The Cell - Community College of Rhode Island
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Transcript The Cell - Community College of Rhode Island
The Cell
Chapter 4
Cells
Marks the boundary between the “living
and the dead”
Structural and functional unit of an
organism
Smallest structure capable of performing
all of the functions necessary for life
What is a cell?
Why do we care?
We have TRILLIONS of them!! (@65)
Every organism is composed of
one or more cells
Basic unit of structure and
function in organisms
All come from pre-existing cells
Cell Theory
All cells…….
Have an outer plasma membrane
Contain DNA
Enclosed within the cell somewhere
Contain cytoplasm
Plasma Membrane and Cytoplasm
All cells surrounded by a
plasma membrane
Phospholipid bilayer
material inside a cell is
the cytoplasm
Everything between
the plasma
membrane and the
region of DNA
Gives cells their
shape
Assist in movement
of cell and organelles
Microscopes
Compound light
microscope
Multiple lenses increase
magnifying power
Two basic kinds of cells
Prokaryotic
Nothing separates the
DNA from
internal cell parts
Eukaryotic
Contain organelle sacs
Nucleus – contains the
DNA
Eukaryotic Cells
Examples of Eukaryotic Cells:
Animal
Plant
Fungi
Protozoa
Cell Walls
Plant cells
Permeable
Protective
In addition to a plasma
membrane
Organelles
Organelles act as their own separate
“organs”
They physically isolate chemical reactions
inside cells
Animals and plants will differ in their
organelles
Nucleus
Encloses the DNA of a
eukaryotic cell
Contains chromosomes
Functions:
Prevents DNA from
getting entangled with
structures in the
cytoplasm
Outer membranes act as
a boundary
Components of the nucleus
Nuclear pores
Nuclear envelope
Nucleolus
Nucleoplasm
DNA
Chromosomes
Chromatin
Nuclear envelope
Double-membrane
system composed of lipid
bilayer (with pores)
Bilayers surround the
fluid part of nucleus
(nucleoplasm)
Continuous with the
endoplasmic reticulum
Nucleolus
Dense mass located
within the nucleus
Produces ribosomes
Ribosomes
Site of protein
synthesis
Occurs in the cytoplasm
Attached to the
endoplasmic reticulum
Differ between
prokaryotes and
eukaryotes
Why is this important
from a health aspect?
Endomembrane System
Helps modify proteins into final form
Lipids are assembled
Compartmentalizes the cell
Main components:
1.
2.
3.
4.
Nuclear envelope
Endoplasmic reticulum (ER)
Golgi body
Various vesicles (transport)
1. Nuclear envelope
Merges with the
membrane of the ER
Consists of
membranous channels
and saccules
2. Endoplasmic Reticulum
Channel that snakes
through the cytoplasm
Lipids assembled and
polypeptide chains modified
into final proteins
Can be rough or smooth
Dependant on the
attachments of ribosomes
Rough ER
Processing and
modification of proteins
Smooth ER
Synthesizes phospholipids
3. Golgi Body (Apparatus)
Series of flattened
sacs
Collects, sorts,
packages, and
distributes materials
such as proteins and
lipids
Contain enzymes
that put the finishing
touches on proteins
and lipids
4. Vesicles
Enzymes from golgi apparatus sort and
package the molecules into vesicles
Tiny sac that moves through cytoplasm
Function in transport, storage, or digestion of
substances
Two main types:
Lysosomes
Peroxisomes
Lysosome
A lysosome is a
membrane-enclosed sac
contains digestive
enzymes to break down:
Macromolecules
damaged organelles
Put it all together……
Energy-Related Organelles
organelles specialize in
converting energy to a
form that can be used
by the cell
Chloroplasts
Requires solar energy
Dissipates as heat
Use solar energy to
synthesize carbohydrates
Carbohydrates then
broken down in the…..
Mitochondria
Produce ATP molecules
Energy-Related Organelles
Photosynthesis
Cellular Respiration
The chemical energy of
carbohydrates is
converted at ATP
Cytoskeleton:
Cilia and Flagella - Movement
Hairlike projections
Help in the movement
of cells
Some examples….
Why would we need
them?
Vacuoles
Membranous sacs
contractile vacuoles of protists
central vacuoles of plants
Prokaryotes
Archae
Bacteria
“Micro”organisms
Characteristics of Cells
Prokaryotic cells
~1.0 µm in diameter
All are microorganisms
Bacteria and archaea
no nucleus
no membrane-bound
organelles
Prokaryotic Cells
Cell Wall
Capsule
Flagellum
Plasma membrane
Nucleoid
Plasmids
Ribosomes
Microbiology
The study of of organisms (microorganisms
or microbes) too small to be seen without
magnification
This includes:
1.
2.
3.
4.
5.
6.
Bacteria
Viruses
Fungi
Protozoa
Helminths (worms)
Algae
The Microbes
• 1. Bacteria
– Single-celled
organisms
– Various shapes
• Spherical
• Rod
• Spiral shapes
– Cellular
– Lack membraneenclosed cellular
structures
– Widely distributed
in nature
Klebsiella pneumoniae,
bacteria that causes
pneumonia in humans
The Microbes
• 2. Viruses
– Acellular
– Composed of
nucleic acid and a
few proteins
– Replicate
themselves to
display other
properties of living
organisms when
they invade living
cells
• 3. Fungi
– Yeasts and molds
• Single-celled,
microscopic
– Mushrooms
• Multicellular,
macroscopic
– Cell nucleus and
other cellular
structures
– Absorb nutrients
from their
environment
– Widely distributed
in water and soil
– Act as
decomposers of
dead organisms
The Microbes
• 4. Protozoa
– Single-celled,
microscopic
organisms
– Have at least one
nucleus and many
cellular structures
– Obtain food by
engulfing or
ingesting smaller
organisms
– Most can move
– Found in many
different
environments
The Microbes
Amoeba
The Microbes
• 5. Helminths
– Large,
multicellular
– Parasitize host
tissues
– Organs for
reproduction,
digestion,
movement,
protection
– Mouthparts
– Ingestion of larvae
or eggs in food
Tapeworm Head
• 6. Algae
– Single-celled
microscopic
organisms
– Have a nucleus
and many
membraneenclosed cellular
structures
– Photosynthesize
their own food
– Widely distributed
in fresh and salt
water
– Important source
of food for other
organisms
The Microbes
Micrasterias, a green algae living in
fresh water