Learn: Atoms, Chemical Bonds, and Organic Molecules in Biology

What is an atom?

The smallest unit of any element, consisting of a nucleus with protons and neutrons, and orbiting electrons.

What is atomic mass?

The sum of protons and neutrons in an atom.

What determines an atom's atomic number?

The number of protons in the atom.

What are electron orbitals?

Distinct energy levels surrounding the nucleus where electrons are found.

How many electrons can the 1st orbital hold?

A maximum of 2 electrons.

How many electrons can the 2nd and 3rd orbitals hold?

A maximum of 8 electrons each.

What are valence electrons?

Electrons located in unfilled outer shells that participate in chemical bonding.

How many bonds can hydrogen (H) form?

One bond, as it needs one more electron to fill its first shell.

How many bonds can carbon (C) form?

Four bonds, as it has four valence electrons.

What is a covalent bond?

A bond formed when valence electrons are shared between atoms.

What is a nonpolar covalent bond?

A bond where electrons are shared equally between two atoms.

What is a polar covalent bond?

A bond where electrons are not shared equally, resulting in a molecule with distinct positive and negative ends.

What is an ionic bond?

A bond formed when one atom completely transfers one or more electrons to another atom.

What is a cation?

An atom that donates electrons and becomes positively charged.

What is an anion?

An atom that receives electrons and becomes negatively charged.

What happens to ionic compounds in water?

They dissociate into their constituent ions due to the polar nature of water.

What is a hydrogen bond?

A weak bond formed between two polar molecules, based on the attraction of opposite charges.

What role do hydrogen bonds play in water?

They contribute to water's surface tension and capillarity.

What is the pH scale?

A logarithmic scale that measures the acidity or alkalinity of a solution, ranging from 0 to 14.

What is a neutral solution's pH?

A pH of 7, where the concentration of H⁺ and OH⁻ ions is equal.

What characterizes an acidic solution?

It has more H⁺ ions than OH⁻ ions, with a pH less than 7.

What characterizes a basic (alkaline) solution?

It has more OH⁻ ions than H⁺ ions, with a pH greater than 7.

What is a buffer?

A solution that resists changes in pH, consisting of a weak acid and a weak base.

What is the bicarbonate buffer system?

A system that maintains blood pH at an average of 7.4, involving bicarbonate and carbonic acid.

What are organic molecules?

Compounds that contain carbon and hydrogen.

What is the significance of carbon's ability to form four bonds?

It allows carbon to create long chains and complex structures in organic molecules.

What are monosaccharides?

Simple sugars with one carbon ring, such as glucose and fructose.

What is a disaccharide?

Two monosaccharides joined by a covalent bond, such as sucrose.

What is a polysaccharide?

Several monosaccharides joined together, such as starch and glycogen.

What is cellulose?

A polysaccharide that forms the cell walls of plants and is indigestible by humans.

What is Dehydration Synthesis?

A process that forms covalent bonds by removing a hydrogen atom from one molecule and a hydroxyl group from another, releasing a molecule of water.

What is Hydrolysis?

A process that breaks bonds between monosaccharides by adding a molecule of water, which splits the larger molecule.

What are lipids?

Hydrophobic molecules consisting of nonpolar hydrocarbon chains and rings, with various functions.

What are triglycerides?

Lipids composed of one glycerol molecule and three fatty acid molecules.

What distinguishes saturated fats from unsaturated fats?

Saturated fats have single bonds between carbon atoms, while unsaturated fats have one or more double bonds.

What are ketone bodies?

Molecules produced by the liver from free fatty acids for energy, especially during low-carbohydrate diets.

What is ketosis?

A condition of elevated ketone levels in the blood, often due to low-carbohydrate diets or uncontrolled diabetes.

What are phospholipids?

Lipids that include a phosphate group, forming a major component of cell membranes.

What is the structure of phospholipids?

They have hydrophilic phosphate heads pointing outward and hydrophobic fatty acid tails pointing inward.

What are steroids?

Lipids characterized by a structure of three six-carbon rings and one five-carbon ring, such as cholesterol.

What role does cholesterol play in the body?

It acts as a precursor to steroid hormones and is used to synthesize essential molecules like vitamin D.

What are prostaglandins?

A type of fatty acid that functions as communication molecules between cells within the same organ.

What are the major functions of proteins?

Structural support, catalyzing chemical processes, immune response, signal reception, and substance transport.

What is the basic structure of an amino acid?

Each amino acid has an amino group, a carboxyl group, and a unique functional (R) group.

What are the four levels of protein structure?

Primary, Secondary, Tertiary, and Quaternary.

What is protein denaturation?

The process where a protein unfolds and loses its function due to changes in pH or temperature.

What are conjugated proteins?

Proteins that must combine with non-protein molecules to become functional, such as glycoproteins and lipoproteins.

What are nucleotides?

The building blocks of nucleic acids, composed of a five-carbon sugar, a phosphate group, and a nitrogenous base.

What are the two categories of nitrogenous bases?

Pyrimidines (single ring) and Purines (double ring).

What is the structure of DNA?

DNA consists of a deoxyribose sugar, phosphate groups, and nitrogenous bases, forming a double helix.

What is the Law of Complementary Base Pairing in DNA?

Cytosine pairs with Guanine, and Adenine pairs with Thymine, essential for DNA replication and transcription.

What are the three key differences between RNA and DNA?

RNA contains ribose sugar, is single-stranded, and includes uracil instead of thymine.

What are the types of RNA involved in protein synthesis?

Messenger RNA (mRNA), Transfer RNA (tRNA), and Ribosomal RNA (rRNA).

What is ATP?

Adenosine triphosphate, the primary energy currency of the cell.

What is cAMP?

Cyclic adenosine monophosphate, a crucial second messenger in many biological processes.

What are NAD and FAD?

Nicotinamide adenine dinucleotide and Flavin adenine dinucleotide, vital coenzymes in cellular respiration.