9/9, 9/11 Class Lecture Chapter 3 Flashcards
What is the plasma membrane composed of?
lipid bilayer and proteins
Are the proteins and the bilayer still or moving
constantly moving, constantly changing
what allows the proteins to move around without damage
fluid mosaic
what does fluid mosaic mean
cell membrane recovers if damaged
What type of role does plasma membrane have in cellular activity
active, dynamic role
What does the lipid bilayer separate
intracellular fluid from extracellular fluid
abbreviation with intracellular fluid
ICF
abbreviation with extracellular fluid
ECF
What does ICF refer too
within cytoplasm
What does ECF refer to
everything outside of the cell
abbreviation for interstitial fluid
IF
what is the IF
things between and among cells, ECF that surrounds the cell
What makes up the membrane lipids
Phospholipids 75%
Glycolipids 5%
Cholesterol 20%
What are the phospholipids apart of
lipid bilayer
what makes up the phospholipids heads
phosphate
what are the phospholipid head properties
polar and hydrophilic
what does hydrophilic mean
likes water
what makes up the phospholipid tails
fatty acid
what are the phospholipid tail properties
non polar hydrophobic
what does hydrophobic mean
water-fearing
what makes up the glycolipids
Lipids with polar sugar groups on outer membrane surface
what does cholesterol do
Increases membrane stability
Gives structural integrity
Can’t live without
structurally essential
what do membrane proteins do
Allow communication with environment, with rest of body, or with things floating around, through hormones
how much of plasma membrane do membrane proteins make up
1/2
where do the membrane proteins live
Some float freely, move around
Some tethered to intracellular structures, some are connected
what are the two types of membrane proteins
integral proteins, peripheral proteins
where are the integral proteins located
Firmly inserted into membrane
what type of regions do integral proteins have
hydrophobic and hydrophilic
what do the hydro properties allow for integral proteins
allows them to have reactions
what do integral proteins function as
as transport proteins (channels and carriers), enzymes, or receptors
where are peripheral proteins located
Loosely attached to integral proteins, bonds not a strong, affected by other chemicals around them
what organelles do peripheral proteins include
filaments on intracellular surface for membrane support
the function of peripheral proteins
Function as enzymes; motor means movement proteins for shape change during cell division and muscle contraction; cell-to-cell connections
6 functions of membrane proteins
Transport Receptors for signal transduction Attachment to cytoskeleton and extracellular matrix Enzymatic activity Intercellular joining Cell-cell recognition
what are cells surrounded by
IF
what does IF contain
amino acids, sugars, fatty acids, vitamins, hormones, salts, waste products, some good, some bad, some neutral, some small enough to fit through the membrane
what does the plasma membrane allow the cell to do
Obtain from IF exactly what it needs, exactly when it is needed, allows some things in and keep some things out
Keep out what it does not need
property of the plasma membrane
selectively permeable
what does selectively permeable mean
Some molecules pass through easily; some do not
Based on size and chemical properties
Charge, polarity
what are the ways that substances cross the membrane
passive process
active process
passive process
No cellular energy (ATP-cell energy) required, don’t use or need cell energy
Substance moves down its concentration gradient from greater to lesser
Natural process no energy needed
Molecule will passively diffuse through membrane if into or out of cells
active process
Energy (ATP) required,
Occurs only in living cell membranes
Does not happen in a non living world
We get our energy from the sun
two types of passive transport
diffusion and filtration
what is diffusion
greater to lesser concentration
Collisions molecule moving around cause molecules to move down or with their concentration gradient
a specialized type of diffusion
osmosis
osmosis
diffusion of water through the membrane