Biology 152

• Levels of biological hierarchy:

  • Biosphere
  • Ecosystems
  • Communities
  • Populations
  • Organisms
  • Organs
  • Tissues
  • Cells
  • Organelles
  • Molecules
• Experimental design includes:

  • Hypothesis/prediction
  • Control(s)
  • Independent and dependent variables
  • Manipulation/measurement of IV & DV
  • Holding other variables constant
  • Replicates (n#)
  • Repeating the experiment
  • Awareness that a hypothesis can never be proven
  • Ethics
  • Confounding effect/bias
• Sexual competition hypothesis for giraffes' long necks:

  • Giraffes evolved long necks because males with long necks win more fights, leading to more offspring (increased fitness)
• Properties of water:

  • Water molecules stick together
  • High surface tension due to hydrogen bonding
  • Excellent solvent
  • Temperature regulation
  • Ice is less dense than liquid water
• Hydrogen bond:

  • Forms only between HO, HN, or HF
• Definitions:

  • Kinetic energy: energy of movement
  • Thermal energy: kinetic energy associated with random movement of atoms
  • Temperature: average kinetic energy of molecules in a body
  • Polar covalent bonds: unequal sharing of a pair of electrons between atoms
  • Non-polar covalent bonds: sharing a pair of electrons between atoms
• Ocean acidification:

  • Increased CO2 levels due to human activities
  • More CO2 dissolves into the ocean, decreasing pH levels and making it more acidic
• DNA, RNA, and nucleotides:

  • DNA provides information for duplication and protein synthesis
  • DNA > RNA > Protein
  • Nucleic acid = polymers, nucleotides = monomers
  • Types of nitrogenous bases: Pyrimidines (cytosine, thymine, uracil), Purines (adenine, guanine)
• Macromolecules:

  • Synthesis and breakdown by enzymes
  • Carbohydrates: fuel and building material
  • Lipids: hydrophobic, vary in form and function
  • Proteins: majority of enzymes, made of amino acids
• Carbohydrates:

  • Monosaccharides, disaccharides, polysaccharides
  • Starch for plants, structural polysaccharides
• Lipids:

  • Mix poorly with water
  • Consist mostly of hydrocarbon regions
  • Types: fats, phospholipids
  • Saturated vs. unsaturated fats
• Proteins:

  • Majority of enzymes
  • Made of amino acids connected by peptide bonds
  • Different types of amino acids with specific properties
  • Primary, secondary, tertiary, and quaternary structures
• Nucleic Acids:

  • Building blocks for DNA and RNA
  • Gene expression for protein synthesis
  • Consist of sugar, phosphate, and nitrogenous base
  • Types of bases: Pyrimidines (C, T, U), Purines (A, G)
• Prokaryotic vs. Eukaryotic cells:

  • Eukaryotes have membrane-bound organelles, prokaryotes do not
  • DNA structure: eukaryotes have linear DNA, prokaryotes have circular DNA
• Organelles:

  • Nucleus, endoplasmic reticulum, Golgi apparatus, lysosomes, centrosome, peroxisome, mitochondria, ribosomes
• Endomembrane system:

  • Includes nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane
• Plasma membrane:

  • Composed of lipids and proteins
  • Phospholipid bilayer forms a stable barrier between aqueous compartments
• Endosymbiont theory:

  • Mitochondria and chloroplasts have circular, single-stranded DNA
  • Single-stranded, circular DNA is found in prokaryotes, supporting the endosymbiosis theory
• Cell cycle:

  -          Interphase

  o   G1 (cell growth)

  o   DNA synthesis/replication

  o   G2 (preparation for mitosis)

  -          Mitotic Phase (mitosis + cytokinesis)
• PMAT stands for Prophase, Metaphase, Anaphase, Telophase
• In Prophase, chromosomes are visible and condensing (46 chromosomes / 92 sister chromatid / 4n)
• Metaphase: chromosomes line up in the middle and the nucleus disassembles (46 chromosomes / 92 sister chromatid / 4n)
• Anaphase: chromosomes move away to the poles of the cells by the centrioles, separating the chromatids using spindles (46 chromosomes / 46 sister chromatid / 2n) – each pole
• Telophase: two new nuclei are formed on both poles of the cell to create new cells (46 chromosomes / 46 sister chromatid / 2n) – in each nucleus
• Cytokinesis is the process of separating the two new cells to produce regular body cells, which are identical
• Cell cycle includes interphase (DNA replication, basic functions, cell growth) and mitosis
• Chromosomes are counted by the number of centromeres
• PMAT #1:

  • Prophase: chromosomes pair up with homologous pairs, crossing over occurs
  • Metaphase: homologous chromosomes line up
  • Anaphase: chromosomes are pulled away from their homologous pairs
  • Telophase: 2 new nuclei are formed
• Meiosis is a reduction division process, dividing one cell into four daughter cells with half the number of chromosomes of the first one, producing gametes with 23 chromosomes
• Mechanisms contributing to genetic variation include crossing over, independent assortment, and random fertilization of gametes
• Mendel's work includes the Law of Segregation and the Law of Independent Assortment
• Pleiotropy is when one gene has multiple phenotypic effects, while epistasis is when a gene at one locus alters the phenotypic expression of a gene at another locus
• Genes are portions of DNA that code for traits, and alleles are variations of genes
• Phenotype refers to observable traits, while genotype refers to genetic traits
• Polygenic Inheritance involves one trait controlled by two or more genes, like hair color or skin color
• Codominance and incomplete dominance are ways in which traits can be expressed in offspring
• ABO blood traits show complete dominance for types A, B, and O, and codominance for type AB
• Humans only need the gene for one X chromosome, as women "shut down" one of the X chromosomes through X inactivation, forming a Barr body where most genes are inactive
• In tortoiseshell cats, the black and orange alleles located on the X chromosome are inactivated in a specific way: one X chromosome inactivates the black allele, and the other X chromosome inactivates the orange allele
• Sex-linked diseases can be X or Y-linked, with Y-linked diseases passed from dad to son, and X-linked diseases passed down regardless of gender