Biology MCAT Vocabulary Flashcards

A muscle that moves a limb away from the center of the body.

The process by which substances are taken up into or across tissues.

A neurotransmitter found throughout the nervous system (somatic motor neurons, preganglionic parasympathetic and sympathetic nerves, and postganglionic parasympathetic neurons); metabolized by acetylcholinesterase.

The large vesicle at the head of a sperm cell containing enzymes that degrade the ovum cell membrane to allow fertilization.

A protein found in the cytoskeleton and muscle cells; it is the principle constituent of the thin filaments and microfilaments.

An abrupt change in the membrane potential of a nerve or muscle caused by changes in membrane ionic permeability; results in conduction of an impulse in nerves or contraction in muscle.

An immune response (antibody production or cellular immunity) acquired in response to exposure to an antigen.

Substrate-binding region of an enzyme.

The development of characteristics that enable an organism to survive and reproduce in its habitat.

Highly specific form of immunity that retains chemical memory of each invader encountered and is able to tailor the immune response to the specific pathogen.

The evolutionary process by which one species gives rise to several species, each specialized for different niches.

A muscle that moves a limb toward the center of the body.

A purine base present in DNA and RNA; it forms hydrogen bonds with thymine and uracil.

A nucleotide molecule consisting of adenine, ribose, and three phosphate moieties; the outer two phosphates are bound by high energy bonds.

Refers to fatty tissue, fat-storing tissue, or fat within cells.

Refers to a biological process that occurs in the presence of molecular oxygen (O2) or to organisms that cannot live without molecular oxygen.

A neuron that picks up impulses from sensory receptors and transmits them toward the CNS.

Type of leukocyte that does not contain cytoplasmic granules, including lymphocytes and monocytes.

Protein synthesized in the liber that maintains the oncotic pressure of the blood and serves as a carrier for many drugs and hormones.

One of four embryonic membranes; it contains the growing embryo's waste products.

Alternative forms of the same gene coding for a particular trait; they segregate during meiosis.

A type of autoimmunity in which a person's immune system becomes over-activated by common substances in the environment.

Basic functional unit of the lung; a tiny-sac specialized for passive gas exchange between the lungs and the blood.

The building blocks of proteins, each containing an amino group, a carboxylic acid group, and a side chain (or R group) attached to the alpha-carbon.

The innermost fluid filled embryonic membrane; it forms a protective sac surrounding the embryos of birds, reptiles, and mammals.

Characteristic of signaling cascade, in which the binding of a single peptide hormone to a membrane bound receptor results in a signal that increases in strength through the signaling cascade.

Refers to a biological process that can occur without oxygen or to organisms that can live without molecular oxygen.

The stage of mitosis or meiosis characterized by the migration o chromatids or homologous chromosomes to opposite poles of the dividing cells.

Any male sex hormone, such as testosterone.

Substance that kills or inhibits the growth of bacteria or fungi (usually by disrupting cell wall assembly or by binding ribosomes, thus inhibiting protein synthesis.)

Immune or protective protein whose synthesis is induced by the presence of foreign substances (antigens) in the body; each antibody binds to a specific antigen in an immune response; also called immunoglobulin.

A substance that binds to an antibody; may be foreign or a self antigen.

Portion of an antibody that is specific for a particular antigen the area of the antibody to which the antigen binds.

One of the semilunar valves, separating the left ventricle from the aorta.

Process by which a cell undergoes programmed cell death in a highly organized manner in response to either external or internal signals.

Peripheral portion of the skeleton consisting of arms, legs, and pelvic and pectoral girdles.

The central cavity in the gastrula stage of embryological development; it is lined by endoderm and ultimately gives rise to the adult digestive tract.

Small arterial structures that link the arteries to the capillaries.

Thick-walled, muscular blood vessels that generally carries blood away from the heart.

Cartilaginous coating at the ends of bones that provides a smooth surface for articulation of bones with a joint.

Any reproductive process that does not involve the fusion of gametes (such as budding).

Star-shaped structures that form around the centrosome during mitosis.

One of two paired structures on either side of the heart, into which blood returning from either the body (right atrium) or the lungs (left atrium) flows.

Form of cell-cell communication in which a cell releases a substance that then binds to the membrane of the releasing cell to either inhibit or activate a cellular activity.

Inappropriate immune response that targets self-antigens.

