The CELL
• Cells Were discovered by Robert Hooke.
He observed the slices of cork from the
bark of an oak tree-dead plant cells.
• Anton Van Leeuwenhoek was the first
person to observe living cells.
• Observations and conclusions of scientists
from the late 17th century to the time of
scientists, Schwann, Schleiden, and
Virchow, are summarized into the Cell
Theory.
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
1. There are two cell types:
1.) Prokaryote-the simplest cells
* Small, 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:
* BACTERIA is the only example!
* Many bacteria have flagella, which are long, threadlike structures
that protrude from the cell’s surface and enable movement.
* A bacterium’s flagella rotates, propelling a bacterium through its
environment.
* Pili- Many species of bacteria have pili (singular, pilus). Pili are small
hair-like projections that emerge from the cell. These outgrowths
assist the bacteria in attaching to other cells and surfaces, such
as teeth, intestines, and rocks. Without pili, many disease-causing
bacteria lose their ability to infect because they're unable to attach
to host tissue.
State Test Question
In prokaryotic cells, the DNA is found—
A.floating in the cytoplasm.
B.attached to the ribosomes.
C.surrounded by the nuclear membrane.
D.contained in the vacuole.
State Test Question
• Which of the following are prokaryotes?
A.Protists
B.Plants
C.Fungi
D.Bacteria
2. Eukaryote
*Large, complex and contain membrane bound organelles
such as a nucleus.
* Example: Plants, Fungi, 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.
* An organelle is a structure that carries out specific
activities in the cell.
– Many single-celled eukaryotes use flagella for movement. Short
hair like structures packed in tight rows, called cilia, protrude
from the surface of some eukaryotic cells. Flagella or cilia propel
some cells through their environment.
– In other cells, cilia and flagella move substances across the cell’s
surface.
» Example: Cilia on cells found in the human respiratory system
sweep mucus and other debris out of the lungs.
State Test Question
• What type of cell is pictured below?
A.
B.
C.
D.
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?
A.Flagellum
B.Cell wall
C.Mitochondrion
D.Lysosome
Cell Size and Shape:
• The symbol “m” stands for the prefix micro.
• A micrometer (mm) 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 (mm). This means that they
are microscopic.
• Most cells are cubical or spherical. A cell’s
shape can determine its function or job.
Both Animal and Plant Cells Contain
These Organelles:
1.
Cell Membrane
– The cell membrane is primarily composed of
phospholipids.
– Various proteins are located in the lipid bilayer of a cell
membrane.
•
–
Small protein molecules found on the cell membrane called
glycoproteins act as receptors to “recognize self” – bringing
other cells/proteins together for structure & support.
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.
Transport proteins aid in the movement of substances
into and out of the cell.
It surrounds and protects the cell, while only allowing
certain substances to pass in and out of the cell.
The cell membrane allows the cell to remain separate
from the environment.
State Test Question
Which of the following is usually measured in
micrometers?
A. Specimen mass
B. Organelle length
C. Tree height
D. Sound intensity
Both Animal and Plant Cells Contain these
Organelles:
• Cell Membrane Cont.
– It is a Selectively permeable membrane, which means it
keeps out some molecules, but allows others to pass
through.
– The cell membrane regulates or controls what comes into
and out of the cell, like gases, nutrients and wastes.
• 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.
Larger molecules need help getting across the membrane by aid
of the transport proteins.
– This control keeps the cell alive and well. If it wasn’t
selectively permeable everything on the outside would
come into the inside.
State Test Question
The unique properties of a cell membrane
arise from the arrangement of two layers
of organic molecules called—
A.cellulose.
B.nitrates.
C.nucleic acids.
D.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
Both Animal and Plant Cells Contain These
Organelles
• 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.
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 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
Both Animal and Plant Cells Contain These
Organelles
• 3. Nucleus
– The control center of “brain” of the cell (Most functions of a
eukaryotic cell are controlled b the cell’s nucleus).
