Biology 30-1 Flashcards
1
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Central Nervous System (CNS)
A
The body’s coordinating centre for mechanical and chemical actions; made up of the brain and spinal cord
2
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Peripheral Nervous System (PNS)
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All parts of the nervous system, excluding brain and spinal cord, that relay information between the central nervous system and other parts of the body.
3
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Glial cell
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Nonconducting cell important for structural support and metabolism of the nerve cells
4
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Neuron
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Nerve cell that conducts nerve impulses
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Dendrite
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Projection of cytoplasm that carried impulses toward the cell body
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Axon
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Extension of cytoplasm that carries nerve impulses away from the cell body
7
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Myelin sheath
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Insulated covering over the axon of a nerve cell
8
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Schwann cell
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Special type of glial cell that produces the myelin sheath
9
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Nodes of Ranvier
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Regularly occurring gaps between sections of myelin sheath along the axon
10
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Neurilemma
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Delicate membrane that surrounds the axon of some nerve cells
11
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Sensory neuron
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Neuron that carries impulses to the central nervous system; also known as afferent neuron
12
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Sensory receptor
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Highly modified dendrites of a sensory neuron that are activated by an environmental stimulus
13
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Ganglion
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Collections of nerve cell bodies located outside the central nervous system
14
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Interneuron
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A neuron of the central nervous system that connects with sensory, motor, and other interneurons to integrate sensory input with motor output; also known as association neuron
15
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Motor neuron
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Neuron that carries impulses from the central nervous system to an effector; also known as efferent neuron
16
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Effector
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A cell or organ that produces a physiological response when stimulated by a nerve impulse.
17
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Reflex arc
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Neural circuit through the spinal cord that provides a framework for a reflex action
18
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Action potential
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The voltage difference across a nerve cell membrane when the nerve is excited
19
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Resting potential
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Voltage difference across a nerve cell membrane when it is not transmitting a nerve impulse (usually negative)
20
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Facilitated diffusion
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Transport of substances across cell membrane down a concentration gradient by a carrier in the membrane; does not use energy
21
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Gated ion channel
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A pore in the cell membrane that allows ioins to move in and out of the cell by opening and closing
22
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Sodium-potassium pump
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A transporter in the cell membrane that moves potassium ions into the cytoplasm while simultaneously removing sodium ions from the cytoplasm to the extracellular fluid
23
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Active transport
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Movement of substances across cell membranes that uses energy; often moves substances against a concentration gradient
24
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Polarized membrane
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Membrane charged by unequal distribution of positively charged ions inside and outside the nerve cell
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Depolarization
Diffusion of sodium ions into the nerve cell resulting in a charge reversal
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Repolarization
Process of restoring the original polarity of the nerve membrane
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Hyperpolarization
Condition in which the inside of the nerve cell membrane has a greater negative charge than the resting membrane; caused by excessive diffusion of potassium ions out of the cell
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Refractory period
Recovery time required before a neuron can produce another action potential
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Saltatory Conduction
Generation of action potentials only at nodes of Ranvier in myelinated axons, resulting in rapid transmission of nerve impulses
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Threshold level
Minimum level of stimulus required to produce a response
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All-or-none response
A nerve or muscle fibre responds completely or not at all to a stimulus
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Synapse
A region between neurons, or between neurons and effectors; also known as the synaptic cleft
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Neurotransmitter
Chemical messenger released by the presynaptic neuron that binds to receptors on the postsynaptic neuron
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Presynaptic neuron
Neuron that carries impulses to the synapse
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Postsynaptic neuron
Neuron that carries impulses away from the synapse
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Acetylcholine
Neurotransmitter released from vesicles in the end plates of neurons, which makes the postsynaptic membranes more permeable to Na+ ions
