Biology: Biochemistry Key Concepts

• Study notes on key concepts in Biology, including biochemistry, elements, isotopes, chemical bonds, intermolecular forces, functional groups, isomers, carbohydrates, and lipids

Biochemistry

• Biochemistry examines the chemistry of molecules that constitute life and their interactions within living organisms, focusing on the physical and chemical properties of biological compounds.

Elements Essential to Life

• Life is composed of 92 naturally occurring elements, with 25 being essential.
• Carbon and hydrogen form the foundational building blocks of biological molecules.
• Nitrogen, phosphorus, sulfur, and oxygen interact with carbon and hydrogen to determine molecules' chemical properties.

Isotopes and Radioisotopes

• Isotopes are atoms with the same number of protons but different neutron counts.
• Protons define an element's identity and elements typically have multiple stable isotopes.
• Radioisotopes are unstable isotopes, featuring an imbalance in neutron count.
• They undergo radioactive decay, emitting subatomic particles or electromagnetic waves to achieve stability, transforming one element into another.

Radioactive Decay and Half-Life

• Radioactive decay occurs when a nucleus rearranges to become stable; instability accelerates this process.
• Radioisotopes' unstable nuclei decay, facilitating their conversion from one element to another.
• Half-life measures the time it takes for a radioactive sample to reduce to half its initial quantity.

Radioisotope Applications

• Radioisotopes are utilized in radiotherapy for cancer treatment.
• They serve as tracers; when injected, their breakdown can be monitored via PET scans.
• Radiometric dating uses the ratios of naturally occurring isotopes to their decay products to estimate the age of rocks and fossils.

Intramolecular Forces

• Intramolecular forces hold atoms together within a molecule.
• Ionic bonds form between cations and anions and are easily disrupted in polar solvents.
• Covalent bonds involve electron sharing to achieve full valence shells.

Electronegativity and Bond Polarity

• Electronegativity describes an atom's capacity to attract shared electrons.
• Oxygen, nitrogen, and chlorine exhibit high electronegativity, while hydrogen, carbon, and phosphorus have low electronegativity.
• Polar covalent bonds arise from unequal electron sharing between elements with differing electronegativity, leading to partial charges.
• Nonpolar covalent bonds occur between elements with similar electronegativity, ensuring equal electron sharing.

Intermolecular Forces

• Intermolecular forces dictate molecular interactions and physical properties of substances and are generally attractive.
• Hydrogen bonding involves hydrogen bonded to electronegative atoms and creates attractive interactions due to partial charges; cumulatively, these bonds can be quite strong.
• Hydrophobic interactions occur between nonpolar molecules and water.
• Hydrophilic interactions occur between polar molecules and water, facilitating hydrogen bond formation.
• The hydrophobic effect is the phenomenon where non-polar molecules cluster together in water

Functional Groups

• Functional groups are atom groups attached to molecules, influencing their chemical and physical behaviors.
• Hydroxyl groups readily form hydrogen bonds, increasing a molecule's water solubility and are present in carbohydrates, proteins, nucleic acids, lipids, and alcohols.
• Carbonyl groups enhance a molecule's water solubility, found in carbohydrates and nucleic acids.
• Carboxyl groups are acidic and donate protons, ionizing to release a hydrogen and create a negative charge; they're found in proteins and lipids.
• Amino groups are basic and accept protons, with water solubility decreasing as carbon number increases; they ionize by accepting a hydrogen ion and becoming positively charged, found in proteins and nucleic acids.
• Sulfhydryl groups are less polar than hydroxyl groups, have a strong odor, and form covalent disulfide bonds; they are found in proteins.
• Phosphate groups are crucial in energy storage and release and nucleotide linking, found in nucleic acids, ATP, DNA, and RNA.

Molecular and Structural Formulas

• Molecular formulas specify element types and quantities in a compound.
• Structural formulas illustrate atomic bonding arrangements.

Isomers

• Isomers share atomic composition but differ in connectivity, leading to distinct properties.
• Structural isomers display variations in bonding arrangements.
• Stereoisomers vary in the spatial arrangement of their groups.

Types of Structural Isomerism

• Positional isomerism involves functional groups at varying locations.
• Chain isomerism features differing carbon backbones.
• Functional isomerism presents different functional groups.

