This document provides an overview of cell structures and functions. It defines key terms related to cells, describes the history of cell discovery, and outlines the cell theory. The main structures of plant and animal cells are compared, including the cell wall, membrane, nucleus, cytoplasm, chloroplasts, mitochondria, vacuoles, and other organelles. Transport mechanisms across the cell membrane like diffusion, osmosis, and active transport are also summarized. The document tours the interior of cells and defines terms related to cellular structures and processes.

1. Tour of the Cell
1. Key Terms to know about he cell organelles
a. organism
b. cell theory
c. micrograph
d. organelle
e. plasma membrane
f. nucleus
g. cytoplasm
h. cell wall
i. prokaryotic cell
j. Eukaryotic cell

2. Cells - History of Discovery
1. Robert Hooke (1665) - observed dead cork (wood bark)and discovered
cells
2. Anton Van Leeuwenhoek (1700) - invented the compound microscope,
observed living cells (saliva & blood),
and discovered algae
3. Matthias Schleiden - discovered that all plants and every part of them
are made up of cells, discovered the cell nucleus
4. Theodor Schwann (1807-1893) -discovered that all animals and every
part of them are made up of cells,
independently announced that yeast
is a living organism
5. Rudolf Virchow (1858) -best known for his theory Omnis cellula e cellula
("every cell originates from another existing cell like
it."), first to recognize leukemia cells

3. Cell Theory
Schleiden, Schwann, and Virchow are credited
for the cell theory.
Cell Theory
1.) that all living things are composed of cells
2.) cells are the basic unit of structure
3.) cells are the basic unit of function in living things

4. Microscopes
1.) Light- up to 1000x - living cells
2.) Electron - up to 1,000,000x - dead cells
a.) SEM surface structure
b.) TEM internal structure

5. Electron Microscope
1.) SEM surface structure-
-images using electrons are reflected from
specimen (looks normal)
-shows depth, high resolution
2.) TEM internal structure-
-images using the electrons pass through
specimen
-silhouettes, projects fine detail on screen

6. Plant Cell
Cell Wall
Cell Membrane
Golgi Vesicles
Golgi Aparatus
Ribosomes
Smooth ER Cholorplast
(Endoplasmic reticulum)
Nucleolus Vacuole membrane
Nucleus
Rough ER
(Ribosomes) Raphide Crystal
Large central Druse Crystal
vacuole
Amyloplast Mitochondria
(starch grain)
Cytoplasm

7. Animal Cell
Pinocytotic vesicle
Mitochondrion
Lysosomes
Golgi Vesicles Golgi Apparatus
Rough ER Nucleolus
(Ribosomes)
Nucleus
Smooth ER
(Endoplasmic Reticulum) Centrioles (2)
Each composed of
9 microtubule triplets
Microtubules
Cell (plasma) Cytoplasm
Membrane
Ribosomes

8. Another view

9. Plant vs. Animal Cell

10. Cell Wall
*Only found in plant cells,
*The cell wall provides the cell with additional
strength.
*Cell walls are thick walls built around the cell.
These walls are made from cellulose.

11. Cell Membrane
*Found in both plant and animal cells, the cell membrane is
the outside wall of a cell.
*In plant cells, it is a second wall, and is found just inside
the main cell wall.
*The cell membranes found in animal cells contain a
chemical called cholesterol. This chemical makes the
membrane harder.
*Plant cells do not need cholesterol, because they have a
cell wall, as a result, their cell membranes are softer.

12. Cytoplasm
* Found in both plant and animal cells
*Helps to hold the cell's organelles
(small organs) in place.
*Gives the cell structure.
*Helps the cell move proteins,
chromosomes and other materials
including the cells organelles around
the cell.

13. Nucleus - Cell’s Brain
*A cell's nucleus, or brain, is responsible for directing
the activities of the cell, in the same way that your brain
directs the activities of your body.
*Nuclear Envelope - has pores, surrounds nucleus.
*In the nucleus you will see many small rod like
objects called Chromosomes. They contain blueprints
for how cells and organisms should be built.
*The chromosomes are made from smaller
molecules called DNA, and RNA (information-rich
molecules)
*Nucleolus contain parts that make up ribosomes.

14. Endoplasmic Reticulum
*Found in both animal and plant cells
*Clear tubes travel to all parts of the cell,
known as the “Cellular Highway”.
*Carries materials where they need to go.
*The ER is also connected to the nuclear
envelope.
*Rough ER: contains ribosomes
*Smooth ER: transports materials

15. Ribosomes
*Found in both animals and plant cells
*They are created in the nucleolus, which is
found inside the cell's nucleus
*They are either suspended in the cytoplasm
or temporarily attached to the rough
endoplasmic reticulum (ER)
*Ribosomes use available materials to build
proteins. These proteins can then be used by
the cell for other purposes, such as to build
new structures, repair damage, and direct
chemical reactions.

