Bio 103 Queensu

Hardy Weinberg

Allele and Genotype frequencies remain constant if no evolutionary force is acting upon them.

Oogamy

A large, non-motile egg (ovum) and a small, motile sperm.

Anisogamy

Fusion of two morphologically dissimilar gametes. Gametes differ in size; one is typically larger (female) and one smaller (male).

Isogamy

Fusion of gametes that are morphologically identical in size and shape. Gametes are usually motile (have flagella).

organization of life

Organism→Population: All individuals of the same species living in a defined area. → Community: All populations of different species living and interacting in an area. → Ecosystem: Community plus the physical (abiotic) environment and their interactions. → Biosphere: All ecosystems on Earth; the global sum of life and environments.

Endosymbiont theory

Idea that early cells contained and replicated small prokaryotes which later became the mitochondria and chloroplasts.

Descent with modification

Idea that present‑day species are related by common ancestry and have changed over time.

Convergent evolution

Independent evolution of similar traits in unrelated lineages due to similar selective pressures.

Co‑evolution

Reciprocal evolutionary change between interacting species (for example predator–prey, host–parasite).

Gene flow

Movement of alleles between populations through migration and breeding.

Genetic drift

Random change in allele frequencies due to chance events, strongest in small populations.

Bottleneck effect

Sharp reduction in population size leading to loss of genetic variation.

Founder effect

Genetic drift effect when a new population is started by a few individuals, carrying only a subset of variation.

Fitness

Relative reproductive success of a genotype or phenotype compared with others.

Directional selection:

Natural selection favoring one extreme phenotype, shifting mean trait values.

Stabilizing selection

Selection favoring intermediate phenotypes and acting against extremes, reducing variation.

Disruptive (diversifying) selection

Selection favoring extreme phenotypes over intermediates, potentially creating bimodal distributions.

Balancing selection

Selection maintaining multiple alleles in a population (for example heterozygote advantage).

Frequency‑dependent selection

Fitness of a phenotype depends on its frequency in the population.

Artificial selection

Human‑driven selection for particular traits in domesticated species.

Prezygotic isolation

Barriers that act before fertilization (for example temporal, ecological, behavioral).

Postzygotic isolation

Barriers after fertilization (for example hybrid inviability or sterility).

Allopatric speciation

Speciation following geographic separation of populations.

Sympatric speciation

Speciation without geographic separation, often via ecological or genetic mechanisms.

Polyploidy

Condition of having more than two sets of chromosomes, important in plant speciation.

Homology

Similarity due to shared ancestry.

Analogy (homoplasy)

Similarity not due to common ancestry but to convergent or parallel evolution.

Endotherm

Organism that primarily uses internal metabolic heat to maintain body temperature (for example mammals, birds).

Ectotherm

Organism whose body temperature depends mainly on environmental heat sources (for example reptiles, many fish).

Signal vs. Sensory Transduction

Signal transduction is the broad mechanism linking any stimulus (mechanical, chemical, electromagnetic) to a cellular response, often via cascades like G-proteins or second messengers; it occurs in many cell types for responses like hormone action.

Sensory transduction is a specific subtype: it converts environmental stimuli (e.g., light, sound) into a receptor potential (graded membrane change) in specialized sensory cells, initiating neural signals to the brain.

Hyperpolarization vs. Depolarization

Depolarization makes the cell's interior less negative (e.g., from -70 mV to -50 mV) by Na⁺/Ca²⁺ influx, often triggering action potentials in excitable cells like neurons.​

Hyperpolarization makes it more negative (e.g., to -90 mV) via K⁺ efflux or Cl⁻ influx, typically inhibiting firing (as in some sensory or inhibitory responses)

4 Main Themes in Physiology

1. It is integrative.

2. It obeys physical and chemical laws.

3. It is shaped by evolution.

4. It is usually regulated.

Reductionism

Looking at a piece to understand a whole. Can help us understand how a whole system will function.

Emergence

The whole is more than the sum of its parts. Systems become more functional as they work together

Acclimation

Changed physiology because of single natural environmental change frequently in lab settings.

Acclimitization

Changed physiology because of multiple natural environmental changes.

Conformers

Organisms that conform to the environment when it changes.

Regulators

Organisms that have their own conditions and they maintain them no matter what the environment is doing.

Intercellular Connections

Animal cells are connected to ECM as well as other factors such as adhesions, surface attachments, and receptors. Tight junctions, gap junctions, desmones.

