ORELA Biology (NT316) flashcards

33 cards. Read the term and the definition here. The deck at the top of this page is optional.

Cell Theory

All organisms consist of one or more cells, the cell is the basic unit of life, and all cells come from pre-existing cells through division.

Prokaryote vs Eukaryote

Prokaryotes lack a membrane-bound nucleus and organelles and have 70S ribosomes; eukaryotes have a nucleus, membrane-bound organelles, and 80S ribosomes.

Mitochondrion Function

The organelle where aerobic respiration occurs: the Krebs cycle runs in the matrix and oxidative phosphorylation occurs along the inner membrane cristae to produce ATP.

Chloroplast Structure

A plant organelle with stacked thylakoid membranes where light reactions occur and a stroma where the Calvin cycle fixes carbon dioxide into sugar.

Rough Endoplasmic Reticulum

Membrane network studded with ribosomes that synthesizes and folds proteins destined for secretion or for the Golgi apparatus and other organelles.

Golgi Apparatus

A stack of flattened membrane sacs that modifies, sorts, and packages proteins and lipids received from the endoplasmic reticulum into vesicles for transport.

Lysosome Function

A membrane-bound organelle containing acid hydrolase enzymes that digest macromolecules, worn-out organelles, and material brought in by phagocytosis.

Endosymbiotic Theory

Mitochondria and chloroplasts originated from engulfed bacteria, supported by their double membranes, circular DNA, 70S ribosomes, and independent division.

Passive vs Active Transport

Passive transport moves substances down a concentration gradient without energy; active transport moves substances against a gradient using ATP or an electrochemical gradient.

Osmosis

The net diffusion of water across a selectively permeable membrane from an area of higher water potential to an area of lower water potential.

Hypertonic Solution Effect

A solution with higher solute concentration than the cell causes water to leave, shrinking animal cells and causing plasmolysis in plant cells.

Enzyme Function

Enzymes are biological catalysts that lower activation energy by binding substrates at the active site and are not consumed in the reaction.

Competitive Inhibition

An inhibitor that binds the active site and competes with substrate; it raises the apparent Km but can be overcome by increasing substrate concentration.

Noncompetitive Inhibition

An inhibitor that binds a site other than the active site, changing enzyme shape; it lowers Vmax and cannot be overcome by adding more substrate.

Allosteric Regulation

Binding of a regulator molecule at a site other than the active site changes enzyme conformation, activating or inhibiting the enzyme's activity.

Central Dogma

The flow of genetic information: DNA is transcribed into mRNA, which is translated by ribosomes into a polypeptide chain.

Semiconservative Replication

DNA replication produces two molecules, each containing one original parental strand and one newly synthesized strand, following complementary base pairing.

Transcription

RNA polymerase reads a DNA template strand and synthesizes a complementary mRNA molecule; in eukaryotes this occurs in the nucleus and requires RNA processing.

Translation

Ribosomes read mRNA codons and transfer RNA delivers matching amino acids, forming a polypeptide chain that folds into a protein.

Monohybrid Cross Ratio

A cross between two heterozygotes for one gene yields a 3:1 phenotypic ratio and a 1:2:1 genotypic ratio in the offspring.

Dihybrid Cross Ratio

When two genes assort independently, a cross between double heterozygotes yields a 9:3:3:1 phenotypic ratio in the offspring.

Test Cross

Crossing an individual of unknown genotype with a homozygous recessive individual reveals whether the unknown is homozygous dominant or heterozygous.

Hardy-Weinberg Equilibrium

Allele and genotype frequencies remain constant when there is no mutation, migration, selection, or genetic drift and mating is random; p² + 2pq + q² = 1.

Natural Selection

Heritable variation in a population combined with differential survival and reproduction causes favorable traits to increase in frequency over generations.

Genetic Drift

Random change in allele frequencies, strongest in small populations; the bottleneck and founder effects are examples that reduce genetic diversity.

Gene Flow

Movement of alleles between populations through migration and interbreeding, which tends to reduce genetic differences among populations.

Trophic Energy Transfer

Only about 10% of energy at one trophic level transfers to the next; the rest is lost as heat through metabolism and in waste.

Taxonomic Hierarchy

The classification order Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species, with species being the most specific and smallest category.

Negative Feedback

A regulatory mechanism in which a change triggers a response that opposes the change, restoring a variable such as blood glucose or body temperature to its set point.

Positive Feedback

A regulatory mechanism in which a change triggers a response that amplifies the change, such as oxytocin release during childbirth or sodium influx during an action potential.

Photosynthesis Overview

Light reactions in thylakoids produce ATP and NADPH and release oxygen; the Calvin cycle in the stroma uses them to fix carbon dioxide into glucose.

Cellular Respiration Stages

Glycolysis in the cytoplasm, the Krebs cycle in the mitochondrial matrix, and oxidative phosphorylation along the inner membrane together harvest ATP from glucose.

Mitosis vs Meiosis

Mitosis produces two genetically identical diploid cells for growth and repair; meiosis produces four genetically varied haploid gametes through two divisions.