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CELLS
• The light microscope was invented by Antony van
Leeuwenhoek, a Dutchman, in about 1660.
• Anton Van Leeuwenhoek was the first person to observe
living cells.
• A few years later, an English microscopist, Robert
Hooke, named and described cells.
– At the time, he was observing cork cells and noted
that they were similar to the small, square rooms in
monasteries--called cells--in which the monks
resided.
• Given nutrients and the right laboratory environment,
somatic (body) cells can last for years outside the body.
• Cytology- study of cells
• In the mid 19th century, two German
scientists, Schleiden and Schwann,
observed that the cell was the basic unit of
all living material. The cell theory
originated from this observation:
Three parts of the cell theory:
1. All living things are made of one or
more cells.
2. The cell is the basic unit of
structure and function in organisms.
3. All cells come from pre-existing
cells.
=
Life
Two Cell Types:
1.) Prokaryote-the simplest cells
* Small (1-10 microns), simple and lack
membrane-bound organelles.
*They have no nucleus.
*DNA is found floating in the cytoplasm
* Prokaryotic cells contain:
*cell wall
*cell or plasma membrane
*cytoplasm
*ribosomes
*Example: ALL bacteria and ONLY
BACTERIA
Draw this Prokaryotic Cell
State Test Question
In prokaryotic cells, the DNA is found—
• floating in the cytoplasm.
• attached to the ribosomes.
• surrounded by the nuclear membrane.
• contained in the vacuole.
State Test Question
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Which of the following are prokaryotes?
Protists
Plants
Fungi
Bacteria
2.)Eukaryotes
• Large (10-100 microns), complex and contain
membrane-bound organelles, such as a nucleus.
– Example: plants, fungi, protists, and animals
• Eukaryotic cells have a nucleus, which is an
internal compartment that houses the cell’s DNA.
– Other internal compartments, called
organelles, enable eukaryotic cells to function
in ways different from bacteria.
State Test Question
• What type of cell is pictured below?
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Prokaryote
Eukaryote
Plant
Animal
State Test Question
• Which of these types of cell has a nuclear
membrane?
• A. Spirillum
• B. Coccus
• C. Liver
• D. Bacillus
State Test Question
• Coded information for heredity and protein
production is contained in DNA found in
the eukaryotic cell structure called the—
• A. nucleus.
• B. plasma membrane.
• C. endoplasmic reticulum
• D. Golgi apparatus.
Cilia
Flagella
State Test Question
• What structure could a cellular organism
use to move through its environment?
• Flagellum
• Cell wall
• Mitochondrion
• Lysosome
Cell Size and Shape:
- The symbol “µ” stands for the prefix micro.
- A micrometer (µm) is a unit of linear
measurement equal to one-millionth of a meter, or
one-thousandth of a millimeter.
- Cell size and organelle size is measured in
micrometers (µm). This means that they are
microscopic.
Organelles:
• cell fractionation- separates the major organelles of
the cells, so their individual functions can be studied.
– An organelle is a structure that carries out specific
activities in the cell.
• Cell Movement:
Microvilli--short finger-like projections on the
exposed surfaces of some cell membranes
that increase the cell's absorptive area
(small intestine epithelium).
cilia--short, multiple, filaments on the surface
of some cells for transporting materials
across the surface of cells (in the lungs).
• Flagella--long, single, whip-like structures
that are usually used for locomotion (sperm).
– pseudopod --means “false foot” & is an
extension of a cell’s cytoplasm; used for moving
amoeba.
• Pili- helps cells STICK to surfaces (look
similar to cilia, but function differently) EX:
When you have strep throat (from
bacteria), the bacteria are not simply
swallowed because their pili allow them to
stick to your throat!
Both Animal and Plant Cells Contain These
Organelles
• 1. Cell Membrane (plasma membrane)
• It protects the intracellular environment from the
extracellular environment
– It surrounds and protects the cell and allows only
certain substances to pass in and out of the cell.
– The cell membrane allows the cell to remain separate
from the environment.
• It is a selectively permeable membrane, which means
it keeps out some molecules but allows others to pass
through.
– Small molecules like H2O, CO2, O2 and soluble end products of
digestion pass through easily.
– Large molecules like glucose and ions do not pass through
easily.
• The cell membrane regulates or controls what comes into and out of
the cell. Like gases, nutrients and wastes. This control keeps the
cell alive and well. If it wasn’t selectively permeable everything on the
outside would come into the inside.
• The cell membrane is primarily composed of phospholipids &
proteins.
– Various proteins are located in the lipid bilayer of a cell membrane.
(transport & proteins)
• Transport proteins aid in the movement of substances into and
out of the cell
– A phospholipid is a lipid made of a phosphate group (head) and
two fatty acids (tails).
