Science 2.1, 2.3, 2.4

theory

explanation based on scientific knowledge resulting from observations and experiments

cell theory

living things are made of one or more cells; the cell is the smallest unit of life; new cells come from preexisting cells

molecule

two or more atoms that are held together by covalent bonds and act as a unit (examples: H2O, CO2)

macromolecule

substance that forms by joining many small molecules

nucleic acid

macromolecule that forms when a long chain of nucleotides join together

nucleotide

group of molecules that, when linked together, form the building blocks of DNA or RNA

protein

macromolecule made of a long chain of amino acid molecules; contains carbon, hydrogen, oxygen, nitrogen, and sometimes sulfur

enzyme

protein that speeds up a chemical reaction in a living thing

lipid

macromolecule made mainly from carbon and hydrogen atoms; includes fats, oils, and waxes; does not dissolve in water

carbohydrate

macromolecule made up of carbon, hydrogen, and oxygen atoms; major source of energy for the human body

passive transport

the movement of substances through a cell membrane without using the cell's energy

3 forms of passive transport that don't require energy

diffusion, osmosis, facilitated diffusion

diffusion

the movement of substances from an area of high concentration to an area of low concentration

osmosis

the diffusion of water molecules only through a membrane

facilitated diffusion

molecules pass through transport proteins in the cell membrane; doesn't require energy because it works with the concentration gradient (study Figure 13 on Leo p.63--compare w/Figure 14)

active transport

molecules pass through transport proteins in the cell membrane; requires energy because it's working against concentration gradient (study Figure 14 on Leo p.64--compare w/Figure 13)

active transport vs. facilitated diffusion

in facilitated diffusion molecules move naturally from areas of high concentration to areas of low concentration; in active transport energy is used to move molecules from areas of low concentration to areas of high concentration

concentration

amount of a particular substance dissolved in a liquid or gas mixture

equilibrium

concentrations are balanced on both sides of the cell membrane

endocytosis

process during which a cell takes in a substance by surrounding it with the cell membrane

exocytosis

the process during which a cell vesicle releases a substance outside the cell

3 forms of transport that require energy

active transport, endocytosis, exocytosis (study Figure 14 on Leo page 64 to distinguish these; compare w/Figure 13)

cellular respiration

the series of chemical reactions that convert the energy in food molecules into a usable form of energy called ATP

aerobic

oxygen is required

anaerobic

oxygen is not required

glucose

a simple sugar with the formula C6H12O6; a type of carbohydrate

glycolysis

Step 1 of cellular respiration; occurs in cytoplasm; glucose is broken down into pyruvate; it produces and uses energy from ATP molecules (doesn't require oxygen)

pyruvate

smaller molecules that glucose is broken down into

aerobic breakdown of pyruvate

Step 2 of cellular respiration; occurs in mitochondria; pyruvate is broken down further; yields 36 ATP molecules, as well as carbon dioxide, and water (requires oxygen)

anaerobic breakdown of pyruvate

known as fermentation; occurs in cytoplasm; doesn't require oxygen; produces less ATP than cellular respiration

adenosine triphosphate

energy molecule in cells abbreviated ATP

photosynthesis

series of chemical reactions that convert light energy, water and carbon dioxide into the food-energy molecule glucose and give off oxygen

chlorophyll

green pigment in the chloroplasts of plants that absorbs light energy

metabolism

the processes essential for life by which the complex substances in the cells of living things are built up (uses energy) or broken down (releases energy)

water & carbon dioxide

reactants of photosynthesis

glucose & oxygen

products of photosynthesis