Anatomy and Physiology Chapter 3 (Tortora)

chromosome

is a single molecule of DNA associated with several proteins and containing thousands of hereditary units called genes

cytosol

is the fluid portion of the cytoplasm containing water, dissolved solutes and suspended particles

carriers

are integral membrane proteins which selectively move polar molecules or ions from one side of the plasma membrane to the other

ligand

is a specific molecule which binds to a receptor protein within the plasma membrane

glycocalyx

is formed by the glycolipids and glycoproteins at the extracellular fluid side of the plasma membrane forming an extensive sugary coat for cells; this sugary coat has many functions

genes

are the hereditary units which control most aspects of cellular structure and function

transmembrane proteins

Integral proteins which span the entire lipid bilayer and protrude into both the cytosol and the extracellular fluid are

phospholipids

are molecules which make up 75% of membrane lipids; they contain phosphorus at their hydrophilic end and two fatty acids at their hydrophobic end.

amphipathic

molecules are molecules which have both polar and nonpolar parts; phospholipids are an example.

glycolipids

are molecules which make up 5% of membrane lipids; they have attached carbohydrate groups and are only found in the part of the bilayer facing the extracellular fluid

cholesterol

is a steriod maolecule which makes up 20% of the membrane lipids: it has the typical four-rings structure of the steriod molecules: it helps stabalize the lipid bilayer

integral proteins

The proteins which extend into or through the lipid bilayer and are firmly embedded in it are

impermeable

means that a structure does NOT permit the passage of substances through it.

linkers

are integral or peripheral protein molecule which anchor proteins in the plasma membranes of neighboring cells to one another or to protein filaments inside or outside the cell

organelles

are small structures found in the cytoplasm which have characteristic shapes and specific functions

hydrophobic

The water-hating, nonpolar part of an amphipathic molecule is said to be

receptors

are integral proteins which are cellular recognition sites; each type of receptor recognizes and binds to a specific type of molecule called a ligand

permeable

means that a structure permits the passage of substances through it.

nucleus

is a large organelle which holds most of a cell's DNA in the form of chromosomes; it is the organelle which controls the functions of the cell

identity markers

are membrane glycoproteins and glycolipids which enable a cell to recognize other cells of the same type during tissue formation or to respond to potentially dangerous foreign cells; the ABO blood type markers are a good example.

glycoproteins

Proteins with carbohydrate groups attached to the end of the protein which protrudes into the extracellular fluid are

peripheral proteins

are proteins which are not firmly embedded in the membrane; they are loosely associated with the polar heads of membrane lipids or with integral proteins at the inner or outer surface of the membrane

membrane fluidity

The property by which most of the plasma membrane lipids and proteins easily rotate and move sideways in their own half of the lipid bilayer;this property allows the membrane to self-seal if torn; proteins seldom flip-flop from one half of the bilayer to the other

enzymes

are either integral or peripheral protein molecules which catalyze specific chemical reactions at the inside or outside surfaces of the plasma membrane of the cell.

ion channels

are integral membrane proteins which form pores or holes in the membrane through which specific ions can move into or out of the cell; most of these are selective for a specific ion

hydrophilic

The water-loving, polar part of an amphipathic molecule is said to be

selectively permeable

means that a structure permits some substances to pass through it but not others; the lipid bilayer is permeable to nonpolar, uncharged molecules but impermeable to ions and large polar molecules.

lipid bilayer

two back-to-back layers made up of three types of lipid molecules, primarily phospholipid

plasma membrane

A cell's flexible selectively-permeable outer surface is its

cytoplasm

all the cellular contents between the plasma membrane and the nucleus.

symporters

are carrier proteins which can move two substances the same direction across the plasma membrane using the concentration gradient of one of the two substances.

hypotonic solution

the solution outside the cell has a lower concentration of solutes than the cytosol inside the cell causing water molecules to enter the cell and rupture it.

secondary active transport

uses energy stored in an ionic concentration gradient to move substances against their concentration gradients.

diffusion

is a passive process in which the random mixing of particles in a solution occurs because of the particles' kinetic energy; both the solute and the solvent particles undergo this process.

