HUMB1000 Lecture Notes - Lecture 5: Citric Acid Cycle, Keto Acid, Fluid Compartments
C5 L1 – Membrane Transport:
The plasma membrane:
- Fluid mosaic model
- It’s the boundary of the cell
- Phospholipid bilayer with the hydrophobic tails in the middle
- Separates intracellular and extracellular
- Attaches cells to other cells and the surrounding cell matrix
- Cells communicate with their environment through the cell membrane
- It’s selectively permeable
- Difference in charge across the membrane is called the membrane potential
- Proteins inserted into lipid bilayer (integral or peripheral)
Channel Protein:
- Tiny channel through the plasma membrane where molecules of a certain size, shape and
charge can pass through
- Non-gated ion channels are always open
- Gated ion channels are opened or closed by certain stimuli
- Passive process
Carrier protein: (transporters)
- Integral proteins move ions from one side of membrane to the other
- Specific binding sites
- Water soluble molecules
- Moving down the gradient, passive
- Protein changes shape to transport ions or molecules
- Resumes original shape after transport
- Uniporters, symporters or antiporters (1 molecule, 2 in same direction, 2 in opposite
direction)
Active transport: (ATP powered transport)
- Requires energy in form of ATP ie. Active and requires enzymes sometimes
- Transports substances AGAINST their concentration gradient so the cell can accumulate
substances
- Eg. Sodium potassium pump (Na+ out and K+ in), uptake of glucose in intestine
find more resources at oneclass.com
find more resources at oneclass.com
-
C5 L2
–
Diffusion and Osmosis:
Solute is dissolved substance in solution ie. ions
Solvent is the liquid that holds solutes ie. Water
Diffusion:
- Molecules move from areas of high concentration to low until evenly distributed
- Certain specific non-lipid soluble molecules or ions diffuse through membrane channels
(gated or non-gated) but for others, where there isn’t a membrane channel, can’t enter the
cell
- Lipid soluble molecules diffuse directly through the plasma membrane
- Passive
- Eg. Gas exchange
Facilitated diffusion:
- Move large, water soluble molecules or electrically charged molecules across the plasma
membrane
- Amino acids and glucose go in, manufactured proteins go out
- Passive
- Down the concentration gradient
- Takes shape of molecules
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Phospholipid bilayer with the hydrophobic tails in the middle. Attaches cells to other cells and the surrounding cell matrix. Cells communicate with their environment through the cell membrane. Difference in charge across the membrane is called the membrane potential. Proteins inserted into lipid bilayer (integral or peripheral) Tiny channel through the plasma membrane where molecules of a certain size, shape and charge can pass through. Gated ion channels are opened or closed by certain stimuli. Integral proteins move ions from one side of membrane to the other. Protein changes shape to transport ions or molecules. Uniporters, symporters or antiporters (1 molecule, 2 in same direction, 2 in opposite direction) Requires energy in form of atp ie. active and requires enzymes sometimes. Transports substances against their concentration gradient so the cell can accumulate substances. Sodium potassium pump (na+ out and k+ in), uptake of glucose in intestine. Solute is dissolved substance in solution ie. ions.