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Cholinesterase
Enzyme, which breaks down acetylcholine, that is released from presynaptic membranes in the end plates of neurons shortly after acetylcholine
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Summation
Effect produced by the accumulation of neurotransmitters from two or more neurons
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Meninges
Protective membranes that surround the brain and spinal cord
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Cerebrospinal fluid
Cushioning fluid that circulates between the innermost and middle membranes of the brain and spinal cord; it provides a connection between neural and endocrine systems
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Cerebrum
Largest and most highly developed part of the human brain, which stores sensory information and initiates voluntary motor activities
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Cerebral cortex
Outer layer of the cerebral hemispheres
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Corpus callosum
Nerve tract that joins the two cerebral hemispheres
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Thalamus
Area of brain that coordinates and interprets sensory information and directs it to the cerebrum
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Hypothalamus
Area of the brain that coordinates many nerve and hormone functions
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Olfactory bulb
Area of the brain that processes information about smell; one bulb in each hemisphere
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Cerebellum
Part of the hindbrain that controls limb movements, balance, and muscle tone
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Pons
Region of the brain that acts as a realy station by sending nerve messages between the cerebellum and the medulla
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Medulla oblongata
Region of the hindbrain that joins the spinal cord to the cerebellum; one of the most important sites of autonomic nerve control
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Sympathetic nervous system
Nerve cells of the autonomic nervous system that prepare the body for stress
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Parasympathetic nervous system
Nerve cells of the autonomic nervous system that return the body to normal resting levels after adjustments to stress
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Vagus nerve
Major cranial nerve that is part of the parasympathetic nervous system
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Sensory adaptation
Occurs once you have adjusted to a change in the environment; sensory receptors become less sensitive when stimulated repeatedly
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Sclera
Outer covering of the eye that supports and protects the eye's inner layers; usually referred to as the white of the eye
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Cornea
Transparent part of the sclera that protects the eye and refracts light toward the pupil of the eye
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Aqueous humour
Watery liquid that protects the lens of the eye and supplies the cornea with nutrients
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Choroid layer
Middle layer of tissue in the eye that contains blood vessels that nourish the retina
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Iris
Opaque disk of tissue surrounding the pupil that regulates amount of light entering the eye
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Retina
Innermost layer of tissue at the back of the eye containing photoreceptors
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Rods
Photoreceptors that operate in dim light to detect light in black and white
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Cones
Photoreceptors that operate in bright light to identify colour
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Fovea Centralis
Area at centre of retina where cones are most dense and vision is sharpest
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Rhodopsin
The pigment found in the rods of the eye
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Accommodation
Adjustments made by the lens and pupil of the eye for near and distant objects
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Glaucoma
Disease of the eye in which increased pressure within the eyeball causes a gradual loss of sight
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Cataract
Condition that occurs when the lens or cornea becomes opaque, preventing light from passing through
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Astigmatism
Vision defect caused by abnormal curvature of surface of the lens or cornea
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Nearsightedness
Condition that occurs when the image is focused in front of the retina
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Farsightedness
Condition that occurs when the image is focused behind the retina
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Pinna
Outer part of the ear that acts like a funnel, taking sound from a large area and channeling it into a small canal
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Auditory canal
Carries sound waves to the eardrum
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Tympanic membrane
Thin layer of tissue that receives sound vibrations, also known as the eardrum
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Ossicles
Tiny bones that amplify and carry sound in the middle ear
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Oval window
Oval-shaped hole in the vestibule of the inner ear, covered by a thin layer of tissue
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Eustachian tube
Air-filled tube of the middle ear that equalizes pressure between the external and internal ear
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Vestibule
Chamber found at the base of the semicircular canals that provides information about static equilibrium
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Semicircular canals
Fluid-filled structures within the inner ear that provide information about dynamic equilibrium
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Cochlea
Coiled structure of the inner ear that responds to various sound waves and converts them into nerve impulses
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Organ of Corti
Primary sound receptor in the cochlea
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Basilar membrane
Anchors the receptor hair cells in the organ of Corti
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Dynamic equilibrium
Describes any system with constant change in which the components can adjust to the changes without disturbing the entire system
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Homeostasis
The process by which a constant internal environment is maintained despite changes in the environment
