A&P Unit 3 - Cell Membrane
protein
A membrane is a collage of different __________ embedded in the fluid matrix of the lipid bilayer These determine most of the of the membrane's specific functions 2% of the molecules in plasma membrane, 50% of its weight
"Antenna" Sensory in inner ear, retina, nasal cavity, and kidney
A single, nonmotile primary cilium is like an "__________" It is located in the following: _________________
10^7 rapid bacterial
Adjacent phospholipids switch positions about ____ times per second. The lateral movements of phospholipids are _______, about 2 µm per second. A phospholipid can travel the length of a typical _________ cell in 1 sec
permeability
As a membrane solidifies, its ______________ changes
maintains fluidity by preventing tight packing
At cool temperatures, cholesterol does what to the phospholipid bilayer?
restrains the movement of phospholipids and reduces fluidity
At warm temperatures (such as 37°C), cholesterol does what to the phospholipid bilayer?
Saline layer
Chloride pumps pump Cl- into ECF, Na+ and H2O follows, and Cilia beat freely in this
9 + 2 array of microtubules Nine pairs form basal bodyAnchors cilium
Describe the microtubules that form the basal body of the cilium
Sweep substances across surface in same direction Power strokes followed by recovery strokes
Describe the movement of motile cilia
concentration gradient.
Diffusion: In the absence of other forces, a substance diffuses from where it is more concentrated to where it is less concentrated, down its __________________
diffuses
Each substance ________ down its own concentration gradient, independent of the concentration gradients of other substances.
microvilli
Extensions of membrane (1-2 mm) increase the surface area for diffusion and minimize any increase in volume.
isolating the cell's contents from the environment regulating the exchange of essential substances communicating with other cells creating attachments within and between other cells providing a surface for biochemical reactions
Functions of plasma membrane
Cilia
Hairlike processes- 7-10 mm long beat to move particles around the membrane, or to move small microscopic organisms
phospholipids covalent
Hydrophobic interactions that cause bilayer: __________ are not bonded together weaker than _________ bonds
adequate saline layer on cell surface
In cystic fibrosis, chloride pumps fail to create _________________
pancreatic ducts, respiratory tract, and genital tracts digestion of nutrients, absorption of oxygen, and transport of gametes respiratory infections 35-37
In cystic fibrosis, thick mucus plugs ________________ There is inadequate _________________ Includes chronic ____________ life expectancy of ______
population
In diffusion, the movements of individual molecules are random. However, the movement of a __________ of molecules may be directional.
normal: cilia move together in wave-like motions to transport mucus towards the mouth; the mucus contains dirt and bacteria cystic fibrosis: cilia are deformed and do not move together, causing a buildup of mucus; the mucus contains dirt and bacteria
In normal cilia lining trachea, what does the cilia do compared to cilia in the cilia lining trachea of someone with cystic fibrosis?
From side with higher water concentration to side with lower water concentration
In osmosis, how is water transported? (what concentration)
membrane proteins
In the fluid mosaic model, the __________ is a fluid-structure with a "mosaic" of various __________ embedded in or attached to a double layer (bilayer) of phospholipids.
selectively permeable
Like all biological membranes, the plasma membrane is, __________________ allowing some substances to cross more easily than others.
hydrophobic
Membrane molecules are held in place by relatively weak _____________ interactions.
"Brush Border" Milking action Actin filaments shorten Push contents into cell
Microvilli form a _____________ they have a _________ action, in which the following two things happen, _________________
transport proteins
Most _______________ are very specific. They transport some substances but not others
drift
Most of the lipids and some proteins ________ laterally in the plane of the membrane but rarely flip-flop from one phospholipid layer to the other.
