Membranes and Transport

Plasma membrane function

Organisms constantly bring in certain molecules and ions while keeping others out using the plasma membrane.

Major components of cell membranes

Phospholipids, protein, and sterols.

Phospholipids in an aqueous environment

Arranged in a bilayer with the polar heads of each layer located at the membrane surface.

Cause of selective permeability

The hydrophobic core formed by the phospholipid tails.

Cystic fibrosis organ

Primarily affects the lungs.

Function of membrane sterols

Maintain membrane fluidity in animal cell membranes.

Most important membrane lipid

Phospholipid.

Dual solubility molecules

Sterols, phospholipids, and proteins.

Peripheral protein example

Microtubules.

Integral proteins location

Embedded in the phospholipid bilayer.

Cell adhesion proteins function

Links cells together by recognizing and binding receptors or chemical groups on other cells or the extracellular matrix.

Transport proteins function

Form channels in the membrane that allow selected polar molecules and ions to pass through and across the membrane.

Receptor proteins function

Recognize and bind molecules from other cells that act as chemical signals.

Recognition proteins function

Identify a cell as part of the same individual or as foreign.

Radioactive iodine experiment explanation

Cells that had high radioactivity levels after treatment contain iodine transporters.

Meaning of 'glyco-'

Carbohydrate groups are attached to the molecules.

Glycocalyx

A surface coat formed by glycolipids and glycoproteins that protects the cell against chemical and mechanical damage.

Fluid part of fluid mosaic model

The phospholipid molecules which vibrate, spin, and exchange places within the same layer of the bilayer.

Fluid mosaic model proposer

S. Singer and G. Nicolson in 1972.

Mosaic part of fluid mosaic model

The membrane proteins.

Phospholipid structure

Polar end contains a phosphate group bound to alcohols or amino acids; nonpolar end contains two fatty-acid tails.

Cell fusion experiment observation

The red and green fluorescent labels will be uniformly distributed throughout the entire membrane.

Hibernation membrane adaptation

Increase in both cholesterol and double covalent bonds in phospholipids.

Barrier vs function membrane components

Lipid component functions as a selective barrier, while the protein component has specific functions such as transport, recognition, and binding.

Membrane differences

Certain proteins are unique to each membrane.

Chloroplast membrane function

Contains the enzymes that convert light energy to chemical energy in eukaryotes.

Selective permeability definition

The ability of only certain molecules to pass across a membrane.

Critical transport function

The controlled transport of ions and molecules across the membrane, vital to ionic and molecular organization.

Active transport definition

Movement of a substance from an area of low concentration to an area of high concentration using energy obtained from ATP.

Carrier molecules utilization

Utilized for both active and passive transport.

Food coloring in water

Diffuse equally throughout the container.

Easily diffused molecules

Small, hydrophobic molecules.

Facilitated diffusion dependence

Depends on a concentration gradient.

Polar and charged molecules crossing

Facilitated diffusion.

Specificity of facilitated diffusion

A specific protein will transport certain polar or charged molecules but not others.

Energy source for facilitated diffusion

Concentration gradients.

Equal solute concentrations behavior

Solute molecules continue to diffuse across the membrane.

Voltage-gated channel

A channel that opens in response to changes in ionic charge across a membrane.

Carrier proteins amino acid transport

Carrier proteins are often used by the cell to transport amino acids.

Aquaporins definition

Specific channels for water transport.

AQP1 gene mutation effect

Inability to produce concentrated urine.

Aquaporin mutation clinical differences

Different aquaporin proteins are localized to different membranes in the cell.

Osmosis water movement

Both diffusion and osmosis.

Osmosis solute concentration

Both diffusion and osmosis (movement of water from lower to higher solute concentration).

Turgor pressure

The force that pushes plant cell membranes tightly against the cell wall and supports softer tissues against gravity.

Osmotic pressure

The pressure that must be applied to a solution to prevent water movement across a membrane.

Red blood cell in beaker swelling

Cytoplasm of the cell was hypertonic to the solution in the beaker, which was hypotonic.

Plant cell in hypotonic solution

The cell wall prevents the cell from bursting.

Distilled water tonicity

Hypotonic to body cells.

Ideal environment for plant vs animal cells

Hypotonic environment for plants, isotonic environment for animal cells.

