Unit 3: Key Terms A and P
Cell
the basic unit of structure and function in the body
Cell components
1. Nucleus, 2. Cytoplasm, 3. Plasma membrane
Nucleus
governing body that directs activities of other cellular components, largely determines type of proteins and production rate
Nuclear envelope
membrane that surrounds nucleoplasm, double phospholipid bilayer
Nucleoplasm
cytosol-like gel containing many components- water, free nucleotides, enzymes, other proteins, DNA, and RNA
Chromatin
DNA and associated proteins in nucleoplasm and loose structural arrangement
Nucleoli
center of nucleus, synthesizes ribosomes
Nuclear pores
allow substances to move between nucleus and cytoplasm
Chromatin
one extremely long DNA molecule and associated proteins: organize and fold molecule to conserve space
Chromosomes
during cell division, chromatin coil tightly an condense, 46 and 23 from each parent
Sister chromatids
identical copies of each chromosome
Organelles
cellular machinery with specific functions vital to maintaining homeostasis: some separated from the cytosol by membrane
Ribosomes
tiny granular non membrane-bound organelles: site of protein synthesis
Endoplasmic reticulum (ER)
large folded phospholipid bilayer continuous with nuclear envelope, has 2 forms
Rough ER (RER)
ribosomes attached to membrane, makes proteins
Smooth ER (SER)
no ribosomes, makes lipids
Golgi apparatus
the "mailroom" of the cell, between RER and plasma membrane, a group of flattened membranes sacs filled with enzymes and other molecules
Lysosomes
"Garbage disposal", organelles responsible for digestion of worn out cells or cellular components
Mitochondria
"power plant" of cell, membrane-bound organelles, provide majority of ATP (energy)
Peroxisomes
membrane-bound organelles, use oxygen and produce hydrogen peroxide, oxidize toxins, liver and kidney
Cytoskeleton
dynamic structure, changes function based on needs of cell
Centrosome
gel matrix containing tubulin subunits
Centrioles
ring of 9 groups of 3, modified microtubules, critical for cellular division
Microvilli
finger-like extensions of the plasma membrane with actin filament core: help maintain shape, increase the surface area of cells in organs specialized for absorption
Cilia
hair-like projections composed of microtubules and motor proteins, move in unison to propel substance past cells
Flagella
solitary: longer than cilia, found only in sperm cells,
Phospholipid bilayer
amphiphilic, polar (hydrophilic), nonpolar (hydrophobic)
Fluid Mosaic model
plasma membrane is a dynamic fluid structure with multiple components: some have the ability to move within bilayer as phospholipids move themselves
Membrane proteins
main component of plasma membranes, two types: integral, peripheral
Integral proteins
span entire membrane, "transmembrane" proteins
Peripheral proteins
found only on one side of membrane or other
Channels
transmembrane proteins allow certain substances to cross membrane and pass into or out of cell
Carrier proteins
integral proteins bind, change shape, and directly transport substances into and out of cell
Structural support
when bound to cytoskeleton, gives cell shape, helps maintain structural integrity
Receptors
bind to chemical messengers trigger sequence of events within cell ex: cell to cell communication
Enzymes
speed up chemical reactions, vital to maintaining homeostasis
Simple Diffusion
mostly nonpolar solutes (oxygen, carbon dioxide, lipids, and hydrocarbons), pass through phospholipid bilayer without membrane protein
Facilitated diffusion
charged or polar solutes, (ions and glucose), cross phospholipid bilayer with help of membrane protein (carrier or channel)
Osmosis
passive process, solvent (usually water) moves across membrane
Osmotic pressure
ability of osmosis to generate pressure
Tonicity
way to compare osmotic pressure gradients between two solutions, cytosol and ECF
Isotonic solution
some osmotic pressure, equal inside and outside, no gain or loss of water
Hypertonic solution
greater solute concentration outside cells, lose water
Hypotonic solution
greater solute concentration inside cells, gain water
Active transport
process that requires energy (ATP) to proceed as solutes move against concentration gradients (low to high)
Sodium-potassium pump
most vital for maintenance of sodium and potassium concentration gradient homeostasis
Endocytosis
fluid, molecules (even cells) taken into cell, two basic types
Phagocytosis
"cell eating", cells ingest large particles like bacteria or dead or damaged parts of the cell
Pinocytosis
"cell drinking", fluid-phase endocytosis, cells engulf fluid droplets from ECF
Receptor-medicated endocytosis
a special form of pinocytosis: receptors fill vesicles with specific molecule (cholesterol, hormones, iron)
Exocytosis
large molecules exit cell (secretion): vesicles fuse with plasma membrane, opening into ECF
Link
adjacent cells to one another
Cholesterol
lipid, stabilizes plasma membranes fluid structure during temperature changes
Glycolipids and glycoproteins
carbohydrate bound to either lipid or protein respectively, identify cell as part of body (cell recognition)
Selectively permeable
allows certain molecules to cross, prohibits passage of other molecules, critical to survival of cell
Passive transport
1. simple diffusion 2. facilitated diffusion 3. osmosis (powered by diffusion)
Active transport
require energy (ATP)
Diffusion
movement of solute molecules from high to low concentration
Equilibrium
no net movement
Concentration gradient
force that drives many types of passive transport