General Biology: Core Concepts and Applications – Study Guide

Natural Selection and Evolution

Principles of Natural Selection

Natural selection is a fundamental mechanism of evolution, describing how organisms better adapted to their environment tend to survive and reproduce more successfully.

• Adaptation: Traits that increase an organism's fitness (ability to survive and reproduce) become more common in a population over generations.

• Survival and Reproduction: Organisms that are more adapted to their environment are more likely to survive and reproduce.

• Example: In a population of moths, those with coloration that camouflages them from predators are more likely to survive and pass on their genes.

Biological Classification and Nomenclature

Scientific Naming (Binomial Nomenclature)

Organisms are given scientific names using a two-part system called binomial nomenclature, which includes the genus and species names.

• Genus: The first part of the name, always capitalized (e.g., Homo).

• Species: The second part, not capitalized (e.g., sapiens).

• Example: Homo sapiens is the scientific name for humans, where Homo is the genus and sapiens is the species.

Properties of Water

Hydration Shells and Heat Absorption

Water's unique properties are essential for life, including its ability to form hydration shells and absorb heat.

• Hydration Shell: Water molecules surround ions or polar molecules, forming a hydration shell. This occurs in mixtures like salt and water, not in nonpolar mixtures like oil and water.

• Heat Absorption: Water has a high heat-absorbing capacity due to hydrogen bonding between molecules. This property stabilizes temperatures in organisms and environments.

• Example: Salt dissolves in water, allowing hydration shells to form around the ions.

Atoms, Ions, and Isotopes

Atomic Structure and Isotopes

Atoms consist of protons, neutrons, and electrons. Isotopes are atoms of the same element with different numbers of neutrons.

• Isotope Notation: The N-15 isotope of nitrogen has 7 protons, 8 neutrons, and 7 electrons.

• Anions: Negatively charged ions formed when atoms gain electrons. They have more electrons than protons and are typically formed by non-metals.

• Example Table:

Particle	Protons	Neutrons	Electrons
N-15 Isotope	7	8	7

Biological Molecules

Proteins: Structure and Function

Proteins are complex molecules with multiple levels of structure, each contributing to their function.

• Primary Structure: Sequence of amino acids in a polypeptide chain.

• Secondary Structure: Local folding patterns such as alpha helices and beta sheets.

• Tertiary Structure: Overall 3D shape formed by further folding of the secondary structure.

• Quaternary Structure: Association of multiple polypeptide subunits; not always held together by ionic bonds (can also involve hydrogen bonds, disulfide bridges, etc.).

• Example: Hemoglobin has a quaternary structure composed of four subunits.

Amino Acids and Functional Groups

Amino acids are the building blocks of proteins, each with a central carbon attached to specific functional groups.

• Functional Groups: Amino group (-NH2), carboxyl group (-COOH), hydrogen atom, and a variable side chain (R group).

• Example: Threonine contains a methyl group, hydroxyl group, and amino group, but not a phosphate group.

Lipids: Saturated and Unsaturated Fatty Acids

Fatty acids are classified based on the presence of single or double bonds in their hydrocarbon chains.

• Saturated Fatty Acids: Only single carbon-carbon bonds; solid at room temperature.

• Unsaturated Fatty Acids: One or more double carbon-carbon bonds; liquid at room temperature.

• Example: Olive oil contains mostly unsaturated fatty acids.

Carbohydrates: Polysaccharides

Polysaccharides are large carbohydrates composed of many monosaccharide units.

• Examples: Starch, cellulose, and glycogen are all polysaccharides.

• Energy Metabolism: Carbohydrates and proteins can be metabolized for energy, but vitamins are not used as energy sources.

Nucleic Acids: Structure and Monomers

Nucleic acids (DNA and RNA) are polymers made up of nucleotide monomers.

• Nucleotide: Consists of a phosphate group, a five-carbon sugar, and a nitrogenous base.

• Example: DNA is a polymer of nucleotides.

Biological Calculations

Polymer Composition

The molecular formula of a carbohydrate polymer can be used to determine the number of monomer units present.

• Example: A polymer with the formula C12H22O11 is composed of two glucose units (since each glucose is C6H12O6, and water is lost during polymerization).

Muscle Proteins

Myofilament Composition

Muscle contraction involves thick and thin myofilaments composed of specific proteins.

• Thick Filaments: Composed primarily of myosin.

• Thin Filaments: Composed primarily of actin.

• Example: In skeletal muscle, myosin and actin interact to produce contraction.

Biotechnology Techniques

DNA Fingerprinting and Gel Electrophoresis

Modern biotechnology uses several techniques to analyze and manipulate DNA.

• DNA Fingerprinting: Involves steps such as digestion with restriction enzymes, separation by gel electrophoresis, blotting, hybridization with probes, and detection.

• Gel Electrophoresis: Technique to separate DNA fragments by size using an electric current.

• Southern Blotting: Uses DNA probes to detect specific DNA sequences after gel electrophoresis and transfer to a membrane.

• Polymerase Chain Reaction (PCR): Amplifies DNA using Taq polymerase, which is heat-stable and remains active at high temperatures required for DNA denaturation.

Technique	Main Purpose	Key Component
Gel Electrophoresis	Separate DNA by size	Agarose gel, electric current
Southern Blotting	Detect specific DNA sequences	DNA probes
PCR	Amplify DNA	Taq polymerase

Essential Elements in Biology

Role of Elements in Biological Molecules

Certain elements are required for the synthesis of specific biological molecules.

• Iodine: Required for the synthesis of thyroxine (a thyroid hormone).

• Iron: Required for the synthesis of hemoglobin (oxygen-carrying protein in blood).

Summary Table: Key Biological Molecules and Their Monomers

Macromolecule	Monomer	Example
Protein	Amino acid	Hemoglobin
Carbohydrate	Monosaccharide	Starch
Lipid	Fatty acid, glycerol	Triglyceride
Nucleic Acid	Nucleotide	DNA

Additional info: Some explanations and context have been expanded for clarity and completeness, including the structure of amino acids, the process of DNA fingerprinting, and the role of essential elements in biological molecules.