Cell Physiology Flashcards
Some small, _________ molecules (like ___________) can diffuse through the lipid bilayer easily due to their hydrophobic nature.
nonpolar, oxygen and carbon dioxide
In carrier-mediated transports, this refers to the specificity of the carrier protein for a particular stereoisomer or enantiomer of a molecule.
Stereospecificity
What is a common feature shared by simple and facilitated diffusion of glucose?
(A) Occurs down an electrochemical gradient
(B) Is saturable
(C) Requires metabolic energy
(D) Is inhibited by the presence of galactose
A
Another name for tight junctions
Zonula occludens
_________ are channel proteins that specifically facilitate the rapid passage of water molecules through the membrane
Aquaporins
Larger or ______ molecules (such as _____________) cannot pass through the bilayer without the assistance of specific transport proteins.
polar, ions and sugars
Sarcoplasmic and endoplasmic reticulum Ca2+-ATPase is called _________.
SERCA
Proteins that are membranous structures of the cell can be ______________ and ______________.
Integral proteins, peripheral proteins
It is a macromolecule that serves as an energy storage, thermal insulation, and an important role in structural integrity of cells. It is an essential component of cell membranes, being mainly insoluble in water.
Lipids
For sodium-potassium pumps, both Na+ and K+ are transported against their electrochemical gradients.
True or false?
True
Van’t Hoff’s law, which states that osmotic pressure
depends on the concentration of osmotically active
particles. The concentration of particles is converted to
pressure according to what equation?
π = g × C × RT
π = osmotic pressure (mm Hg or atm)
g = number of particles in solution (osm/mol)
C = concentration (mol/L)
R = gas constant (0.082 L—atm/mol—K)
T = absolute temperature (K)
What are some functions of proteins in biological systems?
- Enzymes: Catalyze chemical reactions in the cell.
- Structural Proteins: Provide support and shape to cells and tissues (e.g., collagen in connective tissues).
- Transport Proteins: Carry molecules such as oxygen (hemoglobin) or ions across cell membranes.
- Hormones: Regulate various physiological processes (e.g., insulin).
- Antibodies: Part of the immune system and involved in recognizing and defending against pathogens.
- Receptors: Bind to specific molecules (ligands) and transmit signals within cells.
- Motor Proteins: Generate movement within cells (e.g., myosin in muscle contraction).
- Storage Proteins: Store essential molecules or ions for later use (e.g., ferritin stores iron).
This is a characteristic for carrier-mediated transports as structurally related solutes compete for transport
sites on carrier molecules. For example, galactose is a
competitive inhibitor of glucose transport in the small intestine.
Competition
Give some functions of the cell membrane
- Selective transport of molecules
- Cell recognition
- Cell communication
- Tissue organization
- Enzymatic activity
- Cell shape (+ cytoskeleton)
Which of the following processes facilitate the transport of D- and L-glucose proceeding at the same rate down an electrochemical gradient?
(A) Simple diffusion
(B) Facilitated diffusion
(C) Primary active transport
(D) Cotransport
A
What are the types of vesicular transport (under endocytosis)?
Phagocytosis
Pinocytosis
Receptor-mediated cytosis
These are proteins that are attached only to one surface of the membrane and do not penetrate all the way through; only control the transport of substances through the cell membrane “pores.” They are loosely attached to the cell membrane by electrostatic interactions.
Peripheral proteins
These are proteins that protrude all the way through the membrane like structural channels, carrier proteins, and receptors (for water-soluble chemicals)
Integral proteins
They are water-fearing molecules like oil that lacks affinity for water.
Hydrophobic
It is a type of passive transport that is not carrier mediated, not requiring metabolic energy.
Simple diffusion
They are water-loving molecules that get dissolved in water
Hydrophilic
It is a type of passive transport that requires interaction of a carrier protein (carrier-mediated diffusion)
Facilitated diffusion
A measure of the concentration of solute particles (ions or molecules) per unit volume of a solution and is typically expressed in units of osmoles per liter (osmol/L or Osm/L)
Osmolarity
For Na+–K+ pump, Na+ is transported from _________ to ________ fluid and K+ is transported from ____________ to ____________ fluid, maintaining low intracellular [Na+] and high intracellular [K+].
