Biology Flashcards
enzymes
protein catalysts that accelerate reactions by reducing the activation energy without being consumed or altered by the reaction. Note that enzymes affect only the rate of reaction; they do not effect the underlying thermochemistry of the reaction or the number of products that can eventually be formed
Calcitonin
hormone synthesized and released by the thyroid gland that decreases plasma Ca2+ concentration
Tidal Volume
the volume of air that is normally inhaled or exhaled with each breath
Binary Fission
Method of asexual reproduction by which prokaryotes divide. the circular DNA molecule replicates and then moves to opposite sides of the cell. The cell then divides into two daughter cells of equal size
Stabilizing Selection
type of natural selection where the normal phenotype is favored while those outside the norm are eliminated
synapse
the space between the axon terminal of one neuron and the dendrite of another neuron. Synapses are where neurotransmitters are released
Parthenogenesis
The development of an unfertilized egg into an adult organism
Citric Acid Cycle
The cycle begins when the two-carbon acetyl group from acetyl CoA combines with oxaloacetate to form citric acid. This product then proceeds through a series of reactions that result in the regeneration of oxaloacetate and the production of three NADH, one FADH2, and one GTP
peptide hormones
hydrophilic hormones incapable of permeating the cell membrane that bind to surface receptors and act through secondary messengers
Directional Selection
Type of natural selection where one extreme phenotype is favored over the normal phenotype and other extreme phenotypes
Monohybrid Cross
A cross between two organisms where only one trait is being studied.
Gluconeogenesis
A process in the liver by which glucose is produced using by-products of glycolysis, lipids, or fats
Lysosome
membrane-bound vesicle that contains hydrolytic enzymes used for intracellular
Leading Strand
During DNA replication, the strand of DNA that is continuously synthesized in the 5’ to 3’ direction. The template strand is read in the 3’ to 5’ direction
Glycolysis
Through a series of enzymatic reactions in the cytoplasm, glucose is converted into two molecules of pyruvate. The energy released in this process is used to produce a net yield of two ATP and two NADH molecules
Action Potential
A sharp change in the membrane potential of neurons or muscle cells caused by a change in the selective permeability to K+ and Na+ using ion-gated channels. Action potentials are all-or-none events
Genotype
The genetic makeup of an individual
Endometrium
the mucosal lining of the uterus where the embryo implants. Progesterone is necessary for the maintenance of the endometrium during pregnancy
Sister Chromatids
After replication, each chromosome consists of two identical chromatids held together at a central region called the centromere. After the mitotic spindle pulls the sister chromatids apart, each chromatid is referred to as a chromosome
Residual Volume
the amount of air that must remain in the lung at all times in order to prevent lung collapse
Lagging Strand
During DNA replication, the strand of DNA that is synthesized in small fragments called Okazaki fragments and then ligated together. The Okazaki fragments are synthesized in the 5’ to 3’ direction, but the overall synthesis is in the 3’ to 5’ direction. The template strand has a 5’ to 3’ polarity
Negative Pressure Breathing
The contraction of the diaphragm and the intercostal muscles increases the volume of the thoracic cavity, reducing the pressure in the intrapleural space. This decrease in pressure creates a vacuum that causes the lungs to suck in air
Point Mutation
mutation in which one nucleotide base is substituted for another. The protein products are often functional
Active Transport
Membrane transport that utilizes energy. Unlike other methods of transport, active transport can move particles from a region of lower concentration to a region
Bacteriophages
viruses that can infect bacteria
Facultative Anaerobe
an organism that make ATP by aerobic respiration if oxygen is present, but that can switch to fermentation when oxygen is not available
Posterior Pituitary
Stores and releases hormones (oxytocin and ADH) synthesized by the hypothalamus. The release of these hormones is triggered by an action potential that originates in the hypothalamus
osmoregulation
maintenance of water and solute concentrations
Spongy Bone
Lighter and less dense than compact bone, it consists of an interconnecting lattice of bony spinucles (trabeculae). The cavities between the spicules contain bone marrow
Zymogen
Enzymes that must undergo processing before it can catalyze reactions
Sister Chromatids
After replication, each chromosome consists of two identical chromatids held together at a central region called the centromere. After the mitotic spindle pulls the sister chromatids apart, each chromatid is referred to as a chromosome
Fibrin
Protein responsible for blood clotting
inner cell mass
the group of cells in a blastocyst (mammalian blastula) that develop into the embryo
Test cross
a cross between an organism of an undetermined genotype and another that is homozygous recessive for the trait of interest
Non-competitive inhibitor
Molecule that inhibits the activity of an enzyme by binding to a regulatory site on the enzyme, thereby changing the conformation of the enzyme. Because these inhibitors do not directly compete with the substrate, increasing substrate concentration usually has little effect in counteracting this inhibition of the catalytic rate
Cartilage
a firm, elastic, translucent connective tissue consisting of collagenous fibers embedded in chondrin. Produced by cells called chondrocytes. Cartilage is the principal component of embryonic skeletons and can harden and calcify into bone
Passive Immunity
a short-lived immunity resulting from the transfer of antibodies into an individual who does not produce those antibodies
Compact bone
much more dense than spongy bone, compact bone consists of haversian systems (osteons)
chromatin
chromosomes in their uncoiled active state. chromatin is not visible under a light microscope
Villi
fingerlike projections that extend out of the small intestine in order to increase surface area for maximum absoprtion
Chyme
combination of partially digested food and acid that forms in the stomach
Aldosterone
a steroid hormone produced in the adrenal cortex that increases reabsorption of sodium and water and the excretion of potassium
Disruptive Selection
type of natural selection where both phenotypic extremes are favored over the normal phenotype
Active Immunity
immunity resulting from the production of antibodies during a previous infection or a vaccination
Cardiac Output
the total volume of blood the left ventricle pumps into circulation per minute. The cardiac output can be increased by increasing either the heart rate or the stroke volume
Induction
the influence of a group of cells (sometimes called the organizer) on the development of other cells. Induction is achieved by chemical substances known as inducers
Peristalsis
involuntary contractions of smooth muscle that push food through the digestive tract
Capillaries
blood vessels composed of a single layer of endothelial cells, facilitating exchange between the blood and interstitial fluid
Leydig Cells
also referred to as “interstitial cells of Leydig,” Leydig cells are located in the testes and secrete testosterone and other androgens
Thermoregulation
maintenance of a constant internal body temperature
Monosynaptic Reflex
Reflex pathway that has only one synapse between the sensory neuron and the motor neuron (e.g., knee-jerk reflex).