– 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 nucelus is surrounded by a double membrane called
the nuclear envelope or membrane. The nuclear envelope
is made of two bilayers that separate the nucleus form the
cytoplasm.
– 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 below is found in
what part of a eukaryotic cell?
A.Cytoplasm
B.Nucleus
C.Golgi apparatus
D.Smooth endoplasmic reticulum
Both Animal and Plant Cells Contain These
Organelles
• 4. Nucleolus
– Dense structures inside the
nucleus.
– Stores RNA
that forms
ribosomes.
Both Animal and Plant Cells Contain These
Organelles
• 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 on 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.
State Test Question
• The building of proteins from amino acids
occurs on the cell’s—
A.membrane.
B.ribosomes.
C.nucleus.
D.centriole.
State Test Question
• Peptide bonds between amino acids are
formed PRIMARILY on the cell’s—
A.mitochondria.
B.lysosomes.
C.ribosomes.
D.membrane.
State Test Question
• Which of the cellular structures labeled
below is responsible for protein synthesis?
A.Cell membrane
B.Nucleus
C.Ribosomes
D.Golgi apparatus
Both Animal And Plant Cells Have These
Organelles
• 6. Endoplasmic Reticulum
– 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.
State Test Question
• Which of the structures below transports
material within the cell?
A.Ribosomes
B.Endoplasmic reticulum
C.Nucleus
D.Mitochondria
Both Animal And Plant Cells Have These
Organelles
• Endoplasmic Reticulum Cont.
– 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 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.
» A vesicle is a small, membrane-bound sac that transports
substances in cells. By enclosing certain proteins inside
the vesicles, the eukaryotic cell keeps these proteins
separate from proteins that are produced by free
ribosomes in the cytoplasm.
– 2. Smooth ER
» It lacks ribosomes (appearing smooth) and produces
certain lipids.
State Test Question
• Proteins must enter the endoplasmic
reticulum to be—
A.transported to other parts of the cell.
B.used in building new strands of RNA.
C.synthesized into genetic codes.
D.excreted as waste material.
Both Animal And Plant Cells Have These
Organelles
• 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 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.
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.
State Test Question
• Endoplasmic reticulum is to mitochondrion
as road is to—
A.control center.
B.generator.
C.storage tank.
D.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.
– **Plant Cell have a single large vacuole.**
State Test Question
• Golgi apparatus is to vacuole as
packaging is to—
A.protecting.
B.storing.
C.absorbing.
D.hydrating.
Found In Animal cells Only
• 10. Centrioles –have asters
– Tiny, cylindrical structures that are found in
pairs near the nucleus.
– They are involved in cell division.
Found in Animal cells:
• 11. Lysosomes
– Small spherical organelles that contain
digestive enzymes.
– They teak care of foreign particles entering the cell and “digest” worn out cell
parts. (extremely rare
plants)
Found In Plant Cells Only
• 12. Chloroplasts
– Small green pigmented structures that contain
chlorophyll.
– It is the site of photosynthesis.
Found in Plant Cells Only
• 13. Cell Wall
– The cell wall consists of a mixture of proteins
and carbohydrates, including the
polysaccharide cellulose. A polysaccharide
is also known as a 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
**Plant cells have a LARGE vacuole that stores
water which can occupy most of the space in
a plant cell.**
State Test Question
Which of the following organelles are NOT
found in both animal and plant cells?
A.Mitochondria
B.Cell membrane
C.Chloroplasts
D.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—
A.plant cells have a cell wall, but animal
cells do not.
B.animal cells have mitochondria, but plant
cells do not.
C.animal cells have centrioles, but plants
cells do not.
D.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?
A.Cell walls
B.Chloroplasts
C.Single-celled organisms
D.Nuclei
State Test Question
• The cell shown below is NOT an animal
cell because—
• it has a membrane-bound nucleus.
• it has a cell wall.
• it contains mitochondria.
• it is too large.