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Dynamic equilibrium
A state of stability within fluctuating limits
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Negative feedback
The process by which a mechanism is activated to restore conditions to their original state
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Positive feedback
The process by which a small effect is amplified
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Hormones
Chemicals released by cells that affect cells in other parts of the body
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Endocrine hormones
Chemicals secreted by endocrine glands directly into the blood
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Insulin
Hormone produced by the islets of Langerhans in the pancreas; insulin is secreted when blood sugar levels are high
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Human growth hormone (hGH)
Hormone produced by the pituitary gland that stimulates growth of the body; also known as somatotropin (STH)
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Epinephrine
AKA Adrenaline
Hormone, produced in the adrenal medulla that accelerates heart rate and body reactions during a crisis (Fight or flight)
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Islets of Langerhans
Hormone-producing cells of the pancreas; these cells are part of the endocrine system
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Glucagon
Hormone produced by the pancreas; when blood sugar levels are low, glucagon promotes conversion of glycogen to glucose
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Diabetes
Chronic disease in which the body cannot produce any insulin or enough insulin, or is unable to use properly the insulin it does make
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Adrenal medulla
Found at the core of the adrenal gland, produces epinephrine and norepinephrine
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Adrenal cortex
Outer region of the adrenal gland that produces glucocoticoids and mineralocorticoids
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Norepinephrine
Also known as noradrenaline, it initiates the fight-or-flight response by increasing heart rate and blood sugar
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Glucocorticoid
Any of the steroids produced by the adrenal cortex that help to regulate electrolyte and water balance
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Mineralocorticoid
Any of the steroids produced by the adrenal cortex that regulate carbohydrate, lipid, and protein metabolism and inhibit the release of corticotrophin
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Sex hormone
Any hormone that affects the development and growth of sex organs
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Cortisol
Hormone that stimulates the conversion of amino acids to glucose by the liver
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Adrenocorticotropic hormone (ACTH)
Pituitary hormone that promotes cortisol release by the adrenal cortex; also called corticotopin
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Tropic hormone
Hormone that stimulates a specific target gland to secrete other hormones
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Aldosterone
Hormone produced by the adrenal cortex that helps regulate water balance by increasing sodium retention and water reabsorption by the kidneys
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Thyroxine (T4)
Hormone produced by the thyroid gland that increases metabolism and regulates growth
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Triiodothyronine (T3)
Hormone produced by the thyroid gland that increases metabolism and regulates growth; contains three iodine atoms
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Calcitonin
Hormone produced by the thyroid gland that lowers calcium levels in the blood
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Thyroid gland
A two-lobed gland at the base of the neck that regulates metabolic processes
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Parathyroid glands
Four pea-sized glands in the thyroid gland that produce parathyroid hormone to regulate blood calcium and phosphate levels
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Goiter
Disorder that causes an enlargement of the thyroid gland
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Parathyroid hormone (PTH)
Hormone produced by the parathyroid glands, which will increase calcium levels in the blood and lower the levels of phosphates
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Antidiuretic hormone (ADH)
A hormone that causes the kidneys to increase water reabsorption
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Osmoreceptors
Sensory receptors in the hypothalamus that detect changes in the osmotic pressure of the blood and surrounding extracellular fluids (ECF)
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Juxtaglomerular apparatus (JGA)
A functional unit near a kidney glomerulus that controls renin release in response to changes in blood pressure
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Prostaglandins
A group of hormones that act on the cells that produce them in response to cell damage; produced by most cells
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Anabolic steroids
Substances that are designed to mimic many of the muscle-building traits of the sex hormone testosterone
116
Testes
The male gonads, or primary reproductive organs; male sex hormones and sperm are produced in the testes
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Ovary
The female gonad, or reproductive organ; female sex hormones and egg cells are produced in the ovary
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Fertilization
Fusion of a male and female sex cell
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Zygote
The cell resulting from the union of a male and female sex cell
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Embryo
The early stages of an animals development
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Fetus
The later stages of an unborn offspring's development
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Scrotum
The sac that contains the testes
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Vas deferens
Tube that conducts sperm toward the urethra
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Ejaculatory duct
A tubule formed at the union of the vasa deferentia and the seminal vesicle ducts and opening into the urethra
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Semen (seminal fluid)
A secretion of the male reproductive organs that is composed of sperm and fluids
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Seminiferous tubules
Coiled ducts found within the testes, where immature sperm cells divide and differentiate
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Spermatogenesis
Process by which spermatogonia divide and differentiate into mature sperm cells
