Download Chapter 3 The Cell

Chapter 3 The Cell
I. The Cellular Structure (3-A)
A. Parts of the cell
1. cell membrane/cell wall
2. cytoplasm
3. nucleus
B. Cell theory
1. All living things are
composed of cells
2. Cells are basic units of
structure and function in living
things.
3. All cells come from preexisting cells.
C. Cellular functions and
Processes
*see table pg 70
D. Levels of cellular organization
1. unicellular – organism
consisting of one cell. (Ex:
Bacteria)
2. multicellular – organism
consisting of many cells. (Ex:
plants and animals)
3. colonial – collection of
simple cells living together.
4. Multicellular organization –
cellstissuesorganssyste
ms
a. cell- the unit of function and
structure of life.
b. Tissue – similar cells that
are grouped together to
perform similar functions.
c. Organs- tissues grouped
together to perform similar
functions
d. Systems – groups of organs
working together to
accomplish life functions.
E. Eucaryotic – has a true nucleus
with a membrane around the
nucleus. They have organelles.
a. organelles – accomplish the
cells functions. Ex: plant and
animal cells.
F. Procaryotic – lack a true
nucleus. Ex: Bacteria and Blue
Green Algae
G. Cell Boundaries –
1. cell membranes – found in
and around cells.
a. the plasma membranesurrounds the cell’s
cytoplasm. Separates it
from its outside
environment.
b. The internal cellular
membranes – form many of
the structures in the
cytoplasm.
2. Cell membranes are
composed of the following:
a. phospholipids – have a
hydrophobic and
hydrophilic region. In
water, they form a micelle
(a little sphere) or a bilayer.
b. Proteins
3. Cell walls – found only in
procaryotic, algae, plants,
fungi and many protozoans.
Animal cells do not contain a
cell wall.
II. Cytoplasm
 all material inside the plasma
membrane, excluding the
nucleus.
A. Cytoplasmic matrix – watery
substance in which granules are
suspended.
B. Cytoplasmic organelles – tiny
organ-like structures that
perform specific functions.
1. ribosome – made up of
RNA and proteins;
nonmembrane-bound; found in
procaryotic and eucaryotic
cells. Some are attached to
membranes such as ER. Some
are in the cytoplasm. Their
function is that they provide a
site for protein synthesis.
2. Endoplasmic reticulum (ER)
a. smooth ER – folds of
cellular membranes without
ribosomes on the outside. It
is continuous with
membranes outside the
nucleus. Function- transports
materials through the cell.
(serves as a channel).
b. Rough ER – outer surface is
dotted with ribosomes.
3. Mitochondria – “power
house of the cell” – bean
shaped, double membranebound. – inner membrane
having folds called cristae.
Function – place where cell
respiration takes place;
responsible for respiration of
sugars to release usable
energy. Mitochondria matrix –
fluid which is inside the
mitochondria. – found in both
plant and animal cells. Many
are found in muscle cells.
4. Plastids – membrane bound,
found in plant and algae but
not in animal cells.
a. leucoplasts – colorless
storehouses, found in fleshy
storage areas of plants.
(potatoes, root crops and
fruit).
b. Chromoplasts – serves in
synthesis processes. –
contains red, orange, yellow
or other pigments.
1. chloroplast – green sugar
manufacturing organelle.
Where photosynthesis
takes place.
a. stroma –fluid inside
chloroplast
b. thylakoids- flattened
sacs in chloroplast
c. granum – stacks of
thylakoids.
d. Chlorophyll – green
pigment found in
membranes of grana;
catches light energy
and uses it to start the
synthesis of sugar.
5. Golgi bodies or golgi
apparatus – flat curved sacs;
polysaccharides, lipids, and
proteins are processed, packed
in sacs and shipped out into the
cell from the golgi. Ex:
cellulose in plant cell walls is
assembled in the golgi body.
6. Lysosomes – small
membrane bound organelles
which contain special enzyme,
used to break down complex
structures. Many found in
white blood cells.
7. Vacuoles and Vesicles –
membrane bound sac which
contains food, water, waste
products and other materials.
a. Phagocytic vacuole
1. phagocytosis –
engulfing of food by a
cell. Cytoplasm flows
around the food.
