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Membrane & Transport Practice Terms & Concepts NOT COMPLETED, but mostly is.
Complete each statement by writing the correct term or phrase in the space provided.
1. What is homeostasis, and what are the 4 ways that the cell membrane helps maintain homeostasis?
__ maintaining balance in a changing environment. __
2. The __Cell membrane_ is made of a double layer of phospholipids. The double layer of phospholipids
is called a(n) _lipid bilayer __.
3. The lipid bilayer forms because there is __water__ both inside and _outside_ of the cell.
4. The phosphate _head_ of a phospholipid is polar. It is _attracted_ to water.
5. The long fatty acid _tails_ of a phospholipid are nonpolar. They are _afraid of/ repelled by_ water.
6. The lipid bilayer forms a barrier, preventing most molecules from passing through it. Only molecules that
are _small_ in size and _non-polar_ can pass through the lipid bilayer.
7. Ions, which are _polar_ particles, and _polar_ molecules are repelled by the nonpolar interior of the lipid
bilayer.
8. The cell membrane includes various kinds of _proteins_. Some face the inside of the cell. Some face the
_outside_ of the cell. Others span the entire width of the _cell membrane/ phospholipid bilayer_.
9. What are proteins made of? _chains of amino acids_
10. Why do proteins stay within the lipid bilayer of the cell membrane?
___they have both polar and non-polar regions__
11. List the three types of proteins found in a cell membrane.
__integral (in & out of the interior of the membrane), peripheral (In the hydrophilic regions
only), trans-membrane (going from one side to the other = channels and pores)__
12. What is the purpose of cell transport & what is the difference between active transport and passive
transport?
__the purpose of transport is to organize the movement of molecules across the membrane.
Passive and active transport differ in the fact that active transport uses energy and moves
stuff against the concentration gradient__
13. What is equilibrium?
__balance of molecules within a region of space or across a membrane, meaning there are
equivalent numbers of molecules throughout a space__
14. What is diffusion? Why is diffusion an example of passive transport?
__diffusion is the natural spreading of molecules from where there are a lot of them to where there are few.
Think of it similar to a crowd dispersing and spreading out____
15. What is osmosis, and why is it important in cells?
___fascilitated diffusion of water through a membrane; facilitated because water goes through
the membrane, down a concentration gradient (“down the slide”), but THROUGH A WATER
CHANNEL PROTEIN__
16. Explain how water moves across a cell membrane.
____through transport proteins.
17. The transport of a substance across the cell membrane against its concentration gradient is called
__active transport__.
18. The energy needed for active transport is usually supplied by _ATP_.
19. What is the sodium-potassium pump? Describe how it works.
__an active transport mechanism that moves sodium out of the cell and potassium into the
cells, using ATP__
In the space provided, write the letter of the description that best matches each term.
__h__ 20. concentration
a. the movement of a substance from a region where its concentration is higher to a
gradient
region where its concentration is lower
__f__ 21. equilibrium
b. transports specific substances across a cell membrane
__a__ 22. diffusion
c. binds to a signal molecule, enabling the cell to respond to the signal molecule
__l__ 23. osmosis
d. The solution a cell is in is isotonic, meaning that it has the same solute
__e__ 24. phospholipid
__b__ 25. carrier protein
__c__ 26. receptor
protein
__j__ 27. lipid bilayer
__i__ 28. sodiumpotassium pump
__g__ 29. water moves
into the cell
__d__ 30. a state of
ongoing equilibrium
occurs
__k__ 31. water moves
out of the cell
e.
f.
g.
h.
i.
j.
k.
l.
concentration as the cytoplasm does
made of a phosphate group and two fatty acids
the state in which the distribution of a substance is even throughout a region
The solution a cell is in is hypotonic, meaning that it has a lower solute
concentration than the cytoplasm does.
the difference in the concentration of a substance across a distance
type of carrier protein that uses active transport to take sodium ions out of the cell
and bring potassium ions into the cell
a double layer of phospholipids that is the foundation of a biological membrane
The solution a cell is in is hypertonic, meaning that it has a higher solute
concentration than the cytoplasm does
the movement of water through a selectively permeable membrane from a more
dilute solution to a more concentrated solution
Transport Concept Mapping
Using the terms provided below, complete the concept map showing the characteristics of cell transport.
active transport
carrier proteins
channel proteins
osmosis
passive transport
pumps
simple diffusion
Passive transport
Simple
diffusion
sodium-potassium pump
vesicles
concentration gradient
endocytosis
Active transport
pumps
Concentration
gradient
Channel
proteins
osmosis
Carrier
proteins
vesicles
Sodiumpotassium
pump
endocytosis