BSC1105C- Lecture Notes On Membrane Function

BSC1105C- Lecture Notes On Membrane Function
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Anything that enters or leaves the cell must pass through the _____
Plasma Membrane
The Membrane is composed of two Layers______and _____
Bilayer of Phospholipid molecules and Protein molecules embedded in the bilayer.
Heat energy causes molecules to move- allowing molecules to spread out over the available space and enter cells through the membrane
Passive passage of materials into the cell- no energy is need.
Concentration Gradient
difference in the concentration of molecules between the inside and outside of the cell, causing molecules to move in or out
Selectively permeable
Only allows some molecules to enter
Passive transport is ____
diffusion across a cell membrane, because no energy is used
higher water concentration, less solute
lower water concentration, more solute
Having the same concentration
Hydrophilic molecules may enter through transport proteins in a process called______
Facilitated diffusion
The passage(diffusion) of water molecules across a selectively (semipermeable) membrane is called____
When animal cells such as a red blood cell are placed into an Isotonic solution, what happens?
Its volume remains the same- it looses some water but an equal amount diffuses into the cell
When animal cells such as a red blood cell are placed into an Hypertonic(more solute, less water) solution, what happens?
the cell shrinks, water diffuses out of the cell
When animal cells such as a red blood cell are placed into an Hypotonic(less solute, more water) solution, what happens?
The cell Hydrolyzes (swells until it breaks)
Why dont plant cells hydrolyze (swell to bursting)
The cell wall is rigid and prevents the cell from bursting. the cell swells and pushes against the cell wall- this cell is called turgid

What is Plasmolysis? pg 82
When a cell is placed in a hypertonic (more solute, less water) the cell looses water and the plasma membrane pulls inward away from the cell wall
What is the Opposite of passive Diffusion?
Active Transport pg 83
What is active transport? pg 83
requires that a cell use energy to move molecules across a membrane. (ATP is the energy source)

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