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Spermatogonia
Sperm-producing cells found in the seminiferous tubules
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Spermatocyte
A cell that arises from division of spermatogonia during spermatogenesis
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Spermatid
An immature sperm cell that arises from a division of a spermatocyte
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Somatic cell
Any cell in a multicellular organism that is not a reproductive cell
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Sertoli cell
A cell that provides metabolic and mechanical support to developing sperm cells
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Epididymis
Structure located along the posterior border of the testis, consisting of coiled tubules that store sperm cells
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Acrosome
The cap found on sperm cells, containing enzymes that permit the sperm cell to move through the outer layers that surround the egg
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Seminal fluid
The fluid part of the semen, which is secreted by three glands
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Seminal vesicle
Structure that contributes to the seminal fluid (semen), a secretion that contains fructose and prostaglandins
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Prostate gland
Structure that contributes to the seminal fluid (semen), a secretion containing buffers that protect sperm cells from the acidic environment of the vagina
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Coepwer's (bulbourethral) gland
Structure that contributes a mucus-rich fluid to the seminal fluid (semen)
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Primary sexual characteristics
Physical characteristics of an organism that are directly involved in reproduction
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Secondary sexual characteristics
External features of an organism that are indicative of its gender, but are not reproductive organs themselves
141
Testosterone
Male sex hormone produced by the interstitial cells of the testes
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Interstitial cells
Cells found in the testes surrounding the seminiferous tubules that secrete testosterone
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Gonadotropic hormones (gonadotropins)
Hormones produced by the pituitary gland that regulate the functions of the testes in males and the ovaries in females
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Follicle-stimulating hormone (FSH)
In males, hormones that increases sperm production
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Luteinizing hormone (LH)
In males, hormone that regulates the production of testosterone
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Gonadotropin-releasing hormone (GnRH)
Chemical messenger from the hypothalamus that stimulates secretions of FSH and LH from the pituitary
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Inhibin
A hormone produced by the Sertoli cells that inhibits production of FSH
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Ovum (plural ova)
Egg cell
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Oocyte
An immature ovum
150
Uterus (womb)
The hollow, pear-shaped organ located between the bladder and the anus in females
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Endometrium
The glandular inner lining of the uterus
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Fallopian tube (oviduct)
One of the two tubes that connect the ovaries to the uterus
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Fibrium (plural fibria)
A fingerlike projection at the end of a Fallopian tube
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Vagina
The muscular canal extending from the cervix to the outer environment; the birth canal
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Cervix
A muscular band that separates the vagina from the uterus
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Oogenesis
The formation and development of mature ova
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Follicle
Structure in the ovary that contains the oocyte
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Granulosa
The layer of small cells that forms the wall of a follicle
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Ovulation
Release of the secondary oocyte from the follicle held within the ovary
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Corpus luteum
A mass of follicle cells that forms within the ovary after ovulation; secretes estrogen and progesterone
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Menstruation (flow phase)
The shedding of the endometrium during the menstrual cycle
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Follicular phase
Phase marked by the development of ovarian follicles before ovulation
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Estrogen
Hormone that activates development of female secondary sex characteristics, and increased thickening of the endometrium during the menstrual cycle
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Ovulatory phase
Phase in which ovulation occurs
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Luteal phase
Phase of the menstrual cycle characterized by the formation of the corpus luteum following ovulation
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Progesterone
Hormone produced primarily by the corpus luteum, that induces changes in the endometrium during the menstrual cycle
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Menopause
The termination of the female reproductive years
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Follicle-stimulating hormone (FSH)
In females, a gonadotropin that promotes the development of the follicles in the ovary
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Luteinizing hormone (LH)
In females, a gonadotropin that promotes ovulation and the formation of the corpus luteum
170
Cleavage
Cell division of a zygote, in which the number of cells increases without any change in the size of the zygote
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Blastocyst
An early stage of embryo development
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Implantation
The attachment of the embryo to the endometrium
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Chorion
The outer extraembryonic structure of a developing embryo that will contribute to the placenta
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Amnion
A fluid-filled extraembryonic structure
175
Human chorionic gonadotropic hormone (hCH
An embryonic hormone that maintains the corpus luteum
176
Amniotic cavity
The fluid-filled cavity surrounding the developing embryo
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Extraembryonic coelom
Body cavity between the amnion and the chorion
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Yolk sac