Subdivision of the PNS responsible for involuntary activities, which is further subdivided into the parasympathetic and sympathetic nervous systems.

Any chromosome other than a sex chromosome.

Midline structures of the skeleton including the skull, vertebral column, and rib-cage; provides the central framework of the body.

The longer fiber of a neuron; it conducts impulses away from the cell body toward the synapse.

Transition point between the cell body (soma) and the axon of a neuron; the site of action potential initiation.

Red-shaped bacterium.

A virus that invades bacteria and sometimes uses bacterial RNA and ribosomes to self replicate.

Type of granulocytic leukocyte that largely participates in allergic reactions and local inflammation.

A solution of salts, pigments, and cholesterol produced by the liver and stored in the gallbladder; it emulsifies large fat droplets when secreted into the small intestine via the bile duct.

Product of the breakdown of hemoglobin that is modified to a more soluble form in the liver.

A type of asexual reproduction characteristic of prokaryotes in which there is equal nuclear and cytoplasmic division.

The fluid filled central cavity of the blastula.

A mammalian blastula, consisting of the trophoblastic cells and an inner cell mass.

Opening of the archenteron to the external environment in the gastrula stage of embryonic development.

The early embryonic stage during which the embryo is a hollow fluid filled sphere of undifferentiated cells.

Process by which a solid mass of early embryonic cells, known as the morula, becomes the blastula, a hollow fluid filled sphere of undifferentiated cells.

Changes in the affinity of hemoglobin for oxygen caused by changes in the environment; when pH is low (increased concentration of hydrogen ions), the oxyhemoglobin dissociation curve shifts right, indicating a decreased affinity of hemoglobin for oxygen and more efficient off-loading of oxygen from hemoglobin.

An initial dose of medication; in the digestive system, chewed food leaving the moth, traveling through the esophagus, and entering the stomach.

Central portion of bones, especially long bones, that contains fat and developing blood cells, including erythrocytes, leukocytes, and megakaryocytes.

Organic and inorganic minerals that provide strength to compact bone; organic components include collagen, glycoproteins, and other peptides; inorganic components include calcium, phosphate, hydroxide ions (in hydroxyapatite).

The cup-like structure of the nephron; it collects the glomerular filtrate and channels it into the proximal convoluted tubule.

Tube-like passages for air that connect the trachea to the bronchioles.

Passageways for air that start at the bronchi, dividing into continuously smaller passageways that eventually lead to the alveoli, where gas exchange occurs.

Group of enzymes present on the luminal surface of cells lining the duodenum that break down larger biomolecules into monomers that are able to be absorbed.

Part of the conduction system of the heart; it carries impulses from the AV node to the ventricles.

Area of excessive deposition of keratin in response to repeated strain due to friction.

Small canals connecting lacunae within the bone matrix with Haversian canals, allowing for the flow of nutrients and wastes.

Small, thin-walled blood vessel where gas, nutrients, and waste exchange occurs between blood and tissues.

Protein coat surrounding a virus.

Total blood volume pumped by the left ventricle in one minute, found by multiplying the heart rate by the stroke volume.

A firm, elastic, translucent connective tissue produced by cells called chondrocytes.

The chemical breakdown of complex substances (macromolecules) to yield simpler substances and energy.

The first part of the large intestine, accepts material flowing through the ileocecal valve and is the point of attatchment of the appendix.

Portion of a neuron where the nucleus, endoplasmic reticulum, and ribosomes are located; also known as the soma.

A foundational belief in modern biology that all living things are composed of cells, that the cell is the basic functional unit of life, that all cells arise from preexisting cells, and that DNA is the genetic material.

Type of immunity that uses cytotoxic chemicals released from cells to cause death of cells that have been infected by viruses.

The brain and spinal cord.

A small organelle in the cytoplasm of animal cells; it organizes the spindle apparatus during mitosis and meiosis.

The area of a chromosome where sister chromatids are joined; it is also the point of attachment to the spindle fiber during mitosis and meiosis.

Paired cylindrical organelles, located in the cytoplasm, that contain the centrioles.

The section of the mammalian hindbrain that controls muscle coordination and equilibrium.

The outer layer of the forebrain, consisting of grey matter; it is the site of higher cognitive functions in humans.

Lower end of the uterus that marks the transition between the vagina and the uterus.

Enzymatic cleavage of chemical bonds within foodstuffs, resulting in smaller molecules.

