Chapter 3 Flashcards
What is a cell?
The smallest unit capable of carrying out all the basic functions to ensure its own survival.
What is the typical size range of human cells?
10-20 micrometers (range = 2 microns to 1 meter).
How many types of cells are there in humans?
Over 250 types.
What are the main components of a cell?
- Plasma membrane
- Cytoplasm
- Nucleus
What is the function of the plasma membrane?
- Mechanical barrier
- Selective transport
What is the structure of the lipid bilayer in the plasma membrane?
- Phospholipids
- Cholesterol
- Membrane proteins
- Surface carbohydrates
What do the polar heads of phospholipids do?
Orient toward watery extracellular fluid (ECF) and intracellular fluid (ICF).
What do the non-polar tails of phospholipids do?
Orient toward each other inside of the bilayer.
What role does cholesterol play in the plasma membrane?
Makes the bilayer stronger and more flexible.
What are the functions of membrane proteins?
- Form pores (channel proteins)
- Transport larger molecules (transporters)
- Transmit signals (receptors)
- Carry out chemical reactions (enzymes)
- Anchor cytoskeleton and extracellular matrix (attachment)
- Provide cell-cell recognition (glycoproteins)
What is glycocalyx?
Carbohydrate coating on cell surface.
What are the types of cell junctions?
- Tight junctions
- Desmosomes
- Gap junctions
True or False: The plasma membrane is selectively permeable.
True.
What factors determine if a substance will cross the plasma membrane?
- Solubility in lipid
- Size of the molecule
- Presence of a driving force
What is diffusion?
Net movement of molecules from a region of high concentration to a region of low concentration without energy.
What happens when net diffusion equals zero?
The system is at equilibrium.
What factors affect the rate of diffusion?
- Concentration gradient
- Temperature
- Mass (molecular weight)
- Membrane surface area
- Diffusion distance
What is osmosis?
Net diffusion of water down its own concentration gradient.
What is osmolarity?
The concentration of solute in a solution, typically expressed in osmoles per liter.
What are isotonic, hypertonic, and hypotonic solutions?
- Isotonic: equal solute concentration
- Hypertonic: higher solute concentration
- Hypotonic: lower solute concentration
What is facilitated diffusion?
Movement of larger molecules or those with poor lipid solubility using transport proteins.
What is active transport?
Movement of substances against a concentration gradient requiring energy (ATP).
What is vesicular transport?
Transport of very large molecules and fluids requiring energy, involving exocytosis or endocytosis.
What are the three types of endocytosis?
- Phagocytosis
- Pinocytosis
- Receptor-mediated endocytosis
What is phagocytosis?
Cell eating; pseudopods engulf the particle forming a food vacuole.
What is pinocytosis?
Cell drinking; membrane dimples inward and buds off as a vesicle.
What is receptor-mediated endocytosis?
Involves specialized receptors forming a coated vesicle.
What occurs during exocytosis?
Waste products and secretion products are moved out of cells via vesicles fusing to the cell surface.
What is cytosol?
Gel-like fluid component of the cytoplasm.
What are organelles?
Specialized structures within a cell that perform distinct functions.
What is the function of mitochondria?
Produce ATP, the usable form of energy.
What is the role of the rough endoplasmic reticulum (RER)?
Protein synthesis; makes proteins destined for export or cell membranes.
What is the function of the Golgi complex?
Processes, sorts, and directs newly synthesized proteins from the ER.
What do lysosomes do?
Contain digestive enzymes to deal with cell debris or foreign material.
What is the function of the cytoskeleton?
Provides structure and shape, aids in cell motility, and distributes organelles.
What are microvilli?
Surface features that increase the surface area of a cell.
What is the function of cilia?
Movement of fluids across the cell surface.
What is the role of flagella?
Propulsion of the cell.
