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cell

basic unit of life

cell differentiation

process by which a cell becomes specialized for a specific structure or function

tissue

group of similar cells that perform a particular function

nucleus

control center of the cell; contains DNA

cytoplasm

material between the cell membrane and the nucleus

plasma membrane

thin flexible barrier that regulates what enters and exits the cell; composed of two layers of lipids

nucleolus

small, dense region within most nuclei in which the assembly of proteins begins

nuclear membrane

highly porous membrane that separates the nucleus from the cytoplasm

chromatin

long strands of DNA wrapped around proteins; condenses to form chromosomes

nuclear pore

regulates materials passing through nuclear membrane

intracellular fluid

fluid residing inside the cells that provides the medium for cellular reactions

extracellular fluid

all body fluid other than that contained within cells; includes plasma and interstitial fluid

cytosol

fluid portion of the cytoplasm

organelle

specialized structure that performs specific functions within cell

free ribosome

floats around in cytoplasm; makes proteins that will stay within the cell

fixed ribosome

ribosome bound to the endoplasmic reticulum; makes proteins for export outside the cell

smooth endoplasmic reticulum

no attached ribosomes; three main functions: intracellular transport, lipid synthesis, drug and alcohol detoxification

rough endoplasmic reticulum

has attached ribosomes; produces membrane and secretory proteins

Golgi apparatus

stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum

lysosome

organelle that contains digestive enzymes

peroxisome

organelles that contain the hydrogen peroxide produced by lipid metabolism; convert the toxic hydrogen peroxide to water and oxygen using catalase

mitochondria

organelles that convert the chemical energy stored in food into ATP through cellular respiration

cytoskeleton

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

microfilament

thin, solid protein fibers that provide structural support for the cell

microtubule

tubes of protein; form the mitotic spindle during cell division, form cilia and flagella, and are used for intracellular structure and transport

microvilli

projections that increase the cell's surface area

cilia

short, hair-like structures made of microtubules that enable movement of cells or movement of materials outside a cell

flagellum

hair-like projection on a sperm cell that makes it motile

phospholipid bilayer

double layer of phospholipids that makes up plasma and organelle membranes

selective permeability

property of the plasma membrane that allows it to control movement of substances into or out of the cell

passive transport

movement of materials through a cell membrane without using energy

active transport

energy-requiring process that moves material across a cell membrane against a concentration gradient

simple diffusion

movement of molecules across the cell membrane from high to low concentration

osmosis

diffusion of water

isotonic

when the concentrations of solutes outside and inside the cell are equal

hypotonic

when the concentration of solute molecules outside the cell is lower than the concentration in the cytosol

hypertonic

when the concentration of solute molecules outside the cell is higher than the concentration in the cytosol

facilitated diffusion

movement of specific molecules across cell membranes from high to low concentration through protein channels

exchange pump

carrier mechanism that moves ions in opposite directions against their concentration gradients requiring energy

exocytosis

process by which vesicles release their contents outside the cell by fusing with the cell membrane

endocytosis

process by which a cell takes material into the cell by infolding of the cell membrane to form a vesicle

phagocytosis

process in which extensions of cytoplasm surround and engulf large particles and take them into the cell

pinocytosis

process by which certain cells engulf extracellular fluid

interphase

period of the cell cycle between cell divisions

mitosis

division of the cell nucleus

prophase

first and longest phase of mitosis, during which the chromosomes become visible

metaphase

second phase of mitosis, during which the chromosomes line up across the center of the cell

anaphase

third phase of mitosis, during which the chromosome pairs separate and move toward opposite poles

telophase

last phase of mitosis, chromosome are in two new cells and nuclear membranes start to reform

cytokinesis

division of the cytoplasm

cancer

uncontrolled cell division

tumor

a mass of abnormal cells

benign

not cancerous

malignant

cancerous

metastasis

process by which cancer cells spread from their original site through blood or lymph

epithelium

tissue that covers all free surfaces of the body

connective tissue

tissue that binds, supports, and protects body structures, includes cartilage, tendons, fat, blood

avascular

lacking a blood supply

vascular

containing blood vessels

glia

provide physical and functional support to neurons in the brain and spinal cord

irritability

ability to respond to stimuli

conductivity

ability to conduct an electric current

stem cell

unspecialized cell that can develop into a specialized cell under the right conditions

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