Biology: Organization of Living Things

Organization of Living Things

• Living organisms vary in forms, sizes, structures, and functions.
• Unicellular organisms consist of a single cell (e.g., Bacteria, Archaea, Protozoa).
• Multicellular organisms are made up of multiple cells (e.g., Animals, Plants, Fungi).
• Prokaryotic Cells lack a defined nucleus (e.g., Bacteria, Archaea).
• Eukaryotic Cells have a defined nucleus and membrane-bound organelles (e.g., Animals, Plants, Fungi).

Levels of Biological Organization

• Subatomic: particles that comprise an atom.
• Atoms: fundamental chemical elements.
• Molecules: chemical compounds formed from atoms.
• Organelles: membrane-bound cellular structures.
• Cells: the smallest unit of life.
• Tissues: groups of similar cells working together.
• Organs: structures with specific functions within an organism.
• Organ Systems: groups of organs that perform related functions.
• Organism: an individual of a species.
• Population: all individuals of a species in a specific area.
• Biological Community: all populations of different species in a given area.
• Biome: regional vegetation types and communities.
• Biosphere: the global sum of all living organisms.

Metabolism

• Refers to the ability to acquire materials and energy for life processes.
• Involves chemical reactions for breaking down or building up substances.
• Autotrophs: organisms that produce their own food (producers).
• Heterotrophs: organisms that consume other organisms (consumers).

Plant Metabolism

• Processes include photosynthesis, respiration, and organic compound synthesis.
• Photosynthesis is vital for producing substrates for respiration and organic compounds.
• Plants control stomatal opening to minimize water loss and maximize carbon dioxide intake.

Reproduction

• Living organisms can reproduce and transmit hereditary information via DNA.
• Sexual Reproduction: involves genetic recombination from two parents.
• Asexual Reproduction: offspring are genetically identical to one parent.
• Gametophytes: haploid stage in the life cycle of plants; can produce both gametes or just one type.

Evolution

• Refers to the change in characteristics of populations over time.
• Natural Selection: organisms better adapted to their environment tend to survive and reproduce.
• Genetic Variation: differences in traits due to mutations and genetic recombination.
• Adaptation: traits that enhance survival and reproduction in specific environments.
• Fitness: ability to adapt and survive in a changing environment.

Scientific Principles

• The term "scientia" means knowledge, linked to the pursuit of "natural science."
• Science develops theories from repeatedly tested hypotheses and principles verified through application.
• Good science encompasses open practices for verification by the scientific community.

Cell Structure

• The cell unit membrane encloses the cytoplasm, forming the protoplast which includes all living contents.
• Protoplast: living part of the cell without a cell wall.
• Hyaloplasm: fluid portion of the cytoplasm.

Biological Properties of Water

• Cohesion: water molecules bind to each other.
• Adhesion: water binds to other substances.
• Temperature Buffer: water has high specific heat and heat of vaporization.
• Metabolite: water reacts in physiological processes.
• Solvent: dissolves a wide range of substances.

Carbohydrates

• Categorized into three types:
  • Monosaccharides: simplest sugars, cannot be hydrolyzed.
  • Disaccharides: formed from two monosaccharides via dehydration synthesis.
  • Polysaccharides: long chains of monosaccharides, >10 units.

Lipids

• Insoluble in water but soluble in organic solvents; includes fats and oils.
• Saturated Fats: contain no double bonds, typically solid at room temperature.
• Unsaturated Fats: contain one or more double bonds, usually liquid at room temperature.

Proteins

• Comprise most of plant cell dry biomass; built from amino acids.
• Primary structure: amino acid sequence in polypeptide chains.
• Secondary structure: formations like alpha-helices or beta-sheets through hydrogen bonding.
• Tertiary structure: 3D folding due to side chain interactions.
• Quaternary structure: multiple polypeptide chains interacting to form functional proteins.
• Proteins serve various roles, including catalyzing biochemical reactions as enzymes.

Importance of Proteins in Plants

• Structural roles in membranes, signaling, and movement within cells.
• Acts as hormones, toxins, and other functional molecules.

Nucleic Acids

• Long chains crucial for plant life; made of nucleotides.
• Nitrogenous Bases: including pyrimidines (C, T, U) and purines (G, A).
• Adenosine Triphosphate (ATP): main energy carrier in plant cells.
• RNA: single-stranded, involved in protein synthesis and gene expression.

Mitochondria

• Double-membrane organelle involved in energy production.
• Inner membrane contains folds called cristae, increasing surface area for ATP production.
• Mitochondria possess their own ribosomes and DNA, suggesting a symbiotic origin from aerobic prokaryotes.

Chloroplasts

• Enclosed by two membranes; contains thylakoids for light energy capture during photosynthesis.
• Green pigment chlorophyll facilitates energy transformation through photosynthesis.