Respiratory tract, uterine tubes, ventricles of the brain, efferent ductules of testes
Motile cilia are located in the following, _______________
energy
No work must be done to move substances down the concentration gradient; diffusion is a spontaneous process, needing no input of _______
cytoplasmic extracellular combine
On the ______________ side of the membrane, some membrane proteins are attached to the cytoskeleton. On the ____________ side of the membrane, some membrane proteins attach to the fibers of the extracellular matrix. These attachments ________ to give animal cells a stronger framework than the plasma membrane itself could provide.
cytoskeleton
On the cytoplasmic side of the membrane, some membrane proteins are attached to the ____________
extracellular matrix
On the extracellular side of the membrane, some membrane proteins attach to the fibers of the _____________________
nasal cavity/sinuses trachea lung middle ear infertility/fertility problems
Organs affected by cystic fibrosis what kind of problems can be caused?
amphipathic molecules
Phospholipids and most other membrane constituents are ___________________ which have both hydrophobic and hydrophilic regions
Cl-, Na+ ions and H2O
Saline layer at cell surface due to chloride pumps move ______ out of cell. _____ and _____ follow
within slowly
Some large membrane proteins drift _______ the phospholipid bilayer, although they move more ________ than the phospholipids
motor proteins, cytoskeleton cytoskeleton, extracellular matrix
Some proteins move in a very directed manner, perhaps guided or driven by ______________ attached to the ____________. Other proteins never move and are anchored to the _______________ or to the ________________.
steroid cholesterol
The _________________ is wedged between phospholipid molecules in the plasma membrane of animal cells
fluid mosaic model
The arrangement of phospholipids and proteins in biological membranes is described by the
passive transport potential energy
The diffusion of a substance across a biological membrane is ______________ because it requires no energy from the cell to make it happen. The concentration gradient itself represents _______________ and drives diffusion.
the direct activation of the intracellular effector. intermediate molecule
The drug-receptor or receptor-ligand interaction often does not result in..... Instead, often an ________________ is used as a signal to the effector.
filament, hook, basal body
The flagella is made up of 3 main parts:
faster faster long
The higher the temperature, the ________ the rate of diffusion The greater the concentration gradient, the _______ the rate of diffusion Diffusion cannot move molecules rapidly over _______ distances
less fluid less solid
The membrane with cholesterol is __________ at higher temperatures, but ___________ at lower temperatures
facilitated diffusion
The passive movement of molecules down their concentration gradient with the help of transport proteins
1. Transport of specific solutes into or out of cells 2. Enzymatic activity, sometimes catalyzing one of a number of steps of a metabolic pathway 3. Signal transduction, relaying hormonal messages to the cell 4. Cell-cell recognition, allowing other proteins to attach two adjacent cells together 5. The intercellular joining of adjacent cells with a gap or tight junctions 6. Attachment to the cytoskeleton and extracellular matrix, maintaining cell shape and stabilizing the location of certain membrane proteins
The proteins of the plasma membrane have six major functions:
synthesis, degradation amplify, dampen
The rate of __________ and ___________ of an intermediate molecule is tightly regulated to control the magnitude of response to receptor activation, and this regulation can be used to ___________ or __________ the response.
diffuse receptor-ligand
The second messenger molecule can act locally, or can _________ distally to convey the signal to a multitude of targets; and multiple second messenger systems can interact to produce complex responses to ____________ binding
integral and peripheral
There are two major populations of membrane proteins:
active enzymes and appropriate permeability
To work properly with __________________ and _________________, membranes must be about as fluid as salad oil.
Glycocalyx
Unique fuzzy coat external to the plasma membrane Carbohydrate moieties of membrane glycoproteins and glycolipids
Specific proteins facilitate the passive transport of water and selected solutes
What happens in facilitated diffusion?
kidney cells; it allows them to take up water from urine before it is excreted; 180 L
What organ cells has a high level of aquaporins and what does this allow it do to? It has been estimated that a person would have to drink ________ of water per day and excrete the same volume if the organ did not perform this function.
flagella
Whiplike structure with axoneme identical to cilium, but much longer
Glycolipids, 5%
_% of the membrane lipids Phospholipids with short carbohydrate chains on extracellular face
cholesterol, 20%
__% of the membrane lipids Holds phospholipids still and can stiffen membrane in animal membranes, it stabilizes membrane fluidity to make the bilayer strong and flexible.
