Chapter 2- Chemistry of Life

Question 1

Matter

Answer 1

any material that takes up space

Question 2

Energy

Answer 2

the ability to do work. In this context, work means moving matter.

Question 3

Element

Answer 3

A pure substance that cannot be broken down by chemical means into other substances

Question 4

Periodic table

Answer 4

Table the arranges the elements in such a way that their chemical properties repeat in each vertical column

Question 5

Bulk elements

Answer 5

elements that are needed in the largest amounts because they make up majority of every living cell

Question 6

Trace elements

Answer 6

elements that needed in small amounts

Question 7

Atom

Answer 7

the smallest possible “piece” of an element, that retains the characteristics of the element

Question 8

Three types of particles

Answer 8

Protons: carry a positive charge
Neutrons: uncharged
(Protons+Neutrons create the central nucleus)
Electrons: carry a negative charge

Question 9

Atomic number

Answer 9

the number of protons in the nucleus

Question 10

Ion

Answer 10

An atom (or group of atoms) that has gained or lost electrons and therefore has a net negative or positive charge. They also form ionic bonds

If # of protons= # of electrons, then atom of electrically neutral; no net charge

Question 11

Mass number

Answer 11

The total number of protons and neutrons in its nucleus

Question 12

Isotope

Answer 12

Any different forms of a single element

Question 13

Atomic weight

Answer 13

Average mass of all atoms of an element; typically, close to the mass number of the most abundant isotope

Question 14

Radioactive isotopes

Answer 14

Emit energy as ray or particles when they break down into more stable forms. Have a half-life, which is the time it takes for half of the atoms to emit radiation, or “decay” to a different, more stable form.

Question 15

Compound

Answer 15

a molecule composed of two or more different elements. Written in terms of a molecular formula, where the constituent elements are written with subscripts of the number of atoms of each elements ex. H20

Question 16

Orbitals

Answer 16

describes the most likely location for an electron relative to its nucleus

Question 17

Energy shells

Answer 17

Octet rule: 2 electrons in the closest shell, and 8 electrons fill the other shells. Outermost shell is called a valence shell.

Question 18

Electronegativity

Answer 18

the ability of an atom to attract electrons on a scale of 0 to 4

Question 19

Chemical bond

Answer 19

transfer of electrons from one atom to another which creates an attractice force, which holds atoms together

Question 20

Ion

Answer 20

an atom that has lost or gained electrons

Question 21

Ionic bond

Answer 21

one atom donates one or more electrons to another atom because electronegativity is very large (>1.7). Opposite charged ions attract each other.

Question 22

Covalent bond

Answer 22

two atoms share electrons (ex. one bond, two bonds, three bonds)

Polar covalent bond: electrons are shared unequally because electronegativity difference is moderate or large (0.4 to 1.7)

Nonpolar covalent bond: Electrons are shared equally because electronegativity difference is small (<0.4)

Hydrogen bond: An atom with a partial negative charge attracts an atom with a partial positive charge (Weak bond; breaks easily)

Question 23

Properities of water

Answer 23

Cohesion: the tendency of water molecules to stick together
Adhesion: the tendency to form hydrogen bonds with substances other than water
Evaporation: conversion of liquid into vapour

Water is a solvent, meaning its a chemical in which other substances called solutes can dissolve. A *solution *consists of one or more solutes in a solvent.

Question 24

Hydrophillic

Answer 24

readily dissolve in water (“water-loving”); substances are either polar or charged

Question 25

Hydrophobic

Answer 25

do not dissolve in water (aka. form bonds with hydrogen bonds) ("water-fearing"); nonpolar molecules

Question 26

Chemical reaction

Answer 26

two or more molecules "swap" their atoms to make different molecules; equation is marked with reactacts (left) that create products (right) *have same number of atoms of both sides of the equation (atoms are simply rearranged; neither created or destroyed)

Question 27

The pH scale

Answer 27

A neutral solution has a pH of 7. The higher the concentration of hydrogen ions (H+), the more acidic the solution (pH less than 7). The lower the concentration of (H+), and more (OH-) ions, the more basic the solution (pH greater than 7).

Question 28

Organic molecules

Answer 28

chemical compounds that contain both carbon and hydrogen Four main types of organic molecules: carbohydrates, proteins, nucleic acids, and lipids Organic molecules have small groups of atoms, with four most common: hydroxyl, carboxyl, amino, and phosphate groups

Question 29

Proteins, nucleic acids, and some carbohydrates share a common property of being polymers

Answer 29

Polymers are chains of small molecular subunits called monomers. A polymer is made of monomers that are linked together (like a train with individual railcards).

Question 30

Dehydration synthesis

Answer 30

Water is removed and a new covalent bond forms between two monomers (where a hydrogen atom and a -OH hydroxyl group was removed by enzyme from each molecule to form water)

Question 31

Hydrolysis

Answer 31

Water breaks the bond between monomers ( enzyme use atoms from water to make a hydrozyl group -OH in one molecule and a hydrogen atom in the other molecule).

Question 32

Protein

Answer 32

chain of monomers called amino acids. Each amino acid has a central carbon atom bonded to four other atoms or groups of atoms. One is a hydrogen atom; another is a carboyl group; a third is an amino group (nitrogen atom single-bonded to two hydrogen atoms (-NH2); and the fourth is a side chain, or R group, which can be any of 20 Amino Acids

Question 33

Pepetide bond

Answer 33

A single convalent bond that forms between the carboxyl function group of a amino acid and the amine group of another amino acid (bond is formed by a dehydration/condensation chemical reaction (water produced). Bond is broken via hydrolysis reaction (water required).

Question 34

Four levels of protein structure

Answer 34

*Primary structure* (sequence): Amino acid sequence of a polypeptide (not a functional protein) *Secondary structure* ("substructure"): Result of hydrogen bonding between the backbone atoms (not the R groups) of the amino acid, which form alpha helix and/or beta sheets *Tertiary structure* (polypepetide shape):overral shape of one polypeptide; result of different types of bonds that form between the R groups of the amino acids *Quaternary structure* (protein shape): Overral protein shape, arising from bonding of mutiple polypeptides that make up the functional protein. *Typically (but not all the time): you need proceeding structures to have the current structure of protein. The structure/shape of protein is essential in determining its function. To *denature* a protein is to change its shape so it can no longer carry out its function.

Question 35

How does a cell know which amino acids to string together to from a particular protein?

Answer 35

Each protein's primary structure is encoded in a sequence of *nucleic acid*, a polymer consisting of monomers called *nucleotides* (cells contain two types of nucleic acids: DNA (deoxyribonucleic acid) and RNA (ribonucleic acid)

Question 36

What do nucleotide monomers consist of?

Answer 36

Three components: At the center is a *pentose sugar*(five-carbon)- ribose in RNA and deoxyribose in DNA. Attached to the sugar's carbon atoms is one or more *phosphate group*. Attached to the opposite side of sugar is a *nitrogenous base*: adenine (A), thymine (T), guanine (G), cytosine (C), or uracil (U). DNA contains A,T, G, C while RNA contains A,U,G,C