Major Themes in Biology

Major Themes in Biology

• Evolution: All living things are connected through a common ancestor, and species adapt over time.
• Structure and Function: The structure of something determines how it functions. Example: a bird's wings are structured for flight.
• Energy and Matter: All living things need energy. Plants use photosynthesis, while animals consume food.
• Information Flow: DNA provides instructions for life, passed from parents to offspring.
• Interactions: Living things interact with each other and their environment. Example: bees pollinating flowers.

Levels of Biological Organization

• Molecule: The smallest unit of life (e.g., DNA, proteins).
• Cell: The basic unit of life.
• Tissues: Groups of similar cells working together.
• Organism: Individual living things.
• Population: A group of the same species living together.
• Ecosystem: All living and nonliving things in an area.

Common Information Among All Life

• DNA: Instructions for building and running the organism. Both humans and bacteria have DNA, but human DNA is more complex.
• Cells: All living things are made of cells, whether one (bacteria) or many (humans).

Energy Transfer

• Significance: Life needs energy to function (move, grow, reproduce).
• Example: Energy flows from the sun to plants (photosynthesis), then to animals (consuming plants/animals).

Interactions in Biology

• Interactions between organisms (predators and prey).
• Interactions between organisms and their environment (trees absorbing CO2 and releasing O2).

Evolution

• Evolution: Species change over time due to natural selection.
• Significance: Helps understand relationships between species and how they adapt to survive. Example: Giraffes evolving long necks.

Unity of Life

• Common traits: All living things share certain traits.
• DNA: All life uses DNA as the genetic material.
• Cells: All life is made of cells.

Matter, Elements, and Compounds

• Matter: Has mass and takes up space.
• Elements: Pure substance made of one type of atom (hydrogen, oxygen, carbon).
• Compounds: Two or more elements chemically combined (e.g., water - H2O).

Essential Elements for Life

• Carbon, Hydrogen, Oxygen, Nitrogen.

Trace Elements

• Essential for survival in small amounts. Example: Iron is vital for oxygen transport in the blood.

Atoms

• Protons: Positive charge, in the nucleus.
• Neutrons: No charge, in the nucleus.
• Electrons: Negative charge, orbit the nucleus.

Isotopes

• Atoms of the same element with different numbers of neutrons.

Periodic Table

• Atomic number (number of protons).
• Atomic symbol.
• Atomic mass.
• Elements in the same column have similar chemical properties.

Valence Shells

• Outermost electron shell, determines the chemical behavior of an atom. Stability achieved when the valence shell is full.

Ions

• Atoms with a net charge by gaining or losing electrons.
• Cations: Positively charged.
• Anions: Negatively charged.

Electronegativity

• How strongly an atom pulls electrons toward itself. Important in forming bonds.

Molecules

• Group of two or more atoms bonded together.
• Example: Oxygen (O2) or Water (H2O).

Chemical Bonds

• Covalent bonds: Sharing electrons (e.g., H2O).
• Ionic bonds: Transferring electrons (e.g., NaCl).
• Hydrogen bonds: Weak attractions between molecules (e.g., water molecules).

Polar Molecules

• Uneven sharing of electrons, causing a partial positive and negative charge (e.g., water).

Importance of Chemical Bonds

• Chemical reactions occur when bonds are broken or formed.

Water as a Polar Molecule

• Partial positive on hydrogen atoms, partial negative on oxygen. This causes attraction, leading to hydrogen bonds.

Water Bonds and Properties

• Water molecules stick to each other (cohesion).
• Water molecules stick to other surfaces (adhesion).
• High specific heat (resists temperature changes).
• High heat of vaporization (takes a lot of energy to evaporate).
• Ice floats because it is less dense than liquid water (hydrogen bonds).
• Water is a solvent.

Concentration

• The amount of solute (e.g., salt) dissolved in a solvent (e.g., water).

Molecules of Glucose and Anything Else

• One mole of anything contains 6.022 x 10^23 molecules .

