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Biology > Chapter Two: Life's Chemistry and the Importance of Water > Flashcards

Chapter Two: Life's Chemistry and the Importance of Water Flashcards

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1
Q

Each element has a unique number of ______

A

protons

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2
Q

Different isotopes have different numbers of ______

A

neutrons

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3
Q

How do radioisotopes behave?

A

They are unstable and spontaneously breakdown, giving off energy

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4
Q

Atoms with _____ outer shells are stable

A

full

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5
Q

What do atoms do to maximize stability?

A

They react (bond) with other atoms to obtain full outer shells

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6
Q

Why are noble/inert gases non-reactive

A

their shell is full

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7
Q

When does a covalent bond form

A

when the electron orbitals of the two atoms overlap in an energetically favorable manner

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8
Q

When does unequal sharing of electrons occur?

A

when the two atoms are different elements and they have differences in electronegativities

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9
Q

What happens to the electrons in a polar bond?

A

electrons are pulled closer to the nucleus of the more electronegative atom; because of this the more electronegative atom will be slightly negatively charged and the other will be slightly positively charged

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10
Q

What is a nonpolar bond?

A

electrons are shared equally

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11
Q

Electronegativity of Oxygen

A

3.5

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12
Q

Electronegativity of Hydrogen

A

2.1

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13
Q

Properties of the covalent bonds of water

A

Both are polar and have a slight negative on the oxygen and slight positive on the hydrogen

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14
Q

When do covalent bonds form and when do ionic bonds form, based on electronegativities?

A

smaller difference in electronegativity: polar covalent bond
larger difference in electronegativity: ionic bond formation

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15
Q

If the electronegativity of atoms differs by 0.4 or less…

A

Covalent with equal sharing forms

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16
Q

If the electronegativity of atoms differs by 0.4 to 2.0…

A

Covalent with unequal sharing forms

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17
Q

If the electronegativity of atoms differs by more than 2.0…

A

Ionic bond forms

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18
Q

What is an ionic bond?

A

The transfer of electron(s) from one atom to another

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19
Q

When can a complete transfer of an electron occur

A

When the electronegativity difference is greater than 2.0

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20
Q

Cations

A

positively charged ions

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21
Q

Anions

A

negatively charged ions

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22
Q

What are ionic bonds formed by?

A

electrical attraction of anions and cations

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23
Q

Ionic compounds tend to form _____ in which there is a regular arrangement of ______ and _____

A

crystals; anions; cations

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24
Q

Where can hydrogen bonds form?

A

Between two water molecules, water and a polar molecule, or two separate parts of a big molecule

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25
Van der Waals interactions
Attractions between oppositely charged atoms in nonpolar molecules. Movement of electrons results in small temporary dipoles
26
When does Van der Waals result in significant force?
When there are many interactions
27
What does Anabolism do?
Converts subunits to macromolecules
28
What does catabolism do?
Convert macromolecules to subunits
29
What is a subunit?
sugars, amino acids, fatty acids, nucleotides
30
What is a macromolecule?
carbohydrates, proteins, fats, nucleic acids
31
What are energy transformations linked to in cells?
chemical transformations
32
Does catabolic or anabolic reactions need energy input? releases energy?
Anabolic needs energy input, catabolic releases energy
33
What is metabolism?
The sum total of all chemical reactions occurring in a biological system at a given time
34
What is energy?
The capacity to do work
35
What is potential energy?
energy stored as chemical bonds, concentration gradient, charge imbalance, etc.
36
What is kinetic energy?
the energy of movement
37
Define 1st Law of Thermodynamics
Energy is neither created nor destroyed
38
Define 2nd Law of Thermodynamics
When energy is converted from one form to another, some of that energy becomes unavailable to do work
39
What is entropy?
Some energy is converted to a nonusable form associated with disorder or randomness
40
Will a change that decreases entropy occur spontaneously?
No -- only can occur if energy is added to the system
41
In a closed system, the amount of usable` energy _______ with every transformation
decreases
42
Equation for enthalpy
Enthalpy (H) = free energy (G) + entropy (S)
43
What energy can be used for cellular work?
Free Energy (G)
44
∆G Equation
∆G = H-TS = Gproducts - Greactants
45
When G is negative, free energy is ________ and the reaction is _____ . When G is positive, free energy is _____ and the reaction is ____.
released, exergonic; consumed, endergonic;
46
Chemical reaction
when atoms combine or change their bonding partners
47
What is activation energy (Ea)
The additional energy required to initiate the reaction
48
In what type of reactions is Ea required? Why?
Both exergonic and endergonic; Covalent bonds in reactants must be broken
49
In exergonic reactions, do reactants or products have higher free energy?
reactants
50
In endergonic reactions, do reactants or products have higher free energy?
products
51
What is a condensation reaction?
glucose + fructose = sucrose + H20
52
What is hydrolysis?
complex molecule + h20 = simpler molecules
53
Does a condensation reaction have positive or negative G?
positive G, meaning it requires energy
54
Describe exergonic reactions
release free energy, the complexity decreases, the disorder is generated and can occur spontaneously
55
Describe endergonic reactions
consume free energy, complexity increases, localized decrease in entropy, does not occur spontaneously
56
anabolic reactions are ______ and catabolic reactions are _____
Endergonic Exergonic
57
What is equilibrium?
a point where the forward and reverse reactions proceed at the same rate and ∆G=0
58
Heterotrophs
start with chemical energy from photosynthetic cohabitants
59
How do photosynthetic organisms get energy?
capture solar energy and convert it to chemical energy
60
Is work able to be done at equilibrium?
No
61
Why are water molecules polar
unequal charge distribution and asymmetric shape
62
What makes water naturally cohesive?
H bonds
63
Why does water have a high specific heat?
It has a large number of H bonds
64
What molecules are soluble in water
hydrophilic molecules (ionic, polar)
65
How do salts dissolve in water
Anions are surrounded by the hydrogens on a water molecule and cations are surrounded by oxygens
66
Nonpolar molecules are more attracted to _________ _________ than water
one another
67
How do you calculate pH
-log(H+)
68
Does water act as a base or acid?
Water acts as both a weak base and weak acid
69
What happens when acids dissolve in water?
they release hydrogen ions
70
What do bases do?
accept H+ ions; decreases proton concentrations
71
What percent of cells are water?
70%
72
What is intracellular pH
ranges from 7.0 - 7.4
73
What do buffers do?
help maintain constant pH by absorbing or releasing H+ ions
74
What are buffers composed of?
a weak acid and its corresponding base
75
What is homeostasis
the process of living organisms mainting constant internal conditions
76
changes in pH can alter _______
cellular structures
77
Hydroxyl Group
-OH
78
Aldehyde
-C=OH
79
Keto
-C=O I
80
Carboxyl
=COOH
81
Amino
R-NH2
82
What do functional groups do when they attach to larger molecules?
they give their properties to the larger molecules
83
Sulfhydryl
-SH

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