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VOCABULARY ONLY!! (it's a lot)

matter

anything that occupies space and has mass

element

pure substance that cannot be broken down into other substances by chemical or physical means

trace element

element critical to health that makes up less than 0.01 percent of body mass

compound

substance containing two or more elements chemically combined in a fixed ratio

atom

smallest particle of an element

proton

subatomic particle with a single unit of positive electric charge

electron

subatomic particle with a single unit of negative electric charge

neutron

subatomic particle that has no charge

nucleus

in an atom, the central core that contains protons and neutrons (Concept 4.2); in a cell, the part that houses the cell's genetic material in the form of DNA

atomic number

number of protons in an atom's nucleus; is unique for each element

isotope

one of several forms of an element, each containing the same number of protons in their atoms but a different number of neutrons

radioactive isotope

isotope in which the nucleus decays (breaks down) over time, giving off radiation in the form of matter and energy

ionic bond

chemical bond that occurs when an atom transfers an electron to another atom

ion

atom that has become electrically charged as a result of gaining or losing an electron

covalent bond

chemical bond that forms when two atoms share electrons

molecule

two or more atoms held together by covalent bonds

chemical reaction

breaking of old and formation of new chemical bonds that result in new substances

reactant

starting material for a chemical reaction

product

material created as a result of a chemical reaction

polar molecule

molecule in which opposite ends have opposite electric charges

hydrogen bond

bond created by the weak attraction of a slightly positive hydrogen atom to a slightly negative portion of another molecule

cohesion

tendency of molecules of the same kind to stick to one another

adhesion

attraction between unlike molecules

thermal energy

total amount of energy associated with the random movement of atoms and molecules in a sample of matter

temperature

measure of the average energy of random motion of particles in a substance

solution

uniform mixture of two or more substances

solvent

substance in a solution that dissolves the other substance and is present in the greater amount

solute

substance in a solution that is dissolved and is present in a lesser amount

aqueous solution

solution in which water is the solvent

acid

compound that donates H+ ions to an aqueous solution and measures less than 7 on the pH scale

base

compound that removes H+ ions from an aqueous solution and that measures more than 7 on the pH scale

pH scale

a range of numbers used to describe how acidic or basic a solution is; ranges from 0 (most acidic) to 14 (most basic)

buffer

substance that maintains a fairly constant pH in a solution by accepting H+ ions when their levels rise and donating H+ ions when their levels fall

organic molecule

carbon-based molecule

inorganic molecule

non-carbon-based molecule

hydrocarbon

organic molecule composed of only carbon and hydrogen atoms

functional group

group of atoms within a molecule that interacts in predictable ways with other molecules

hydrophilic

attracts water molecules

monomer

small molecular unit that is the building block of a larger molecule

polymer

long chain of small molecular units (monomers )

carbohydrate

organic compound made of sugar molecules

monosaccharide

sugar containing one sugar unit

disaccharide

sugar containing two monosaccharaides

polysaccharide

long polymer chain made up of simple sugar monomers

starch

polysaccharide in plant cells that consists entirely of glucose monomers

glycogen

polysaccharide in animal cells that consists of many glucose monomers

cellulose

polysaccharide consisting of glucose monomers that reinforces plant-cell walls

lipid

one of a class of water-avoiding compounds

hydrophobic

avoids water molecules

fat

organic compound consisting of a three-carbon backbone (glycerol) attached to three fatty acids

saturated fat

fat in which all three fatty acid chains contain the maximum possible number of hydrogen atoms

unsaturated fat

fat with less than the maximum number of hydrogens in one or more of its fatty acid chains

steroid

lipid molecule with four fused carbon rings

cholesterol

steroid molecule present in the plasma membranes of animal cells

protein

polymer constructed from a set of 20 amino acid monomers

amino acid

monomer that makes up proteins; contains carboxyl and amino functional groups

polypeptide

chain of linked amino acids

denaturation

loss of normal shape of a protein due to heat or other factor

activation energy

minimum amount of energy required to trigger a chemical reaction

catalyst

agent that speeds up chemical reactions

enzyme

specialized protein that catalyzes the chemical reactions of a cell

substrate

specific reactant acted on by an enzyme

active site

region of an enzyme into which a particular substrate fits

cell theory

generalization that all living things are composed of cells, and that cells are the basic unit of structure and function in living things

micrograph

photograph of the view through a microscope

organelle

part of a cell with a specific function

plasma membrane

thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surroundings

nucleus

in an atom, the central core that contains protons and neutrons (Concept 4.2); in a cell, the part that houses the cell's genetic material in the form of DNA

cytoplasm

region of a cell between the nucleus and the plasma membrane

cell wall

strong wall outside a plant cell's plasma membrane that protects the cell and maintains its shape

prokaryotic cell

cell lacking a nucleus and most other organelles

eukaryotic cell

cell with a nucleus (surrounded by its own membrane) and other internal organelles

phospholipid bilayer

two-layer "sandwich" of molecules that surrounds a cell

diffusion

net movement of the particles of a substance from where they are more concentrated to where they are less concentrated

equilibrium

point at which the number of diffusing molecules moving in one direction is equal to the number moving in the opposite direction

selectively permeable membrane

membrane that allows some substances to pass more easily than others and blocks the passage of some substances altogether

passive transport:

diffusion across a membrane requiring only the random motion of molecules with no energy expended by the cell

facilitated diffusion

pathway provided by transport proteins that helps certain molecules pass through a membrane

osmosis

passive transport of water across a selectively permeable membrane

hypertonic

having a higher concentration of solute than another solution

hypotonic

having a lower concentration of solute than another solution

isotonic

having a solute concentration equal to that of another solution

active transport

movement of molecules across a membrane requiring energy to be expended by the cell

vesicle

small membrane-bound sac that functions in moving products into, out of, and within a cell

exocytosis

process of exporting proteins from a cell by a vesicle fusing with the plasma membrane and spilling the proteins outside the cell

endocytosis

process of taking material into a cell within vesicles that bud inward from the plasma membrane

nuclear envelope

double membrane that surrounds a cell nucleus

nucleolus

ball-like mass of fibers and granules in a cell nucleus

ribosome

cluster of proteins and nucleic acids that constructs proteins in a cell

endoplasmic reticulum

network of membranes within a cell's cytoplasm that produces a variety of molecules

