Anatomy & Physiology Bio 168 Chapter 3

Phagocytosis

"Cell eating"

Autolysis

"cell suicide": digestion of a surplus cell by itself

Chemical first messenger

(epinephrine) binds to a surface recepto

Chromatin

(thread-like) composed of DNA and protein

aquaporins

- water channel proteins

One osmole (osm)

1 mole of dissolved particles

Cell theory

1) All living things made of cells

Human cell size

10-15um in diamete

Membrane proteins

2% of the molecules but 50% of the weight of membrane

Cholesterol

20% of the membrane lipids Holds phospholipids still and can stiffen membrane

Glycocalyx

A fuzzy sticky carbohydrate rich area at the cell surface unique to everyone except identical twins

Osmolarity

A measure of the total solute concentration per liter of solution

Phospholipids

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

Cytoskeleton

A network of fibers that holds the cell together, helps the cell to keep its shape, and aids in movement

selectively permeable

A property of cell membranes that allows some substances to pass through, while others cannot

Organelles

A tiny cell structure that carries out a specific function within the cell.

Kinases

Add a phosphate group to a molecule

Glycolipids

Are complexes of carbohydrates and lipids 5% of the membrane lipids

Peripheral proteins

Are proteins that are attached to the surface of the membrane. does not penetrate tethered to the cytoskeleton

Plasma membrane

Boundary of cell. Holds things together and controls entry and exit of substances.

Secondary active transport

Carrier moves solute through membrane but only uses ATP indirectly

antiport

Carries two or more solutes in opposite directions

symport

Carries two or more solutes through a membrane simultaneously in the same direction.

Pinocytosis

Cell drinking

Cytoplasm

Consists of organelles, cytoskeleton, and cytosol

Nucleus

Control center of the cell largest organelle (5 m in diameter)

Nonmembranous organelles

Cytoskeleton, centrioles, ribosomes

Exocytosis

Expulsion or secretion of materials from a cell. Replacement of plasma membrane removed by endocytosis

Three mechanisms of carrier-mediated transport

Facilitated diffusion, primary active transport, secondary active transport

cilia

Hairlike projections that extend from the plasma membrane and are used for locomotion

transport proteins

Lets things in and out of cells passively or actively.

Na+−K+ pump functions

Maintains steep Na+ concentration gradient allowing for secondary active transport Regulates solute concentration and thus osmosis and thus cell volume Maintains negatively charged resting membrane potential Produces heat

The Cytoskeleton is composed of

Microtubles, intermediate filaments, microfilaments

Receptor-mediated endocytosis

More selective endocytosis Enables cells to take in specific molecules that bind to extracellular receptors

Membranous Organelles

Nucleus, ER, golgi, lysosomes, peroxisomes, and mitochondria

Basic components of a cell

Plasma, Cytoplasm, Extracellular fluid

Exocytosis

Process by which a cell releases large amounts of material.

Glycocalyx Functions

Protection - Cell adhesion Immunity to infection Fertilization Defense against cancer -Embryonic development Transplant compatibility

Functions of membrane proteins include:

Receptors, second-messenger systems, enzymes, channels, carriers, cell-identity markers, cell-adhesion molecules

Golgi vesicles

Some vesicles become lysosomes Some vesicles migrate to plasma membrane and fuse to it Some become secretory vesicles that store a protein product for later release

Plasma Cell

Surrounds cell, defines boundaries Made of proteins and lipids

Flagella

Tail of a sperm—only functional flagellum in humans

Axoneme

The core of motile cilia, usually in a "9 + 2" array, at the center of a cilium or flagellum.

Extracellular fluid (ECF

The fluid outside the body's cells includes tissue

Inclusions

Two kinds of inclusions Stored cellular products Glycogen granules, pigments, and fat droplets Foreign bodies Viruses, intracellular bacteria, dust particles, and other debris phagocytized by a cell

Clathrin-coated vesicle in cytoplasm

Uptake of LDL from bloodstream

Centriole

a short cylindrical assembly of microtubules arranged in nine groups of three microtubules each

Golgi complex

a system of cisternae that synthesizes carbohydrates and puts finishing touches on protein synthesis

Tonicity

ability of a surrounding solution (bath) to affect fluid volume and pressure in a cell