16. Moving Proteins
*Some proteins are made by
ribosomes (the red structure) on the
rough ER and packaged in vesicles.
*After further processing in other
parts of the cell, these proteins will
eventually move to other organelles or
to the plasma membrane.

17. Golgi Apparatus (bodies)
*Found in both plant and animal cells
*Modifies, stores, and dispatch products
*Takes the proteins which were created
by the ribosomes, and makes them bigger
and better
*When the golgi apparatus is done, it
releases the new proteins into the cell,
where they can be used to strengthen and
build up the cell.

18. Lysosome
* Only found in animal cells
*Lysosomes contain digestive
enzymes that break down food for cell
use.
*They breakdown and digest older
parts of a cell.

19. Membrane Pathways -how they work
*Products made in the ER move
through membrane pathways in a
cell.

20. Vacuoles
*Large ones found in plant cells, small ones in animal
cells
*This large membraned sac’s function is to store
a. water & food
b. waste
c. undigested nutrients
d. minerals
e. proteins
f. pigments
*It helps in plant growth, and plays an important
structural role for the plant.

21. Chloroplasts
*Only found in plant cells
*Small pill shaped organelle that is like a
miniature “solar collector”
*The discs are green because they are
filled with a green pigment, or chemical
called Chlorophyll that reacts with light
*Chlorophyll is used by a plant to
capture light energy from the sun, which
transforms into chemical energy through
photosynthesis to create food.

22. Mitochondrion
*Found in plant and animal cells
*responsible for energy production inside a cell
* a. site of cellular respiration
b. release energy from sugars
c. changes ADP to ATP ( stored energy)
d. ATP to ADP ( releases energy)
*Cellular respiration in the mitochondria
releases the energy that drives a cell. The
many folds of each mitochondrion's inner
membrane are the sites of ATP production.

23. Tour of the Cell
2. Key Terms to know about the Cell Membrane
1. Terms:
a. phospholipid layers
b. diffusion
c. equilibrium
d. selectively permeable
membrane
e. passive transport
f. facilitated diffusion
g. osmosis
h. hypertonic
i. hypotonic
j. isotonic
k. active transport
l. vesicle
m. exocytosis
n. endocytosis
2. Structure of Cell Membrane

24. Moving through the cell membrane
*A cell's plasma membrane contains a diversity
of proteins that drift about in the phospholipid
bilayer.
*Even the phospholipid molecules themselves
can move along the plane of the fluid-like
membrane.
*Some membrane proteins and lipids have
carbohydrate chains attached to their outer
surfaces.

25. Transport- Diffusion
Dye molecules diffuse across a membrane. At equilibrium, the
concentration of dye is the same throughout the container.

26. Passive Transport
Both diffusion and facilitated diffusion are forms of passive transport, as
neither process requires the cell to expend energy. In facilitated
diffusion, solute particles pass through a channel in a transport protein.

27. Osmosis
OSMOSIS IS DIFFUSION OF
WATER FORM REGION OF LESSER
CONCENTRATION OF SOLUTE TO
GREATER CONCENTRATION OF
SOLUTE UNTIL EQUILIBRIUM
OCCURS
A selectively permeable membrane
(the bag) separates two solutions of
different sugar concentrations. Sugar
molecules cannot pass through the
membrane.

28. Active Transport
Like an enzyme, a transport protein recognizes a specific
solute, molecule or ion. During active transport, the protein
transport
uses energy, usually moving the solute in a direction from
lesser concentration to greater concentration.

29. Transport of large molecule
Active transport plays a part in maintaining the cell's chemical environment.
Pinocytosis- Pino= drink (liquid) Phagocytosis- Phago= eat (solid)
Exocytosis (top left) expels
molecules from the cell
that are too large to pass
through the plasma
membrane.
Endocytosis (bottom left)
brings large molecules into
the cell and packages
them in vesicles.

30. The cell theory never states that cell must be small.
But, there are two reasons given for their size:
1. Efficiency- surface area is increased. Cells require
nutrients and oxygen to get rid of waste and must move
across the membrane to do so. If the cell were too big,
these nutrients and wastes would have to cover large
distances in order to get to the proper destination inside
the cell.
2. Specialization- having numerous small cells permits
specialization and different cells have different
functions.

31. Prokaryotic Cell
These are the simplest of all cells.
Most only have a cell wall and ribosomes.
1. DNA loop- naked in the cytoplasm, which
contains all genetic info(processes)
2. Ribosomes- freely floating in the
cytoplasm for protein synthesis(antibiotics,
like tetracycline, bind to ribosome and
interfere with protein synthesis)
3. Plasmids- contain small loop of
extrachromosomal DNA

32. Prokaryotic Cell
4. Cell Wall- gives shape and protection from
unfavorable outside environment for cell membrane
Two types of cell walls that classify bacteria:
Gram Positive- contain a thick peptidoglycan(protein-
carbohydrate mix) layer and no outer membrane layer
Gram Negative- have a multilayered and complex wall
made of an outer lipopolysaccharide and thin
peptidoglycan inner layer
Antibiotics like penicillin inhibit cell wall development, which prevents
reproduction of the prokaryotic cell.
Enzymes in tears, mucus, and saliva dissolve the cell wall, rupturing the cell and
killing the bacteria.

