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Ch. 7: Cells (Cytology)
I. The Cell Theory
A. Schleiden & Schwann
1. Cells are the basic unit of struc & fcn.
2. New cells produced from existing cells
(biogenesis).
3. All living things are composed of cells.
B. Hooke
1. coined the term “cells”
II. Two Basic Cell Types
A. Cells that do not contain internal
membrane-bound structures=
prokaryotic cells
1. smaller/simpler
2. no true nucleus
3. single cell (unicellular)
4. bacteria
B. Cells containing membrane-bound
structures=eukaryotic cells
1. true nucleus
2. most multi-cellular
plants/animals/fungi/protists
3. complex
4. Membrane-bound structures within
eukaryotic cells =organelles (cell parts)
a. each organelle has a specific function
that contributes to cell survival
III. Organelles
A. Nucleus is the central membrane-bound
organelle that manages cellular functions.
1. control center
2. hereditary info (chromosomes)
3. nucleolus, nuclear membrane
Nucleus and cell control
Nucleolus
Chromatin
Nuclear
Envelope
B. Endoplasmic reticulum (ER) is
an organelle that is suspended
in the cytoplasm & the site of
cellular chem rxs.
1. smooth
2. rough (ribo present)
C. Golgi Apparatus
1. packages substances to be
secreted (vesicles)
D. Vacuoles
1. Vacuoles are membrane-bound spaces used
for temporary storage of materials.
a. animal cells-small, many
b. plant cells-one large
Animal
Cell
Vacuole
Plant
Cell
E. Chloroplasts
1. capture light energy
& produce food to
store for a later time
(photosynthesis)
a. stroma
b. thylakoids (sacs)
*grana (stack)
2. contain green pigment-chlorophyll (traps light
energy & gives leaves/stems their
green color)
3. plants & algae
F. Mitochondria
1.membrane-bound
organelles in plant &
animal cells that transform
energy for the cell
a. matrix (space)
b. cristae (folds)
2. involved in cell respiration-ATP
G. Cytoskeleton
1. support structure within the cytoplasm
2. composed of microtubules & microfilaments
a. microtubules-thick
b. microfilaments-thin
H. Lysosomes
1. contain digestive enzymes (digest
macromolecules)
2. autophagy (recycling)
I. Ribosomes
1. protein synthesis
2. suspended in cyto or bound to membranes
J. Centrioles
1.cell division
2. animal cells only
K. Plasma membrane is the boundary
between the cell & its environment.
1. cell membrane/plasmalemma
2. regulates what enters/exits
(bouncer)
3. semipermeable (selective),
permeable, impermeable
Plasma (Cell)
Membrane
Water
4. “Fluid Mosaic Model”-Singer & Nicolson
a. Fluid because the phospholipid molecules
move within the membrane. Proteins in the
membrane that move (icebergs) among the
phospholipids create the mosaic pattern.
* 2 layers of phospholipids back- toback (bilayer)
*phospholipid has polar
(head) & nonpolar
(tails) ends
* glycoproteins/glycolipids (cell
to cell recognition)
* proteins-integral or
peripheral
(transport)
* cholesterol plays the important role of
preventing the fatty acid chains of the
phospholipids from sticking together
Cholesterol
Molecule
L. Cell wall is a fairly rigid
structure located outside the plasma
membrane that provides additional
support & protection.
1. plants
M. Cilia & Flagella
1. structures that aid in locomotion or
feeding
a. Cilia are short,
numerous, hairlike projections
that move in a
wavelike motion.
* Paramecium
Cilia
b. Flagella are long
projections (usually one
or two) that move in a
whip-like motion
*Euglena
Flagella
IV. Animal vs. Plant
A. Animal
1. round
2. no cell wall
3. small vacuoles
4. centrioles
B. Plant
1. square/rectangular
2. cell wall
3. chloroplasts
4. one large water
vacuole
V. Movement through the Cell(memb)
1. Passive Transport
a. No ATP (E) req.
b. Brownian movement to
reach equilibrium/balance
(random)
c. 3 key factors-conc, temp,
pressure, size
d. semipermeable memb
e. Diffusion=movement of ions from high conc to
low conc (concentration gradient)
*facilitated diffusion-protein channels
f. Osmosis=special diffusion of water
*Hypotonic-cell gains water, swells (bursts)
*Hypertonic-cell loses water, crenate
(shrinks)
*Isotonic-no net movement of water,
no change in cell size
g. Plants (large water vacuole)
* turgid (hypo)
* plasmolyze/flaccid(hyper)
2. Active Transport
a. Reqs. E (ATP)
b. Carrier proteins (specific)
c. Movement from low to high conc (against
the conc gradient)
d. Types*endocytosis (phagocytosis-food,
pinocytosis-liquid)-into cell
*exocytosis-out of cell
VI. Cell Size
1. Small cells more efficient
a. diffusion fast/efficient over short distances
& slow as distances become larger
2. Large surface area (memb) to volume ratio
a. exchange substs. more readily, no
need to travel as far to reach center of
sm. cell
b. nucleus can better control sm. cell
3. Cell would starve or be poisoned due to
waste build-up if cell is too large!
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