A membranous sac that forms during embryo development of most vertebrates; in humans, it does not contain yolk
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Placenta
The site for the exchange of nutrients and wastes between mother and fetus
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Chorionic villi
Vascular projections of the chorion
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Allantois
Extraembryonic structure that contributes to the blood vessels of the placenta
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Umbilical cord
Structure that connects the fetus to the placenta
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First trimester
The period during pregnancy from conception until the end of the third month
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Gastrulation
Process by which a gastrula is formed
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Gastrula
Stage of embryonic development in which the embryo is composed of three layers: ectoderm, mesoderm, and endoderm
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Ectoderm
The outer layer of cells in an embryo
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Mesoderm
The middle layer of cells in an embryo
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Endoderm
The inner layer of cels in an embryo
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Second trimester
The period during pregnancy from the fourth month to the end of the sixth month
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Third trimester
The period during pregnancy from the seventh month until birth
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Teratogen
Any medication, chemical, infectious disease, or environmental agent that might interfere with the normal development of a fetus or embryo
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Parturition
The act of giving birth; labour
193
Relaxin
A hormone produced by the placenta prior to labour; causes the ligaments within the pelvis to loosen
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Oxytocin
A hormone from the pituitary gland; causes strong uterine contractions
195
Prolactin
A hormone produced by the pituitary gland and associated with milk production
196
Cell cycle
The sequence of stages through which a cell passes from one cell division to the next
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Mitosis (M)
A type of cell division in which a daughter cell receives the same number of chromosomes as the parent cell
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Cytokinesis
The division of the cytoplasm
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Interphase
The time interval between nuclear divisions when a cell increases in mass, roughly doubles the cytoplasmic components, and duplicates its chromosomes
200
Chromatin
The complex of DNA and protein that make up chromosomes
201
Centromere
The structure that holds chromatids together
202
Sister chromatids
A chromosome and its duplicate, attached to one another by a centromere until separated during mitosis
203
Centriole
Small protein body found in the cytoplasm of animal cells that provides attachment for spindle fibres during cell division
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Spindle fiber
Protein structure that guides chromosomes during cell division
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Enucleated
The condition where a cell does not contain a nucleus
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Telomere
The cap at the end of a chromosome
207
Meiosis
Two-stage cell division in which the chromosome number of the parental cell is reduced by half
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Haploid
Refers to the number of chromosomes in a gamete
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Diploid
Refers to twice the number of chromosomes in a gamete
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Homologous chromosomes
Paired chromosomes similar in shape, size, gene arrangement, and gene information
211
Tetrad
A pair of homologous chromosomes, each with two chromatids
212
Synapsis
The pairing of homologous chromosomes
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Crossing over
The exchange of genetic material between two homologous chromosomes
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Gametogenesis
The formation of gametes (sex cells) in animals
215
Ootid
An unfertilized oovum
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Nondisjunction
The failure of a pair of homologous chromosomes to separate properly during meiosis
217
Polyploidy
A condition in which an organism has more than two complete sets of chromosomes
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Trisomy
The condition in which there are three homologous chromosomes in place of a homologous pair
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Monosomy
The condition in which there is a single chromosome in place of a homologous pair
220
Karotype chart
A picture of chromosomes arranged in homologous pairs
221
Progeny
New individuals that result from reproduction (offspring0
222
Dominant trait
A characteristic that is expressed when one or both alleles in an individual are the dominant form
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Recessive trait
A characteristic that is expressed only when both alleles in an individual are the recessive form
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Allele
One of alternative forms of gene
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Homozygous
Having identical alleles for the same gene
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Heterozygous
Having different alleles for the same gene
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Genotype
The genetic complement of an organism
228
Phenotype
The observable characteristics of an organism
229
Segregation
The separation of alleles during meiosis
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Phenotypic ratio
The ratio of offspring with a dominant trait to the alternative, recessive trait
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Punnet square
A chart used to determine the predicted outcome of a genetic cross
232
Genotypic ratio
The ratio of offspring with each possible allele combination from a particular cross
233
Pedigree chart
A chart used to record the transmission of a particular trait or traits over several generations
234
Pleiotropic gene
A gene that affects more than one characteristic
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Wild type
The most common allele of a gene with multiple alleles
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Mutant
Any allele of a gene other than the wild type allele
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Incomplete dominance
The expression of both forms of an allele in a heterozygous individual in the cells of an organism, producing an intermediate phenotype
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Codominance
The expression of both forms of an allele in a heterozygous individual in different cells of the organism.