33. Prokaryotic Cell
5. Capsule- a jelly-like coating that surround the cell
wall; there are four functions of the capsule:
1. prevents from drying out
2. helps cells stick together on other surfaces
3. helps slide on surfaces
4. defense mechanism from being destroyed by host organisms’ cells
6. Flagella- can be one or many; provide locomotion by
spinning like a propeller; they are structurally different
from plant/animal flagella
7. Pili- short bristle-like appendages that have two
functions:
1. attach to surfaces
2. assist in the transfer of DNA from one to another

34. Prokaryotic Cell
Eubacteria Shapes:
1. Coccus- spherical shape allows for less
distortion in a dried out environment
2. Bacillus- rod shape has more surface area to
take up more nutrients from the environment
3. Spirillium- spiral shape
4. Spirochete- spiral shape with flagella
5. Vibrio- 1/2 spiral
Spiral shapes are very motile, they move using a
corkscrew type of movement.

35. Prokaryotic Cell
Movement is by way of something called
chemotaxis.
Chemotaxis is the movement of an organism
towards or away from a chemical. Chemicals
influence the organism to move toward them
are called attractants (positive chemotaxis) or
away from them are called repellents
(negative chemotaxis).

36. Prokaryotic Cell
Survival
When environmental conditions are unfavorable,
bacteria will become inactive.
Some species form endospores in which a thick
wall forms around the genetic material and the
rest of the cell disintegrates.
Endospores are dormant and do not reproduce
or show any signs of life, withstanding the
harshest of environmental conditions.
When conditions improve, endospores germinate
and form an active cell again.

37. Prokaryotic Cell
Reproduction
1. Asexual fission- single loop of DNA is copied and
the cell splits in half by pinching between the two DNA
loops.
2. Sexual conjugation- a bridge is formed between two
cells using pili. Requires the F plasmid (F for fertility)
and controls the formation of the F pilus. If the cell
contains this plasmid, it is an F+ cell and can give an
F- cell these genes, thus making it an F+ cell.
R plasmids contain the genes for making a cell
resistant to antibiotics and must integrate into main
DNA of cell to make it resistant.

38. Reproduction cont.
Transformation- living bacteria absorb the
genetic material of a dead or naked genetic
material in the environment
Transduction- transfer of DNA from a host to
another cell by means of a virus. Viruses
are non-living, pieces of DNA or RNA
enclosed by a protein coat that can infect
bacteria. Their DNA is small and contains
information for making proteins involved in
infection.

39. Metabolic Diversity
Heterotroph- dependent on outside sources of organic molecules
Photoheterotrophs- can use light to produce ATP but must obtain carbon
from another source
Chemoheterotrophs- most bacteria assume this metabolism, there are three
types:
Saprobes- decomposers that absorb the nutrients from dead or decaying
organic matter
Parasites- absorb nutrient from the body fluids of living hosts
Phagotrophs- ingest food and digest it enzymatically within cell or
multicellular bodies
Autotrophs- synthesize organic molecule from inorganic substances
Photosynthetic- harness light energy to drive organic compounds from CO2
and use an internal membrane system with light absorbing pigments
Chemosynthetic- use energy from specific inorganic substances to produce
organic substances from CO2
Chemoautotrophs- need only CO2 as their carbon source and obtain
energy from by oxidizing inorganic nutrients like H2S, NH4, Fe2O3; a unique
group for prokaryotes

40. O2 Requirements
Oxygen requirements also helps classify
prokaryotic organisms:
1. Obligate aerobes- must need and use
oxygen for cellular respiration- cannot be
without it
2. Facultative anaerobes- will use oxygen if
present, but can grow by fermentation
without oxygen
3. Obligate anaerobes- cannot use oxygen
and are killed by the presence of it

41. Archaebacteria
Primitive forms of modern day bacteria that
are thriving in different environment
conditions
1. Methanogens- use hydrogen to reduce CO2 into methane; are obligate
anaerobes that live in swamps, marshes and the guts of animals like
cows, sheep, and camels; are used as important decomposers in sewage
treatment plants
2. Extreme Halophiles- like high salinity (salt) environments; this can color
water pink because of their photosynthetic pigment bacteriorhodopsin
3. Thermoacidophiles- need an environment that is hot (140-180 degrees
fahrenheit) and acidic (pH of 2-4), they have no cell wall and can grow
aerobically or anaerobically; examples are hot springs, water heaters, and
coal piles