Module 2 : Introduction to Chemistry Flashcards
1
Q
What are the major elements in the body and how much of the total body mass do they represent?
A
Oxygen, Carbon, Hydrogen and Nitrogen. They represent 96% of our body weight
2
Q
What are the lesser elements which add up to 98.5% of our body weight ?
A
Calcium and phosphorus
3
Q
For what percentage of body mass do the trace elements account ?
A
0.4%
4
Q
What is the mass number of an atom ?
A
The total number of protons and neutrons
5
Q
What is an ion ?
A
An atom with an unequal number of electrons and protons
6
Q
What is an isotope ?
A
An atom of a specific element with the same number of protons and electrons, but different number of neutrons
7
Q
What is a radioactive isotope ?
A
An isotope that is unstable and emits radiation (energy)
8
Q
What do we call two or more different atoms that come together ?
A
A compound
9
Q
What is a molecule ?
A
When two or more atoms share electrons
10
Q
What is the difference between ion and free radical ?
A
An ion is a charged atom. A free radical is also charged, but can be an atom or molecule. It’s particularity is that a single free unpaired electron is in its outer shell.
11
Q
How can a free radical be stabilized ?
A
By giving up the unpaired electron or taking one from another molecule.
12
Q
What is the use of antioxydants ?
A
To inactivate oxygen-derived free radicals
13
Q
Place the types of chemical bonds in order of strength
A
Hydrogen bonds, ionic bonds and covalent bonds
14
Q
What is an ionic bond ?
A
When two ions of opposite polarity attract each other and exchange electrons
15
Q
In what state is an ionic compound generally found ?
A
Solid
16
Q
What is called an ionic compound that when dissolved in liquid breaks into cations and anions?
A
An electrolyte
17
Q
What is covalent bonding ?
A
The sharing of electron pairs in a molecule
18
Q
What is polar covalent bonding ?
A
A covalent bond, but with unequal sharing of electrons, creating a direction of the charge
19
Q
How do hydrogen bonds form ?
A
The polar covalent bonding of hydrogen to oxygen or nitrogen creates a positive partial charge, because hydrogens does not attract electrons very strongly. This partial positive charge will bond to partial negative charges from other molecules. This is the hydrogen bond.
20
Q
What is the role of hydrogen bonds ?
A
- Provide the 3-dimensional shape of proteins and enzymes.
- Bond specialized molecules such as hormones and enzymes
21
Q
What is potential energy ?
A
The nergy stored by matter due to its position
22
Q
What is chemical energy ?
A
Form of potential energy stored in bonds of compounds or molecules
23
Q
What is kinetic energy?
A
Energy associated with matter in motion
24
Q
When do a chemical reaction occur?
A
When new bonds are formed or old bonds break between atoms
25
What is a synthesis reaction and what is its other name ?
It's a reaction when two or more atoms, molecules or ions combine to form a new and larger molecule. It's also called an anabolic reaction
26
Give an example of a synthesis reaction
The synthesis of water from oxygen and hydrogen molecules
27
What is a decomposition reaction ?
A reaction where a complex molecule is broken down to smaller parts
28
How is called a decomposition reaction in the body?
Catabolic
29
What is oxidation ?
When a molecule looses an electron
30
What is reduction ?
When a molecule gains an electron
31
What happens to the potential energy of the molecule if it gets oxidized, and if it gets reduced ?
Potential energy decreases in oxidations and increases in reduction
32
What happens in an oxidation-reduction reaction ?
An electron is taken from the oxidized atom by the reduced atom
33
What are the differences between organic and inorganic compounds ?
Inorganic compounds are usually simple molecules, bound by ionic or covalent bonds. Organic molecules, are more complex structures, always composed or carbon and hydrogen, always have covalent bonds, and usually contain oxygen,
34
Give examples of inorganic compounds
Water, acids, salts, bases
35
Give the main organic compounds of the body
Carbohydrates, lipids, proteins, nucleic acids, adenosine triphosphate
36
What is the most important inorganic compound in all living systems ?
Water
37
What is the most important property of water and what does it allow ?
