Cells Flashcards
Components of plasma membrane
membrane lipids, membrane proteins, membrane carbohydrates
Types of lipids in the plasma membrane
phospholipids, cholesterol, glycolipids
functions of the plasma membrane
physical barrier, selective permiability, electrochemical gradients, communication
true or false: half of the weight of the plasma membrane is proteins
true
true or false: an enzyme is a membrane protein
true
passive membrane transport
no expenditure of energy required. substances move down concentration gradient
active membrane transport
requires energy (hydrolysis of ATP) involves movement of a substance up a concentration gradient or the formation or loss of a vesicle
substances that participate in simple diffusion
O2 and CO2, some fatty acids, ethanol, urea
channel mediated diffusion
movement of small ions through water filled protein channels
Carrier mediated diffusion
small polar molecules cross membrane with carrier proteins (down gradient)
Primary ion responsible for establishing resting membrane potential
Potassium
primary active transport
uses energy directly from the breakdown of ATP
_____ K ions into the cell, while moving ____ Na ions out of the cell in the K/Na pump
2,3
secondary active transport
uses energy from movement of the 2nd substance down its gradient.
Symport
two substance moved in the same direction
antiport
two substance move in opposite directions
exocytosis and endocytosis are examples of what kind of transport
Vesicular
neurotransmitters releasing from nerve cells is a great example of what?
exocytosis
T/F: The cell membrane is equal parts lipid and protein (50/50) by weight.
True
What 2 types of substances are able to penetrate the plasma membrane without assistance?
Small (O2, CO2) and non polar (H20)
Name the 3 types of lipids found in a plasma membrane.
Phospholipids, Glycolipids, and cholesterol
What are the 2 roles of cholesterol in the lipid bilayer?
Strengthen the membrane
Stabilize the membrane against temperature extremes
Glycolipids are found on the inside/outside of the membrane?
Outside
Glycolipids help form the sugar coating on the outside of the membrane, known as the __________.
Glycocalyx
Name the 4 functions/characteristics of the plasma membrane.
Physical barrier
Selective permeability (regulates entry and exit of ions/nutrients, waste molecules)
Electrochemical gradient
Communication (through receptors)
Name the type of membrane protein that is embedded within and extends across the bilateral
Integral protein
Name the membrane protein that is not embedded in the bilayer and is loosely attached to the external or interior surfaces of the membrane.
Peripheral proteins
Name the 6 different types of membrane proteins.
Transport Receptor (for ligands) Identity marker (communicate health and “self”) Enzymes Anchoring site for cytoskeleton Cell adhesion molecule
T/F: a transport protein is necessary for passive simple diffusion.
False (they go right through the membrane for simple diffusion)
Facilitated diffusion is a passive process and can be either _______ mediated or _______ mediated.
Channel, Carrier
Secondary active transport uses energy from the movement of another substance. Two examples are ________, which moves substances in the same direction, and _________, which moves two substances in opposite directions.
Symport and antiport
The rate of passive diffusion of a substance down its concentration gradient is determined by what 3 things?
“Steepness” of concentration gradient
Temperature (Fever)
Molecular size (bigger moves slower)
Facilitated diffusion through channels or carriers is for_______ or __________ solutes.
Charged, polar
Channels are for movement of what?
Small ions, K+, Na+
Channels can be leak or gated. Leak are always open. Name the two things that stimulate gated channels to open.
Voltage, Hormones (ligands)
__________ mediated diffusion occurs when a substance binds and changes the protein shape, releasing substances on the other side of the membrane.
Carrier
Primary active transport uses ATP. What pump have we talked about that is primary active transport?
Na+K+ ATPase pump
How many of each ion, Na+ and K+ does ATPase move in/out?
3Na+ out, 2 K+ in
Describe the 4 steps of the Na+/K+ pump.
- Na+ and ATP bind to pump
- ATP splits into ADP and Pi, protein changes conformation, moves 3 Na+ out
- Pi released, 2 K+ bind
- Pump changes conformation, 2 K+ released inside cell
___________ involves invagination of the plasma membrane and is an active process.
Endocytosis/pinocytosis
_______ uses pseudopodia to engulf and eat and is an active process.
Phagocytosis
Receptor-mediated endocytosis uses a ________ coated pit.
Clathrin