(1) intracellular, extracellular
(2) extracellular, intracellular
What are some fat-soluble substances (NONPOLAR)?
O2
CO2
alcohols
cholesterol
steroid hormones
other lipids
Give examples of macromolecules
Carbohydrates, lipids, proteins, nucleic acids
These are attachments between cells that permit intercellular communication.
Gap junctions
If two solutions have different calculated osmolarities, the solution with the higher osmolarity is ________ and the solution with the lower osmolarity is _________.
hyperosmotic, hyposmotic
A highly specialized and efficient form of vesicular transport that relies on specific cell surface receptors that bind to particular molecules, such as ligands or target proteins, in the extracellular fluid
Receptor-mediated endocytosis
A type of vesicular transport or endocytosis that involves the engulfing and internalization of large particles, such as bacteria, dead cells, or other solid materials
Phagocytosis
It is a macromolecule composed of carbon (C), hydrogen (H), and oxygen (O) atoms. Its simplest form are monosaccharides, which cannot be further broken down into smaller sugar molecules (e.g., glucose, fructose, and galactose.).
Carbohydrate
Proteins can either be _____ proteins and ______ proteins.
structural, functional
The ______ percent of the total human body weight is constituted to fluid (mainly a water solution of ions and other substances)
60
It is a type of active transport where two or more solutes is coupled. For instance, one of the solutes (usually Na+) is transported “downhill” and provides energy for the “uphill” transport of the other solute(s).
Secondary active transport
A type of active transport that occurs against an electrochemical gradient (“uphill”) and requires direct input of metabolic energy in the form of adenosine triphosphate (ATP)
Primary active transport
They are molecules that are those not soluble in lipids or other non-polar solvents.
Lipophobic
It’s a concept that describes how substances move from one point to another when there is a difference in energy (gradient) between the two points.
Flow down gradients
For secondary active transport, if the solutes move in opposite directions across the cell membranes, it is called ________________, exchange, or antiport.
(Examples are Na+-Ca2+ exchange and Na+–H+ exchange)
countertransport
A type of vesicular transport, specifically endocytosis, in which cells ingest small droplets of extracellular fluid containing dissolved substances (such as ions, nutrients, and molecules) by forming small vesicles
Pinocytosis
For sodium-potassium pumps, the usual stoichiometry is 4 Na+/2 K+.
True or false?
False
it’s 3 Na+/2 K+
What are some water-soluble substances (POLAR)?
ions
water (H2O)
glucose
urea
The flow of water across a semipermeable membrane from a solution with low solute concentration to a solution with high solute concentration
Osmosis
The amount of pressure required to prevent the inward flow of water across a semipermeable membrane.
Osmotic pressure
A characteristic of carrier-mediated transports at which the transport rate increases as the concentration of the solute increases, until the carriers are saturated (since all the binding sites on the carrier proteins become occupied by substrate molecules)
Saturation
It is the maintenance of nearly constant conditions in the internal environment
Homeostasis
They are molecules that combine with or dissolve in lipids or fats
Lipophilic
This is a type of cell transport that is against a gradient “uphill”, requiring added energy.
Active transport
Which of the following will double the permeability of a
solute in a lipid bilayer?
(A) Doubling the molecular radius of the solute
(B) Doubling the oil/water partition coefficient of the solute
(C) Doubling the thickness of the bilayer
(D) Doubling the concentration difference of the solute
across the bilayer
B
This is a type of cell transport that follows a gradient “downhill”, which does not require added energy.
Diffusion/Passive transport
For secondary active transport, if the solutes move in the same direction across the cell membrane, it is called __________ or symport.
(Examples are Na+-glucose cotransport)
cotransport
What equation can be used to calculate osmolarity?
Osmolarity = g × C
Osmolarity = concentration of particles (Osm/L)
g = number of particles in solution (Osm/mol)
C = concentration (mol/L)
It is a macromolecule that is composed of amino acids linked together by peptide bonds to form long chains or polypeptides.
Proteins
The cytoplasm is made of? (6 substances)
- Water
- Ions (e.g. Na+, K+, Ca++)
- Carbohydrates (e.g. glucose)
- Proteins
- Lipids
- Nucleic acids