primary active transport

is the process in which some solutes, which must enter or leave cells against their concentration gradients, can be moved by use of ATP specifically for energy by the cell.

transport maximum

Once all of the carrier proteins are occupied, the number of solute molecules that can move across the membrane is limited by the..

aquaporins

Integral membrane proteins which serve as water channels are called

concentration gradient

A difference in the concentration of a chemical from one side of the plasma membrane to the other side is called a

facilitated diffusion

is the process by which solutes which are too polar or highly charged can cross the plasma membrane assisted by an integral membrane protein.

tonicity

The measure of a solution's ability to change the volume of cells by altering their water content is .

hemolysis

The process in which cell membranes are ruptured because the solution outside the cell has a lower concentration of solutes than the cytosol inside the cell causing water molecules to enter the cell is called .

channel-mediated facilitated diffusion

is a process in which a solute moves down its concentration gradient through a membrane channel (mostly ion channels) which may be gated or not gated; this process is slower than simple diffusion.

isotonic solution

the concentrations of solutes that cannot cross the plasma membrane are the same on both sides of the membrane.

passive transport

The process by which substances move down their concentration or electrical gradients to cross the plasma membrane using their own kinetic energies is

osmosis

A type of diffusion in which there is a net movement of solvent (usually water) down its concentration gradient through a selectively permeable membrane; this passive process is called .

vesicle

small, spherical sac composed of a lipid bilayer

endocytosis

process that moves materials into a cell in a vesicle formed from the plasma membrane.

transcytosis

process that moves materials across a cell in a vesicle.

crenation

When the solution outside the cell has a higher concentration of solutes than the cytosol inside the cell causing water to move out of the cell and shrinking the cell, the process is called .

primary active transport pumps

are carrier proteins which mediate primary active transport; they use 40% of the ATP produced in a typical body cell.

simple diffusion

is a passive process in which substances move freely through the lipid bilayer without the help of membrane transport proteins.

antiporters

are carrier proteins which can move two substances opposite directions across the plasma membrane using the concentration gradient of one of the two substances.

rates of diffusion

depend on many factors such as steepness of a concentration gradient, temperature, the mass of a diffusing substance, the surface area for diffusion and the diffusion distance.

receptor-mediated endocytosis

is a highly selective process in which cells take up specific ligands.

electrical gradient

A difference in electrical charge between one side of the plasma membrane to the other side is called a/an

sodium-potassium pump

is a very important type of primary active transport pump; all body cells have thousands of them.

exocytosis

process that moves materials out of a cell by fusion of a vesicle with the plasma membrane.

active transport

is the process in which some solutes which must enter or leave cells, moving "uphill" against their concentration gradients, can be moved by use of energy by the cell.

hypertonic solution

the solution outside the cell has a higher concentration of solutes than the cytosol inside the cell causing water to move out of the cell and shrinking or shriveling the cell.

carrier-mediated facilitated diffusion

is a process in which the solute binds to a carrier protein to move down its concentration gradient and the protein changes shape to move the solute into or out of the cell.

phagocytosis

is a form of endocytosis in which the cell engulfs large solid particles such as worn-out cells, whole bacteria or viruses.

pinocytosis

is the process by which tiny droplets of extracellular fluid are taken into a cell; no receptor proteins are involved and all the solutes in the extracellular fluid are brought into the cell.

bulk-phase endocytosis

is the process by which tiny droplets of extracellular fluid are taken into a cell; no receptor proteins are involved and all the solutes in the extracellular fluid are brought into the cell.

phagocyte

Macrophages and neutrophils are the two main types of .

pseudopods

are extensions of the plasma membrane of a phagocyte which are used to surround a solid particle such as a worn-out cell, whole bacterium or virus particle.

phagosome

a vesicle formed by pseudopods to engulf a solid particle.

organelles

are specialized structures within a cell that have characteristic shapes and perform specific functions in cellular growth, maintenance and reproduction.

cytoskeleton

a network of protein filaments which extends throughout the cytosol.

microfilaments

are composed of the protein, actin, and are the thinnest elements of the cytoskeleton; found mostly at the edge of the cell to generate movement and provide mechanical support as in microvilli, they anchor the cytoskeleton to integal proteins in the plasma membrane.