• A phospholipid “head” is polar, and its two fatty acid “tails” are
nonpolar.
– Integral proteins penetrate the membrane and serve as conduits
(pipelines) for transporting substances in and out of the cell.
– Peripheral proteins are loosely attached to the inner or outer
membrane surfaces and serve in enzymatic and structural
functions.
State Test Question
• Which of the following is usually measured in
micrometers?
• A. Specimen mass
• B. Organelle length
• C. Tree height
• D. Sound intensity
State Test Question
The unique properties of a cell membrane
arise from the arrangement of two layers
of organic molecules called—
• cellulose.
• nitrates.
• nucleic acids.
• phospholipids.
State Test Question
• The part of a eukaryotic cell that allows it
to remain separate from the outside
environment is the—
• A. cell membrane.
• B. ribosome.
• C. cytoplasm.
• D. golgi vesicles
•
2. Cytoplasm
A fluid-like material that fills the space between the cell membrane and the nucleus.
• Contains the organelles.
• The cytoskeleton (in the cytoplasm) is a web of protein fibers that holds the cell
together and keeps the cell membrane from
collapsing or folding.
– microfilaments--rod-like structures of varying length that are formed from
the protein actin. They provide cellular shape and support as well as assist
in cellar movements.
• Act like shocks to absorb tension pseudopodia are made of
microfilaments that are used by amoebas.
– microtubules--large, relatively straight, cylindrical structures that consist of
the protein tubulin.
• They are structural units for centrioles, cilia, and flagella.
• These are used in the separation of chromosomes.
• Dynein is a motor protein that causes the bending of cilia and flagella
intermediate filaments--are intermediate in size between microfilaments and
microtubules.
• They also provide structural reinforcement inside cells and help hold the
organelles in place.
• Made of keratins.
State Test Question
• Animal cells maintain their shape by
having—
• A. cytoskeletons.
• B. cell walls.
• C. cytoplasm.
• D. chromosomes.
State Test Question
• Which of the following is NOT a function of
the cytoskeleton?
• Cell movement
• Selective permeability
• Containing spindle fibers for cell division
• Anchoring organelles
State Test Question
• Which of the following structures
would you expect to find when
examining a bacteria cell?
• A cellulose cell wall
• Chromosomes within a nucleus
• A phospholipids cell membrane
• Cytoplasmic organelles
• 3. Nucleus
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The control center or “brain” of the cell
– The nucleus directs cell activities and stores DNA.
– Stores DNA which forms long strands called chromatin.
– Chromatin is made of DNA and proteins that become chromosomes
during cell division.
– **Chromosomes carry the genes (DNA) and are in the nucleus of
eukaryotic cells**
The nucleus is surrounded by a double membrane called the Nuclear
envelope or membrane.
– The nuclear envelope is made of two bilayers that separate the nucleus
from the cytoplasm.
– This nuclear envelope has pores located throughout.
• Each pore is lined with a pore complex regulating the passage of
certain large macromolecules and particles.
– The inside of the nuclear envelope is lined with nuclear lamina a
network of protein filaments that maintains the shape of the nucleus.
Substances that are made in the nucleus include ribosomal proteins and
RNA, which move into the cytoplasm through nuclear pores.
State Test Question
• The structure shown above is found in
what part of a eukaryotic cell?
• Cytoplasm
• Nucleus
• Golgi apparatus
• Smooth endoplasmic reticulum
Both Animal and Plant Cells Contain These
Organelles
• 4. Nucleolus
– Dense structures inside the
nucleus.
- AKA – “Little
Nucleus”
– Stores RNA
that forms
ribosomes.
• 5. Ribosomes
– Tiny “dot” organelles located on the
rough ER and throughout the cytoplasm.
– They are the site of protein synthesis.
– A cell makes proteins using ribosomes
– The building of proteins from amino
acids occurs on the cell’s ribosomes.
– Some ribosomes float freely in the
cytoplasm, while others are attached to
the endoplasmic reticulum.
• Endomembrane System: Membranes are either directly
continuous or connected via transfer of vesicles, sacs of
membranes.
– Members of these systems: nuclear envelope, ER, Golgi
apparatus, lysosomes, vacuoles, and the plasma membrane.
State Test Question
• The building of proteins from amino acids
occurs on the cell’s—
• membrane.
• ribosomes.
• nucleus.
• centriole.
State Test Question
• Peptide bonds between amino acids are
formed PRIMARILY on the cell’s—
• mitochondria.
• lysosomes.
• ribosomes.
• membrane.
State Test Question
• Which of the cellular structures labeled
above is responsible for protein synthesis?
• Cell membrane
• Nucleus
• Ribosomes
• Golgi apparatus
• 6. Endoplasmic Reticulum.