239
Selective breeding
The crossing of desired traits from plants or animals to produce offspring with both characteristics
240
Inbreeding
The process whereby breeding stock is drawn from a limited number of individuals possessing desirable phenotypes
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Polygenic trait
Inherited characteristics that are determined by more than one gene
242
Epistatic gene
A gene that masks the expression of another gene or genes
243
Dihybrid cross
A genetic cross involving two genes, each of which has more than one allele
244
Autosome
A chromosome not involved in sex determination
245
Linked genes
Genes that are located on the same chromosome
246
Sex-linked trait
Trait that is determined by genes located on the sex chromosomes
247
Recessive lethal
A trait that, when both recessive alleles are present, results in death or severe malformation of the offspring. Usually, recessive traits occur more frequently in males.
248
Barr body
A small, dark spot of chromatin located in the nucleus of a female mammalian cell
249
Linkage group
A group of linked genes on a chromosome
250
Locus (plural loci)
A specific location along a chromosome where a particular gene is found
251
Marker gene
A gene that confers an easily identifiable phenotype and is used to trace the inheritance of other genes that are difficult to identify; it must be located on the same chromosome, and ideally, at a very small distance from the gene being followed.
252
Continuity of life
A succession of offspring that share structural similarities with those of their parents
253
Bacteriophage
A virus that infects bacteria
254
Isotope
One of two or more atoms of the same element containing the same number of protons but a different number of neutrons
255
Radioisotope
An unstable isotope that decays spontaneously by emitting radiation
256
Nucleotide
A molecule having a five-carbon sugar with a nitrogenous base attached to its 1' carbon and a phosphate group attached to its 2' position
257
Nitrogenous base
An alkaline, cyclic molecule containing nitrogen
258
Phosphate group
A group of four oxygen atoms surrounding a central phosphorus atom found in the backbone of DNA
259
Oswald Avery, Maclyn McCarty, and Colin MacLeod
Demonstrated that DNA was the transforming principle of pneumococcus bacteria
260
Erwin Chargaff
Discovered that in the DNA of numerous organisms the amount of adenine is equal to the amount of thymine, and the amount of guanine is equal to that of cytosine
261
Alfred Hershey
Used radioactively labelled viruses, infected bacterial cells; observed that the infected bacterial cells contained radioactivity originating from DNA of the virus, suggesting that DNA is hereditary material
262
Rosalind Franklin
Produced an X-ray diffraction pattern of DNA that suggested it was the shape of a double helix
263
James Watson and Francis Crick
Deduced the structure of DNA using information from the work of Chargaff, Franklin, and Maurice Wilkins.
264
Who discovered the double helix DNA structure?
Watson and Crick
265
Complementary base pairing
Pairing of the nitrogenous base of one strand of DNA with the nitrogenous base of another strand
266
Antiparallel
Parallel but running in opposite directions; the 5' end of one strand of DNA aligns with the 3' end of the other strand in a double helix
267
DNA replication
The process whereby DNA makes exact copies of itself
268
Semiconservative replication
Process of replication in which each DNA molecule is composed of one parent strand and one newly synthesized strand
269
Template
A single-stranded DNA sequence that acts as the guiding pattern for producing a complementary DNA strand
270
DNA helicase
The enzyme that unwinds double-helical DNA by disrupting hydrogen bonds
271
DNA polymerase III
The enzyme that synthesizes complementary strands of DNA during DNA replication
272
Leading strand
The new strand of DNA that is synthesized towards the replication fork and continuously during DNA replication
273
Lagging strand
The new strand of DNA that is synthesized away from the replication fork and in short fragments, which are later joined together
274
DNA polymerase I
An enzyme that removes RNA primers and replaces them with the appropriate nucleotides during DNA replication
275
DNA ligase
An enzyme that joins DNA fragments together
276
Gene expression
Conversion of a gene into a specific trait through the production of a particular polypeptide
277
Ribonucleic acid (RNA)
A nucleic acid consisting of nucleotides comprised of the sugar ribose and nitrogenous bases.
