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Biology- Cell Membrane II
Terms in this set (68)
Cell membranes of unicellular organisms are - so the organism can move.
What is meant by homeostasis?
Balanced Internal condition of cells
Homeostasis is also called-
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?
Fluid inside the cell is called the -
A - bilayer makes up most of the cell membrane
Are phospholipids heads polar or nonpolar? the tails?
heads are polar tails are nonpolar
how many fatty acid chains are in a phospholipid?
describe the heads of the phospholipids.
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.
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.
With simple diffusion molecules move from an area of - concentration to an area of - concentration
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
- is the diffusion of - across a cell membrane.
If water potential is high, solute concentration is -
If water potential is low, solute concentration is -
water moves from - water potential to - water potential.
Water diffuses through the pores called- of the cell membrane.
What is an isotonic environment?
10% NaCL 90% H2O
What is meant by NO NET movement?
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
- occurs whenever water moves into the cells causing them to swell and burst
what happens to a red blood cell placed in distilled water. concentrated salt solution.
RED blood cell
hypotonic-> hypertonic-> isotonic
hypertonic-> isotonic-> hypotonic
plans prefer- environments, while animal cells do best in - environments
materials move down their concentration gradient
aided by both concentration gradient and transport protein
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 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.
Do all carrier proteins extend across the cell membrane?
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.
- transport requires additional energy to move materials.
Active transport uses cellular energy known as
Active transport moves materials AGAINST the concentration gradient or from - to - concentration.
The - pump is an example of active transport.
The sodium-potassium pump moves - sodium ions out for every - potassium ions moved into the cell creating voltage across the cell called the - potential.
Moving very large particles out of the cell is called
In exocytosis, wastes are moved out of the cell in - that fuse with the cell membrane.
- involves moving large particles into the cell.
Taking in a large liquid droplets is called - or "cell drinking"
- - endocytosis involves protein - recognizing hormones to help move them into the cell.
how does cholesterol get into a cell?
receptor meditated endocytosis
"cell eating" is known as
White blood cells engulfing bacteria is an example of
- is the opposite of exocytosis.
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