Importance of Concentration in Biology

• Affects how nutrients are absorbed in cells and how enzymes work.

Acidity

• Based on hydrogen ion concentration.
• Higher concentration of H+ ions = more acidic.
• pH scale measures acidity.

Buffers

• Maintain a stable pH by absorbing or releasing H+ ions.

Organic Compounds

• Contain carbon and often hydrogen, oxygen, nitrogen, and other elements.

Carbon's Bonding

• Forms four covalent bonds, enabling complex structures like DNA.

Organic Molecules

• Functional groups determine properties of organic molecules (e.g., hydroxyl (-OH), carboxyl (-COOH)).

Isomers

• Molecules with the same molecular formula but different structures. Examples of isomers include Glucose and Fructose.

Monomers and Polymers

• Monomers: Small building blocks.
• Polymers: Large molecules made by linking monomers. Example: Glucose is a monomer of carbohydrates, and starch is a polymer.

Dehydration and Hydrolysis

• Dehydration: Removing water to join monomers.
• Hydrolysis: Adding water to break polymers into monomers.

Structure and Function of Carbohydrates

• Based on the number of carbons and arrangement of atoms. Example: Glucose and fructose.

Covalent Bonds in Carbohydrates

• The bond formed between monosaccharides is a glycosidic bond.

Polysaccharide Examples

• Starch: Plant energy storage.
• Glycogen: Animal energy storage.
• Cellulose: Plant structural support.

Nucleic Acids

• Monomer: Nucleotide.
• Components of nucleotides: Sugar, phosphate group, and a nitrogenous base.

DNA vs. RNA

• DNA: Double-stranded; thymine (T).
• RNA: Single-stranded; uracil (U).

Proteins

• Monomers: Amino acids.
• Structure: Chains of amino acids (polypeptides) joined by peptide bonds.
• Differences: R group variations determine properties (e.g., polarity).

Lipids

• Fats: Glycerol and fatty acids
• Saturated: No double bonds, solid at room temp.
  • Unsaturated: Double bonds, liquid at room temp.
• Phospholipids: Two fatty acids + a phosphate group ; crucial for cell membranes.
• Steroids: Four fused carbon rings (e.g., cholesterol, hormones).

Cell Theory

• All living things are made of cells
• Cells are the basic unit of life
• All cells come from pre-existing cells.

Cell Size and Surface Area to Volume Ratio

• Small cells have a higher ratio that allows for faster material exchange.

Cellular Components

• Mitochondria: Powerhouse, produces ATP.
• Chloroplasts: Photosynthesis occurs here.
• Endomembrane System: ER, Golgi, and vesicles for protein and lipid transportation.
• Ribosomes: Protein synthesis.
• Nucleus: Contains DNA
• Nucleolus: Creates ribosomal RNA

Cytoskeleton

• Structures: Microfilaments (actin), intermediate filaments, microtubules (hollow tubes)
• Function: Support, movement, transportation within the cell.

Organelles

• Lysosomes: Digestion.
• Vacuoles: Storage.

Endosymbiosis

• Mitochondria and chloroplasts were once free-living bacteria. Evidence includes their own DNA and ribosomes.

Evidence of Endosymbiosis

• Mitochondria and chloroplasts contain their own DNA.
• These organelles have a double membrane.

Mitochondria Structures

• Cristae (folds in inner membrane): Increase surface area for energy production (ATP).
• Matrix: Fluid inside, where reactions like the citric acid cycle occur.

Chloroplast Structures

• Thylakoids: Stacked into grana, part of photosynthesis.

Cytoskeleton Function

• Network of proteins providing structure, movement, and transport for the cell.

Microtubules

• Transport materials.

This quiz explores the fundamental themes and levels of biological organization in life sciences. You'll learn about evolution, structure and function, energy and matter, as well as how information flows through DNA. Test your knowledge on how living organisms interact within their ecosystems and the hierarchy of biological organization.