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A membrane system of folded sacs and tunnels that functions as an intracellular
highway (a path for molecules to move from one part of the cell to another). The
canals of the ER connect the cell membrane to the nuclear membrane.
Materials can be moved around within a cell by using the endoplasmic
reticulum.
The rough ER helps transport the proteins that are made by its attached
ribosomes.
– As each protein is made, it crosses the ER membrane and enters the ER.
The portion of the ER that contains the completed protein then pinches off to
form a vesicle.
– A vesicle is a small, membrane-bound sac that transports substances in
cells.
– By enclosing certain proteins inside vesicles, the eukaryotic cell keeps these
proteins separate from proteins that are produced by free ribosomes in the
cytoplasm.
Proteins must enter the endoplasmic reticulum to be transported to other
parts of the cell.
Transport vesicles then bring the proteins to the next step of the endomembrane
system
– The inside of the ER is called cisternae. This is connected with the space
between the two membranes of the nuclear envelope.
State Test Question
• Which of the structures below transports
material within the cell?
• Ribosomes
• Endoplasmic reticulum
• Nucleus
• Mitochondria
Both Animal And Plant Cells Have These
Organelles
– The canals of the ER connect the cell membrane with the
nuclear membrane.
Two Types of ER:
– 1. Rough ER
» Has ribosomes on the membrane and helps transport
the proteins that are made by its attached ribosomes.
» Glycoproteins are proteins attached to a carbohydrate.
» 2. Smooth ER
» It lacks ribosomes (appearing smooth) and produces
certain lipids such as phospholipids and steroids.
» Muscle cells have specialized smooth ER that pumps
calcium ions from the cytosol and stores them to
release them when stimulated to do so.
State Test Question
• Proteins must enter the endoplasmic
reticulum to be—
• transported to other parts of the cell.
• used in building new strands of RNA.
• synthesized into genetic codes.
• excreted as waste material.
• 7. Golgi Apparatus
– Vesicles that contain newly made proteins move through the
cytoplasm from the ER to an organelle called the golgi apparatus.
– It is stacks of flattened membranes with vesicles that packages
and assembles many cell products.
– The golgi has two sides…1st the cis side located near the ER and
brings the vesicle into the golgi, the other side is the trans side which
sends the vesicle to its new location.
– The Golgi Apparatus serves as the packaging and distribution
center.
– It receives, chemically modifies, and repackages proteins into forms
the cell can use, expel, or keep stored.
– The modified proteins are then enclosed in new vesicles that bud
from the surface of the golgi apparatus.
• Some of these vesicles include lysosomes.
• Before vesicles exit the trans side, they are tagged with identifies
such as phosphate groups.
– These act like ZIP codes on mailing labels to identify the
product’s final destination.
– Inclusions (inclusion bodies; vacuoles)--organelles that contain
fluids or materials that are brought into the cell, produced by
the cell, or extruded from the cell.
SIX types of inclusion bodies are recognized:
• Lysosomes
• membranous sacks containing digestive enzymes that are
released by the Golgi complex and distributed throughout the
cytoplasm
– They take care of foreign particles entering the cell and
“digesting” food and worn out cell parts.
– If there is a massive rupture of many lysosomes, the cell
will be destroyed by auto-digestion.
– Ameobas eat by engulfing smaller organisms by
phagocytosis.
– The food vacuole formed by phagocytosis fuses with a
lysosome, whose enzymes digest the food.
– The hands of human embryos are webbed between the
fingers until lysosomes digest the cells in the tissue.
• This is called: apoptosis-programmed cell death.
•
• Peroxisomes--structurally similar to
lysosomes but are smaller. Peroxisomes
enzymes for detoxification.
– They contain enzymes, such as Catalase, that
oxidize various harmful organic substances,
like alcohol.
• Endosomes--cellular compartments
through which ingested materials pass
before being digested by lysosomes.
– They sort out and divert usable molecules to
meet cell metabolic needs.
• Phagosomes(phagocytic vesicles)--vesicles
formed from "cell eating," or physically taking
materials into the cell.
– The materials taken in by phagocytic cells are
digested by lysosomes and either
toxicologically neutralized or utilized by the
cell for metabolic energy.
• Pinosomes(pinocytic vesicles)--vesicles formed
from "cell drinking," or physically taking water
into the cell.
• Exosomes(exocytic vesicles)--vacuoles
resulting from the expulsion of cell products and
waste materials from the cell.
Both Animal And Plant Cells Have These
Organelles
• 8. Mitochondria
– They are called the “powerhouse” of the
cell because it produces energy (ATP).
– They are the site of aerobic cellular
respiration.
