Cells Chapter 2 cell Basic units of structure

Cells Chapter 2

cell • Basic units of structure and function in living things

microscope • An instrument that makes small objects look larger

Cell Theory • a widely accepted explanation of the relationship between cells and living things 1. all living things are composed of cells 2. Cells are the basic units of structure and function in living things 3. All cells are produced from other cells

Cell wall • Rigid layer that surrounds the cells of plants and some other organisms

Cell membrane • Controls which substances pass into and out of a cell

nucleus • Large oval structure that acts as a cell’s control center, directing all of the cell’s activities

organelles Structures that carry out specific functions within a cell

Cytoplasm • A thick, clear, gel -like fluid that fills the region between the cell membrane and the nucleus

Mitochondria • Organelle that converts energy stored in food to energy the cell can use to live and function

Endoplasmic reticulum (ER) • Organelle with a network of membranes that produces many substances

Golgi apparatus • Organelle that receives proteins and other newly formed materials from the ER, packages them, and distributes them to other parts of the cell or to the outside of the cell

vacuole • Water-filled sac organelle that floats in the cytoplasm, stores water, food, waste products, or other materials needed by the cell.

chloroplasts • Green organelle found in plant cells that captures energy from sunlight and changes it to a form of energy cells can use in making food

lysosomes • Sac-like organelle in animal cells that contain substance that break down large food particles into smaller ones, as well as old cell parts and release the substance so they can be used again

Multi-cellular • Made of many cells

unicellular • Made of one cell

tissue • A group of similar cells that work together to perform a specific function

organ • Different kinds of tissues that function together

Organ system • A group of organs that work together to perform a major function

elements • Any substance that cannot be broken down into simpler substances

compounds • Compounds form when two or more elements combine chemically

carbohydrates • Energy-rich organic compounds made of the elements carbon, hydrogen, and oxygen

Lipids • Compounds made of carbon and hydrogen and some oxygen

proteins • Large organic molecules made of carbon, hydrogen, oxygen, nitrogen, and in some cases sulfur.

enzymes • Type of protein that speeds up a chemical reaction in a living thing

Nucleic acids • Very long organic molecules consisting of carbon, oxygen, hydrogen, nitrogen, and phosphorus • Contain the instructions that cells need to carry out all the functions of life

DNA (Deoxyribonucleic acid) • Type of nucleic acid • Genetic material that carries information about an organism and is passed from parent to offspring

Double helix • The shape of a DNA molecule • Twisted rope ladder

Selectively permeable • Means that some substances can cross the membrane while others cannot

Passive transport • The movement of dissolved materials across a cell membrane without using the cell’s energy

diffusion • The process by which molecules move from an area of higher concentration to an area of lower concentration

osmosis • The diffusion of water molecules across a selectively permeable membrane

Active transport • The movement of materials across a cell membrane using cellular energy

endocytosis • The cell membrane changes shape and engulfs the particle

exocytosis • Allows large particles to leave a cell