Cell Membrane Flashcards
Cells are a open system, they…
Exchange energy with surroundings
The cell membrane separates the ______ from the ________ (inside and outside)
Intracelular
Extracellular
What does semi-permeable mean
The membrane selectively allows materials to cross
The membrane is made up of…
- a phospholipid bilayer (a double lined layer made of phosphates)
- proteins which are suspended into the bilayer
What does the cell membrane do?
Prevents substances from entering the cell
- most organelles have a membrane
What is the purpose of proteins on the cell membrane?
Can move large substances that cant diffuse in and out of the cell
The inside of the cell membrane is hydro______
Hydrophobic
The outside of the cell membrane is hydro
______
Hydrophilic
The most common cell membrane model (which will probably be used on the test) is the….
Fluid mosaic model
Peripheral membrane proteins:
Span the surface for cellular recognition
Integral membrane proteins:
Act as channels to enter and exit the cell membrane
——-
Cell membranes are always moving and changing
What are the three functions of the cell membrane
- Barrier - keeps out wastes and toxins
- Organization - surrounds packages in vesicles to move and transport
- Selective filter - only allows certain substances in or out
What are the three types of cell membrane transport?
- Passive transport
- Facilitated diffusion
- Active transport
Passive transportation is from ____ concentrations to _______ concentration
High to low
____ energy is required for passive transport
No energy is required
Passive transport is also known as….
Diffusion
Facilitated diffusion is another form of…
Passive transport
Facilitated diffusion is for…
For molecules too large for diffusion (i.e glucose)
Substances that are not soluble in lipids
How does facilitated diffusion work?
Carrier proteins bind to larger molecules and change their shape so it can diffuse through
Channel proteins, which are in between the membrane, provide water filled pores for charges ions to pass through
Uses concentration gradients
Active transport is from _____ concentration to ______ concentration
Low to high
Active transport requires…
Carrier proteins and ATP
What is a concentration gradient?
When different concentrations of dissolved particles exist across a cell membrane
Qualities of concentration gradients (5)
- drives diffusion and osmosis
- must involve different concentrations
- may be separated by a cell membrane
- involves molecules or ions of a single type
- molecules or ions move along the gradient separately of each other
Brownian motion:
Matter is made up of particles in constant motion
(In relation to particles)
S
P
A
M
Space - space in between particles
Particles - all matter is made up of particles
Attraction - are attracted to one another
Movement - always moving
The greater the _______ in concentration, the ______ particles move
Greater
Faster
Equilibrium is reached faster is the gradient concentration is….
Larger
In endocytosis and exocytosis, the cell membrane is used to…
The cell membrane is used to create vesicles to bring in particles (endocytosis) or release them (exocytosis)
Endocytosis and exocytosis is used for…
Substances to large for passive or active transport
What are the two types of endocytosis?
- Phagocytosis
- Pinocytosis
What is phagocytosis?
Cells eating (solids)
What is Pinocytosis?
Cells drinking (liquids)
How does endocytosis and exocytosis work?
The cell membrane forms a vesicle around the substance, once the vesicle touches the cell membrane, the vesicle merges with the membrane and the substance gets released.
Diffusion over a large distance is inefficient because….
It cannot be diffused to the center fast enough, by the time it reaches the center there is nothing to provide. This creates dead zones, killing the cell.
The surface area of a cell is the…
Cell transport ability (because there is a larger membrane)
The volume of a cell is the….
Transport required (because there are more organelles using up transport)
In order to have a efficient cell the SA:VOL ratio has to be…
Large
You want more SA than VOL
The SA increases (more rapidly/less rapidly) than the volume
Less rapidly
Small needs =
Small ability
Shapes that increase a cells SA (4)
Unfolding of membrane
Flat shape
Plant root hair cells
Microvilli