278
Transcription
The process of converting DNA into messenger RNA
279
Messenger RNA (mRNA)
The product of transcription of a gene; mRNA is translated by ribosomes into protein
280
Translation
The process of synthesizing a specific polypeptide as coded for by messenger RNA
281
Promoter
Sequence of DNA that binds RNA polymerase in front of a gene
282
Template strand
The strand of DNA that the RNA polymerase uses as a guide to build complementary mRNA
283
Termination sequence
Sequence of bases at the end of a gene that signals the RNA polymerase to stop transcribing
284
Codon
Sequence of three bases in DNA or complementary mRNA that serves as a code for a particular amino acid
285
Start codon
Specific codon (AUG) that signals the start of translation
286
Stop codon
Specific codon that signals the end of translation
287
Ribosome
An organelle composed of RNA and protein located in the cytoplasm that carries out protein synthesis
288
Transfer RNA (tRNA)
The form of RNA that delivers amino acids to a ribosome during translation
289
Anticodon
Group of three complementary bases on tRNA that recognizes and pairs with a codon on the mRNA
290
Recombinant DNA
Fragment of DNA composed of sequences originating from at least two different sources
291
Genetic transformation
Introduction and expression of foreign DNA in a living organism
292
Restriction endonuclease
An enzyme that cuts double-stranded DNA into fragments at a specific sequence; aka restriction enzyme
293
Recognition site
A specific sequence within double-stranded DNA that a restriction endonuclease recognizes and cuts
294
Palindromic
Reading the same forwards and backwards
295
Sticky ends
Fragment ends of a DNA molecule with short single-stranded overhands, resulting from cleavage by a restriction enzyme
296
Blunt ends
Fragment ends of a DNA molecule that are fully base paired, resulting from cleavage by a restriction enzyme
297
Methylase
An enzyme that adds a methyl group to one of the nucleotides found in a restriction endonuclease recognition site
298
Polymerase chain reaction (PCR)
A technique for amplifying a DNA sequence by repeated cycles of strand separation and replication
299
Vector
A vehicle by which foreign DNA may be introduced into a cell
300
Transgenic
A cell or an organism that is transformed by DNA from another species
301
Plasmid
A small double-stranded circular DNA molecule found in some bacteria
302
Multiple-cloning site
A region in a vector that is engineered to contain the recognition site of a number of restriction enzymes
303
Point mutation
A mutation at a specific base pair
304
Gene mutation
A mutation that changes the coding for amino acids
305
Silent mutation
A mutation that does not result in a change in the amino acid coded for
306
Missense mutation
A mutation that results in the single substitution of one amino acid in the polypeptide
307
Nonsense mutation
A mutation that converts a codon for an amino acid into a stop codon
308
Deletion
The elimination of a base pair or group of base pairs from the DNA sequence
309
Insertion
The placement of an extra nucleotide in a DNA sequence
310
Frameshift mutation
A mutation that causes the reading frame of codons to change
311
Translocation
The transfer of a fragment of DNA from one site in the genome to another location
312
Inversion
The reversal of a segment of DNA within a chromosome
313
Spontaneous mutation
A mutation occurring as a result of errors made in DNA replication
314
Mutagenic agent
An agent that can cause a mutation
315
Induced mutation
A mutation caused by a chemical agent or radiation
316
Phylogeny
Proposed evolutionary history of a species or group of organisms
317
Allele frequency
The proportion of gene copies in a population of a given allele
318
Fixed frequency
The frequency of an allele within a population when only a single allele is present for a particular gene (100%)
319
Genetic drift
Changes to allele frequency as a result of chance
320
Founder effect
Genetic drift that results when a small number of individuals separate from their original population and find a new population
321
Bottleneck effect
A dramatic, often temporary reduction in population size, usually resulting in significant genetic drift
322
Gene flow
The movement of alleles from one population to another through the movement of individuals or gametes
323
Sexual selection
Differential reproductive success that results from variation in the ability to obtain mates; results in sexual dimorphism and mating and courtship behaviours
324
Sexual dimorphism
Striking differences in the physical appearance of males and females not usually applied to behavioural differences between sexes
325
Fecundity
Number of offspring
326
Population size
The number of individuals of a specific species occupying a given area/volume at a given time
327
Population density
The number of individuals of the same species that occur per unit area or volume
328
Ecological density
Population density measured in terms of the number of individuals of the same species per unit area or volume actually used by the individuals
329
Population dispersion
The general pattern in which individuals are distributed through a specified area
330
Clumped dispersion
The pattern in which individuals in a population are more concentrated in certain parts of a habitat
331
Uniform dispersion
The pattern in which individuals are equally spaced throughout a habitat
