Chapter 2 Flashcards
(19 cards)
Cell
The smallest unit of life.
Cell membrane
The outer layer or coating that surrounds the cell and controls which molecules enter and leave the cell.
Cell wall
A tough, rigid outer covering that protects certain cells and gives them shape.
Chloroplast
An organelle that absorbs light energy and converts it to chemical energy for the manufacture of food in the process called photosynthesis.
Compound
A chemical combination of atoms of two or more different elements.
Cytoplasm
A jelly-like fluid made up of water, salts, and dissolved organic molecules that is enclosed by the cell membrane and provides the right environment for the many chemical reactions needed to produce energy, convert organic molecules into needed proteins, or break down old proteins to be recycled.
Cytoskeleton
An internal Skeleton in cells, made of a network of fibers that holds the organelles of the cell in place, maintains the shape of the cell, and provides a system of “tracks” that motor proteins use to move cell products from place to place inside the cell or to the cell membrane.
Element
One of the 118 different types of atoms of which all matter is composed.
A substance composed of atoms with the same atomic number.
Enzyme
A protein that controls and speeds up chemical reactions without being changed or used up.
Eukaryotic cell
A membrane-bound cell that contains a membrane-bound nucleus.
Hormone
A protein that directs cells to perform specific tasks.
Mitochondrion
An organelle that provides energy for all the energy-requiring processes of cells
Plural of mitochondrion is mitochondria
Nucleus (of a cell)
The organelle that directs the cell’s activities and stores DNA
Organic molecule
A molecule that contains carbon and hydrogen.
Prokaryotic cell
A cell that lacks internal membrane-bound structures such as a nucleus and other organelles.
Ribosome
An organelle made of protein and RNA that assembles proteins from amino acids.
What causes matter to change state from solid to liquid or from liquid to gas?
The amount of energy in the particles of a substance determine the state it is in. Solids possess the lowest amount of particle energy, liquids possess a greater amount of particle energy, and gases possess the highest amount of particle energy. Th energy in the particles of a substance is increased by heating. Th is is why heating a solid causes it to melt into a liquid, and heating the liquid causes it to vaporize into gas.
What determines the chemical identity of an atom?
An atom’s chemical identity is determined by how many protons the atom has in the atomic nucleus.
Compare and contrast elements and compounds.
An element is a substance composed of atoms with the same atomic number, that is, all the atoms have the same number of protons in their nuclei. A compound is formed when atoms of two or more diff erent elements are chemically bound together.