intermediate filaments

are composed of several different proteins and they are thicker than microfilaments; found in parts of the cell subject to mechanical stress, they help stabilize positions of organelles such as the nucleus and help attach cells to one another.

microtubules

are long, unbranched hollow tubes composed mainly of the protein, tubulin; they help determine cell shape and function in movement of organelles and chromosomes during cell division; they also move cilia and flagella.

centrosome

located near the nucleus and it consists of two components: a a pair of centrioles and a pericentriolar material.

pericentriolar material

surrounds the centrioles and contains hundreds of ring-shaped complexes composed of the protein, tubulin; the complexes are the organizing centers for growth of the mitotic spindle.

centrioles

cylindrical structures each of which is composed of 9 clusters of 3 microtubules arranged in a circular pattern; the two centrioles lie at right angles to one another; they are essential for cell division because they organize the mitotic spindle.

tubulin

protein which is found in microtubules.

cilia

numerous, short, hairlike projections that extend from the surfaces of cells and function to move fluids and mucous along the apical surfaces of the cells.

flagella

longer than cilia; their function is to move entire cells; in humans, found only on sperm cells.

ribosomes

sites of protein synthesis; they contain rRNA and consist of 2 subunits which are produced in the nucleolus; some are attached to the outer surface of the rough endoplasmic reticulum; others are free in the cytoplasm.

rough endoplasmic reticulum

a network of memebranes in the form of flattened sacs continuous with the nuclear membrane and studded with ribosomes; it produces secretory proteins, membrane proteins and organelle proteins.

smooth endoplasmic reticulum

extends from the rough endoplasmic reticulum but does not contain ribosomes on its outer surface; it synthesizes fatty acids and steroids, detoxifies drugs, and releases glucose into the blood stream.

Golgi complex

consists of 3 to 20 flattened membranous sacs called cisternae; its function is to modify, sort and package proteins, which it has received from the rough ER, for transport.

cisternae

the flattened membraneous sacs which form the Golgi complex.

transfer vesicles

They bud from the edges of the cisternae of the Golgi complex; they function to move enzymes back toward the entry face of the Golgi complex and to move proteins toward the exit face.

secretory vesicles

They leave the exit face of the Golgi complex carrying proteins which are delivered to the plasma membrane where they undergo exocytosis into the extracellular fluid.

membrane vesicles

They carry processed proteins from the exit face of the Golgi complex to the plasma membrane for incorporation into the plasma membrane itself.

lysosomes

membrane-enclosed vesicles that form from the Golgi complex and contain as many as 60 kinds of powerful digestive and hydrolytic enzymes; they help recycle worn-out cell components or even destroy entire cells.

autophagy

the process by which entire worn-out organelles are digested.

autophagosome

a vesicle formed around a worn-out organelle; this vesicle then fuses with a lysosome which digests the organelle.

autolysis

the process in which entire cells are destroyed due to a pathological condition or after death of an organism.

matrix

the central fluid-filled cavity that lies inside the inner mitochondrial membrane.

cell cycle

an orderly sequence of events by which a somatic cell duplicates its contents and divides into 2 daughter cells.

sex chromosomes

a homologous pair which does NOT contain all of the same genes; the X chromosome from the female is larger than the Y chromosome from the male; the X chromosome contains more genes than the Y chromosome.

ribosomal RNA

together with proteins forms the two segments of the ribosome.

nucleosome

one bead of the beads-on-a-string structure of chromatin; each one is a double-stranded DNA wrapped twice around a core of 8 histone proteins.

cristae

the folds in the inner mitochondrial membrane.

transfer RNA

It binds to an amino acid and holds it in place on a ribosome until it is incorporated into a protein during translation; one end carries the amino acid and the opposite end is the anticodon which attaches to the messenger RNA.

anaphase

During this the centromeres split, separating the 2 members of each chromatid pair (now called chromosomes) which then are pulled toward opposite poles of the cell by the spindle microtubules.

genome

the total genetic information carried in a cell or organism.

messenger RNA

directs the synthesis of a protein at the ribosome.

nuclear pores

large openings that extend through the nuclear membrane; small molecules pass through by diffusion; large molecules are transported through by active transport.