Chapter 3 words

Cytology

The study of cells

Gametes

The sperm of males or the oocytes of females

Somatic cells

All of the other cells in the human body

Plasma membrane

The outer boundary of a cell

Phospholipid bilayer

A two-layered covering containing phospholipids

Channel

central pore that forms a passageway

Cytoskeleton

a network of supporting filaments in cytoplasm

Integral proteins

Proteins that cannot be removed from the membrane without damaging or destroying it

Peripheral proteins

Proteins that can be easily removed from the membrane

Carrier proteins

Proteins that bind solutes and transport them across the plasma membrane

Cytoplasm

A general term for the material located between the plasma membrane and the membrane surrounding the nucleus

Organelles

structures that are suspended within the cytosol that perform specific functions for the cell

Cytosol or intracellular fluid

Fluid within a cell that contains dissolved nutrients, ions, soluble and insoluble proteins, and waste products

Nonmembranous

The adjective for organelles that are not completely enclosed by membranes

Membranous

The adjective for organelles that are completely enclosed by membranes

Actin

The protein that comprises the microfilaments in a cell

Microtubules

Small tubes comprised of tubulin

Microvilli

Small, finger-shaped projections of the plasma membrane on a cell's surface

Centrioles

Cylinders formed from microtubules; these pull chromosomes apart during mitosis

Centrosome

The cytoplasm surrounding the centrioles

Cilia

long, slender extensions of the plasma membrane that beat together to move things past the cell

Ribosomes

The organelles responsible for protein synthesis.

Proteasomes

Organelles that contain an assortment of protein-digesting enzymes

Endoplasmic reticulum

large organelle, may or may not have ribosomes on it, involved in production of proteins, lipids, etc

Transport vesicles

Little packages or sacs of proteins produced by the rough endoplasmic reticulum

Golgi apparatus

An organelle that packages, sorts and refines proteins

Lysosomes

A loose body that provides a safe place for potentially dangerous chemical reactions

Autolysis

Cell self-destruction

Peroxisomes

Break down fatty acids and produce hydrogen peroxide

Mitochondria

Produce energy within a cell

Aerobic metabolism

A method of ATP production that involves oxygen

Nucleus

The control center of a cell

Nuclear envelope

A double membrane surrounding the nucleus

Nuclear pores

Small holes in the nuclear envelope

Nucleoli

Found within the nucleus

Chromosomes

Formed from chromatin; 23 pairs of these in humans

Genetic code

The language of cells and their DNA

Gene

The functional unit of heredity

Protein synthesis

The creation of polypeptides (proteins)

Impermeable

Like a shield; not able to be penetrated

Permeability

The property of a plasma membrane that determines what can pass and what cannot

Selectively permeable

plasma membranes, for example, because they are neither impermeable nor freely permeable

Freely permeable

a membrane through which anything can pass without difficulty is said to be this

Diffusion

The tendency to move from high concentration to low concentration

gradient

areas of higher and lower solute concentration form a concentration \_____________________

Leak channels

Special passive channels through which ions can move

Osmosis

the passive movement (diffusion) of water

Osmotic pressure

An indication of the force with which pure water moves into a solution

Hydrostatic pressure

Pushing against a fluid; opposes osmotic pressure

Osmolarity or osmotic concentration

Total solute concentration in an aqueous solution (two terms)

Isotonic

a term that means solute concentration is the same on both sides of a membrane

Hypotonic

a term that means solute concentration is lower outside a membrane than inside the membrane

Hypertonic

a term that means solute concentration is higher outside a membrane than inside the membrane

Hemolysis

The bursting of a red blood cell

Crenation

The shrinking of red blood cells

Carrier-mediated transport

The type of transport in which proteins bind to ions or substrates and carry them across the plasma membrane

Cotransport (aka symport)

The type of transport in which the carrier transports two substances in the same direction simultaneously

Countertransport (aka antiport)

The type of transport in which substances are moving in opposite directions

Facilitated diffusion

A passive type of transport in which substances must be helped across the membrane by carrier proteins

Receptor site

The location on a carrier protein where facilitated diffusion takes place

Active transport

The type of transport in which ATP provides the energy needed to move ions or molecules across the membrane.

Ion pumps

Carrier proteins that carry cations and anions across a plasma membrane

Exchange pump

Carrier proteins that can perform countertransport

Sodium-potassium exchange pump

An exchange pump that ejects sodium ions and recaptures lost potassium ions

Vesicles

Small membranous sacs that form at, or fuse with, the plasma membrane

Endosomes

Another name for vesicles, especially in terms of endocytosis

Receptor-mediated endocytosis

A highly selective process in which vesicles are produced that contain a specific target molecule in high concentrations

Pinocytosis

"Cell drinking"

Phagocytosis

"Cell eating"

anchoring proteins

proteins that attach the plasma membrane to other structures and stabilize its position

recognition proteins

proteins that identify cells

receptor proteins

proteins in the plasma membrane that are sensitive to the presence of specific extracellular molecules called ligands

ligand

A molecule that binds specifically to a receptor site of another molecule.

intermediate filaments

fibers which give cells strength; insoluble and the most durable of the cytoskeletal elements

microfilaments

the smallest of the cytoskeletal elements; made of actin

myosin

a protein that comprises thick filaments

actin

a protein that comprises microfilaments

tubulin

a globular protein that comprises microtububles

thick filaments

relatively massive bundles of subunits made of myosin

basal body

the structure just beneath the cell surface to which microtubules are anchored

primary cilium

a single, nonmotile attachment which acts as a signal sensor

flagellum

an extension of the plasma membrane; beats in a wavelike fashion

small and large ribosomal subunit

two components of a functional ribosome

free ribosome

a type of functional ribosomes scattered throughout the cell

fixed ribosome

a type of functional ribosome attached to the endoplasmic reticulum

cisternae

the name of the chambers inside the endoplasmic reticulum

membrane flow

the continuous movement and exchange of membrane segments

cristae

the folds of the inner membrane of mitochondria

matrix

the fluid contents of the mitochondrion

endocytosis

Active transport process where a cell engulfs materials with a portion of the cell's plasma membrane and releases the contents inside of the cell.

exocytosis

Mechanism by which substances are moved from the cell interior to the extracellular space as a secretory vesicle fuses with the plasma membrane.

citric acid cycle

an enzymatic pathway that breaks down the absorbed pyruvate

pyruvate

Organic compound with a backbone of three carbon atoms. Two molecules form as end products of glycolysis

glycolysis

a reaction sequence that breaks down a glucose molecule into two molecules of pyruvate

perinuclear space

the space between the two layers of the nuclear envelope

nuclear matrix

a network of fine filaments that provides structural support and may be involved in the regulation of genetic activity

histones

nucleoli are composed of RNA, enzymes, and proteins with this name

nucleosome

a complex created when the DNA strands wind around histones

chromatin

a tangle of fine filaments comprised of nucleosomes within the nucleus of a cell that is not dividing

gene activation

before a gene can affect the cell, the portion of the DNA molecule containing that gene must be uncoiled and the histones temporarily removed, a process known as