Its polarity. It allows the molecules to be a very versatile solvent. Its bent shape allows the molecules to interact with several ions or molecules.
38
What is the difference between hydrophilic and hyrophobic compounds ?
Hydrophilic molecules are charged or contain polar covalent bonds and dissolve easily in water. Hydrophobic molecules are composed mainly of non-polar covalent bonds and do not dissolve in water
39
How is the dissolvant property of water useful in the body?
It can enable reactants to form products or dissolve wastes
40
Why is water the ideal medium for chemical reactions in the body ?
Because it dissolves many substances. It can participate as a reactant or as a product
41
What is hydrolysis and what is an example of its use ?
It breaks large molecules into simpler ones and it allows nutrients to be absorbed in the body during digestion
42
What is dehydration synthesis ?
When two simple molecules join together and loose a water molecule in the process
43
What is water heat capacity ?
It's the ability to absord an amount of heat before changing its temperature. It is relatively high in water
44
What is the use of a high heat capacity in water for the body ?
It moderates changes in the environment temperature thereby helping maintain the homoestasis of body temperature
45
Is water surface tension high or low ? What does il allow in terms of body functions ?
It is high, there is good cohesion between molecules. Therefore, it takes large amounts of heat to break down water molecules, so when water evaporates from the body as sweat, it is a good cool down mechanism
46
What is the use of water in saliva and mucus ?
It acts as a lubricant
47
Define acid
Acids ionize in water into one or more hydrogen ion and one or more anions
48
Define base
Base dissociate in water into one or more hydroxide anions and one or more cations. Base are proton receptors
49
Define salt
A compounds that ionizes in cations and anions, but neither are hydrogen or hydroxide
50
What does a pH of 7 mean ?
It means that there is 10^(-7) moles of H+/L in the solution
51
Acids have what pH ?
Below 7
52
What is a buffer, what is it composed of and what is its use ?
A buffer maintains pH in various body structures at a fairly constant level. It is composed of a weak acid and a weak base. Its function is to convert strong acids or bases into weak acids or bases
53
Name one important buffer in the body
Carbonic acid-bicarbonate buffer system
54
What is the pH of blood ?
7.35-7.45
55
What is the pH of saliva ?
6.35-6.85
56
What is the pH of water ?
7
57
What is the pH of urine ?
4.6-8.0
58
What are carbohydrates (give types and composition)
Organic compounds that include sugars, glycogen, starches and cellulose. The elements present are carbon, hydrogen and oxygen with a hydrogen to oxygen ratio of 2:1
59
What are the categories of carbohydrates and what are the categories based on ?
Monosaccharides, disaccharides and polysaccharides. The categories are based on the size of the molecules.
60
What is the role of carbohydrates in the body ?
- Provide most energy needed for life
- Can be converted into other substances which are used to build structures and to generate ATP
- Some act as food reserves
61
What are monosaccharides and how are they formed? Give an example
The building block of all saccharides. They are formed by dehydration synthesis and separated by hydrolysis. An example is glucose or ribose
62
What is the role of glucose ?
It serves as a source of chemical energy for generating the ATP that fuels metabolic reactions
63
What are disaccharides ? Give an example
Simple sugars that consist of two monosaccharides joined by a covalent bond. They form by dehydration synthesis. Glucose and fructose join together to form sucrose (table sugar).
64
What are polysaccharides?
Large, complex carbohydrates that contain tens or hundreds of monosaccharides joined through dehydration synthesis reactions.
65
What is the main polysaccharide in the body and where is it stored ?
Glycogen, made of glucose units joined in branches. It is stored in the liver and skeletal muscles.
66
What are lipids ?
Lipids are molecules made of carbon, hydrogen and oxygen. Lipids include most of the substances that are insoluble in water but soluble in non-polar solvents such as chloroform or ether.
67
What is the result of the bigger hydrogen to oxygen ratio in lipids ?
They have less oxygen, so less polar covalent bonds. This makes them less soluble in polar solvents like water (hydrophobic). However, lipids are soluble in non-polar solvents like alcohol.
68
What are the members of the lipids family ?
Triglycerides, phospholipids, steroids, fatty acids and fat-soluble vitamins.
