ch 3 - cell form & function - 'active recall'

What are the 3 basic components of a cell?

Plasma membrane, cytoplasm, extracellular fluid

What are the components of cytoplasm?

Organelles, cytoskeleton, inclusions, cytosol

What does amphipathic mean?

Has hydrophilic head and hydrophobic tail

What maintains membrane fluidity & stability?

Cholesterol

What is glycocalyx made of and do?

Glycoproteins & glycolipids

Provides protection, cell recognition, and stability to the cell membrane.

What are the 3 gated channels?

1. Ligand-gated channels—respond to specific chemical messengers when they bind to receptors

2. Voltage-gated channels—respond to electrical charge changes

3. Mechanically-gated channels—respond to physical stress on cell

What is the difference between cilia & microvilli?

Cilia are longer structures that aid in movement

• Motile cilia (those that bend and move materials)

• Nonmotile cilia (those that don’t bend or move materials) found on nearly every cell

Microvilli are shorter, and increase surface area for absorption

What is the difference between passive and active transport?

Passive = no ATP, down gradient

Active = uses ATP, against gradient

What factors affect the diffusion rate through a membrane?

• Temperature: ­^­temp, ­^­motion of particles

• Molecular weight: larger molecules move slower

• Steepness of concentration gradient: ^difference, ­^rate

• Membrane surface area: ^area, ^rate

• Membrane permeability: ^permeability, ^rate

What is osmosis?

Movement of water toward higher solute concentration

(across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration)

• Higher osmolarity/osmolality = ↑ solute concentration

• Lower osmolarity/osmolality = ↓ solute concentration

What is the normal osmolarity of body fluids?

300 mOsm/L

What is tonicity?

The ability of a surrounding solution to affect fluid volume & pressure in a cell

• Depends on concentration of solutes relative to ICF

What happens in a hypotonic solution?

Causes cell to absorb water & swell, possibly even burst (lysis)

• Has a lower solute concentration than intracellular fluid (ICF)

• Distilled water is an extreme example

What happens in a hypertonic solution?

Causes cell to lose water & shrivel (crenate)

• Has a higher solute concentration than ICF

• Sea water is an example

What happens in an isotonic solution?

The cell maintains its normal shape and volume, with no net movement of water in or out

Concentrations of solutes in solution & ICF are the same

• Normal saline (0.9% NaCl) is an example

How many Na⁺ and K⁺ are moved per cycle of the sodium-potassium pump?

3 Na⁺ out, 2 K⁺ in

• Keeps K+ concentration higher & Na+ concentration lower within the cell than in ECF

  • Necessary because Na+ and K+ constantly leak through membrane

How many ATP are used per cycle of the sodium-potassium pump?

1 ATP

Why is the sodium-potassium pump important?

Maintains resting membrane potential & Na gradient

Define uniport

Carries one type of solute

• One of the Carrier-Mediated Transport mechanisms for moving substances across membranes

  • Example: Calcium pump & aquaporin

Define symport

Carries 2 or more solutes simultaneously in the same direction (cotransport)

• Example: sodium-glucose transporters

Define antiport

Carries two or more solutes in opposite directions (counter transport)

• Example: sodium-potassium pump removes Na+ from cell, brings K+ into cell

Where are ribosomes produced?

Found in nucleoli, cytosol, outer surfaces of rough ER, and nuclear envelope

• Assemble amino acids into proteins specified by the genetic code

• Small granules of protein & rRNA

What does rough ER do?

Synthesizes, edits & modifies proteins

• parallel, flattened sacs covered with ribosomes

What does smooth ER do?

Lipid synthesis, detox alcohol & drugs, Calcium storage

What does the Golgi apparatus do?

Receives newly synthesized proteins from rough ER —> Packages & sorts proteins for —> secretion and delivery to lysosomes

What is the function of lysosomes?

Intracellular digestion of proteins, nucleic acids, complex carbohydrates, phospholipids, and other substances

What is the function of peroxisomes?

Neutralize free radicals

Detoxify alcohol, other drugs, and a variety of blood-borne toxins

• In all cells, but abundant in liver and kidney

What is the function of mitochondria?

Produce ATP

‘Powerhouse of the cell’

Which junction seals cells together so substance cant pass between?

Tight junction

Which junction resists cells from pulling apart?

Desmosomes

Which junction allows ion passage?

Gap junctions

What is the difference between multipotent and unipotent stem cells?

Multipotent → multiple cell types. Unipotent → one cell type.

What is endocytosis?

A vesicular processes that bring material into cell

• Phagocytosis = “cell eating,” engulfing large particles

• Pinocytosis = “cell drinking,” taking in droplets of ECF containing molecules useful in the cell

• Receptor-mediated endocytosis = particles bind to specific receptors on plasma membrane

What is exocytosis?

Discharging material from the cell

What is transcytosis?

Moving materials across the cell

• Utilizes motor proteins energized by ATP