Adhesions

Tissues grown together that are normally separate. Like cells holding hands. cells to other cells, surfaces, or extracellular matrix components

Surface Attachment

Cells connected like an anchor to the surface.

Animal Tissue Types

Epithelial, connective, muscle and nerve.

Hormone producers

Pituitary, thyroid, parathyroid, adrenal, pineal, thymus, pancreas, testes and ovaries.

Forms of Chemical Signalling

Autocrine: Cell releases ligand that binds receptors on itself for self-regulation.​

Juxtracrine signaling: Signaling directly via cell to cell contact

Paracrine: Ligand acts on nearby target cells (local effect).

Endocrine: Hormones travel via bloodstream to distant target cells (systemic effect)

Three Types of Plasma Membrane Receptors

Ligand gated channels, G-protein coupled receptors, and enzyme receptors.

Anterior Pituitary

Makes 6 different peptide hormones.

ACTH

GH

LH

TSH

FSH

Prolactin

Posterior Pituitary

Stores two different peptide neurohormones.

Oxytocin.

ADH.

Second messenger

Small intracellular molecule (e.g., cAMP, Ca²⁺, IP₃) that amplifies signals from receptors, often activating protein kinases or altering gene expression.

Neurotransmitter:

Chemical (e.g., acetylcholine, glutamate, GABA) released at synapse to bind postsynaptic receptors.

Integration

CNS processing of sensory input to produce appropriate motor/output response.

Gonadotropin-releasing hormone (GnRH)

Hypothalamic hormone stimulating FSH/LH release.

Follicle-stimulating hormone (FSH)

Promotes gamete production (sperm/oocytes).

Luteinizing hormone (LH)

Triggers ovulation, steroidogenesis.

Trivers and willard hypothesis

suggests that mammals, including humans, bias their investment towards male offspring when in good condition and toward female offspring when in poor condition. Genes may not be passed on if given to a male.

Hypothalamic-pituitary-adrenal (HPA)

Hypothalamus CRH →pituitary ACTH → Adrenal cortisol

Hierarchical Organization of muscle

Filaments→sarcomeres→firbrals→fibers→muscles

Myosin

ATP-dependent motor proteins that convert chemical energy (ATP) into mechanical force, driving actin-based movements like muscle contraction. When pulling Actin, muuscle contraction occurs.

Actin

primary component of the cytoskeleton, providing structural support, determining cell shape, and enabling motility, cell division, and muscle contraction via interaction with myosin. When pulled by myosin, muscle contraction occurs

Involuntary movement

Reflex and conditioned responses. 100 ms or more for voluntary while involuntary can be 20ms

Encephalization

Formation of distinct heads leading to a central nervous system

Four Criteria of evolution

1.) the trait under selection must be VARIABLE in the population, so that the encoding gene has more than one variant, or allele.

2.) the trait under selection must be HERITABLE, encoded by a gene or genes

3.) the STRUGGLE OF EXISTENCE: that many more offspring are born than can survive in the environment.

4.) individuals with different alleles have DIFFERENT SURVIVAL AND REPRODUCTION that is governed by the fit of the organism to its environment

Vicariant speciation

Type of allopatric speciation where a physical, geographic barrier (e.g., mountain range, ocean, river) splits a widespread population into isolated groups, halting gene flow.

Principle of parsimony

States that the criterion for choosing the best phylogenetic hypothesis is to favor the tree that requires the fewest evolutionary changes. It is derived from the general scientific rule known as Occam's Razor.

Acclimation vs Acclimitization

Change in physiology as a response to a single factor vs change in physiology in response to a natural environment. Essentially, lab conditionsare compared to natural conditions.

Striated muscle

A type of muscular tissue characterized by a striped appearance under a microscope, caused by organized, repeating sarcomeres

B cells and T cells

Types of lymphocytes produced in bone marrow and the thymus gland, respectively which work in the immune system. Bone marrow lymphocytes produce antibodies, and each recognize only one antigen, while thymus lymphocytes attack infected cells

Cell-mediated immunity and humoral ( Antibody-Mediated) immunity

Branches of the adaptive immune system. The first is related to T cells and cellular immunity while the second is related to B cells and antibody immunity.

