Biochemistry Flashcards
1
Q
Proton
A
● Subatomic particles inside an atom
● Relatively positive charge
2
Q
Neutron
A
● Subatomic particles inside an atom
● Neutral in charge
3
Q
Electron
A
● Subatomic particles inside an atom
● Negative charge
4
Q
Ground state
A
When all the electrons in an atom are in the lowest available energy levels
5
Q
Excited state
A
When an atom absorbs energy, and its electrons move to a higher energy level
6
Q
Isotopes
A
● Atoms of one element that vary only in the number of neutrons in the nucleus
● Chemically, all isotopes of the same element are identical because they have the same number of electrons in the same configuration
7
Q
Half-life
A
Amount of time needed to convert 50% of the parent compound into daughter compound
8
Q
Radioisotopes
A
● Radioactive isotopes
● Used in medicine and dating
9
Q
Tracer
A
Can be incorporated into a molecule and used to trace the path of carbon dioxide in a metabolic pathway
10
Q
Ionic bonds
A
Result from the transfer of electrons
11
Q
Anion
A
A negative ion
12
Q
Cation
A
A positive ion
13
Q
Covalent bonds
A
Form when atoms share electrons
14
Q
Nonpolar
A
When electrons are shared equally between two atoms
15
Q
Diatomic molecules
A
Two identical atoms form a nonpolar covalent bond
16
Q
Polar
A
When electrons are shared unequally between two atoms
17
Q
Hydrophobic
A
● Water hating
● Nonpolar and lipid-soluble
18
Q
Hydrophilic
A
● Water loving
● Include substances that are polar or that carry a charge or that are ionic
19
Q
Hydrogen bonds
A
Bonds formed between two water molecules
20
Q
Specific heat
A
Amount of heat a substance must absorb to increase 1 gram of the substance by 1 degree
21
Q
Transpirational-pull cohesion tension
A
● As one molecule of water is lost from the leaf by transpiration, another molecule is drawn in at the roots
● One of the way to move water molecules up
22
Q
Capillary action
A
● Combined forces of cohesion and adhesion
● Water moves up a thin tube
23
Q
Surface tension
A
● Hydrogen bonds are slightly stronger on the surface of water
● Allows insects to walk on water without breaking the surface
24
Q
Spring overturn
A
● The cycling of the nutrients in the lake
● Oxygen from the surface is returned to the depths, and nutrients released by the activities of bottom-dwelling bacteria during winter are carried to the upper layers of the lake
25
pH
● A measure of the acidity and alkalinity of a solution
● Ranges from 1 - 14
- 7 is neutral
● pH = - log [H+]
26
Buffer
● Substances that resist changes in pH
● It works by either absorbing excess hydrogen ions or donating hydrogen ions when there are too few
● The most important buffer in human blood is the bicarbonate ion
27
Isomers
Organic compounds that have the same molecular formula but different structures
28
Structural isomers
Differ in the arrangement of their atoms
29
Cis-trans isomers
Differ onl in spatial arrangement around double bonds, which are not flexible like single bonds are
30
Enantiomers
● Molecules that are mirror images of each other
| ● L- (left-handed) D- (right-handed)
31
Organic compounds
Compounds that contain carbon
32
Carbohydrates
● The body uses them for fuel and as building materials
| ● Consist of three elements -- carbon, hydrogen, oxygen
33
Lipids
● Hydrophobic organic compounds that include fats, oils, waxes, and steroids
● Most lipids consist of 1 glycerol and 3 fatty acids
Functions
● Energy storage -- 1 gram lipid = 9 calories
● Structural -- phospholipids, cholesterol
● Endocrine
34
Proteins
● Complex, unbranhced macromolecules
Functions
● Growth and repair
● Signaling from one cell to another
● Regulation -- hormones such as insulin lower blood sugar
● Enzymatic acivity -- catalyzing chemical reactions
● Movement -- actin and myosin are protein fibers responsible for muscle contractions
35
Nucleic Acids
● Encode all hereditary information
| ● Include ribonucleic acid (RNA) and deoxyribonucleic acid (DNA)
36
Dehydration synthesis
Release of one molecule of water to form polymers
37
Hydroalysis
Breakdown of a compound by adding water
38
Monosaccharides
● Monomer of carbohydrates
● Have a chemical formula of C6H12O6
● Three examples are glucose, galactose, and fructose
39
Disaccharides
● Consist of two monosaccharides joined together
| ● Have the chemical formula C12H22O11
40
Polysaccharides
● Polymer of carbohydrates
● Macromolecules
● Formed as many monosaccharides joined together
● Cellulose and starch are found in plants
● Chitin and glycogen are found in animals
41
Glycerol
An alcohol that makes up the "head" of lipids
42
Fatty acid
● Hydrocarbon chain with a carboxyl group at one end
| ● Exist in two varieties, saturated and unsaturated
43
Saturated fatty acid
● Come from animals
● Solid at room temperature
● Linked to heart disease when ingested in large quantities
● Butter
● Contain only single bonds between carbon atoms
44
Unsaturated fatty acid
● Extracted from plants
● Liquid at room temperature
● Considered to be healthy dietary fats
● Have at least one double bond formed by the removal of hydrogen atoms in the carbon skeleton
● They hold fewer hydrogen atoms than saturated fatty acids
45
Steroids
● Lipid that do not have the same general structure as other lipids
● Consist of four fused rings
● Cholesterol, testosterone, estradiol
46
Phospholipids
● Modified lipids
● Consist of only two fatty acids attached to the glycerol backbone, forming two hydrophobic "tails"
