Honors BIO - Unit 1

Acid

A chemical substance that donates hydrogen ions (protons) to a solution and has a pH level below 7. Strong acids release all their hydrogen ions quickly, while weak acids release only some of them

Adhesion

The binding or attraction between dissimilar cells, molecules, or surfaces, which allows cells to stick together to form tissues. It sends chemical signals that control cell growth, movement, and development

Aqueous Solution

A mixture where a substance (solute) is dissolved in water (solvent). Water is the universal solvent.

Atom

The basic unit of matter and the smallest particle of a chemical element that keeps its unique properties. Atoms are made of the nucleus (protons - positive charge - and neutrons - neutral charge) and the electron cloud (outer space holding orbiting electrons (negative charge). All living things are made of atoms, and 96% of living matter relies on carbon, hydrogen, oxygen, and nitrogen.

Atomic number

The total number of protons found in the nucleus of an atom. This is also what identifies an element, and can be the same as the electron number when it’s a neutral atom.

Atomic mass

the total mass of a single atom, made of protons and neutrons because electrons are too small to count.

Base

A nitrogenous base that builds genetic code in DNA and RNA, although, it also describes any chemical substance with pH levels greater than 7 that accept hydrogen ions.

Biology

The scientific study of life and living organisms. Structure - how living things are built, from tiny cells to complex organs. Function - how living bodies work and keep homeostasis. Evolution - how species change and adapt over generations. Ecosystems - How organisms interact with each other and their environment.

Buffer

A aqueous solution that resists sudden change in pH levels by absorbing or releasing hydrogen ions. Relies on chemical reaction between solutions and protects enzymes or proteins from denaturing.

Denaturation

The process where proteins or nucleic acids lose their natural three-dimensional shape and biological activity due to external stress or chemicals.

Chemical compound

A pure substance made of two or more different elements joined by chemical bonds in fixed proportions. They can only break apart from a chemical reaction, not physically filtering

Chemical reaction

a process where starting materials, called reactants, change into new substances, called products, by breaking and forming chemical bonds inside living things.

Cohesion

The attractive force that causes molecules of the same substance to stick together. Cohesion pulls water into spherical droplets, and creates surface tension.

Covalent bond

A strong chemical link where two atoms share one or more pairs of electrons to become stable in their valence shell. They’re very hard to break, and they hold together atoms in DNA, proteins, and water

Electron

A stable, negatively charged subatomic particle that drives life processes through energy transfer, chemical bonding, and metabolic reactions.

Electron shell

an energy level or region surrounding an atomic nucleus where electrons are most likely to be found. The outermost shells are valence shells which determine how an atom interacts with other atoms.

Element

A pure substance that cannot be broken down into simpler substances by ordinary chemical reactions. Each one is made of a specific type of atom that share the same proton number in their nucleus

Heat

The transfer of thermal energy between living systems and their environment. Heat moves from warmer to cooler objects (thermal energy transfer), and maintain homeostasis.

Homeostasis

A self-regulating process by which biological systems maintain a stable internal environment while adjusting to change external conditions.

Hydrogen bond

A weak electrostatic attraction between a partially positive hydrogen atom and a partially negative electronegative atom like oxygen or nitrogen. It does not transfer electrons, and it uses a special intermolecular or intramolecular attraction. They’re easily broken and reformed, though strong in large numbers.

Intermolecular

Attractive or repulsive non-covalent interactions between separate molecules

Intramolecular

existing, acting, or occurring within a single molecule

Hydration shell

the ordered layer of water molecules that surrounds a charged or polar solute (like an ion, protein, or carbohydrate) in an aqueous solution

Ion

An atom or molecule that has an electric charge because it gained or lost one or more electrons. Cation is a positive ion, and forms when the atom loses electrons. Anion is a negative ion and forms when an atom gains electrons.

Ionic bond

A type of chemical link formed through the electrostatic attraction between oppositely charged ions, created when one atom completely transfers one or more electrons to another.

Isotope

One of two or more forms of the same chemical element that contains equal numbers of protons but different number of neutrons. Atomic mass is different than an element because they change neutrons in nucleus. Stable isotopes don’t decay over time, but radioisotopes contain nucleus that emits radiation and breakdown down the stable form.

Mass number

The total number of protons and neutrons in an atomic nucleus

Matter

Anything that has mass and takes up space, forming the physical building blocks of all living organisms. Matter is usually made by carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur.

Molecule

A group of two or more atoms held together by chemical bonds to form the smallest unit of a substance that keeps its chemical properties. They are the building blocks for all living things, and they’re built on carbon, hydrogen, oxygen, and nitrogen.

Neutron

A neutral subatomic particle found in atomic nuclei which biology relies on for atomic structure

Non-polar covalent bond

A chemical bond where two atoms share valence electrons because they have similar or identical electronegativities (electron-pulling strengths). They’re hydrophobic and have no partial charges. (electors distributed evenly, leaving no extremes)

Nucleus

Positively charged center of an atom made of protons and neutrons, even though nucleus usually means the genetic control center of a cell.

pH scale

A logarithmic number line from 0 to 14 that measures how acidic or basic a water-based solution is by tracking hydrogen ion concentration

Polar molecule

A structure with a partial positive charge on one side and a partial negative change on the other, caused by an unequal sharing of electrons. They love water. Oxygen and nitrogen pull shared electrons closer to themselves than hydrogen and carbon atoms don’t.