Integrative Bio Final Flashcards!

Phenotype

Observable traits resulting from genotype and environment.

Levels of Organization

Cell → Tissue → Organ → Organ System → Organism; classification clarifies structural-functional relationships.

Structure-Function Example

Bird's ear (outer shape directs sound; tympanic membrane & ossicles transmit; inner cochlea converts mechanical to neural signals).

Proximate Causation

Immediate physiological causes (e.g. hormone-triggered song production).

Ultimate Causation

Evolutionary reasons (e.g. mate attraction enhances reproductive success).

Flowchart: Gene to Protein

DNA transcription (RNA polymerase + promoter) → pre-mRNA → RNA processing (splicing, cap, tail) → mRNA export → Translation initiation (ribosome + start codon) → Elongation (tRNA brings amino acids) → Termination (stop codon) → Polypeptide folding → Functional protein.

Nucleotides

Composed of phosphate, pentose sugar (deoxyribose or ribose), and nitrogenous base.

DNA

Uses deoxyribose; RNA uses ribose (with 2' OH).

Purines

Adenine (A), Guanine (G).

Pyrimidines

Cytosine (C), Thymine (T in DNA), Uracil (U in RNA).

Base Pairing

A-T (2 H‑bonds), G-C (3 H‑bonds).

Polymerization

Phosphodiester bonds connect 3′‑OH of one sugar to 5′‑phosphate of next.

Directionality

5′ phosphate end vs 3′ hydroxyl end; antiparallel complementary strands.

Stability

Higher GC content increases thermal stability (more H‑bonds).

DNA Monomer

Deoxyribonucleotide.

RNA Monomer

Ribonucleotide.

Protein Monomer

Amino acid.

DNA Sugar

Deoxyribose.

RNA Sugar

Ribose.

DNA Bases

A, T, G, C.

RNA Bases

A, U, G, C.

DNA Strands

Double.

RNA Strands

Single.

DNA Stability

High (no 2′ OH).

RNA Stability

Lower.

Protein Stability

Variable.

Diversity Shape of DNA

Low.

Diversity Shape of RNA

Moderate.

Diversity Shape of Protein

High.

DNA Functions

Genetic storage.

RNA Functions

Multiple (catalysis, info).

Protein Functions

Catalysis, structure, signaling.

mRNA

Carries coding information.

Monomer (DNA)

Deoxyribonucleotide

Monomer (RNA)

Ribonucleotide

Monomer (Protein)

Amino acid

Sugar (DNA)

Deoxyribose

Sugar (RNA)

Ribose

Bases (DNA)

A, T, G, C

Bases (RNA)

A, U, G, C

Strands (DNA)

Double

Strands (RNA)

Single

Stability (DNA)

High (no 2′ OH)

Stability (RNA)

Lower

Stability (Protein)

Variable

Diversity shape (DNA)

Low

Diversity shape (RNA)

Moderate

Diversity shape (Protein)

High

Functions (DNA)

Genetic storage

Functions (RNA)

Multiple (catalysis, info)

Functions (Protein)

Catalysis, structure, signaling

tRNA

Brings amino acids to ribosome.

rRNA

Structural & catalytic in ribosome.

Transcription

Process where RNA polymerase binds promoter (TATA box), unwinds DNA, adds ribonucleotides 5′→3′, and releases RNA at terminator.

Translation

Process where ribosome subunits bind mRNA, tRNA moves through E → P → A sites, and release factors bind stop codons to release polypeptide.

Mutation Types

Silent < Missense < Nonsense < Frameshift in impact severity.

Randomness (Mutations)

Occur without respect to benefit; raw material for evolution.

Heritability

Proportion genetic variance.

Plasticity

Environmental responsiveness.

Theory (Scientific)

A well-supported explanation based on evidence, broader than a hypothesis.

Evolution

Change in allele frequencies in a population over time.

Adaptation

Trait that increases fitness in a specific environment.

Fitness

Reproductive success; number of surviving offspring.

Directional Selection

Shifts mean trait value toward one extreme; reduces variation.

Stabilizing Selection

Favors intermediate phenotypes; decreases variation.

Adaptation Nuances

Not all traits increase fitness; mutations are random, may be neutral or deleterious.

Altruism vs. Selfishness

Altruism can evolve via kin or group selection; selfish behaviors can offer individual fitness benefits.

Advantageous Variation

Only heritable and expressed variation can respond to selection.

Mean & Variance Definitions

Mean = average trait value; variance = spread of trait values.

Directional Selection

Selective breeding for smaller limb length in Dachshunds; leads to gene frequency shift.

Directional Selection

Breeding Bulldogs for wider skulls.

Disruptive Selection

Breeding both very large (Great Danes) and very small (Chihuahuas) sizes from ancestral.

Disruptive Selection

Selecting coat variations (very short vs. very long hair).

Sexual Selection

Differential mating success due to traits that enhance attractiveness or competition.

Survival vs. Mating

Acts primarily on mate acquisition, not survival or parental care.

Intrasexual Competition

Competition among same sex (e.g. male deer antler fights).

Intersexual Competition

Mate choice (e.g. peacock tail).

Tradeoffs

Showy traits may reduce survival (predation risk).

Pre-copulatory

Courtship displays.

Post-copulatory

Sperm competition.

Parental Investment

Higher investment sex is choosier.

Gene Flow

Movement of alleles between populations; homogenizes genetic differences.

Founder Effect

Few individuals establish new population.

Bottleneck Effect

Drastic size reduction; both reduce variation and cause drift.

Genetic Drift

Random allele frequency changes due to sampling error; strongest in small populations.

Fixation vs. Loss

Fixation = allele frequency 1; loss = frequency 0.

Hardy-Weinberg Equilibrium

p²+2pq+q² under no evolution.

Assumptions of HWE

No selection, drift, flow, mutation, nonrandom mating; rarely fully met.

Non-Random Mating

Alters genotype, not allele, frequencies; can impact evolution via inbreeding.

Skin Color & Race

Skin pigmentation is one of many traits; race is social, not strictly genetic.

UV Benefits

Dark skin protects folate in high UV; light skin enhances vitamin D synthesis in low UV.

Cancer Selection

Skin cancer typically post-reproductive; weak selection against lighter skin.

Allelic Differences

Most genetic variation is within, not between, populations.

Diffusion

Passive movement of molecules from high to low concentration (e.g., O₂ across alveolar membranes).

Osmosis

Water diffusion across a semipermeable membrane toward higher solute concentration (e.g., water uptake by plant root cells).

Facilitated Diffusion

Passive transport via channel or carrier proteins (e.g., GLUT transporters moving glucose).

Active Transport

Energy-dependent movement against concentration gradients via pumps (e.g., Na⁺/K⁺ ATPase).

Transport Proteins

Channels (pores), carriers (conformational change), pumps (ATP-driven).

Relative Rates

Small nonpolar cross fastest; polar/ions require proteins; size and charge slow transport.

Membrane Potential

Voltage difference across membrane; inside negative (~-70 mV) due to K⁺ leak channels and Na⁺/K⁺ pump.