Golgi apparatus

cellular organelle that modifies, stores, and routes cell products

vacuole

membrane-bound sac that buds from the endoplasmic reticulum or the Golgi apparatus

lysosome

`membrane-bound sac containing digestive enzymes that can break down proteins, nucleic acids, and polysaccharides

chloroplast

organelle found in some plant cells and certain unicellular organisms where photosynthesis takes place

mitochondria

cellular organelles where cellular respiration occurs

ATP

(adenosine triphosphate) main energy source that cells use for most of their work

microtubule

straight, hollow tube of proteins that gives rigidity, shape, and organization to a cell

microfilament

solid rod of protein, thinner than a microtubule, that enables a cell to move or change shape

flagella

long, thin, whip-like structures, with a core of microtubules, that enable some cells to move

cilia

short structures projecting from a cell and containing bundles of microtubules that move a cell through its surroundings or move fluid over the cell's surface

chromatin

combination of DNA and protein molecules, in the form of long, thin fibers, making up the genetic material in the nucleus of a eukaryotic cell

chromosome

condensed threads of genetic material formed from chromatin as a cell prepares to divide

sister chromatid

one of a pair of identical chromosomes created before a cell divides

centromere

region where two sister chromatids are joined tightly together

cell cycle

sequence of events from the production of a eukaryotic cell to the time the cell itself reproduces

interphase

stage of the cell cycle during which a cell carries out its metabolic processes and performs its functions in the body

mitotic phase

stage of the cell cycle when a cell is actively dividing

mitosis

process by which the nucleus and duplicated chromosomes of a cell divide and are evenly distributed, forming two daughter nuclei

cytokinesis

process by which the cytoplasm of a cell is divided in two; usually follows mitosis and meiosis

spindle

framework of microtubules that guide the movement of chromosomes during mitosis and meiosis

centrosome

region of cytoplasmic material that in animal cells contains structures called centrioles

prophase

first stage of mitosis and of meiosis I and II, when the already replicated chromosomes condense

metaphase

second stage of mitosis and of meiosis I and II when the spindle is fully formed and all of the chromosomes are held in place

anaphase

third phase of mitosis and of meiosis I and II, in which the sister chromatids separate and move toward the poles of the spindle

telophase

final stage of mitosis and of meiosis I and II, in which the chromosomes reach the spindle poles, nuclear envelopes form around each set of daughter chromosomes, and the nucleoli reappear

meiosis

type of cell division that produces cells with half as many chromosomes as the parent cell

karyotype

display of a person's 46 chromosomes

homologous chromosome

one of a matching pair of chromosomes, one inherited from each parent

diploid

having two homologous sets of chromosomes

haploid

having a single set of chromosomes

trait

variation of a particular inherited character

genetics

study of heredity

cross-fertilization

process by which sperm from one flower's pollen fertilizes the eggs in a flower of a different plant

hybrid

offspring of two different true-breeding varieties

monohybrid cross

mating of two organisms that differ in only one character

allele

alternative form of a gene

homozygous

having identical alleles for a gene

heterozygous

having different alleles for a gene

dominant

descriptive of an allele in a heterozygous individual that appears to be the only one affecting a trait

recessive

descriptive of an allele in a heterozygous individual that does not appear to affect a trait

Punnett square

diagram showing the probabilities of the possible outcomes of a genetic cross

phenotype

observable traits of an organism

genotype

genetic makeup of an organism; an organism's combination of alleles

testcross

mating of an individual of unknown genotype but dominant phenotype with a homozygous recessive individual

dihybrid cross

mating of two organisms that differ in two characters

intermediate inheritance

inheritance in which heterozygotes have a phenotype intermediate between the phenotypes of the two homozygotes

codominance

inheritance pattern in which a heterozygote expresses the distinct traits of both alleles

polygenic inheritance

combined effect of two or more genes on a single character

chromosome theory of inheritance

generalization that genes are located on chromosomes and that the behavior of chromosomes during meiosis and fertilization accounts for inheritance patterns

gene locus

specific location of a gene on a chromosome

genetic linkage

tendency for alleles of genes on the same chromosome to be inherited together

sex-linked gene

gene located on a sex chromosome

virus

package of nucleic acid wrapped in a protein coat that must use a host cell's machinery to reproduce itself

bacteriophage

: virus that infects bacteria; also called a "phage"

deoxyribonucleic acid (DNA

molecule responsible for inheritance; nucleic acid that contains the sugar deoxyribose

nucleotide

building block (monomer) of nucleic acid polymers

nitrogenous base

single or double ring of carbon and nitrogen atoms with attached functional groups, found in nucleic acids

pyrimidine

single-ring nitrogenous base

purine

double-ring nitrogenous base

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