69
What are the most plentiful lipids in the body?
Triglycerides
70
What are the functions of triglycerides ?
Provide protection, insulation and energy (immediate and stored)
71
What is a triglyceride composed of ?
A glycerol molecule and three fatty acids
72
What is a saturated fat ?
A fatty acid chain that contains only single covalent bonds between carbon atoms. Because there is no double bonds, all carbon atoms are saturated with hydrogen. Mainly solid at room temperature, cause health problems.
73
What is a mono-unsaturated fat ?
A fatty acid chain that contains one double covalent bond between two fatty acid carbons. Decrease risk of heart disease.
74
What is a polyunsaturated fat ?
A fat made of fatty acid chains that contan more than one double covalent bond between fatty acid carbons.
75
What are phospholipids ?
A lipid with a glycerol backbone, two fatty acids attached to the first two carbons and a phosphate group to the third carbon that links a small charged group. The non-polar fatty acid chains act as 'tails' and the polar head as hydrophilic 'head'. They line up to make important membrane components.
76
What are steroids ? Give examples of steroids
Lipids that are composed of four rings of carbon atoms. Cholesterol, estradiol, testosterone. They provide hormone membrane structure.
77
What is the building block of proteins ?
Amino acids
78
What are amino acids composed of (atoms and molecules) ?
Carbon, hydrogen, nitrogen, sometimes sulfur. Each amino acid has an amino group at one end, a carboxyl group at the other end, a hydrogen and a different side chain in the middle.
79
How are the bonds linking amino acids together called, and what is the type of bond ?
They are peptide bonds, and it is a covalent bond
80
What are the functions of proteins ?
- Give structure to the body
- Regulate processes
- Provide protection
- Help muscles to contract
- Transport substances
- Act as enzymes
81
What happens when a protein encounters a hostile environment ?
Denaturation, it looses its shape and hence is not able to perform its function
82
How do enzyme speed up chemical reactions ?
- By increasing the frequency of collisions between molecules
- Lowering the activation energy
- Properly orienting coliding molecules
83
What are called catalysts in the living cells and why do we need them ?
They are called enzymes. We need them because at our body temperature, not enough chemical reactions would naturally occur to maintain life.
84
With what suffix can we recognize enzymes ?
'Ase'
85
What are the three important properties of enzymes ?
Specificity, efficiency and control
86
Describe specificity of enzymes
Each particular enzyme catalyzes a particular chemical reaction that involves specific substrates (molecule on which the enzyme acts) and products (molecules produced by the reaction)
87
Describe control of enzymes
Enzymes are subject to a number of cellular controls. Their rate of synthesis and concentration are under the control of a cell's gene.
88
What are nucleic acids (what are they composed of )
Huge organic molecules composed of carbon, hydrogen, oxygen, nitrogen and phosphorus.
89
What are the two types of nucleic acids ?
Deoxyribonucleic acid and ribonucleic acid
90
What is the building block of nucleic acids ?
Nucleotides
91
What are nucleotides composed of in DNA?
One of four nitrogenous bases, a five-carbon monosaccharide called deoxyribose and a phosphate group
92
What are the four bases in DNA?
Adenine, thymine, cytosine and guanine
93
What are the functions of DNA ?
Form the genetic code inside each cell and thus regulates most of the activities that occur in our cells through our lifetime
94
What are the functions of RNA ?
Carries instructions from the genes in the nucleus of the cell to guide how the ribosomes assemble aminoacids into proteins
95
What are the four bases of RNA ?
Guanine, adenine, cytosine and uracil
96
What is the role of adenosine triphosphate ?
It's the principal energy-storing molecule in the body
97
What is ATP composed of ?
Three phosphate groups attached to adenosine, which is adenine and ribose.
98
How is energy released from ATP and what is left after the reaction ?
The energy-transferring reaction occurs via hydrolysis. A phosphate group is liberated, as well as a water molecule, leaving adenosine diphosphate (ADP)
99
How is ATP formed from ADP ?
A phosphate group is reattached to ADP using the breakdown of glucose as energy, in a process called cellular respiration.
