Chapter 2 - The Chemistry and Energy of Life Flashcards
What is the difference between an element and a molecule?
An element is composed of only one kind of atom; molecules can be composed of more than one kind of atom
Which type of bonds or interactions between atoms is the strongest?
Covalent Bonds
Covalent bond formation depends on the ability of atoms to do what
Share electrons with other atoms
Table salt, NaCl, is electrostatically neutral. When dissolved in water, NaCl does what
dissociates to form Na+ and Cl- ions that interact with water molecules
What property of water affect(s) life less than the others? Cohesiveness High heat capacity High heat of vaporization Hydrogen Bonds Nearly Colorless
Nearly Colorless
The “building blocks” ; of polysaccharides are _____, and these blocks are covalently linked together by _____.
monosaccharides; glycosidic linkages
What is true of starch?
It is a straight-chain shaped molecule
It is a polymer of fructose
It is formed by the condensation of simple monosaccharides
The properties of starch are very similar to those of cellulose
It cannot be digested by people
It is formed by the condensation of simple monosaccharides
Fatty Acids are
Part of membrane structure
Phospholipids differ from triglycerides in that phospholipids
are amphipathic
An example of a statement that would receive a bad grade on a biology exam covering the first and second laws of thermodynamics
the total energy of a system is available to do work
the synthesis of complex molecules _____ energy, whereas their degradation ______ energy. This synthesis occurs with _____ in entropy
Requires; releases; a decrease
Entropy is
related to the disorder or randomness of a system
Six most common chemical elements in living organisms
Carbon C Hydrogen H Nitrogen N Oxygen O Phosphorus P Sulfur S
What can be found in the nucleus
Protons and Neutrons of significant mass
Protons
Positively charged
Neutrons
No charge, neutral
Electrons
Negatively charged
Orbit the nucleus and are of very low mass
How many electrons are in each orbital?
First Shell: up to 2 electrons
Second Shell: up to 8 electrons
Third Shell: up to 18 electrons
Fourth and subsequent shells: up to 32 electrons
Covalent Bond
Forms when two atoms attain stable electron numbers in their outermost shells by sharing one or more pairs of electrons. EX: H2
The number of electrons in the outer shell of a given atom determines what?
how many covalent bonds it can form
electronegativity
attractive force that an atomic nucleus exerts on electrons in a covalent bond. Electronegativity depends on how many positive charges it has
Bond strength from strongest to weakest
Covalent, ionic, hydrogen, van der waal forces
Nonpolar Covalent Bonds
Hydrophobic
Polar covalent bonds
When electrons are drawn to one nucleus more than to the other
Hydrophilic
Ionic bonds
form as a result of the attraction between ions bearing opposite charges
(between cations and anions) EX: NaCl
Cation
Positively charged ion EX: Na+
Anion
Negatively charged ion EX: Cl-
Hydrogen Bonds
form when slightly electronegative regions of molecules attract slightly electropositive regions of molecules.
play important roles in determining and maintaining the 3D shapes of giant molecules
contributes to several properties of water
what are the four major groups of biomolecules
Carbs
Lipids
Proteins
Nucleic Acids
What make up most of the macromolecules
molecular subunits called monomers
Condensation Reaction (aka dehydration synthesis)
the removal of water links monomers together
EX: formation of triglycerides and the formation of (covalent) peptide bonds during protein synthesis
Hydrolysis Reactions
The addition of water breaks a polymer into monomers
EX: Hydrolysis of proteins and fats, sometimes called proteolysis, and lipolysis
carbohydrates
CHO
complex carbs serve in energy storage and structure for living organisms.
what is the most abundant organic molecule on earth
Cellulose
Lipids
CHO
most common units of lipids are triglycerides (contains 3 Fatty acid chains and 1 glycerol)
Are fats hydrophobic or hydrophilic
Hydrophobic
Phospholipids
amphipathic molecules, that have both hydrophobic and hydrophilic regions.
Especially important in forming membranes, also called phospholipid bilayers.
Saturated Fats
Single bonds, straight, solid at room temp, steak fat
Unsaturated Fats
Have varying amounts of double bonded carbons (C=C) a
are typically liquids at room temperature
what happens when bonds are broken in fats and why?
fats generally have many atoms, and breaking apart the C-C bonds generates lots of potential for energy transfers.
Laws of thermodynamics
Energy is neither created nor destroyed.
Useful energy tends to decrease (no physical process or chemical reaction is 100 percent efficient)
what are functional groups?
covalently bonded groups of atoms that confer specific properties to biological molecules
