Essential Biological Principles

Essential Biological Principles

• Biology is the study of living organisms and life processes.
• Adaptation is the process of organisms adjusting to new or changing environments.
• Levels of hierarchy range from cells to organisms (cells → tissues → organs → systems → organisms).
• Quantitative data is numeric, qualitative is descriptive.
• Hypotheses are testable predictions.
• Pseudoscience lacks scientific validity.
• Controlled experiments vary one variable at a time.
• Homeostasis is maintaining a stable internal environment.
• Stimuli evoke responses in organisms.
• Living things exhibit properties like metabolism, growth, and reproduction.
• Metric system is a standardized measurement system used in science.
• Independent variables are manipulated; dependent variables are measured.
• Serendipity involves accidental discoveries.
• Technology advances scientific knowledge.
• Review of safety symbols is crucial for laboratory safety.
• The control is the standard of comparison in an experiment.

Chemical Foundations

• Atoms are the basic units of matter.
• Ions are atoms with unequal numbers of protons and electrons.
• Organic compounds are carbon-based molecules vital for life.
• Covalent bonds form by sharing electron pairs.
• Ionic bonds form between oppositely charged ions.
• Balanced equations have equal numbers of atoms on each side.
• Solutes are substances dissolved in a solvent.
• Biomolecules are molecules found in living organisms.
• Carbohydrates, like glucose, provide cellular energy.
• Lipids are hydrophobic, forming cell membranes.
• Nucleic acids (DNA and RNA) store and transfer genetic information.
• Polar molecules have partial charges.
• pH measures acidity/alkalinity.
• Saturated and unsaturated fats differ in the presence or absence of double bonds.
• Protons are positively charged particles in an atom's nucleus.
• Products are substances formed in a chemical reaction.
• Bases decrease the hydrogen ion concentration.
• Isotopes are atoms of the same element with varying numbers of neutrons.
• Hydrogen ions are involved in acid-base reactions.

Key Cellular Components

• Cells are the basic units of life.
• Plasma membranes are semi-permeable cell enclosures.
• Robert Hooke coined the term "cell".
• Vacuoles are storage organelles in cells.
• Mitochondria are the cell's powerhouses, producing ATP.
• Golgi apparatus modifies, sorts, and packages proteins.
• Prokaryotes are single-celled organisms without a nucleus.
• Cell theory states all living things are composed of cells.
• Homeostasis maintains internal equilibrium within cells.
• Active transport moves molecules against concentration gradients using energy.
• Diffusion moves molecules from high to low concentration passively.
• Endoplasmic Reticulum (ER) synthesizes proteins and lipids.
  • Rough ER has ribosomes for protein synthesis.
  • Smooth ER has no ribosomes for lipid synthesis.
• The nucleus is the cell's control center, containing DNA.
• Lysosomes contain digestive enzymes.
• Microtubules provide structural support and aid in movement/cell division.
• Cytoplasm is the gel-like substance within the cell membrane.
• Selective permeability allows certain substances to pass through the plasma membrane.
• Hypertonic, hypotonic, and isotonic solutions describe relative solute concentrations.

Energy Mechanisms

• Energy is the capacity to do work.
• ATP is the main energy carrier in cells.
• The Krebs cycle oxidizes acetyl-CoA to generate energy.
• Autotrophs produce their own food.
• Photosynthesis converts sunlight to chemical energy.
• Cellular respiration breaks down glucose to produce ATP.
• Chlorophyll is a pigment in photosynthesis.
• Fermentation is an anaerobic energy-producing process without oxygen.
• CAM is a photosynthetic adaptation in arid conditions.
• Thylakoids are membrane structures in chloroplasts where photosynthesis occurs.
• Electron transport chains transfer electrons to generate ATP.
• Heterotrophs consume other organisms for energy.
• Rubisco is an enzyme in carbon fixation.
• Glycolysis breaks down glucose to pyruvate.
• Mitochondria are the site of cellular respiration.

Reproduction Processes

• Cytokinesis is the division of the cytoplasm during cell division.
• Ethical considerations govern research and applications.
• The cell cycle is the sequence of events in cell growth and division.
• Mitosis divides a single nucleus into two genetically identical nuclei.
• Binary fission is asexual reproduction in prokaryotic cells.
• Cancer cells undergo uncontrolled division.
• Plant and animal cells differ in cytokinesis.
• Stages of the cell cycle: G1 (growth), S (DNA replication), G2 (preparation for mitosis), and M (mitosis).
• Mitosis stages: Prophase, Metaphase, Anaphase, Telophase.
• Interphase is the normal functioning phase of a cell.
• Carcinogens are cancer-causing substances.
• Stem cells can develop into different cell types.
• Centromeres hold sister chromatids together.
• Cyclins regulate the cell cycle.
• Spindle apparatus aids in chromosome movement.

Genetic Principles

• Meiosis produces four genetically different haploid cells.
• Haploid cells have one set of chromosomes.
• Diploid cells have two sets of chromosomes.
• Alleles are different forms of a gene.
• Dominant traits express over recessive traits.
• Recessive traits are expressed only when two recessive alleles are present.
• Punnett squares predict genetic trait distribution.
• Crossing over exchanges genetic material between homologous chromosomes during meiosis.

Advanced Genetic Concepts

• Pedigree symbols track inheritance patterns in families.
• Galactosemia is an inherited disorder affecting galactose metabolism.
• Homozygous individuals have identical alleles.
• Heterozygous individuals have different alleles.
• Genotype is genetic makeup; phenotype is physical expression.
• Codominance is the full expression of both alleles.
• Incomplete dominance results in a blended phenotype.
• Karyotypes show chromosome numbers and appearances.
• Down syndrome is a genetic disorder with an extra chromosome 21.
• Nondisjunction is the failure of chromosomes to separate correctly during meiosis.
• Sex-linked traits are associated with genes on sex chromosomes.
• Carriers have a recessive allele.
• Achondroplasia, Albinism, and Cystic Fibrosis are examples of genetic disorders.
• Trisomy is having an extra chromosome; monosomy is having one less.
• Autosomes are non-sex chromosomes.
• Epistasis is gene interaction where one gene masks another.