Life Processes: Chap 2

Matter

Matter is anything that takes up space and has mass.

Element

An Element is a basic building block of matter.

Abundant Elements in Humans

The four most abundant elements in the human body are Carbon, Nitrogen, Oxygen, and Hydrogen, which together make up about 90% of the human body.

Atom

An Atom is the smallest unit of an element that still retains the chemical and physical properties of the element.

Components of Atoms

Atoms are made up of Protons, Neutrons, and Electrons.

Atomic Number

The atomic number is the number of protons in the nucleus.

Mass Number

The mass number is the number of protons and neutrons (plus the minimal mass from the electrons).

Atomic Mass

The Atomic Mass is the actual mass of the protons, neutrons, and the electrons.

Isotopes

Isotopes are members of the same element (same number of protons) that have different numbers of neutrons.

Stability of Isotopes

Isotopes can be stable or radioactive.

Radioisotopes

Radioisotopes release various types of energy (radiation) in the form of rays or sub-atomic particles.

Radiation Levels

Low levels of radiation are normal and can be useful. High levels of radiation cause tissue damage and can be carcinogenic or lethal.

Molecules

Molecules are formed when atoms bond.

Compounds

Compounds are formed when atoms of different elements bond.

Valence Shell

A Valence shell is the outermost shell of electrons of an atom.

Ions

Ions are positively or negatively charged atoms (particles).

Sodium Ion Example

Na begins with 11 protons and 11 electrons (0 charge). It donates 1 electron to Cl, so, Na gets a +1 charge, and Cl gets a -1 charge.

Ionic Bond

The attraction between the two equally and oppositely charged particles creates an Ionic Bond.

Covalent Bond

In some situations, atoms can share electrons between their valence shells to form a Covalent Bond.

Covalent Bonds and Electron Pairs

Every pair of electrons shared creates an additional covalent bond. Two oxygen atoms can share two pairs (4 total) electrons, creating a double covalent bond. Triple covalent bonds can also be formed in a similar fashion.

Properties of water

Polar - has one positive end and two negative ends

Hydrogen Bonds

attraction between water molecules created by polarity

High heat capacity

it takes a relatively large amount of energy to change water's temperature

High heat of evaporation

it takes a lot of heat to turn water from a liquid to a gas

Water is a solvent

polar compounds can be dissolved in water

Water is Cohesive

it attaches to itself (forms drops)

Water is Adhesive

it attaches to surfaces

Hydrogen Bond

the attraction of a slightly positive, covalently bonded hydrogen to a slightly negative atom in the vicinity

First cells evolved in water

because of this (and hydrogen bonds), all living organisms are 70% - 90% water.

Hydrogen bonds effect on water

Without hydrogen bonds, water would freeze at -100º C and boil at -91º C.

Acids

substances that release hydrogen (H+) ions in water.

Bases

substances that take up hydrogen (H+) ions or release hydroxide (OH-) ions in water.

Buffer

compound that resists changes in pH when acid or base is added to it.

Organic molecules

Contain Carbon and Hydrogen

Macromolecules

a molecule that contains many subunits.

Dehydration synthesis

builds macromolecules by connection subunits via the removal of water.

Hydrolysis

breaks down macromolecules by adding water between the subunits.

Carbohydrates

almost universally the energy source for living organisms (including humans).

Carbohydrates composition

All carbohydrates have Carbon, hydrogen, and oxygen atoms grouped: H-C-OH. There are approximately twice as many hydrogen atoms as oxygen atoms.

Monosaccharides

consist of one sugar molecule. Glucose is an example of a monosaccharide.

Disaccharides

consist of two sugar molecules joined by a dehydration synthesis reaction. Maltose and sucrose are examples of disaccharides.

Polysaccharides

(complex carbohydrates) - consist of more than two sugar molecules joined by a dehydration synthesis reaction.

Starch

the polysaccharide that plants use to store large amounts of glucose.

Glycogen

the polysaccharide that animals use to store large amounts of glucose.

Cellulose

the polysaccharide that plants use for the structure of their cell walls (fibers).

Cellulose indigestibility

Alternation of bonds between subunits make it nearly indigestible.

Lipids

type of macromolecule with hydrophobic nonpolar groups (do not dissolve in water).

Energy density of lipids

Gram for gram, lipids are the most energy dense biological molecule.

Phospholipids

Lipids that are constructed like fats, except that they have a phosphate group instead of a third fatty acid group.

Fatty acid

A carbon-hydrogen that ends with an acidic group (-COOH).

Saturated fatty acid

Fatty acids with no double bonds between carbon atoms.

Unsaturated fatty acid

Fatty acids that have double bonds in the carbon chain whenever there are fewer than two hydrogens per carbon.

Unsaturated trans fatty acid

Fatty acids that have some double bonds with hydrogens that end up on opposite sides of the carbon chain around the double bonds.

Emulsification

Process by which a class of chemical (emulsifier) position themselves around an oil droplet so that their polar ends project outward.

Emulsifiers

Chemicals that have a polar end and a non-polar end.

Fats

Usually animal-based and solid at room temperature (lard, butter, etc.).

Oils

Usually plant-based and liquid at room temperature (olive oil, soybean oil, etc.).

Hydrophilic head

The polar part of a phospholipid.

Hydrophobic tail

The nonpolar part of a phospholipid.

Steroids

Lipids that have a backbone of four fused carbon rings.

Proteins

Macromolecules made of amino acid subunits.

Amino acid

A central carbon atom with an amino group, a carboxyl group (acid), and a variable R group.

Protein function

Directly associated with its structure.

Denaturation

Occurs when exposure to extreme heat or pH irreversibly changes a protein's shape.

Support

Keratin (hair, nails) and collagen (ligaments, tendons, and skin).

Enzymes

Proteins that act as catalysts to accelerate chemical reactions.

Transport

Channel carrier proteins in plasma membranes and hemoglobin in red blood cells.

Defense

Antibodies that protect the body from pathogens.

Hormones

Regulatory proteins, intercellular messengers that influence cellular metabolism (e.g., insulin, HGH).

Motion

Contractile proteins (actin & myosin) that allow muscles to contract.

Nucleic Acids

Polymers made up of nucleotides.

Nucleotide

Molecular complex composed of three subunits: a phosphate, a pentose sugar, and a nitrogen-containing base.

DNA

Deoxyribonucleic acid; stores information about how to replicate itself and the order in which all proteins need to be synthesized to create an organism.

RNA

Ribonucleic acid; involved in the replication and expression of genetic information.

Metabolically active biomolecules

Nucleic acids that participate in metabolic processes.