332
Random dispersion
The pattern in which individuals are spread throughout a habitat in an unpredictable and patternless manner
333
Natality
The number of births per unit of time
334
Mortality
The number of deaths per unit of time
335
Immigration
The number of individuals that move into an existing population per unit of time
336
Emigration
The number of individuals that move away from an existing population per unit of time
337
N
A variable describing the number of individuals in a population
338
∆N
A variable describing the change in the number of individuals in a population
339
Growth rate (gr)
The change in population size per unit of time
340
Per capita growth rate (cgr)
The change in population size relative to the initial size of the population, per unit time
341
Open population
A population in which change in number and density is determined by natality, mortality, immigration,, and emigration
342
Closed population
A population in which change in size and density is determined by natality and mortality
343
Exponential growth
A pattern of population growth in which the population size increases by a fixed rate per a fixed unit of time
344
r
A variable indicating the rate of increase of a population experiencing exponential growth; r is limited only by the biotic potential of the organisms in the population
345
Doubling time
The time needed for a population that is growing exponentially to double
346
Environmental resistance
Any factor that limits a population's ability to realize its biotic potential when it nears or exceeds the environment's carrying capacity
347
Logistic growth
A model of population growth describing growth that levels off as the size of the population approaches its carrying capacity
348
Lag phase
The initial stage in which population growth rates are slow as a result of a small population size; characteristic of geometric, exponential, and logistic population growth
349
Log phase
The stage in which population growth rates are very rapid; characteristic of geometric, exponential, and logistic growth
350
Stationary phase
The phase in which population growth rates approach zero as the population size reaches the carrying capacity and stabilizes; the defining characteristic of logistic population growth
351
K
A variable indicating the number of individuals in a population at the carrying capacity of an environment
352
Biotic potential
Reproductive capability
353
Environmental resistance
All factors causing death in a population
354
Density-dependent factor
A factor that influences a population at a particular density
355
Intraspecific competition
An ecological interaction in which individuals of the same species compete for resources in their habitat
356
Predation
An ecological interaction in which a predator (a member of one species) kills and consumes prey (usually a member of another species)
357
Minimum viable population size
The smallest number of individuals needed for a population to continue for a given period of time
358
Density-independent factor
A factor that has the same influence on a population at any population density
359
K-selected organism
An organism that is adapted to survive at or near the carrying capacity of its environment
360
r-selected organism
An organism that is adapted to increase population size rapidly
361
Symbiosis
Various interactions in which two species maintain a close, usually physical association; includes parasitism, mutualism, and commensalism
362
Interspecific competition
Competition between individuals of different species
363
Interference competition
Interspecific competition that involves aggression between individuals of different species who fight over the same resources
364
Exploitative competition
Interspecific competition that involves consumption of shared resources by individuals of different species, where consumption by one species may limit resource availability to other species
365
Competitive exclusion
The concept that, if resources are limited, no two species can remain in competition for exactly the same niche indefinitely; aka Gause's Principle
366
Resource partitioning
Avoidance of, or reduction in, competition for similar resources by individuals of different species occupying different non-overlapping ecological niches
367
Mutualism
A symbiotic relationship in which both organisms benefit; as neither is harmed, it is categorized as a +/+ relationship
368
Commensalism
A symbiotic relationship in which one organism benefits and he other organism is unaffected; it is categorized as a +/0 relationship
369
Parasitism
A symbiotic relationship in which the parasite benefits at the expense of its host which is often harmed but usually not killed; it is categorized as a +/- relationship
370
Social parasite
A parasite that completes its life cycle by manipulating the social behaviour of its hosts
371
Succession
The slow, progressive replacement of one community by another during the development of vegetation in any area
372
Climax community
The final, relatively stable community reached during successional stages
373
Primary succession
The occupation, by plant life, of an area not previously covered by vegetation
374
Secondary succession
Succession in an area that was previously covered by vegetation and still has some soil
375
Pioneer community
The first species to appear during succession