Movement of cells toward or away from a chemical within the environment.

Sites where crossing over occurs between homologous chromosomes during meiosis.

Cells within the stomach that secrete pepsinogen, a zymogen that is converted to its active form, pepsin, by the acidic environment of the stomach.

Elastic cartilage matrix substance secreted by chondrocytes.

A differentiated cartilage cell that synthesizes the cartilaginous matrix.

Each of the two chromosomal strands formed by DNA replication in the S phase of the cell cycle; held together by the centromere.

A filamentous body found within the nucleus of a eukaryotic cell or nucleoid region of a prokaryotic cell, composed of DNA.

Soluble lipid molecule that consists of triglycerides and esterified cholesterol molecules; absorbed into lacteals from the digestive tract.

Aqueous mixture of food and secretions that leaves the stomach to enter the duodenum.

Projection from a cell involved in movement of materials on the outside of the cell.

A behavioral pattern based on a 24-hour cycle, related to cycling of hormones such as cortisol and melatonin.

A series of mitotic divisions of the zygote immediately following fertilization, resulting in progressively smaller cells with increased nucleus to cytoplasmic ratios.

Phenomenon in which only B- or T- cells specific to a particular pathogen are activated.

Spherically shaped bacterium.

A genetic effect in which the phenotype of a heterozygote is a distinct reflection of both alleles at a particular locus.

Describes a cell capable of responding to induction signals.

The temporary joining of two organisms via a tube called a pilus, through which genetic material is exchanged; a form of sexual reproduction used by bacteria.

Animal tissue composed of cells lying in an extracellular proteinaceous network that supports, connects, and surrounds the organs and structures of the body.

Portion of an antibody molecule that is not variable and participates in the binding other other immune modulators.

The process by which unrelated organisms living in a similar environment develop analogous structures.

Layer of cells surrounding an oocyte that aids in the development of the ovum.

The remnant of the ovarian follicle, which after ovulation continues to secrete progesterone. It degeneration leads to menstruation; it also maintains the uterine lining during pregnancy.

The external layer found in many organs of the body, including the brain, adrenal glands, and kidney.

Release of calcium ions by the ovum after fertilization, resulting in the creation of a fertilization membrane, a structure that prevents fertilization of an ovum by multiple sperm cells.

Steroid hormones produced in the adrenal cortex, including glucocorticoids (cortisol), mineralocorticoids (aldosterone), and cortical sex hormones.

The exchange of genetic material between homologous chromosomes during meiosis.

An intracellular second messenger in the signaling cascade initiated by a peptide hormone; synthesized from ATP by adenylate cyclase.

Chemical substance that stimulates inflammation and recruits additional immune cells to a specific area.

The division and distribution of parent cell cytoplasm to the two daughter cells during mitotic and meiotic cell division.

The fluid and solutes within a cell membrane, external to the nucleus and cellular organelles.

T-cell that seeks out infected cells and induces apoptosis in these cells to prevent spread of the pathogen.

A type of genetic mutation in which some variable amount of DNA is removed.

The portion of a neuron that receives stimuli and conveys them toward the cell body.

The layer of skin cells under the epidermis. Contains sweat glands, hair follicles, fat, and blood vessels.

Rapid mitotic divisions ocurring in an embryo that result in cells with predetermined fates; these cells are only capable of differentiating into certain kinds of tissues within an organism.

Designation of a cell within an embryo as having a particular future function.

Thin, muscular structure that divides the thorax from the abdomen and provides the driving force for inhalation.

Cylindrical shaft of a long bone.

The period of relaxation of cardiac muscle during which the atrioventricular valves open and the ventricles fill with blood.

The process by which unspecialized cells become specialized. Involves selective transcription of the genome.

The breakdown of macromolecular nutrient material via mechanical and chemical means to simple molecular building blocks; this facilitates absorption.

Having two chromosomes of each type per cell; symbolized by 2n.

Substance secreted into the bloodstream that causes a change in the physiological activity of cells without requiring an intermediary.

Selective pressures favor the development of an extreme phenotype that provides a selective advantage; this phenotype emerges as the primary phenotype over time.

Type of selection in which selective pressures favor extreme phenotypes over the norm..

A process of change whereby organisms with a common ancestor evolve dissimilar structures (such as dolphin flippers and human arms).

Refers to an allele that requires only one copy for expression.