Synapomorphies

Shared, derived (newly evolved) character states that indicate a common ancestor for a specific group of organisms (clade)

Darwin’s Postulates of Natural Selection

Variation in phenotype exists among individuals

high reproductive potential means populations increase geometrically

individuals compete for limited resources

fit offspring with characteristics matched to present environment are more likely to survive and reproduce

Population

Organization level consisting of members of the same species living in the same location

Natural selection Vs evolution

Natural selection is a primary mechanism or process driving evolution, where organisms better adapted to their environment tend to survive and produce more offspring. Evolution is the broader, long-term result—a change in the inherited characteristics of a population over generations. Selection explains how evolution occurs

Crassulacean Acid Metabolism (CAM)

a water-efficient photosynthetic pathway used by plants in arid environments to minimize water loss. By closing stomata during the day and opening them at night, CAM plants fix into organic acids at night and release it for photosynthesis during the day, reducing photorespiration. Convergent Evolution example.

C4 photosynthesis

An advanced carbon fixation mechanism utilized by specialized plants (e.g., maize, sugarcane) to minimize photorespiration and maximize efficiency in hot, dry conditions. Example of Convergent evolution. Evolved several times independently.

Biogeography

Biology relating to specific geographic features, areas and timelines

Anthropogenic

Human-Generated. That which has been originated by humans

Lamarckism

Early 19th-century theory of evolution proposing that organisms pass physical characteristics, acquired through usage or disuse during their lifetime, to their offspring.

Lamarckism Vs Darwinism

Lamarckism proposes that evolution occurs through the inheritance of acquired traits (use/disuse), where individuals change during their lifetime and pass these changes to offspring. Darwinism, or natural selection, argues that variations exist randomly within populations, and individuals with favorable traits survive and reproduce more successfully

Allele

Specific variant form of a gene

Balanced Polymorphism

Stable genetic state where natural selection maintains multiple alleles (gene variants) at high frequencies within a population. Often caused by heterozygote advantage (overdominance), where individuals with two different alleles have higher fitness than either homozygote, this mechanism prevents any single allele from being eliminated, ensuring long-term genetic diversity.

Bottleneck and Founder Effect

Both forms of genetic drift—random, non-selective changes in allele frequencies that reduce genetic variation. A bottleneck occurs when a large population is drastically reduced by disaster, while the founder effect occurs when a small group splits off to establish a new population

Gene flow vs Drift

Both mechanisms of evolution, but they differ in that gene flow is the transfer of genetic material between populations through migration, increasing genetic similarity, while genetic drift is a random, chance-based change in allele frequencies within a population, typically reducing genetic variation and increasing divergence.

Runaway selection

Evolutionary mechanism where an exaggerated male trait, such as a peacock's tail, evolves due to a positive feedback loop with female preference. Females preferring a trait mate more with males possessing it, passing on both the trait and the preference, which can lead to extreme, sometimes disadvantageous, ornamentation.

Negative frequency-dependent selection (NFDS)

An evolutionary mechanism where the fitness of a phenotype or genotype increases as it becomes rarer and decreases as it becomes more common. This process, a form of balancing selection, maintains genetic polymorphism and biodiversity by preventing any single trait from dominating the population.

Clade

Group of organisms consisting of a common ancestor and all its descendants (a monophyletic group).

Point mutation

Change affecting a single nucleotide pair in DNA.

Chromosomal mutation

Large‑scale change in chromosome structure or number. Translocations/inversions and duplications

Germ‑line mutation

Mutation in cells that give rise to gametes, can be passed to offspring.

Commensalism

Interaction where one species benefits and the other is unaffected.

Innate immunity

Non-specific, rapid defense (barriers, phagocytes, inflammation, complement, NK cells).​

Adaptive immunity

Specific, memory-based (T/B lymphocytes, antibodies, MHC).

Antigen

Molecule triggering immune response.

Antibody

Y-shaped protein from B cells binding specific antigens.​

Cytokine

Signaling protein (e.g., interleukins) coordinating immune cells.​

Parthenogenesis

A form of asexual reproduction in which an egg develops into an embryo without fertilization by sperm.

The Red Queen hypothesis

Species must constantly evolve and adapt simply to survive while competing with ever-evolving, interrelated species. Suggests that ecological interactions—like predator-prey or parasite-host relationships—act as a "running" race where continuous adaptation is required just to maintain fitness, not necessarily to improve

Biomagnification

Increasing concentration of toxic, persistent substances (like mercury, DDT, or PCBs) in the tissues of organisms at successively higher trophic levels in a food chain.

Keystone Species