Plasma membranes
meet, they fuse,
leaving the substance
in a food vacuole.
b. Food vacuole – site of
cellular digestion.
Lysosomes fuse with food
vacuoles releasing
digestive enzymes.
c. Waste vacuoles
d. Secretion vesicle
e. Pinocytic vesicle –
pinocytosis – cellular
drinking.
f. Central vacuole – found
in most plant and algae
cells. Large vacuole filled
with water. Puts pressure
on the cytoplasm which
puts pressure on the cell
wall.
g. Contractile vacuole –
found in single cell
organisms. When water
enters cell because of the
environment, the
contractile vacuole collects
the water, fuses with the
membrane and releases the
water.
C. Cytoskeleton – internal
structure of cytoplasm.
Composed of microfilaments
and microtubules.
D. Centrioles, flagella and cilia
1. centrioles – occur in pairs,
aid in cell division.
2. Flagella – long tubular
extension of plasma
membrane. Used for
locomotion of the cell.
3. Cilia – similar to flagella
but shorter and usually cover
the entire cell or portion of the
cell.
E. Nucleus – “Control center of
the cell” – contains DNA – code
for all function of the cell.
1. structure of the nucleus
a. nuclear envelope – double
membrane around it.
b. Nuclear pores – allows
nuclear material to flow into
the cytoplasm.
c. Chromatin material –
composed of DNA and
proteins. (in nucleus).
d. Nucleolus – large amounts
of RNA; involved in decoding
of DNA to RNA.
- Where ribosomes
are made.
III. The Living State of Cells
 Homeostasis – “steady state” –
dynamic equilibrium of the cell.
A. Optimal point and Range of
Tolerance
1. all cells function best at
their optimal point but can
function reasonably well in
their range of tolerance.
2. The farther away from the
optimal point the poorer the
cell will function.
B. Solutions around cells
1. the concentration of the
materials in the solution around
the cell influence the cell. Ex:
alcohol can break down the fat
in the cell membrane and cause
the cell to die.
2. Some valuable substances
like water, ions and food
dissolved in the cells
environment can cause
problems for cells.
a. isotonic solution – the ratio
of solutes to water is the same
inside and outside the cell
membrane.
b. Hypotonic solution – the
outside of the cell has a
higher concentration of water
molecules and a lower
concentration of solutes than
the inside.
 water will rapidly diffuse
into the cell causing it to
expand and burst .
 cytolysis- cell bursting from
internal pressure
c. hypertonic solution –
outside of the cell has a lower
concentration of water
molecules and a higher
concentration of solutes than
the inside.
 water will diffuse out of the
cell
 the cell will shrink
 plasmolysis- a collapse of
the cell’s cytoplasm.
IV. Transport across membranes
A. Passive Transport
1. diffusion – process by which
molecules tend to scatter
themselves throughout the
available space.
a. molecules move down their
concentration gradient.
b.Plasma membrane is a
barrier to diffusion.
Molecules move passively
through if:
1. small enough to pass
through pores
2. can dissolve in the
fatty portion of the
membrane. This is
considered simple
diffusion.
c. osmosis – diffusion of
water across a selectively
permeable membrane.
d.Facilitative diffusion –
larger molecules can not fit
through pores, use a carrier
protein.
2. Filtration – process by
which water and solutes are
forced through a membrane.
a. pressure gradient – solute
containing fluid is actually
pushed from a higher
pressure to a lower
pressure. Not as selective
Ex: In kidneys.
B. Active Transport Process –
when energy is used to move
substances across the membrane.
1. solute pumping – (active
transport) – similar to
facilitated diffusion. – both
require carrier proteins.
a. facil. diff. -  uses kinetic
energy
b.sol. pump  uses ATP to
energize protein carriers.
- solute pumps – most move
against concentration
gradient. Ex: Na+ are moved
out of the cell by solute
pumps.
- Sodium-potassium pumps –
carries sodium out and
potassium in. ** Needed for
transmission of nerve
impulses.
2. Bulk Transport – substances
that could not get in or out any
other way are by bulk
transport.
a. Exocytosis – moves
substances out of a cell.
b.Endocytosis – cell takes up
or engulfs extracellular
substances
1. phagocytosis – engulfing
of large particles or dead
cells.
2. Pinocytosis – cell
drinking.