Ch. 8-3 Flashcards
to study for part of the final
Every living cell lives in a ______ environment
liquid
How do cell membranes maintain homeostasis?
by regulating molecule movement from one side of the membrane to the other
Do solutes move all the time or stay still?
They move all the time
Particles naturally move from ____ to _____ concentration. This is known as _______.
high to low;
diffusion
Molecules move from an area of high to low concentration until they reach…
equilibrium
True or False: Because molecules move after equilibrium is reached, the concentration of one side of the membrane changes.
FALSE: The molecules move in opposite directions across the membrane at the same rate, so there’s no net change in concentration.
The movement of molecules across the cell membrane without using cellular energy
Passive transport
What kinds of molecules can go directly through the cell membrane?
small and uncharged molecules
What kinds of molecules CAN’T go directly through the cell membrane?
Also give an example
ions (which are charged) & large molecules
e.g., Chloride, glucose
What carbon compound lets certain molecules go through facilitated diffusion?
Proteins acting as carriers
How many kinds of proteins can help with facilitated diffusion?
Can a protein work with any molecule?
Hundreds;
No, they are specific to certain molecules
Does facilitated diffusion require cellular energy
No
Why can’t water molecules directly go through the cell membrane?
Because parts of the membrane (the lipid’s tails) are hydrophobic.
The channel protein that helps water go through the membrane
aquaporins
Define osmosis
the facilitated diffusion of water through a selectively permeable membrane
In osmosis, water moves from _____ to ____ concentration
Hint: how is it like in diffusion normally?
high to low
Higher solute concentration means there is a ______ water concentration (assuming the solute is dissolved in water) and vice versa
lower
In osmosis, water moves from one side to another or to both sides?
Both, but there’s a net movement to wherever there’s a higher solute concentration
When will water stop moving across the membrane?
When equilibrium is reached
When the concentration of water & a solute is the same on both sides of a membrane, the solutions are…
isotonic (same strength/solute)
To have a greater solute concentration than the other solution
hypertonic (above strength/solute)
To have a smaller solute concentration than the other solution
hypotonic (below strength/solute)
Osmotic pressure
The net movement of water out of or into a cell
In what solution will an animal cell shrink?
Hypertonic solution
Animal cells in hypotonic solutions will…
swell or burst
With respect to freshwater, are cells hypertonic or hypotonic? Why?
Hypertonic, because they have salts, sugars, proteins etc.
In freshwater, do cells swell or shrink?
swell
In plant cells, osmotic pressure can change the size of the ______ to shrink or swell.
central vacuole
Are cells of large organisms likely to burst? Why or why not?
No,because those cells are surrounded by blood or other isotonic solutions, rather than freshwater
Why is osmotic pressure not a problem for frog & fish eggs?
Those cells don’t have water channels, so the water moves in too slow to harm them
Why is osmotic pressure not a problem for bacteria & plants?
The cell walls stop them from expanding
What kind of cell holds their shape in both hypertonic and hypotonic solutions?
A) animal cells
B) plant cells
C) both
D) neither
B) plant cells
Increased osmotic pressure makes plant cells vulnerable to…
cell wall injuries
Define active transport
the movement of particles against a concentration difference, requiring energy
The protein that transports ions & small molecules across the cell membrane
Transport proteins i.e, protein pumps
Endocytosis & exocytosis transport… (hint: 2 answers)
large molecules & clumps of material
The transport of large materials sometimes requires the cell membrane to…
change shape
The energy from ____ pumps molecules through protein pumps
ATP
ATP becomes _____ when giving off energy for active transport
ADP
Do the protein pumps change shape or not during active transport?
They change shape
Name an example of an ion proteins transport
calcium, potassium, and sodium ions
Do cells spend a considerable or insignificant portion of their energy on molecular transport?
A considerable portion
What does the use of energy in molecular transport allow the cell to do?
It allows the cell to concentrate substances in a specific location
Define bulk transport
the transport of large molecules & solid clumps of material
The form of bulk transport depends on the _____ and ______ of the material moving into & out of the cell
size and shape
The process by which materials are take INTO the cell
Endocytosis
How is endocytosis carried out?
via infoldings (i.e, pokcets) of the cell membrane
The pocket _____ from the cell membrane to form a ______.
breaks; vesicle
Name three things endocytosis can take in
large molecules, clumps of food and whole cells
a type of Endocytosis wherin extensions of the cytoplasm surround a particle & package it in a food vacuole, which the cell then engulfs
Phagocytosis
Name one cell that uses phagocytosis
- White blood cells
- amoebas
Phagocytosis requires considerable or insignificant amounts of energy?
considerable amounts
a type of Endocytosis wherin tiny pockets form a long the cell membrane, fill themselves with liquid, and pinch off to form vacuoles
Pinocytosis
The process by which materials are take OUT of the cell
Exocytosis
How does exocytosis work?
A material is surrounded by the membrane of the vesicle or vacuole. The membrane of the vesicle or vacuole fuses with the cell membrane, which expels the material out of the cell.
An example of exocytosis
water being removed by a contractile vacuole
