AP Biology Unit 2

theory

well-tested explanation that unifies a broad range of observations

cell theory

idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells

microscope

an optical instrument used for viewing very small objects, such as mineral samples or animal or plant cells, typically magnified several hundred times.

vacuole

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

cytoplasm

A jellylike fluid inside the cell in which the organelles are suspended

lysosome

A small, round cell structure containing chemicals that break down large food particles into smaller ones.

organelle

A tiny cell structure that carries out a specific function within the cell

centriole

structure in an animal cell that helps to organize cell division

chloroplast

An organelle found in plant and algae cells where photosynthesis occurs

cytoskeleton

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

nucleus

A part of the cell containing DNA and RNA and responsible for growth and reproduction

nuclear envelope

A double membrane that surrounds the nucleus in the cell

nucleolus

Found inside the nucleus and produces ribosomes

cell wall

A rigid structure that surrounds the cell membrane and provides support to the cell in plant cells

chromosomes

threadlike structures made of DNA molecules that contain the genes

plasmid

A small, circular section of extra DNA that confers one or more traits to a bacterium and can be reproduced separately from the main bacterial genetic code.

Endoplasmic Reticulum

A system of membranes that is found in a cell's cytoplasm and that assists in the production, processing, and transport of proteins and in the production of lipids.

ribosome

site of protein synthesis

Golgi apparatus

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

vesicle

A membrane bound sac that contains materials involved in transport of the cell.

Mitochondrion

converts the chemical energy stored in food into compounds such as glucose

cilia

Hairlike projections that extend from the plasma membrane and are used for locomotion

flagellum

A long, hairlike structure that grows out of a cell and enables the cell to move.

prokaryotic cell

A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles; found only in the domains Bacteria and Archaea.

eukaryotic cell

A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Examples of organisms with these cells are protists, plants, fungi, and animals.

plant cell

contains a cell wall, chloroplast and large vacuole

animal cell

these cells have lysosomes

compartmentalization

Membrane-bound organelles allow different parts of the cell to perform different functions at the same time

concentration gradient

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

osmosis

Diffusion of water through a selectively permeable membrane

osmotic pressure

pressure that must be applied to prevent osmotic movement across 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 (more particles outside the cell)

hypotonic

when comparing two solutions, the solution with the lesser concentration of solutes (less particles outside the cell)

cell membrane

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

facilitated diffusion

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

phospholipid

A molecule that is a constituent of the inner bilayer of biological membranes, having a polar, hydrophilic head and a nonpolar, hydrophobic tail.

active transport

Energy-requiring process that moves material across a cell membrane against a concentration difference

fluid mosiac model

the membrane is a fluid structure with a "mosaic" of various proteins embedded in or attached to a double layer (bilayer) of phospholipids

endocyotsis

when the cell membrane uses vesicles to move large amounts into cell

selective permeability

A property of biological membranes that allows some substances to cross more easily than others.

exocytosis

movement of particles out of the cell

passive transport

the movement of substances across a cell membrane without the use of energy by the cell

diffusion

The process of spread of a feature or trend from one place to another over time

solute potential

This measurement has a maximum value of 0; it decreases as the concentration of a solute increases.

water potential

the potential energy of a volume of water, expressed as a pressure