● The thrid hydroxyl group of the glycerol attaches to a phosphate group, which is charged and therefore hydrophilic
● Phospholipid bilayer is the structural basis of all plasma membranes
47
Amino acids
● Monomer of proteins
● Consist of a carboxyl group, an amine group, and a variable (R) all attached to a central asymmetric carbon atom
- The R group differs with each amino acid
48
Peptide bonds
Bonds that join amino acids together to form polymers of proteins
49
Primary structure of proteins
The unique linear sequence of amino acids
50
Secondary structure of proteins
● Results from hydrogen bonding with the polypeptide molecule
● Refers to how the polypeptide coils or folds into two distinct shapes -- an alpha helix or a beta pleated sheet
- Peptide bond and hydrogen bond
51
Tertiary structure of proteins
● Intricate 3-D shape of a protein that is superimposed on its secondary structure
● Determines the protein's specificity
52
Quaternary structure of proteins
Proteins that consist of more than one polypeptide chain
53
Fibrous proteins
Proteins that exhibit either alpha helix or beta pleated sheet or both
54
Denaturation
Lost of a protein's characteristic shape as well as its function
55
Conformation
Unique shape of each protein that determines what job it performs and how it functions
56
Chaperone protiens/Chaperonins
Molecules that assist in folding other proteins
57
Prions
Misfolded proteins
58
Nucleotides
● Monomer of nucleic acids
| ● Consists of a phosphate (P), a 5-carbon sugar (deoxyribose/ribose), and a nitrogen base
59
Function groups
● The components of organic molecules that are most often involved in chemical reactions
● These groups are attached to the carbon skeleton, replacing one or more hydrogen atoms that would be presnet in hydrocarbon
60
First law of thermodynamics
● States that energy cannot be created or destroyed, only transformed from one form to another
● Often known as the law of conservation of energy
61
Second law of thermodynamics
States that during energy conversions, the universe becomes more disordered
62
Gibb's free energy
Free energy, represented by the letter G
63
Exergonic
If energy is released during the course of a reaction, the reaction is exergonic or exothermid and change is G is negative
64
Endergonic
If in a chemical reaction energy is absorbed, the reaction is endergonia or endotehrmic and change in G is positive
65
Metabolism
The sum of all the chemical reactions that take place in cells
66
Catabolism
Reactions that break down molecules and release energy
67
Anabolism
Reations that build up molecules and absorb energy
68
Enzymes
```
● Serve as catalytic proteins that speed up reactions by lowering the energy of activation
● Made up of protein
● Substrate specific
● Can be reused after a reaction
● Catalyze reactions in both directions
```
69
Energy of activation
The amount of energy needed to begin a reaction
70
Transition state
The reactive (unstable) condition of the substrate after sufficient energy has been absorbed to initiate the reaction
71
Induced-fit model
● Describes how enzymes work
● As the substrate enters the active site, it induces the enzyme to alter its shape slightly so the substrate fits better
72
Cofactors
Inorganic molecules that help enzyme's functions
73
Coenzymes
Organic molecules that help enzyme's functions
74
Competitve inhibitors
● Compounds that resemble the substrate molecules and compete for the same active site on the enzyme
● They reduce the amount of product by preventing or limiting the substrate from binding to the enzyme
● Can be overcome by increasing the concentration of substarte
75
Allosteric regulators/noncompetitve inhibitors
● Bind to a site distinct and separate from the active site of the enzyme
● This binding of the inhibitor to the alternate site causes the enzyme to change shape in a way that inhibits the enzme from catalyzing substrate into product
76
Feedback inhibition
The end product of the pathway is the allosteric inhibitor for an enzyme that catalyzes an early step in the pathway
77
Cooperativity
● A type of allosteric activation
● The binding of one substrate molecule to one active site of one subunit of hte enzyme causes a change in the entire molecule and locks all subunits in an active position
● This mechanism amplifies the response of an enzume to its substrates
78
What happened to the energy when a bond is formed? Why?
● Energy is released
| ● Atoms acquire a more stable configuration by completing their outer shell
79
What is required to break a bond?
Energy must be supplied
80
What are the five intramolecular factors that contribute to the tertiary structure?
● Hydrogen bonding between R groups of amino acids
● Ionic bonding between R groups
● Hydrophobic interactions
● Van der Waals interactions
● Disulfide bonds between cysteine amino acids
81
What does protein structure depend on?
```
● The primary structure of a protein
● Physical and chemical consditions in the environment
- pH
- Salt concentration
- Temperature
```
82
What are the three complementary techiniques that are used to reveal the 3D shape of proteins?
● X-ray crystallography
● Nuclear magnetic resonance (NMR) spectroscopy
● Bioinformatics
83
What are the four nitrogen bases?
● Adenine (A)
● Cytosine (C)
● Guanine (G)
● Thymine (T) / Uracil (U)
84
What are the four ways to regurate enzymes?
● Competitive inhibitors
● Allosteric inhibitors
● Feedback inhibition
● Cooperativity
