Biology basics

What are elements in chemistry?

Elements are substances that cannot be broken down into simpler substances by chemical means.

Which four elements are crucial for building biological molecules?

Oxygen (O), carbon (C), hydrogen (H), and nitrogen (N).

What are trace elements?

Trace elements are elements required by an organism only in very small quantities, such as iron (Fe), iodine (I), and copper (Cu).

What are protons?

Protons are positively charged (+) particles found in the nucleus of an atom.

What defines an ionic bond?

An ionic bond is formed between two atoms when one or more electrons are transferred from one atom to the other.

How do hydrogen bonds contribute to the properties of water?

Hydrogen bonds create cohesion, adhesion, surface tension, high heat capacity, and expansion on freezing.

What is pH and how is it measured?

pH is a scale from 1 to 14 that indicates whether a solution is acidic, basic, or neutral, with 7 considered neutral.

What are macromolecules?

Macromolecules are large complex molecules made up of smaller building blocks called monomers.

What is dehydration synthesis?

Dehydration synthesis is the process in which monomers are joined to form polymers by the removal of a water molecule.

What distinguishes carbohydrates from other organic compounds?

Carbohydrates contain carbon, hydrogen, and oxygen in an approximate ratio of 1:2:1.

What is the function of ribosomes in a cell?

Ribosomes are the sites of protein synthesis, manufacturing all proteins required by the cell or secreted by the cell.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotic cells are simpler and smaller without membrane-bound organelles, while eukaryotic cells are more complex with various organelles.

What is the fluid-mosaic model?

The fluid-mosaic model describes the arrangement of phospholipids and proteins in the plasma membrane.

What happens during glycolysis?

Glycolysis is the process of splitting glucose into two molecules of pyruvic acid, resulting in a net production of 2 ATP and 2 NADH.

Dihybrid crosses examine what?

Dihybrid crosses study the inheritance patterns of two traits simultaneously.

What is natural selection?

Natural selection is the process by which individuals with favorable traits are more likely to survive and reproduce.

What is the role of mutations in evolution?

Mutations introduce genetic variations into a population, which can lead to evolutionary changes.

What is the purpose of the Hardy-Weinberg principle?

The Hardy-Weinberg principle describes how allele frequencies remain constant in a population under certain conditions.

What is the significance of the ribosome structure during protein synthesis?

Ribosomes have binding sites (A, P, E) for tRNA and mRNA, facilitating the assembly of amino acids into polypeptides.

What is the structure of DNA?

DNA is a double helix composed of two strands of nucleotides linked by base pairs Adenine with Thymine, and Cytosine with Guanine.

What does the central dogma of molecular biology describe?

The central dogma describes the flow of genetic information from DNA to RNA (transcription) and then to protein (translation).

Elements

Substances that cannot be broken down into simpler substances by chemical means.

Main Elements of Life

Oxygen (O), Carbon (C), Hydrogen (H), Nitrogen (N) are the four main elements used to build biological molecules.

Trace Elements

Elements required by an organism only in very small quantities (e.g., iron, iodine, copper).

Subatomic Particles

Protons (+), Neutrons (neutral), and Electrons (–) are the building blocks of atoms.

Isotopes

Atoms with the same number of protons but different numbers of neutrons.

Compounds

Substances made up of two or more elements held together by chemical bonds.

Ionic Bond

A bond formed when one or more electrons are transferred from one atom to another.

Covalent Bond

A bond formed when electrons are shared between atoms.

Polar Covalent Bond

A bond where electrons are shared unequally between two atoms.

Non-Polar Covalent Bond

A bond where electrons are shared equally between two atoms.

Water Properties

Water exhibits cohesion, adhesion, surface tension, high heat capacity, and expansion upon freezing.

Cohesion

The tendency of water molecules to stick together.

Adhesion

The tendency of water molecules to stick to other substances.

Capillary Action

The ability of water to rise up against gravity due to cohesion and adhesion.

Acidic Solution

A solution that contains a high concentration of hydrogen ions (H+).

Basic Solution

A solution that contains a high concentration of hydroxide ions (OH–).

pH Scale

A scale from 1 to 14 that measures the acidity or alkalinity of a solution.

Neutral pH

A pH of 7, indicating equal concentrations of H+ and OH– ions.

Organic Molecules

Molecules that contain carbon and are essential for life.

Polymers

Chains of building blocks (monomers) in macromolecules.

Monomers

The individual building blocks of polymers.

Dehydration Synthesis

A reaction that forms polymers by removing a water molecule.

Hydrolysis

The process of breaking down polymers into monomers by adding water.

