Biology Holt McDougal Chapter 3

cell theory

theory that states that all organisms are made of cells, all cells are produced by other living cells, and the cell is the most basic unit of life

Robert Hooke

Determined that all living things are made of cells; came up with the name of "cells"

cytoplasm

jellylike substance inside cells that contains molecules and, in some cells, organelles

eukaryotic cell

cell that has a nucleus and other membrane-bound organelles

prokaryotic cell

cell that does not have a nucleus or other membrane-bound organelles

organelle

structure that is specialized to perform a distinct process within a cell

cytoskeleton

network of proteins, such as microtubules and microfilaments, inside a eukaryotic cell that supports and shapes the cell

nucleus

organelle made up of a double membrane that acts as the storehouse for most of a cell's DNA

endoplasmic reticulum

interconnected network of thin, folded membranes that produce, process, and distribute proteins

ribosome

organelle that links amino acids together to form proteins; makes proteins

Golgi apparatus

stack of flat, membrane-enclosed spaces containing enzymes that process, sort, and deliver proteins

vesicle

small organelle that contains and carries materials within the cytoplasm

mitochondrion

bean-shaped organelle that supplies energy to the cell and has its own ribosomes and DNA

vacuole

organelle that is used to store materials such as water, food, or enzymes, that are needed by the cell

lysosome

organelle that contains enzymes

centriole

small cylinder-shaped organelle made of protein tubes arranged in a circle; divided in mitosis

cell wall

rigid structure that gives protection, support, and shape to cells in plants, algae, fungi, and bacteria

chloroplast

organelle made up of numerous membranes that are used to convert solar energy into chemical energy; contains chlorophyll

cell membrane

double-layer of phospholipids (bilayer) that forms a boundary between a cell and the surrounding environment and controls the movement of substances into and out of a cell

phospholipid

molecule that forms a double-layered cell membrane; made up of glycerol, a phosphate group, and two fatty acids

fluid mosaic model

model that describes the arrangement and movement of the molecules that make up a cell membrane

selective permeability

condition or quality of allowing some, but not all, materials to cross a barrier or membrane

receptor

protein that detects a signal molecule (ligand) and performs an action in response

passive transport

movement of molecules across the cell membrane without energy input from the cell

concentration gradient

difference in the concentration of a substance from one location to another

diffusion

movement of dissolved molecules in a fluid or gas from a region of higher concentration to a region of lower concentration

osmosis

diffusion of water molecules across a semipermeable membrane from an area of higher water concentration to an area of lower water concentration

isotonic

solution that has an equal concentration of dissolved particles compared with another solution

hypertonic

solution that has a higher concentration of dissolved particles compared with another solution

hypotonic

solution that has a lower concentration of dissolved particles compared with another solution

facilitated diffusion

diffusion of molecules assisted by protein channels that pierce a cell membrane

active transport

movement of molecules across a membrane from a region of lower concentration to region of higher concentration; requires energy input by a cell

endocytosis

uptake of liquids or large molecules into a cell by inward folding of the cell membrane; a form of active transport

exocytosis

release of substances out a cell by the fusion of a vesicle with the membrane; a form of active transport

phagocytosis

uptake of a solid particle into a cell by engulfing the particle