Download NOTES: 7.3-7.4 - Cell Transport

NOTES: 7.3-7.4 – CELL TRANSPORT & HOMEOSTASIS
● Selectively permeable: property of biological membranes which
● Transport proteins: membrane proteins that
across
biological membranes
Movement across the cell membrane can be:
1) Passive:

 substance moves from where it is MORE concentrated to where it is LESS concentrated.
2) Active:

from where it is LESS concentrated to
where it is MORE concentrated (“UPHILL”)
1) PASSIVE TRANSPORT (types):
DIFFUSION:
● movement of a substance from where it is conc. to where it is less conc. (“
”)
FACILITATED DIFFUSION:
● diffusion of solutes across a membrane,
(passive transport because it is movement down a concentration gradient; cell does not need to spend any energy)
OSMOSIS:(a type of facilitated diffusion…water moves through special channels in cell membrane called
aquaporins)
●
through a selectively permeable membrane; water moves DOWN
its concentration gradient (which is to say opposite the solute concentration!)
-the direction of water movement can be described / predicted based on if the cell’s ENVIRONMENT is:
● ISOTONIC:
compared to inside a cell
● HYPERTONIC:
than inside a cell
● HYPOTONIC:
compared to inside a cell
**
!!!
In animal cells:
• in a HYPERTONIC environment, water exits the cell;
• in a HYPOTONIC environment,
and possibly burst
In cells with cell walls (i.e. plant cells):
• in a HYPERTONIC environment, water exits the cell;
• in a HYPOTONIC environment,
TURGID.
; cells become more
ACTIVE TRANSPORT
2) ACTIVE TRANSPORT: energy-requiring process; molecules are moved across the cell membrane.
(“uphill”)
Active Transport:
● Molecular Transport
● Bulk Transport
Active Transport:
● Molecular Transport
-small molecules & ions are moved across membranes by
BULK TRANSPORT: ENDOCYTOSIS & EXOCYTOSIS
•
into or out of the cell
(e.g.
and
ENDOCYTOSIS
*
vesicles out of the cell membrane
)
EXOCYTOSIS
by forming
*
fusing w / the cell membrane
by vesicles
**vesicle forms in a small region of cell membrane
**vesicle buds
cell membrane
and migrates to
***used by cells to bring in larger, extracellular
substances (e.g.
)
***used by cells to export products
(e.g.________________________________________)
2 types of Endocytosis:
1) Phagocytosis:
(”
“)
2) Pinocytosis:
(”
“)
7.4: Homeostasis & Cells
● sometimes an organism can be a single cell
● unicellular organisms dominate life on Earth…they include:
-prokaryotes:
-eukaryotes: protists (amoeba, paramecium, Euglena)
-eukaryotes:
(yeast)
Unicellular Organisms:
● unicellular organisms must maintain homeostasis
● HOMEOSTASIS:
● to maintain homeostasis, unicellular organisms
, respond to the environment,
, and
Multicellular Life:
● the cells in a multicellular organism must
● in a multicellular organism,
so that different cell types play different roles
CELL SPECIALIZATION:
● some cells are specialized
(i.e. muscle cells)
● some cells are specialized
(i.e. nerve cells)
● some cells are specialized
substances (i.e. red blood cells)
● some cells are specialized
(i.e. white blood cells)
LEVELS OF ORGANIZATION:
● CELLS…are organized into…
● TISSUES:
performing the same function
● ORGAN:
working together
-ex: stomach
● ORGAN SYSTEM:
working together
-ex: digestive system (stomach, intestines, pancreas, etc.)
● ORGANISM: collection of all of the above!...specialization and interdependence at all levels allows an
organism to
!
CELLULAR COMMUNICATION:
● Cells communicate with one another by using
(i.e. hormones)
● in order to respond to a particular chemical signal, a cell must have the appropriate
the
● cells respond to chemical signals in a variety of ways:
-liver cell takes up & stores glucose from blood
-
to replace injured cells
to which