Chapter 7: Cell Structure and Function

cell

basic unit of all forms of life

cell theory

fundamental concept of biology that states that all living things are composed of cells; that cells are the basic units of structure and function in living things; and that new cells are produced from existing cells

cell membrane

thin, flexible barrier around a cell; regulates what enters and leaves the cell

nucleus

structure that contains the cell's genetic material in the form of DNA

eukaryote

organism whose cells contain a nucleus

prokaryote

unicellular organism that lacks a nucleus

cytoplasm

all cellular contents outside of the nucleus

organelle

specialized structure that performs important cellular functions within a eukaryotic cell

vacuole

Cell organelle that stores materials such as water, salts, proteins, and carbohydrates

lysosome

cell organelle that breaks down lipids, carbohydrates, and proteins into small molecules that can be used by the rest of the cell

cytoskeleton

network of protein filaments in a eukaryotic cell that gives the cell its shape and internal organization and is involved in movement

centriole

structure in an animal cell that helps to organize cell division

ribosome

cell organelle consisting of RNA and protein found throughout the cytoplasm in a cell; the site of protein synthesis

endoplasmic reticulum

internal membrane system found in eukaryotic cells; place where lipid components of the cell membrane are assembled

golgi apparatus

organelle in cells that modifies, sorts, and packages proteins and other materials from the endoplasmic reticulum for storage in the cell or release outside the cell

chloroplast

organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy

mitochondrion

cell organelle that converts the chemical energy stored in food into compounds that are more convenient for the cell to use

cell wall

strong, supporting layer around the cell membrane in some cells

lipid bilayer

flexible double-layered sheet that makes up the cell membrane and forms a barrier between the cell and its surroundings

selectively permeable

property of biological membranes that allows some substances to pass across it while others cannot; also called semipermeable membrane

diffusion

process by which molecules tend to move from an area where they are more concentrated to an area where they are less concentrated

facilitated diffusion

process of diffusion in which molecules pass across the membrane through cell membrane channels

aquaporin

water channel protein in a cell

osmosis

Diffusion of water through a selectively permeable membrane

isotonic

when the concentration of two solutions is the same

hypertonic

when comparing two solutions, the solution with the greater concentration of solutes

hypotonic

when comparing two solutions, the solution with the lesser concentration of solutes

homeostasis

relatively constant internal physical and chemical conditions that organisms maintain

tissue

group of similar cells that perform a particular function

organ

group of tissues that work together to perform closely related functions