Population Dynamics: Growth & Influences

Population Dynamics: Key Concepts & Historical Influences

• The agricultural revolution led to settled communities through increased food production.
• The industrial revolution decreased death rates and rapidly increased populations due to medical, sanitation, and technological advancements.
• Developed countries exhibit declining birth rates linked to improved education, increased workforce participation for women, and access to family planning.

Population Dynamics: Calculations and Graph Interpretation

• Ecological Density = Population / Usable Habitat Area
• Example: 350 deer in a valley of 530 km² with an 80 km² lake results in a usable area of 450 km² and a density of approximately 0.78 deer per km².
• Exponential growth occurs when resources are unlimited.
• Logistic growth is an S-shaped curve, exhibiting a lag phase, an exponential phase, and a stationary phase.
• Lag Phase: Slow initial population growth.
• Exponential Phase: Rapid population growth occurs due to reproduction outpacing mortality.
• Stationary Phase: Growth levels off as it approaches carrying capacity.
• Logistic Equation: P(t) = K / [1 + ((K - P₀)/P₀)e⁻ʳᵗ], where K = carrying capacity, P₀ = initial population, and r = intrinsic growth rate.
• Introducing a competitor typically lowers the carrying capacity and alters the population growth trend.

Biochemistry: Biochemical Reactions

• Condensation (Dehydration Synthesis): Molecules join with the loss of water, such as glucose + fructose → sucrose + water.
• Hydrolysis: Bonds are broken by the addition of water.
• Redox Reactions: Involve electron transfer, such as the conversion of pyruvate to lactate or oxidation of Fe to Fe²⁺.
• Neutralization: An acid-base reaction forms water and a salt, such as HCl + NaOH → NaCl + H₂O.

Biochemistry: Bonding and Cellular Processes

• Covalent Bonds: Atoms share electrons, crucial for molecular structure.
• Exocytosis: Vesicles fuse with the cell membrane to release substances.
• Endocytosis: Cells engulf materials.
• Enzymes lower activation energy by stabilizing the transition state and bringing substrates into close proximity.
• Applying salt to a turkey draws out water via osmosis, leading to a dry texture.

Metabolic Processes: Cellular Energy and ATP

• ATP is composed of adenine, ribose, and three phosphate groups.
• Energy is stored in the high-energy bonds between phosphate groups in ATP.
• The conversion of ATP to ADP releases energy, which is fundamental for cellular activities.

Metabolic Processes: Photosynthesis and Cellular Respiration

• Photosynthesis Equation: 6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂
• Light-Dependent Reactions: Occur in thylakoid membranes, produce ATP, NADPH, and oxygen.
• Light-Independent Reactions (Calvin Cycle): Occur in the stroma, use ATP and NADPH to convert CO₂ into glucose.
• Aerobic Cellular Respiration Equation: C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + 36 ATP
• In yeast, anaerobic conditions lead to the production of ethanol and CO₂.

Molecular Genetics: DNA Structure and Replication

• The Watson & Crick Model: DNA is a double helix with a sugar-phosphate backbone.
• Complementary base pairing (A–T and C–G) occurs via hydrogen bonds.
• Complementary Base Pairing: For a DNA strand 5' ATTGCATTGGGGTA 3', the complementary strand is 3' TAACGTAACCCCAT 5'.
• DNA Helicase: Unwinds the double helix.
• DNA Polymerase: Adds nucleotides to the new strand.
• RNA Primase: Lays down RNA primers.
• DNA Ligase: Joins Okazaki fragments.
• DNA Gyrase: Prevents supercoiling.

Molecular Genetics: Transcription, Translation, and Mutations

• Transcription: Converts DNA to mRNA (uracil replaces thymine).
• Translation: Ribosomes read mRNA codons to synthesize proteins using the genetic code.
• Missense Mutation: One amino acid change.
• Nonsense Mutation: Premature stop codon.
• Silent Mutation: No change in amino acid sequence.

Molecular Genetics: Biotechnology Techniques

• PCR (DNA Amplification): Copies target DNA sequences.
• Gel Electrophoresis: Separates DNA fragments by size.
• Restriction Enzymes: Cut DNA at specific sites.
• DNA Barcoding: Uses genetic markers for species identification.
• Fluorescent ddNTPs: Used in sequencing to determine nucleotide order.

Homeostasis: Urine Formation

• Filtration: Blood plasma is filtered in the glomerulus, creating a filtrate with water, ions, and small molecules.
• Reabsorption: Essential substances (water, glucose, ions) are reabsorbed in the renal tubules through passive and active transport.
• Secretion: Additional wastes and excess ions are secreted into the tubules to form urine.

Homeostasis: Hormonal Regulation and Nerve Function

• Estrogen: Produced by the ovaries; regulates reproductive functions such as the menstrual cycle.
• Cortisol: Produced by the adrenal glands; plays a role in metabolism and the stress response.
• After an action potential, K⁺ channels open to allow potassium ions to leave the cell, restoring the negative resting potential.

Homeostasis: Ecological Interactions

• Ecological Interactions: Relationships like mutualism, commensalism, parasitism, and competition maintain ecological balance.