Fetal structure that shunts blood from the pulmonary artery to the aorta to bypass the developing lungs.

Shunt from the umbilical vein to the inferior vena cava, allowing oxygenated blood returning from the placenta to bypass the liver and enter the systemic circulation.

First segment of the small intestine; the contents of the stomach and the pancreatic and bile ducts empty into it; side of digestion and some absorption.

Outermost embryonic germ layer; it gives rise to the skin, nervous system, inner ear, lens of the eye, and other structures.

An organ, muscle, or gland used by an organism to respond to a stimulus.

A neuron that transmits nervous impulses from the central nervous system to an effector.

An organism at the early developmental stage; in humans, the erm refers to the first eight weeks after fertilization.

A form of cell-cell communication that involves the secretion of hormones into the bloodstream by ductless glands; these hormones then travel to distant locations within the organism to cause a change in cellular activity.

Innermost embryonic germ layer; it later gives rise to the linings of the alimentary canal and of the digestive and respiratory organs.

Uterine lining that is regenerated each month in preparation for implantation of an embryo; absence of an embryo results in sloughing off of the endometrium in a process known as menstruation.

Membrane bound channels in the cytoplasm that transport proteins and lipids to various parts of the cell.

Lining of blood vessels consisting of endothelial cells.

Collection of neurons within the gastrointestinal tract that governs peristalsis.

Type of granulocytic leukocyte that largely participates in the immune response against parasites; also involved in the pathogenesis of allergies.

The outermost layer of the skin.

The coiled tube in which sperm gain motility and are stored after production in the testes.

The small flap of cartilage that covers the glottis during swallowing, preventing food from entering the larynx.

A hormone synthesized by the adrenal medulla; it stimulates the fight or flight response; also a neurotransmitter in the sympathetic nervous system.

Cartilaginous structure in the epiphysis where growth occurs.

Dilated end of a long bone.

A specialized subset of plasmids capable of integrating into the genome bacteria under specific circumstances.

The cellular layer that covers internal and external surfaces of body structures and cavities.

Red blood cells; a biconcave, dic-shaped cell that contains hemoglobin and has no nucleus.

Portion of the alimentary canal connecting the pharynx and the stomach.

A unicellular or multicellular organism composed of cells that contain a membrane bound nucleus and other membrane bound organelles.

The changes in the gene pool from one generation to the next caused by mutation, nonrandom mating, natural selection, and genetic drift.

Glands that release their secretions into ducts (such as the parts of the liver and sweat glands).

Varying expression of disease symptoms despite identical genotypes.

A muscle used in the straightening of a limb.

Prokaryotes that can exist with or without oxygen.

Fusion of two gametes.

Structure created by the cortical reaction after fertilization of an ovum by a sperm cell; prevents fertilization of an ovum by multiple sperm cells.

A developing organism that has passed the early developmental stages. In humans, the term refers to an embryo from the ninth week after fertilization until birth.

The insoluble protein that forms the bulk of a blood clot.

Offspring in a genetic cross; may be supplemented with a subscript to show how many generations out from the parents.

In the nephron, the process by which blood plasma is forced (under high pressure) out of the glomerulus into Bowman's capsule.

Reproductive success of an individual, measured in increased number and survival of offspring.

A microscopic, whip-like filament that functions in the locomotion of sperm cells and some unicellular organisms; composed of microtubules.

A muscle used in the bending of a limb.

The set of cells surrounding a developing or mature ovum. Secretes nutrients and estrogen and atrophies into the corpus luteum after ovulation.

Shunt within the fetal heart between the right and left atria that allows the circulation to largely bypass the developing lungs.

Organ below the liver that stores bile; contracts in response to stimulation by cholecystokinin, resulting in release of bile into the biliary system and eventually into the duodenum.

Sperm or ovum; a cell that has half the number of chromosomes of a somatic cell (haploid) and can fuse with another gamete to form a zygote.

A mass of neuron cell bodies outside the central nervous system.

The embryonic stage characterized by the presence of ectoderm, mesoderm, and endoderm.

The basic unit of heredity; a region on a chromosome that codes for a specific product.

All of the alleles for every gene in every individual in a given population.

Variations in the gene pool caused by chance.

A diagrammatic representation of a chromosome indicating distance between two genes on a chromosome as determined by recombination frequencies.

An organism's complete set of chromosomes.

The genetic composition of an entire organism or in reference to a particular trait.