Transfer of things Flashcards
Why is the fluid mosaic model called that?
Because of the proteins scattered throughout the plasma membrane
Do phospholipids arrange themselves in a bilayer spontaneously?
yes
What are the types of lipids in a plasma membrane?
phospholipids
glycolipids
cholesterol
What is the difference between glycolipids and phospholipids?
Glycolipids have a variety of sugars formed together to form a carbohydrate chain instead of a hydrophilic head
What reduces the permeability of the membrane to most biological molecules?
cholesterol
What kind are the proteins in a membrane ?
peripheral proteins or integral proteins
Where is a peripheral protein located?
Inner or outer layer of phospholipid bilayer
Where is an integral protein located
embedded in whole phospholipid bilayer
What one has a hydrophilic head and hydrophobic body: peripheral protein or integral protein?
integral
What kind of protein are many integral proteins
glycoproteins
What do glycoproteins have?
Attached carbohydrate chain that projects externally
Is the plasma membrane symmetrical?
no
Where to the chains of glycolipids and proteins occur and attach
occur on outside surface of cytofilaments
attach on outside surfaces
At room temperature what consistency does the phospholipid bilayer have?
like olive oil
How does the phospholipid molecule move?
Hydrocarbon tails wiggle
Are proteins free to drift in fluid bilayer?
some are
others are held in place by cytoskeletal filaments
What determine a membranes specific function?
integral proteins
How do channel proteins transport something?
Through it
How does a carrier protein transport something?
Combines with a substance to help it move across
How do receptor proteins transport things?
Has specific shape that allows it to bond with a specific molecule
What do enzymatic proteins do?
Carry out metabolic reactions directly
What do peripheral proteins often have a role in?
Structural role
They help stabilize the shape of the plasma membrane
What does cholesterol control
fluidity
act to stiffen the membrane
What do receptor proteins do?
bind substances in the environment and trigger cell responses
What direction on the concentration gradient odes passive transport move?
High to low
What drives passive mechanisms
random kinetic energy
What kind of transport if diffusion an example of
passive transport
What does active transfer require?
carrier protein
How does active transport move cell products?
Through vesicle formation
What Is exocytosis?
Vesicle mediated transport out of the cell
What is endocytosis?
Vesicle mediated transport into the cell
What is pinocytosis?
Cell drinking
What is phagocytosis?
cell eating
What is diffusion?
Movement of molecules from and area of high concentration to an area of low concentration
What can diffuse freely across cell membrane?
lipid soluble molecules, gases, and some water soluble molecules
What is osmosis?
Diffusion of water across a semi permeable membrane
What is and what causes osmotic pressure?
Force that causes water to move in a direction
due to number of non-diffusible particles in solutions
What happens in hypotonic solutions?
cell swells and bursts
What happens in hypertonic solutions?
cell shrinks
What happens in isotonic solutions?
no change
What is receptor-mediated?
Specific kind of pinocytosis which occurs in response to receptor stimulation
Can macromolecules diffuse across the plasma membrane?
no, too big
Can ions and charged molecules diffuse across membrane?
no, can’t enter the hydrophobic phase of the lipid bilayer
Can non-charged molecules (oxygen and alcohols) pass through the membrane?
yes
are lipid soluble
can slip in between the hydrophobic heads of the phospholipids
Can small polar molecules (CO2 H2O) cross the membrane?
yes, follow the concentration gradients
Are carrier proteins specific to the substance they carry across?
yes
How does facilitated transport move things ?
from high on the concentration gradient to low
What are the passive methods of transport?
diffusion
facilitated transport
What are the active ways to cross a membrane?
include active transport, endocytosis, exocytosis
What is tonicity?
Strength of a solution in relationship to osmosis
What is lysis?
term refers to disrupted cells
What is hemolysis?
rupture of RBCs
What is turgor pressure?
created by swelling of plant cell in a hypotonic solution
What is turgor pressor important to?
plant’s erect position
What happens when a plant is placed in a hypotonic solution?
cytoplasm expands
What is crenation?
Shrinkage of cells when surrounding solution is hypertonic to cytoplasm
What is plasmolysis?
shrinking of cytoplasm due to osmosis
What explains the passage of amino acids and glucose (they are not lipid soluble) across membrane?
facilitated transport
What are proteins that are involved in active transport often called?
pumps
What do pumps do?
use energy to move a substance against concentration gradient
What does the sodium potassium pump do?
Moves sodium ions outside of cell and potassium ions inside the cell
What cells is the sodium potassium pump exceptionally active?
nerve and muscle cells
What allows the carrier to combine alternately with sodium and potassium in a sodium potassium pump?
change in carrier shape
What is diffused when NA+ is pumped across the membrane?
Cl-
Factors that effect rate of diffusion?
size shape concentration charge lipid solubility temperature
