Ch. 2 The Chemistry of Life - OpenStax Concepts of Biology

Elements in living things

Carbon, hydrogen, nitrogen, oxygen, sulfur, phosphorus

Macromolecules in living things

Carbohydrates, nucleic acids, proteins, lipids/fats

Nutrients

The matter an organism needs to survive

Matter

Occupies space and has mass

Element

Has its own chemical symbol and unique properties

3 parts of an atom

Proton, neutron, electron

Proton

Positively charged subatomic particle that is found in the nucleus of an atom

Neutron

Subatomic that has no charge and is found in the nucleus of an atom

Electron

Negatively charged subatomic particle that is found rotating around the nucleus of an atom

Isotopes

Different forms of the same element (have the same number of protons), but have a different number of neutrons.

Radioactive isotopes

Unstable and lose protons, other subatomic particles, or energy to form more stable elements, and are used to determine how old things are and can be used in imaging in healthcare.

Carbon-14

A particular radioactive isotope that is used to determine how old something is.

How elements interact with one another

Depends on how their electrons are arranged.

2

The maximum number of electrons that the shell closest to the nucleus of an atom can hold.

8

The maximum number of electrons that the 2nd and 3rd electron shells (if an atom has them) can each hold

Ion

When an atom does not contain equal numbers of protons and electrons; these can be positive or negative

Ionic bond

Occur when one atom loses an electron and becomes positively charged and another atom gains an electron and becomes negatively charged and the opposite charges attract

NaCl (table salt)

Example of ionic bonding

Covalent bonds

Occur when an electron is shared between two elements

Nonpolar covalent bond

A bond formed between two atoms of the same element or between different elements that share electrons equally

Polar covalent bond

A bond formed between two atoms with the electrons are shared unequally and spend more time closer to one nucleus than to the other nucleus, generating partial charges on the atoms.

O2

Example of a nonpolar covalent bonding

H2O

Example of polar covalent bonding

Hydrogen bond

A bond between the partially positive hydrogen of one molecule and a partially negative atom of another molecule

Many water molecules

Example of hydrogen bonding

Water

The liquid that is essential for life

Polar

A property of water meaning that it has a partially positive end of the molecule and a partially negative end of the molecule

Hydrophilic

"Water-loving" molecules, ex. sugars, salts, that can dissolve in water

Hydrophobic

"Water-fearing" molecules, ex. lipids/fats, that are not able to be dissolved in water

Water's temperature-stabilizing ability

The hydrogen bonds in water allow it to absorb and release heat energy more slowly than many other substances

Water's unique density

Water is less dense as a solid (ice) than as a liquid

Water's solvent abilities

Due to its polarity, water can easily dissolve ionic and polar molecules

Cohesion

Water molecules that attract to each other because of hydrogen bonding

Surface tension

The effect of the cohesion of water

Adhesion

The attraction between water molecules and other molecules.

Buffers

Substances that resist pH change and keep pH within a proper range.

Acidic

pH 0-less than 7

Neutral

pH 7

Alkaline/basic

pH above 7-14

Carbon

Element that can form 4 bonds and is the foundation element of life

Sugars

Make up carbohydrates

Polysaccharides/complex carbohydrates

Many sugars; ex. starch, glycogen, cellulose, chitin

Fatty acids

Make up lipids/fats

Amino acids

Make up proteins

Nucleotides

Make up nucleic acids (DNA & RNA)

Carb-loading diet

When people eat a lot of complex carbs (usually starchy) in order to stockpile energy; usually done by endurance athletes such as marathon runners

Ketogenic diet

Eliminating carbs from the diet so that the body breaks down stored fat

Regular, most-recommended diet

A balanced, unprocessed diet, rich in very colorful fruits and vegetables, lean meats, fish, whole grains, nuts, seeds, olive oil, and lots of water

Monosaccharide

1-sugar, ex. glucose; short-term energy storage molecule

Disaccharides

2-sugars, ex. sucrose; short term energy-storage molecule

Starch

Intermediate energy storage molecule in plants; made up of glucose molecules bonded together.

Glycogen

Intermediate energy storage molecule in animals; made up of glucose molecules bonded together.

Cellulose

Structural molecule in the cell walls of plants; made up of glucose molecules bonded together, not digestible by humans (serves as fiber), but it digestible by bacteria in the guts of cows, termites, etc.

Chitin

Structural molecule in the cell walls of fungi and also in the exoskeletons of insects, etc.; not digestible by humans

Description of lipids

Nonpolar, hydrophobic molecules

Functions of lipids

Long-term energy storage, insulation from the environment, signaling, and structural molecules

Saturated fatty acids

Subunits that make up lipids, do not contain any double bonds in the "tail" portion of the molecule, saturated with hydrogens, and solid at room temp.

Unsaturated fatty acids

Subunits that make up lipids, contain 1 or more double bonds in the "tail" portion of the molecule, have some hydrogens removed, and are liquid at room temp.

Triglycerides

Contain 3 fatty acids, are for long-term energy storage in fat cells

Trans fats

Unhealthy fat molecules that are worse than saturated fats; required labeling of them on nutrition labels has curbed their use in the food industry.

Phospholipids

Structural lipids that make up membranes, are unique in that they have a hydrophilic end and a hydrophobic end.

Steroids

Carbon ring-structured lipids that can serve as signaling hormones or can be structural.

Waxes

Complex mixtures of lipids that are protective and give a water-repellent covering

Protein functions

Molecules that can be structural, regulatory, contractile, protective, transport, storage, toxins, enzymes, or hormones

Enzymes

Biological catalysts, usually proteins, that make reactions go faster than they would otherwise.

Insulin

Protein hormone that helps to maintain blood sugar (glucose) levels.

Cholesterol

A lipid steroid molecule that stabilizes the cell membranes of animal cells.

Denaturation definition

Destruction of a protein's structure and its function, so that it won't work.

Denaturation causes

Heat, incorrect pH, chemicals such as salt, etc.

Amino acid general structure

Central carbon atom, with a hydrogen, amino group, carboxyl group, and an "R" variable group attached.

Primary structure of a protein

Amino acid sequence that determines the function of the protein

Tertiary structure of a protein

Functional protein level of structure, globular in shape

DNA purpose

Stores genetic information

RNA purpose

Disposable copy of the information in DNA that is used to make proteins

Nucleotide structure

Composed of a sugar, phosphate group, and a base

Structure of DNA

Double helix