Geometric Isomerism

• Geometric isomerism features similar groups and different arrangements about a double bond.
• Cis isomers have like groups on the same side.
• Trans isomers have like groups on opposite sides.

Enantiomers

• Enantiomers share molecular formulas and connectivity but are non-superimposable mirror images which occur with asymmetrical carbons (carbons attached to 4 different groups).

Carbohydrates

• Carbohydrates have a ratio of CnH2nOn, containing numerous hydroxyl and carbonyl groups, rendering them polar and water-soluble.
• They serve as immediate energy sources or long-term storage, with sugars and starches offering readily accessible energy.

Monosaccharides

• Monosaccharides contain 3-7 carbon atoms, are rich in hydroxyl groups, and are water-soluble; examples include glucose, fructose, and galactose.

Glucose Stereoisomers

• The position of the hydroxyl group on carbon 1 determines if glucose is alpha (OH on bottom) or beta (OH on top).
• Both forms exist in water.

Disaccharides

• Glycosidic linkages bond two monosaccharides, either 1-4 to form chains or 1-6 to form branches.
• Glucose + fructose = sucrose
• Glucose + glucose = maltose
• Glucose + galactose = lactose

Amylose, Amylopectin, Starch, and Glycogen

• Amylose is unbranched, constituting 20% of starch, while amylopectin is branched, making up the remaining 80%.
• Both starch and glycogen store energy, but glycogen's branched structure facilitates quicker breakdown due to higher surface area.

Cellulose Characteristics

• Cellulose is a key component of plant cell walls.
• Beta-glycosidic bonds between glucose monomers make it indigestible for humans, who lack the necessary enzyme.
• Cellulose lacks nutrient value but aids digestion; high fiber content indicates high cellulose levels.

Glycosidic Linkages

• Alpha glycosidic linkages mean the joining monomers' OH groups share orientation.
• Beta glycosidic linkages mean they have opposing orientations which requires one monomer to flip.

Lipids and Their Properties

• Lipids contain carbon, hydrogen, and oxygen, with higher carbon and hydrogen levels and less oxygen.
• Used majorly by animals for long-term energy storage due to energy-rich C-H bonds
• They yield twice the energy per gram compared to carbohydrates but are less accessible due to hydrocarbon chains and are hydrophobic but soluble in oils and nonpolar solvents; examples include oils, fats, waxes, phospholipids, and steroids.

Lipid Functions

• Lipids facilitate long-term energy storage and insulation.
• They are used for steroid hormone production and protection.
• Phospholipids are major components of cell membranes.
• Lipids also create water repellent layers covering fruits, leaves, fur, feathers.

Triglycerides Formation

• Triglycerides consist of one glycerol and three fatty acids
• Glycerol has three carbons with a hydroxyl group each; fatty acids are long hydrocarbons ending in a carboxyl group.
• The bond between glycerol's hydroxyl and a fatty acid's carboxyl forms an ester.

Types of Fatty Acids

• Saturated fatty acids contain only single bonds.
• Monounsaturated acids have at least one double bond.
• Polyunsaturated acids contain two or more double bonds.
• Trans fats contain a trans double bond.

Hydrogenation impact on fats

• Hydrogenation adds hydrogen to liquid oils to create solid fats, converting cis fats to trans fats.

Phospholipids vs. Triglycerides

• Phospholipids contain only two fatty acids; the third is substituted by phosphate and choline.

Phospholipid Bilayer

• The hydrophilic heads face the aqueous environment in the extracellular fluid (ECF) and cytoplasm.
• Hydrophobic tails form the interior.

Steroids

• Steroids are lipids based on four carbon rings.
• Arrangement of carbon rings and functional groups determine steroid type.
• Cholesterol, testosterone, estrogen, medicines (steroid ointments), Anabolic Steroids.

Waxes function and states

• Waxes are solid at room temperature.
• Plants produce waxes to coat leaves and fruits, preventing water loss and repelling insects.
• Animals produce them to provide water repellency on skin, fur, feathers, and insect exoskeletons.

Brief study notes on key concepts in Biochemistry, including the elements of life, isotopes, and the properties of essential biological molecules. Includes the role of carbon, hydrogen, nitrogen, and other elements.