A cell that requires a lot of energy, like a
muscle cell, would contain large numbers of
mitochondria
• Consists of a smooth outer membrane and a convoluted inner
membrane with foldings called cristae
• The inter-membrane space, a narrow region between the inner
and outer membranes is called the mitochondrial matrix and is a
fluid-filled space with DNA, ribosomes, and enzymes
State Test Question
• Endoplasmic reticulum is to mitochondrion
as road is to—
• control center.
• generator.
• storage tank.
• toll gate.
=
Mitochondria
Power
Both Animal And Plant Cells Have These
Organelles
• 9. Vacuole
• Small, fluid-filled structures that store materials like food, enzymes,
and other materials needed by the cell.
• Jobs of the central vacuole; stockpiling proteins or inorganic ions,
disposing of metabolic byproducts, holding pigments, and storing
defensive compounds that defend the plants against herbivores.
– 3 Types:
• Food Vacuoles are formed by phagocytosis and fuse with
lysosomes
• Contractile Vacuoles found in freshwater protists that pump
excess water out of the cell to maintain the appropriate
concentration of salts.
• A large central vacuole found in many mature plants.
– Tonoplast- surrounds the central vacuole
State Test Question
• Golgi apparatus is to vacuole as
packaging is to—
• protecting.
• storing.
• absorbing.
• hydrating.
Found In Animal cells Only
• Centrioles
– Tiny, cylindrical structures that are found in pairs
near the nucleus.
– They are involved in cell division.
– Peroxisomes contain enzymes that transfer
hydrogen from various substrates to oxygen.
– Hydrogen peroxide is a poisonous substance and is
converted by peroxisomes to water and oxygen.
Found In Plant Cells Only
• Plastids--found only in plants.
• They produce and store food materials.
• There are 3 basic Plastid types:
– Chloroplasts--green and trap light energy for
photosynthesis.
– Myloplasts (leucoplasts)--are colorless plastids that
store starch in roots and tubers
– Chromoplasts--contain pigments that give fruits and
flowers their many characteristic colors.
– Stroma- Innermost membrane is a fluid-filled
space that contains the flat membranous sacs
called the thylakoids. Stacked thylakoids are
called grana.
Found in Plant Cells Only
• 2. Cell Wall
• The cell wall consists of a mixture of proteins and
carbohydrates, including the polysaccharide cellulose.
– A polysaccharide is also known as a complex sugar.
• Structure found outside of the cell membrane in plants
that provides strength and rigidity, but does not affect
passages of materials in and out of the cell.
– Thickness and chemical composition depends upon
species of plants.
• Cell wall consists of a primary cell wall, a middle lamella
with sticky polysaccharides that holds the cells together
and layers of a secondary cell wall.
State Test Question
Which of the following organelles are NOT
found in both animal and plant cells?
• Mitochondria
• Cell membrane
• Chloroplasts
• Vacuoles
State Test Question
• When viewed under a microscope, a cell
has several structures visible, including a
membrane-bound nucleus, a cell wall, and
several mitochondria. What type of cell is
it?
• A. Bacterial cell
• B. Prokaryote
• C. Plant cell
• D. Animal cell
State Test Question
• All of the following statements about plant
and animal cells are accurate EXCEPT—
• plant cells have a cell wall, but animal cells
do not.
• animal cells have mitochondria, but plant
cells do not.
• animal cells have centrioles, but plants
cells do not.
• both plant and animal cells are eukaryotic.
State Test Question
• When viewed through a microscope,
which of the following would indicate
that a sample contained eukaryotic
cells?
• Cell walls
• Chloroplasts
• Single-celled organisms
• Nuclei
State Test Question
• The cell shown above is NOT an animal
cell because—
• it has a membrane-bound nucleus.
• it has a cell wall.
• it contains mitochondria.
• it is too large.
Multicellular Organization
A. Cells are specialized to perform one or a
few functions in multicellular organisms
B. Cells in multicellular organisms depend
on each other
C. The levels of organization include:
Cells  tissues  organs  organ system
 organism
D. Tissues are groups of cells that perform a
particular function (eg: Muscle)
E. Organs are groups of tissues working
together to do a job (eg: heart, lungs,
kidneys, brain)
F Organ systems are made of several
organs working together to carry out a life
process (e.g. Respiratory system for
breathing)
G. Plants have specialized tissues & organs different
from animals
1. dermal tissue forms the outer covering of plants
2. ground tissue makes up roots & stems
3. vascular tissue transports food & water
a. xylem – transports water throughout
the plant
b. phloem – transports food throughout
the plant
4. The four plant organs are: root, stem, leaf, &
flower
H. Colonial organisms are made of cells living closely
together in a connected group but without tissues &
organs (eg: volvox)