Requirement for osmosis

A selectively permeable membrane must be present.

Plasmolysis

Extreme wilting in plants where cells retract from the cell wall due to water loss.

Isotonic solution solute concentration

Equal to the solute concentration inside the cell.

Dynamic equilibrium with glucose

The volumes of the solution will be different, with a higher volume on the side that originally contained the higher concentration of glucose.

Active transport net movement

The net movement of molecules or ions from a low concentration to a higher concentration.

Active transport gradient movement

Active transport moves materials against a concentration gradient.

Membrane potential

The voltage across a membrane.

Na+/K+ pump charges

Creates a negative charge inside the cell and a positive charge outside the cell.

Electrochemical gradient

A gradient created as ions diffuse across membranes.

Calcium ion active transport

Actively transported to regulate pollen growth and fertilization.

Na+/K+ pump transport ratio

3 sodium ions out and 2 potassium ions in.

Antiport transport system

A transport system in which the transport of an ion in one direction provides energy for active transport in the opposite direction.

Secondary active transport (both high outside)

As the driving ion moves in, the transport ion moves out.

Secondary active transport (driving high, transport low)

As the driving ion moves in, the transport ion moves in.

Exocytosis purpose

To secrete protein and wastes from the cell.

Exocytic secretory vesicles origin

The Golgi complex.

Pinocytosis and phagocytosis mechanism

Accomplished in the cell by the plasma membrane.

Clathrins

Molecules that coat the inside of the cytosolic membrane to help form endocytic vesicles.

Familial hypercholesterolemia

Receptor-mediated endocytosis is inhibited.

LDL tagging heavy metal

Iron.

Exocytosis matching

Secretory vesicles that have moved through the cytoplasm along microtubules contact the plasma membrane and release their contents.

Osmosis matching

Movement of water from a hypotonic solution into a hypertonic solution across a selectively permeable membrane.

Facilitated diffusion matching

Diffusion of molecules across the plasma membrane with the assistance of transport proteins.

Phagocytosis matching

Large particles are enveloped by the cell membrane and internalized.

Pinocytosis matching

A process in which liquid droplets are ingested by living cells.

Receptor-mediated endocytosis matching

Cells internalize molecules into a cell by the inward budding of vesicles possessing receptors specific to the molecule being transported.

Diffusion matching

Movement of a molecule from an area of high concentration to an area of lower concentration.

Microfilament labeling

Found at position C in the plasma membrane diagram.

Carbohydrate groups labeling

Found at position B in the plasma membrane diagram.

Integral proteins labeling

Found at position A in the plasma membrane diagram.

Peripheral proteins labeling

Found at position E in the plasma membrane diagram.

Cholesterol labeling

Found at position D in the plasma membrane diagram.

Isotonic red blood cells micrograph

Depicted in panel C.

Hypertonic red blood cells micrograph

Depicted in panel A.

Hypotonic red blood cells micrograph

Depicted in panel B.

Blood transfusion compatibility (AB and A)

Type AB blood recognizes both A and B proteins so it does not attack type A blood, whereas type A blood lacks B protein recognition and attacks AB blood.

Membrane cold adaptation mechanism

Increasing double bonds in membrane lipids prevents tight packing, stopping lipids from freezing at lower temperatures.

Water membrane crossing mechanism

Water slips through transient spaces between flexing phospholipid tails or passes specifically through aquaporins.

Transport specificity and directionality

Directional because ions/molecules move strictly in or out; specific because only certain ions and molecules can cross.

Na+/K+ pump mechanism steps

Three cytosolic sodiums bind, ATP hydrolyzes causing conformation change, sodiums release extracellularly, two potassiums bind, transporter changes conformation to release potassiums into cytosol and resets.

CFTR mutation ion transport

False - chloride

Cholesterol and membrane thickness

False - fluid

Facilitated diffusion saturation

False - simple diffusion

Facilitated diffusion membrane components

True - proteins

Animal cell in hypertonic solution swelling

False - hypotonic

Hypertonic environment for healthy plant

False - hypotonic

Primary active transport ATP hydrolysis

True

Calcium pump concentration gradient

True

Bulk endocytosis alias

True

Receptor-mediated endocytosis coated pit

True