Ch. 7-1: Cell Structure
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How were cells discovered?
What defines cell shape and size?
What enables eukaryotes to perform more
specialized functions than prokaryotes do?
Cells are the basic unit of life.
By studying cells, biologists can better
understand life’s processes
Cells and their discovery
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Cells are the smallest units of matter that can
be living
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Characteristics of living include: take in energy,
highly organized, reproduce, homeostasis, adapt,
respond, grow and made of cells
Cells are composed of C,H,N,O,P,S; often
arranged into macromolecules
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Proteins, carbohydrates, lipids and nucleic acids
Persons involved in discovery
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Anton von Leeuwenhoek : microscope
Robert Hooke : term ‘cell’
Robert Brown : nucleus
M. Schleiden : all plants have cells
T. Schwann : all animals have cells
R. Virchow : cells from other cells
Diversity of cells
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Human body has at least 200 types of cells (within
our trillions of cells)
Size
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Shape
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Squamous, cuboidal, spherical
Internal Organization
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Can be meters long, but only mm thick
Surface area to volume ratio limits size, inefficient if either
too large or too small
Organelles = ‘little organ’ or ‘organ –like’
“Cell Specialization”
Microscope Types
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Compound Light Microscope (CLM)
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Stereo scope or Dissecting scope
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Light through, stain, 2000x
3-D
Electron Microscope
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Scanning Electron Microscope (SEM)
Transmission Electron Microscope (TEM)
Prokaryotes vs. Eukaryotes
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Cell membrane
Cytoplasm
Genetic material
And ribosomes
Bacteria only
Small
Many have cell wall that is
either carb (Gram+) or lipid
(Gram-)
May have cilia or flagella
Only 1 circular chromosome
(+ maybe some plasmids)
No membrane-bound
organelles
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Cell membrane
Cytoplasm
Genetic material
And ribosomes
Plants, animals, protista and
fungi
Plants have CW= cellulose and
fungi have CW = chitin, some
protista have walls
Variety of organelles and
structures
Many chromosomes in a
NUCLEUS
Lots of membrane bound
organelles
Cell Theory
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Cells are the basic structural and
functional units of all living organisms
All parts of all plants are made of cells
All parts of all animals are made of
cells
All cells come from pre-existing cells
“Working document” with new discoveries added as the
technology becomes available. For instance viruses are not
cells and we are trying to create cells. Accumulation of
information since 1600’s through electron microscopes
Cell Membrane
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Refers to all membranes
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Selectively permeable
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Two rows of lipid tails that face each other with phosphate
head that are on the surfaces
Fluid mosaic
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Certain substances are allowed to enter freely, some are
carried across, some are rejected
Phospholipid bilayer
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everywhere cells have them
in all cells.
Proteins that are within membrane can migrate
Integral proteins
Peripheral proteins
LOTS more on this in Chpt. 8
Cytoplasm (aka protoplasm)
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Everything inside the cell membrane
Just the liquid is called cytosol
Cyto = cell
Mostly water
Dissolved proteins, enzymes, amino acids,
carbohydrates, salts, minerals, organic
compounds……
Site of all chemical reactions
‘parts’ within the cell are organelles
7-2 Organelles
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What does the cytoskeleton do?
How does DNA direct activity in the
cytoplasm?
What organelles participate in protein
production?
What is the role of vesicles in the cell?
How do cells get energy?
Knowing how cells work helps you
understand how your body functions and
what goes wrong when you get sick.
Organelles – USE your chart
(Chart will be a handout and on website)
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Mitochondrion
Ribosome ; free and attached
Endoplasmic reticulum ; smooth and rough
Golgi apparatus/body
Lysosome and peroxisomes
Cytoskeleton ; microtubules and microfilaments
Cilia and flagella
Nucleus – nuclear membrane, chromosomes and centrioles
Cell wall
Vacuoles – food, water, pigment
Plastids - Chloroplast, chromoplast and leukoplast
Water vacuole in plants sometimes called tonoplast
Sample PROTISTA
7-3: From Cell to Organism
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What makes cells and organisms different?
How are cells organized in a complex,
multicellular organism?
What makes an organism truly multicellular?
Diverse cells have unique cells
and cellular organization.
Organization
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Unicellular – organisms like bacteria and
algae that are complete, but only one cell
Colonial organisms – function as a group with
some division of labor, but no specialized
tissues. Ex. volvox
Multicellular – organisms composed of many
(thousands to billions) of cells that are
organized around collections of specialized
tissues
Multicellular Organization
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Similar cells = tissue
Tissues doing a similar job = organ
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Plants have reproductive, vegetative and
ground tissue
Organs then collect into organ systems to
make the organism
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Integumentary, skeletal, muscular, nervous
(CNS, PNS), digestive, circulatory, respiratory,
reproductive, excretory and endocrine. Also
immune system and lymphatic system.
Critical thinking questions: leave space for answers
These HW questions are due on ___________
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1. Mature RBC’s have no nucleus or mitochondria. They are mostly
membrane with hemoglobin. What is the advantage? __________
2. Coils of a radiator provide a huge surface area where heat is
radiated into a room – which organelle is similar? How is structure
related to function? ______________________________________
3. What characteristic of eukaryotic cells gives them greater capacity
for specialization than prokaryotic cells? ______________________
4. Livestock in the western US die after eating locoweed (Astragalus
toanus). The chemical in the plant is poisonous. How does the plant
keep from poisoning itself? _________________________________
5. Explain the relationship between surface area and volume. ______