Inductive vs Deductive Reasoning and Cell Theory

• Inductive reasoning forms conclusions from specific observations, while deductive reasoning applies general laws to specific cases.

Scientific Certainty

• Scientific certainty ranges from hypothesis (most doubt) to natural law (least doubt).
• A hypothesis needs testing
• A theory is backed by evidence and support, but natural law is mathematical and verifiable.
• Scientific uncertainty decreases as one moves from hypothesis to natural law.

Provisional Science

• Science is always evolving.
• New discoveries and technologies improve our understanding.
• Cell theory states that all living things are made of cells, which are the smallest form of life and come from preexisting cells.

Cell Theory and Origin of Life

• Life is a self-sustaining chemical system that can evolve through natural selection.
• Key aspects include self-sustainment, chemical reactions, and evolution via natural selection.
• Life organizes into compartments for optimal function, utilizing DNA and RNA for information.

Key Scientists and Discoveries

• Robert Hooke coined the term "cells".

• Antoine Van Leeuwenhoek made microscopes to study cells.

• Mathias Schleiden observed plant cells.

• Theodore Schwann coined "metabolism" and recognized cells as the basis of life along with Schleiden.

• Virchow observed mitosis.

• Louis Pasteur worked on vaccines, bacteria, and disproved spontaneous generation.

• Life is organized, can evolve, metabolizes, has genetic material, and can create offspring.

• The Oparin-Haldane theory suggests that early Earth's reducing atmosphere and energy sources allowed for the formation of organic compounds.

• The Miller-Urey experiment showed that life could be created abiotically in a closed system with gases and electrical energy.

• The oldest possible fossils are 3.7 billion years old, while known fossils date to 3.5 billion years ago.

• RNA is vital for life and is found in all cells.

• Key considerations for the origin of life include genetics (self-replicating RNA), metabolism (energy sources), and compartments.

Diversity of Life

• Life is classified into Eukaryotes, Bacteria, and Archaea.
• Eukaryotes have a nucleus and membrane-bound organelles.
• Bacteria lack a nucleus and organelles, with circular genetic material and peptidoglycan walls.
• Archaea share traits with both but are closer to eukaryotes and can withstand extreme conditions.
• Major characteristics of archaea include circular chromosomes, different RNA polymerase, and histone proteins.

Eukaryotic Kingdoms

• Animals lack cell walls and are circular.
• Plants have cellulose walls and are rectangular.
• Fungi secrete digestive enzymes and have chitin walls.
• Protists are diverse and "misfits" with mixed traits.

Horizontal Gene Transfer

• Horizontal Gene Transfer drives bacterial diversity through transformation, transduction, and conjugation.
• Transformation occurs when bacteria release DNA for uptake.
• Transduction involves mixing of bacterial and host cell DNA
• During conjugation, a pilus transfers genetic material between cells.
• The tree of life forms a interconnected web.

Eukaryotic Organization

• Eukaryotes utilize compartments for organization, including a phospholipid bilayer, lysosomes, peroxisomes, mitochondria, and chloroplasts.
• The nucleus contains a protein pore complex for transport and a laminate for structure.
• Rough ER has ribosomes and lots of folds and ridges inside its lumen.
• Smooth ER is tubular with a folding membrane.
• The golgi apparatus has cis and trans sides for material processing and transport
• Lysosomes and peroxisomes bud material.
• Mitochondria have membranes for electron transport.
• Chloroplasts have three membranes for photosynthesis.
• Plant cells have a protective cellulose cell wall.
• Chloroplasts and mitochondria were once bacteria engulfed by eukaryotic cells, supported by their own DNA and double membranes hence endosymbiotic theory
• Phagocytosis describes how these bacteria were engulfed and formed extra membranes, which eventually disappeared.

Protein Structure

• Proteins consist of 20 amino acids.
• Each protein has a unique function.
• Amino acids are linked by alpha carbon, a carboxyl group, an amino group, a hydrogen, and an R group, each with unique chemical properties.
• The "backbone" consists of all components but the R-group which determines the character of the amino acid.

Protein Structure Levels

• Primary structure: linear chain of amino acids linked by peptide bonds.
• Secondary structure: local folding stabilized by hydrogen bonds (alpha helices and beta sheets).
• Tertiary structure: overall 3D shape dictated by R group interactions; structure determines function.
• Quaternary structure: multiple tertiary structures combine (not always required).
• Protein folding is driven by the repulsion of hydrophobic acids by water, which influences its shape and stabilization as well as other bonds such as vander der waals

Alpha Helices and Red Blood Cells

• Alpha helices: hydrogen bonds within the structure and non polar components stick outwards to allow structure to pass
• Normal red blood cells transport oxygen efficiently, but shape changes from Glu to Val.
• Ligands signal molecules and hemoglobin binds oxygen for transport.
• Fetal hemoglobin binds more oxygen than adults.

Enzyme Binding Sites

• Ligand must have target to bind to
• Enzymes in the body must have ideal binding sites for ligands (signaling molecules).
• Examples include glucose binding to GLUT1, lactose to lactase, glucose to hexokinase, and proteins to chymotrypsin or cAMP.

Enzyme Inhibitors

• Competitive inhibitors bind to the active site.
• Noncompetitive inhibitors alter the active site shape
• Allosteric regulation lowers reaction rates by altering the active site without diluting the substrate.

Membrane Structure and components

• Phospholipid bilayers form membranes with tails facing inward and heads outward.
• Permeability influenced by saturated and unsaturated fatty acids and glycolipids
• Intergral and peripheral proteins assist the membrane's funcitons
• The lipid composition includes saturated and unsaturated fatty acids helping the protein with multiple functions
• Saturated fatty acids keep membrane stable shape

Fluid Mosaic Model

• The fluid mosaic model describes membrane flexibility depending on permeability.
• Temperature, pH, and cholesterol affect permeability.
• Kinks maintain fluidity in the cold.

Membrane Permeability

• Membrane permeability allows orderly material transport.
• Hydrophobic molecules, small uncharged polar molecules, and large uncharged polar molecules pass through the bilayer.
• Nonpolar substance rely on facilitate diffusion while ions use active transport via pumps and animals favor Na+

Membrane Transport

• Passive transport moves with the gradient, while active transport uses energy to move against it.
• Small, nonpolar molecules use passive transport while polar molecules use facilitated diffusion requiring a transport protein.
• GLUT1 is involved in metabolosim
• Open and closed channels allow molecules to pass and may require a ligand

Active Transport

• Active transport moves molecules against their concentration gradient, consuming ATP and forming electrochemical gradients.
• Primary: directly linked to ATP vs directly using ATP
• The Na+/K+ pump and Na+/glucose pumps exemplify active transport mechanisms of ATP versus existing gradients.
• Na+ and H+ can drive molecule transport, with plants preferring H+ and animals Na+.

Explore inductive and deductive reasoning in science. Understand scientific certainty from hypothesis to natural law. Learn about cell theory, stating all living things are made of cells, the smallest form of life that come from preexisting cells.