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Biology- Cell Membrane II

Terms in this set (68)

Cell membranes of unicellular organisms are - so the organism can move.
flexible
What is meant by homeostasis?
Balanced Internal condition of cells
Homeostasis is also called-
equilibrium
How does the plasma membrane help maintain homeostasis?
It controls what enters and leaves the cell
Give 2 functions of the plasma membrane
protective barrier, contains the cytoplasm
What is meant by the term selectively permeable?
regulates transport in and out of the cell
What are cell junctions?
interlocking cells
Fluid inside the cell is called the -
cytoplasm
A - bilayer makes up most of the cell membrane
lipid
Are phospholipids heads polar or nonpolar? the tails?
heads are polar tails are nonpolar
how many fatty acid chains are in a phospholipid?
two
describe the heads of the phospholipids.
round
The - - - describes the appearance of the cell membrane.
fluid mosaic model
Why is the cell membrane said to act like a fluid?
the phospholipids and proteins move side to side within the layer
What causes the mosaic pattern of the cell membrane when viewed from above?
because of the pattern produced by the scattered molecules.
the phospholipid - of the cell allows - molecules to pass through easily, but - do NOT.
bilayer hydrophobic hydrophilic
Materials soluble in - can pass easily through the cell membrane.
lipids
Because the cell membrane is -, only - molecules and larger - molecules can move through easily.
semipermeable small hydrophobic
List 3 substances that pass through the cell membrane.
O2 CO2 H2O
-,- molecules larger than water, and large - molecules do NOT move easily through the phospholipids of the cell membrane.
ions, hydrophilic protein
Simple - requires NO energy to move things across the cell membrane.
diffusion
With simple diffusion molecules move from an area of - concentration to an area of - concentration
high-low
Why is diffusion considered a passive process?
no energy is used to make molecules move
Explain what happens to a drop of food coloring put into a beaker of water.
diffusion occurs and the dye is easily distributed
when solutes diffuse through a membrane, they move from - to - concentration
high-low
- is the diffusion of - across a cell membrane.
osmosis-water
If water potential is high, solute concentration is -
low
If water potential is low, solute concentration is -
high
water moves from - water potential to - water potential.
high-low
Water diffuses through the pores called- of the cell membrane.
aquaporin
What is an isotonic environment?
10% NaCL 90% H2O
What is meant by NO NET movement?
equilibrium
What is an hypotonic environment?
20% NaCL 80% H2O
What is an hypertonic environment?
5% NaCL 95% H2O
- occurs whenever water moves out of a cell & the cell shrinks in size
plasmolysis
- occurs whenever water moves into the cells causing them to swell and burst
cytolysis
what happens to a red blood cell placed in distilled water. concentrated salt solution.
cytolysis-plasmolysis
RED blood cell
hypotonic-> hypertonic-> isotonic
Plant cell
hypertonic-> isotonic-> hypotonic
plans prefer- environments, while animal cells do best in - environments
hypotonic-isotonic
simple diffusion
materials move down their concentration gradient
facilitated diffusion
aided by both concentration gradient and transport protein
active transport
molecules again move through transport protein, but now energy must be expended to move them.
passive transport does - require additional energy & moves materials from - to - concentration.
not high low
give 2 examples of passive transport in cells.
oxygen or carbon dioxide
- diffusion is a type of - transport because energy is not required.
facilitated
facilitated diffusion uses - proteins to help move materials from - to - concentration
transport high low
name 2 types of transport proteins found in cell membranes.
channel proteins change shape
describe channel proteins
they are embedded in the cell membrane & have a pore for materials to cross.
How do carrier proteins help move materials across a cell membrane?
they can change shape
Channel proteins have an opening or - through which molecules can passively move by - diffusion.
pores facilitated
Do all carrier proteins extend across the cell membrane?
NO
Explain how these carrier proteins move materials across the membrane.
they bond and drag molecules through the lipid bilayer
Some carrier proteins can change - to move materials across the cell membrane.
shape
- transport requires additional energy to move materials.
active
Active transport uses cellular energy known as
ATP
Active transport moves materials AGAINST the concentration gradient or from - to - concentration.
low high
The - pump is an example of active transport.
sodium-potassium
The sodium-potassium pump moves - sodium ions out for every - potassium ions moved into the cell creating voltage across the cell called the - potential.
membrane
Moving very large particles out of the cell is called
exocytosis
In exocytosis, wastes are moved out of the cell in - that fuse with the cell membrane.
vesicles
- involves moving large particles into the cell.
endocytosis
Taking in a large liquid droplets is called - or "cell drinking"
pinocytosis
- - endocytosis involves protein - recognizing hormones to help move them into the cell.
receptor-meditated receptors
how does cholesterol get into a cell?
receptor meditated endocytosis
"cell eating" is known as
phagocytosis
White blood cells engulfing bacteria is an example of
phagocytosis
- is the opposite of exocytosis.
endocytosis
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