Bio 103 Queensu

Hardy Weinberg

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

Genotype frequency: p2 + 2pq + q2 = 1

Allel frequency: p+q=1

Where p is dominant and q is recessive

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

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.

Acclimitization

Changed physiology because of 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, signalling across gap junctions, paracrine, and endocrine

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

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 favour 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)