
one example)
Found only in plants
Function:
Leukoplasts: Store food/starch
Chromoplasts: Store pigments (give color to
fruits & veggies)
Cytoskeleton
Cytoskeleton
Structure:
Microtubules - hollow tubes of proteins
Examples: cilia, flagella, centrioles
Function:
Framework
Provide cell with support, structure and
shape
Movement (cilia, flagella)
Microfillaments - allow movement of cytoplasm
within the cell (cytoplasmic streaming)
Plant vs. Animal Cell
Animal Cell
Plant Cell
Please . . .
List 3 organelles you learned about
today.
Describe the function of each of the
organelles you listed.
Yes, you should write your name on the
paper