Biology 30 Diploma flashcards
Biology 30 Diploma · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Resting potential
- The electrical charge difference across a neuron membrane at rest, about -70 mV, maintained by the sodium-potassium pump and selective ion permeability.
- Threshold
- The minimum depolarization a neuron must reach, typically around -55 mV, before voltage-gated sodium channels open and an action potential fires.
- Saltatory conduction
- Rapid impulse travel in myelinated neurons where the action potential jumps between nodes of Ranvier, greatly increasing conduction speed along the axon.
- Refractory period
- A brief interval after an action potential when a neuron cannot fire again, ensuring impulses travel one direction and limiting maximum firing frequency.
- Neurotransmitter
- A chemical released from axon terminals into the synaptic cleft that binds receptors on the next cell, exciting or inhibiting it before being broken down or reabsorbed.
- Acetylcholinesterase
- An enzyme in the synaptic cleft that rapidly breaks down acetylcholine, ending the signal and allowing the postsynaptic membrane to return to resting state.
- Negative feedback
- A control mechanism in which a change triggers a response that reverses that change, restoring homeostasis such as stable blood glucose or body temperature.
- Positive feedback
- A control mechanism in which a change triggers responses that amplify it, such as oxytocin increasing contractions during childbirth until the process completes.
- Insulin
- A hormone from pancreatic beta cells that lowers blood glucose by stimulating cells to take up glucose and store it as glycogen.
- Glucagon
- A hormone from pancreatic alpha cells that raises blood glucose by promoting glycogen breakdown in the liver and release of glucose into the blood.
- ADH
- Antidiuretic hormone from the posterior pituitary that increases water reabsorption in kidney tubules, concentrating urine and raising blood water content.
- Thyroxine
- A thyroid hormone that raises basal metabolic rate, increases oxygen consumption, and supports growth and nervous system development in humans.
- Genotype
- The specific combination of alleles an organism carries for a trait, such as homozygous dominant, heterozygous, or homozygous recessive.
- Phenotype
- The observable expression of a trait, produced by the interaction of an organism's genotype with its environment.
- Monohybrid cross
- A cross tracking one trait between parents; heterozygote by heterozygote yields a 3:1 phenotype ratio and a 1:2:1 genotype ratio.
- Dihybrid cross
- A cross tracking two traits at once; heterozygote by heterozygote yields a 9:3:3:1 phenotype ratio when genes assort independently.
- Testcross
- A cross of an individual with unknown genotype against a homozygous recessive individual, revealing the unknown genotype by the phenotypes of the offspring.
- Incomplete dominance
- A pattern where neither allele fully masks the other, so heterozygotes show an intermediate phenotype, such as pink flowers from red and white parents.
- Codominance
- A pattern where both alleles are fully expressed in heterozygotes, as in AB blood type where both A and B antigens appear on red blood cells.
- Sex-linked trait
- A trait controlled by a gene on a sex chromosome, usually the X; recessive X-linked disorders appear more often in males, who have only one X.
- Linked genes
- Genes located close together on the same chromosome that tend to be inherited together, producing offspring ratios that deviate from independent assortment.
- Crossing over
- Exchange of genetic material between homologous chromosomes during meiosis, producing recombinant chromosomes and increasing genetic variation in gametes.
- Nondisjunction
- Failure of chromosomes to separate properly during meiosis, producing gametes with extra or missing chromosomes and causing conditions such as trisomy 21.
- DNA replication
- Semiconservative copying of DNA in which the double helix unwinds and each strand serves as a template for a new complementary strand.
- Transcription
- The process in which RNA polymerase builds a messenger RNA copy from a DNA template, occurring in the nucleus of eukaryotic cells.
- Translation
- The process at ribosomes where mRNA codons are matched to tRNA anticodons, assembling amino acids into a polypeptide chain.
- Codon
- A sequence of three mRNA bases that specifies one amino acid or a stop signal during protein synthesis.
- Mutation
- A change in the DNA base sequence, such as substitution, insertion, or deletion, that may alter protein structure and be inherited if it occurs in gametes.
- Hardy-Weinberg equilibrium
- A model predicting stable allele frequencies in a large, random-mating population free of selection, mutation, and migration, expressed as p^2 + 2pq + q^2 = 1.
- Natural selection
- A process in which individuals with heritable traits better suited to their environment survive and reproduce more, increasing those alleles in later generations.
- Genetic drift
- Random change in allele frequencies in small populations, including bottleneck and founder effects, which can reduce variation independently of natural selection.
- Species
- A group of organisms that can interbreed in nature and produce fertile offspring, remaining reproductively isolated from other such groups.