Carbohydrates

Organic compounds containing carbon, hydrogen, and oxygen, usually in a ratio of 1:2:1.

Monosaccharides

The simplest form of carbohydrates, serving as an energy source (e.g., glucose, fructose).

Disaccharides

Carbohydrates formed by the union of two monosaccharides (e.g., maltose).

Polysaccharides

Carbohydrates composed of many monosaccharides (e.g., starch, cellulose, glycogen).

Glycogen

A sugar storage molecule found in animals.

Starch

A sugar storage molecule found in plants.

Cellulose

A polysaccharide that provides structural support in plant cell walls.

Chitin

A polymer of β-glucose that serves as a structural molecule in fungi and arthropods.

Proteins

Biological molecules essential for structure, function, and regulation of the body.

Amino Acids

Building blocks of proteins, containing carbon, hydrogen, oxygen, and nitrogen.

Peptide Bond

The bond formed between two amino acids.

Polypeptide

A chain of amino acids that folds into a functional protein.

Primary Structure

The linear sequence of amino acids in a protein.

Secondary Structure

The local folding of the polypeptide chain into alpha helices or beta sheets.

Tertiary Structure

The overall three-dimensional shape of a folded polypeptide.

Quaternary Structure

The arrangement of multiple polypeptide chains into a single functional protein.

Lipids

Organic molecules made primarily of carbon and hydrogen, including triglycerides and phospholipids.

Triglycerides

The most common type of lipid, composed of a glycerol molecule and three fatty acid chains.

Saturated Fats

Fatty acids with no double bonds in their carbon chains.

Unsaturated Fats

Fats with one or more double bonds in their carbon chains.

Phospholipids

Lipids with two fatty acid tails and a phosphate group, essential for cell membranes.

Cholesterol

A type of lipid that stabilizes cell membranes.

Nucleic Acids

Biomolecules made up of nucleotides, essential for genetic information storage and transfer.

DNA

Deoxyribonucleic acid, the hereditary material in organisms.

RNA

Ribonucleic acid, involved in protein synthesis.

Cell Theory

States that all living things are composed of cells, the cell is the basic unit of life, and all cells arise from preexisting cells.

Prokaryotic Cells

Simple, smaller cells without a nucleus or membrane-bound organelles.

Eukaryotic Cells

Complex cells with a nucleus and membrane-bound organelles.

Plasma Membrane

The outer boundary of the cell, regulating the movement of substances in and out.

Nucleus

The organelle that houses the cell's DNA and controls cellular activity.

Ribosomes

Structures where protein synthesis occurs, made of rRNA and proteins.

Endoplasmic Reticulum (ER)

A network of membranes involved in protein and lipid synthesis.

Golgi Apparatus

The organelle that modifies, sorts, and packages proteins for secretion.

Mitochondria

The powerhouse of the cell, producing ATP through cellular respiration.

Lysosomes

Organelles containing digestive enzymes to break down waste materials.

Vacuoles

Storage organelles for water, nutrients, and waste.

Cytoskeleton

A network of protein fibers that maintains cell shape and support.

Cilia and Flagella

Structures that aid in cell movement.

Plant Cells vs. Animal Cells

Plant cells have cell walls, chloroplasts, and large central vacuoles, while animal cells do not.

Transport across Membranes

Movement of molecules across cell membranes can occur via passive or active transport.

Passive Transport

Movement of substances across a cell membrane without energy expenditure.

Active Transport

Movement of substances against their concentration gradient requiring energy.

Diffusion

The movement of molecules from an area of high concentration to low concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Tonicity

The ability of a solution to affect the flow of water into or out of a cell.

Hypertonic Solution

A solution with a higher concentration of solutes compared to the cell, causing cell shrinkage.

Hypotonic Solution

A solution with a lower concentration of solutes compared to the cell, causing cell swelling.

Isotonic Solution

A solution with an equal concentration of solutes as the cell.

Endocytosis

The process by which cells take in large particles by engulfing them.

Exocytosis

The process by which cells expel materials in vesicles.

Glycolysis

The first step in cellular respiration, breaking down glucose into pyruvate.

Krebs Cycle

A series of reactions that produce energy carriers from acetyl-CoA.

Electron Transport Chain

A series of proteins that transfer electrons and pump hydrogen ions to generate ATP.

Photosynthesis

The process by which plants convert light energy into chemical energy.

Light Reactions

The first stage of photosynthesis where sunlight is converted into ATP and NADPH.

Dark Reactions (Calvin Cycle)

The phase of photosynthesis that uses ATP and NADPH to make glucose.