Enzymes
____________ in the membrane may become inactive if their activity requires them to move within the membrane
Dynein arms ATP
_______________ "crawl" up adjacent microtubule, bending the cilia uses energy from ______
receptor-ligand, degraded
an intermediate molecule is synthesized or released in response to the _____________ interaction, and then ___________ afterwards.
aquaporin
channel protein that facilitates the diffusion of water
fluidity buffer
cholesterol acts as a "_______________" for the membrane, resisting changes in membrane fluidity as temperature changes
axoneme
core of cilia that is the structural basis for movement
second messenger
molecule inside cells that acts to transmit signals from a receptor to a target.
1. chemical messenger 2. breakdown products 3. ions 4. CAM of another cell 5. receptor 6. enzyme 7. ion channel 8. gated ion channel 9. cell-identity marker 10. cell-adhesion molecule
name these parts of this diagram that show proteins in the plasma membrane
peripheral proteins
not embedded in the lipid bilayer at all. Instead, they are loosely bound to the surface of the membrane, often to integral proteins
hook
part of a flagellum that connects filament to basal body aka the motor portion
basal body
part of a flagellum that is anchored in the cytoplasmic membrane and cell wall, it is a rotary molecular motor
filament
part of a flagellum: long, thin, helical structure extending from cell
integral proteins
penetrate the hydrophobic interior of the lipid bilayer, usually completely spanning the membrane as transmembrane proteins.
amphiphilic
phospholipids are ________ molecules arranged in a bilayer
fluid rotate
phospholipids drift and move like a _________ They drift laterally and __________
hydrophilic, hydrophobic
phospholipids have a ________________ head (polar) and a _______________ tail (non-polar)
98%, 75%
phospholipids make up ____ of molecules and ____ of membrane lipids
channel proteins
provide hydrophilic corridors for the passage of specific molecules or ions
phospholipids, steroids, proteins, and other molecules
the bilayer is a mosaic mixture of __________________
organization of cell membranes hydrophobic interactions that cause bilayer
the fluid mosaic model describes the _________________ and ________________
identical twins
the glycocalyx is unique to everyone but ___________
lipids and proteins, carbohydrates
the main macromolecules in membranes are __________ and ________, but ___________ are also important
phospholipids
the most abundant lipid in the plasma membrane
osmosis
the passive transport of water. Specifically, diffusion of water from one side of a selectively permeable membrane to the other
diffusion
the random movement of molecules of any substance to spread out in the available space
channel proteins & carrier proteins
two types of transport proteins facilitate the movement of molecules or ions across membranes
Hydrophobic molecules
type of second messenger system: DAG and phosphatidylinositols which do most of their work from the intermembrane space
soluble proteins
type of second messenger system: Jak/STAT, NF-kB, etc
ions
type of second messenger system: ionised calcium, potassium and sodium
gases
type of second messenger system: nitric oxide (NO) and carbon monoxide (CO) which diffuse easily through lipid and water alike
Hydrophilic molecules
type of second messenger system: type of second messenger system: cAMP, cGMP and IP3 - which diffuse freely in the cytosol
Hydrophobic molecules Hydrophilic molecules Ions Gases Soluble proteins
types of second messenger systems
Movement is more undulating, snakelike No power stroke or recovery stroke as in cilia
describe the movement of flagella
passive transport
diffusion of a substance across a membrane with no energy investment`
tail of sperm
example of a flagellum
Protection Cell adhesion Immunity to infection Fertilization Defense against cancer Embryonic development Transplant compatibility
functions of the glycocalyx
glycocalyx
glycolipids contribute to ____________
microvillus
has a dense bundle of cross-linked actin filaments, which serves as microvilli's structural core.
cystic fibrosis
hereditary disease causing abnormal chloride pumps
transmembrane proteins
integral proteins that span the membrane; membrane carriers through either Active transport or facilitated diffusion
the presence or absence of an electrical, chemical, or physical stimulus.
ion channels or gated channels open and close depending on?
gated channels
many ion channels function as ___________
Antiport (countertransport) Na+ is transported into the cell as H+ is transported out
membrane carriers - carries 2+ solutes in opposite directions example?
Symport (cotransport) glucose binding to symporter in the membrane this binding alters the shape of symporter, then both glucose and Na+ are transported into the cell
membrane carriers - carries 2+ solutes simultaneously in same direction example?
uniport glucose carriers in urine
membrane carriers - either active transport or facilitated diffusion - carries one solute at a time example?
