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Chapter 7
Cell Structure
and Function
Unit 3
Cells
Cytology: the study of cells
IMPORTANT CELL
STRUCTURES
Cell Theory
1.Cells are made from
preexisting cells.
2.Cells are the smallest units of
life.
3.All living things are made from
at least one cell.
Understanding
• Canning and preservation of foods,
medical sanitation, sterilization of dental
and hospital equipment, use of
disinfectants, quarantines against
disease… all are base upon the fact that
cells are made from preexisting cells .
• But, if cells come from preexisting cells,
where did the first cells come from?
Cell History
Brief history
•
•
•
•
•
•
Hooke (1660’s)
Leeuwenhoek (1670’s)
Schleiden & Schwann(1830’s)
Virchow (1850’s)
Brown (1830’s)
Margulis (1985)
Robert Hooke
• Mid-1600s
• Used microscope to
observe living tissues
• Named chambers
“cells”
Anton van Leeuwenhoek
• Mid-1600s
• Used hand lens
microscope to
observe microscopic
life in pond water
German cell biologists
1830s: Matthias Schleidan:
concluded all plants made
from cells
1830s: Theodor Schwann:
concluded that all animals
made from cells
Rudolph Virchow
• 1855
• Concluded
that the
nucleus was
responsible
for cell
division.
Robert Brown
•
•
1883
Recognized that
cells contained a
prominent feature
and named it the
nucleus.
Louis Pasteur (1860s)
Discovers that Cells come from Cells
Lynn Margulis
Born in 1938
proposed the endosymbiotic theory
“Organelles in larger,
complex cells may
have been free-living
prokaryotic cells in
the past.”
In 2000 she received the U.S. National Medal of Science
Cell theory
(based on 200+ years of discoveries)
1. Cells are made from
preexisting cells.
2. Cells are the
smallest units of life.
3. All living things are
made from at least
one cell.
Cells dividing
Brief History of Cells
Microscopy
• the use of
microscopes to study
cells
• Different types of
microscopes
– Light microscope
– Transmission electron
microscope
– Scanning electron
microscope
Cells are the basic unit of life
• Unicellular: organisms made up
of only one cell
–Ex: bacteria, protist, fungus
• Multicellular: organisms made
up of more than one cell
–Ex: protist, fungus, plant, animal
ALL CELLS CONTAIN THESE FOUR PARTS…
1. Plasma membrane: cell membrane, made of
2 layers of phospholipids
2. Cytoplasm/Cytosol: a carbohydrate and
water based solution located in the
cytoplasm that suspends all internal parts of
the cell
3. Ribosomes: produces proteins
4. DNA: genetic material made of nucleic acids
Types of cells
There are 2 types of
cells
• Prokaryote: bacteria, archaebacteria
• Eukaryote: protist, fungus, plant, animal
Prokaryotes & Eukaryotes
Bacteria pic
– Life, p.459
You carry
oats, I eat
‘em!
“Pro” = Before
“Eu” = True
“Karyote” from Greek karyon = Kernal
Prokaryote (bacteria) cell
features
•
•
•
•
•
No nucleus
No organelles
Small
Simple
Plasma membrane,
ribosome, cytoplasm,
DNA
Label the bacteria cell in IAN
Prokaryotic
(Bacterial) Cell
Capsule
Label the bacteria cell
in IAN on pg. 9
Prokaryotic cell structure
• Capsule: durable outer covering that
some bacteria have for protection against
water, acids, and viruses
• Flagella: movement
• Cell wall: protective layer around plasma
membrane + structural integrity
• Pili: anchoring and DNA exchange
Eukaryotic Cell
• Complex
• 4 basic components +
organelles
• Organelles: “little
organs” that carry out
specialized functions
within a cell
• Many variations
Nucleus
•
•
•
•
Directs cell activities
Nuclear Envelope
(with pores) → outer
boundary
Chromosomes →
(DNA) carry genetic
information
Nucleolus → (contain
RNA) produces
ribosomes
chromatin
Nucleus
• Stores ______
______
• DNA helps to regulate
______ production.
• Proteins ______
cellular activity.
Ribosomes
• small structures on endoplasmic reticulum and
throughout the cell that function to produce protein
Endoplasmic reticulum
• an interconnecting system of “pathways,” for transport.
• May be Rough ER (with ribosomes attached) or
Smooth ER (without ribosomes attached).
Golgi apparatus (body)
• Modify, package, and sort protein
packages for secretion, outside of cell
• flattened compartments with vesicles
for secretion (packaging & shipping)
Lysosome
• Organelle that produces enzymes to
destroy foreign molecules and waste
• small filled sacs, for digestion
Understanding
• A student drew this recycling symbol on
their notebook cover to represent the
lysosome; Why would this be an accurate
representation?
Vacuole
• Primarily in plants
and Protists
• Large,
compartment
for storing liquids
– Food, water, salt,
or waste
Mitochondria
• Organelle responsible for breaking down
glucose molecules into ATP energy
molecules
• They are rod-shaped with folds, for
releasing energy (ATP) by respiration
Understanding
• Hypothesize which cells would have more
mitochondria, cardiac cells or skin cells.
• Why?
Chloroplast
• Organelle in plants and algae that produces
sugar molecules by photosynthesis
• Why are chloroplasts green?
Understanding
• A student takes a green plant into pitch
dark room, closes the door and turns off
the light. What color is the plant?
Cytoskeleton
•Hollow fibers for
support & shape and
to move cytoplasm
•Made of
•Microfilaments
•Microtubules
Cell membrane
Endoplasmic
reticulum
Microtubule
Microfilament
Ribosomes
Mitochondrion
Comparing Cell Structures
with Viruses
Plant
Animal
Bacterial
Viruses
Bacteria
Plant
Animal
Protist
•Cytoplasm is the
chasm
•Cytosol fills it up!
Virus
Comparison of Cells to Viruses
Cells
Viruses
Cells have:
Viruses have:
Cells do:
Viruses DON’T do:
Comparison of Cells to Viruses
Cells
Cells have:
1. Membranes
2. Cytoplasm/cytosol
3. Genetic material - DNA
4. Ribosomes
Cells do:
1. Digestion
2. Excretion
3. Respiration
4. Response to stimuli
5. Need and use energy –
metabolism
6. Grow & develop
7. Reproduce themselves
Viruses
Viruses have:
1. Genetic material DNA or
RNA
2. Protein coat
Viruses DON’T do:
1. Digestion
2. Excretion
3. Respiration
4. Response to stimuli
5. Need and use energy –
metabolism
6. Grow & develop
7. Reproduce themselves