Cell Membrane (Phospholipid Bilayer)

Question 1

Exocytosis

Answer 1

Exocytosis is a process in which an membrane bounded sphere moves to the plasma membrane and subsequent fusion of the vesicular membrane and plasma membrane ensues. Many cellular processes involve exocytosis.

Question 2

Phagocytosis

Answer 2

In cell biology, phagocytosis (from Ancient Greek φαγεῖν (phagein) , meaning “to devour”, κύτος, (kytos) , meaning “cell”, and -osis, meaning “process”) is the process by which a cell—often a phagocyte or a protist—engulfs a solid particle to form an internal vesicle known as a phagosome.

Question 3

Contractile vacuole

Answer 3

A contractile vacuole (abbreviation: CV) is a sub-cellular structure (organelle) involved in osmoregulation. It is found predominantly in protists and in unicellular algae. It was previously known as pulsatile or pulsating vacuole.

Question 4

Osmosis

Answer 4

the tendency of a fluid, usually water, to pass through a semipermeable membrane into a solution where the solvent concentration is higher, thus equalizing the concentrations of materials on either side of the membrane.

Question 5

Facilitated diffusion

Answer 5

Facilitated diffusion (also known as facilitated transport or passive-mediated transport) is the process of spontaneous passive transport (as opposed to active transport) of molecules or ions across a biological membrane via specific transmembrane integral proteins.

Question 6

Plasmolysis

Answer 6

Plasmolysis is the process in which cells lose water in a hypertonic solution. The reverse process, cytolysis, can occur if the cell is in a hypotonic solution resulting in a lower external osmotic pressure and a net flow of water into the cell.

Question 7

Vesicle

Answer 7

a small sac or cyst.

Question 8

Concentration gradient

Answer 8

The formal definition of concentration gradient is the process of particles, which are sometimes called solutes, moving through a solution or gas from an area of higher number of particles to an area of lower number of particles. The areas are typically separated by a membrane.

Question 9

Equilibrium

Answer 9

a state in which opposing forces or influences are balanced.

Question 10

Turgor pressure

Answer 10

Turgor pressure pushes the plasma membrane against the cell wall of plant, bacteria, and fungi cells as well as those protist cells which have cell walls.

Question 11

Phagocyte

Answer 11

Phagocytes are cells that protect the body by ingesting harmful foreign particles, bacteria, and dead or dying cells.

Question 12

Endocytosis

Answer 12

Endocytosis is a form of active transport in which a cell transports molecules (such as proteins) into the cell (endo- + cytosis) by engulfing them in an energy-using process.

Question 13

Ion channel

Answer 13

Ion channels are pore-forming membrane proteins whose functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by gating the flow of ions across the cell membrane, controlling the flow of ions across secretory and epithelial cells, and regulating cell volume.

Question 14

Cytolysis

Answer 14

Cytolysis, or osmotic lysis, occurs when a cell bursts due to an osmotic imbalance that has caused excess water to move into the cell.

Question 15

Isotonic

Answer 15

one of three types of tonicity that characterize a solution’s concentration. A sports drink that contains similar concentrations of salt and sugar to the human body.

Question 16

Hypotonic

Answer 16

In a hypotonic solution the total molar concentration of all dissolved solute particles is less than that of another solution or less than that of a cell. If concentrations of dissolved solutes are less outside the cell than inside, the concentration of water outside is correspondingly greater.

Question 17

Hypertonic

Answer 17

Any solution with a higher salt concentration than normal body cells so that the water is drawn out of the cells by osmosis; any solution with a higher osmotic pressure than another solution

Question 18

Diffusion

Answer 18

Diffusion refers to the process by which molecules intermingle as a result of their kinetic energy of random motion. Consider two containers of gas A and B separated by a partition. The molecules of both gases are in constant motion and make numerous collisions with the partition.

Question 19

Passive transport

Answer 19

Passive transport is a movement of biochemicals and other atomic or molecular substances across cell membranes without need of energy input.

Question 20

Active transport

Answer 20

Active transport is the movement of molecules across a cell membrane from a region of their lower concentration to a region of their higher concentration in the direction against some gradient or other obstructing factor (often a concentration gradient). Requires energy

Question 21

Sodium potassium pump

Answer 21

The process of moving sodium and potassium ions across the cell membrance is an active transport process involving the hydrolysis of ATP to provide the necessary energy. It involves an enzyme referred to as Na+/K+-ATPase.

Question 22

carrier protein

Answer 22

carrier proteins are involved in the movement of ions, small molecules, or macromolecules, such as another protein, across a biological membrane.

Question 23

Pinocytosis

Answer 23

In cellular biology, pinocytosis (pino- + cytosis), otherwise known as cell drinking, fluid endocytosis, and bulk-phase pinocytosis, is a mode of endocytosis in which small particles are brought into the cell, forming an invagination, and then suspended within small vesicles.