Channel proteins

allow hydrophilic solutes and water to pass through membrane some are always open, some are gated

Limit on cell size

an overly large cell cannot support itself, may rupture For a given increase in diameter, volume increases more than surface area

Receptors

bind chemical signals

Carriers

bind solutes and transfer them across membrane

Facilitated diffusion

carrier moves solute down its concentration gradient

Primary active transport

carrier moves solute through a membrane up its concentration gradient

uniport

carries only one solute at a time

Enzymes

catalyze reactions including digestion of molecules, production of second messengers

Hypotonic solution

causes cell to lose water and shrivel (crenate)

Isotonic solution

causes no change in cell volume

Second messenger systems

communicate within cell receiving chemical message

Pseudopods

continually changing extensions of the cell that vary in shape and size

Autophagy

digestion of cell's surplus organelles

Ciliopathies

diseases that result from defects in cilia

Nuclear envelope

double membrane around nucleus

Evolution of Mitochondrion

evolved from bacteria that invaded primitive cell but survive

Microvilli

extensions of the plasma membrane. best developed in absorption

cystic fibrosis

fibrosis—hereditary disease in which cells make chloride pumps, but fail to install them in the plasma membrane

Cell-identity markers

glycoproteins acting as identification tags

Proteosomes

hollow, cylindrical organelle that disposes of surplus proteins

Osmotic pressure

hydrostatic pressure required to stop osmosis

Transmission electron microscope (TEM)

improved resolution (ability to reveal detail)

Scanning electron microscope (SEM)

improved resolution further, but only for surface features

98% of membrane molecules are

lipids

Nucleoli

masses where ribosomes are produced

Nucleoplasm

material in nucleus

Cell-adhesion molecules

mechanically link cell to extracellular material

Receptor-mediated endocytosis

moves it into the cell and exocytosis moves it out the other side

Vesicular transport

moves large particles, fluid droplets, or numerous molecules at once through the membrane in vesicles—bubble-like enclosures of membrane

Osmosis

net flow of water through a selectively permeable membrane

Simple diffusion

net movement of particles from place of high concentration to place of lower concentration

Nuclear envelope is supported by

nuclear lamina

Motile cilia

occur in respiratory tract, fallopian tubes, internal cavities of the brain, and testes. power stroke and recovery stroke

Mitochondria

organelles specialized for synthesizing ATP Continually change shape from spheroidal to thread-like

Reverse osmosis

osmosis—process of applying mechanical pressure to override osmotic pressure Allows purification of water

Lysosomes

package of enzymes bound by a membrane Generally round, but variable in shape

Rough endoplasmic reticulum

parallel, flattened sacs covered with ribosomes

Filtration

particles are driven through membrane by physical pressure

Receptor-mediated endocytosis

particles bind to specific receptors on plasma membrane

Integral proteins

penetrate the hydrophobic core of the lipid bilayer, often completely spanning the membrane (as transmembrane proteins).

G protein

relays signal to adenylate cyclase which converts ATP to cAMP (second messenger) cAMP activates cytoplasmic kinases

Active mechanisms

require energy, consume energy. These include active transport and vesicular support

Passive mechanisms

require no ATP, includes filtration, diffusion, and osmosis

Peroxisomes

resembles lysosomes but contain different enzymes and are produced by endoplasmic reticulum Function is to use molecular oxygen to oxidize organic molecules In all cells, but abundant in liver and kidney

Voltage-gated channels

respond to charge changes

Ligand-gated channels

respond to chemical messengers

Mechanically-gated channels

respond to physical stress on cell

Light microscope (LM)

revealed plasma membrane, nucleus, and cytoplasm (fluid between nucleus and surface)

Cytology

scientific study of cells

centrosome

small clear area in cell Play important role in cell division

Ribosomes

small granules of protein and RNA Found in nucleoli, in cytosol, and on outer surfaces of rough ER, and nuclear envelope

Endoplasmic reticulum

system of channels (cisternae) enclosed by membrane

Factors affecting diffusion rate through a membrane

temperature, space, size of particle

Transcytosis

transport of material across the cell by capturing it on one side and releasing it on the other

Transport maximum

transport rate when all carriers are occupied

Endocytosis

vesicular processes that bring material into cell