Biological Molecules 1 Flashcards
(116 cards)
1
Q
What is a Monomer?
A
The smaller units from which larger molecules are made.
2
Q
What is a Polymer?
A
Molecules made from a large number of monomers joined together.
3
Q
What is a Monosaccharide?
A
The monomers from which larger carbohydrates are made.
Examples include glucose, fructose, galactose.
4
Q
What is a Disaccharide?
A
Formed by the condensation of two monosaccharides, held together by a glycosidic bond.
Examples include maltose, sucrose, lactose.
5
Q
What are polysaccharides formed from?
A
Polysaccharides are formed by the condensation of many glucose units.
Example: starch, glycogen, cellulose
6
Q
What type of bonds hold polysaccharides together?
A
Polysaccharides are held by glycosidic bonds.
7
Q
What is cellulose?
A
Cellulose is a polysaccharide in plant cell walls formed by the condensation of B-glucose.
8
Q
What is glycogen?
A
Glycogen is a polysaccharide in animals formed by the condensation of a-glucose.
9
Q
What is starch?
A
Starch is a polysaccharide in plants formed by the condensation of a-glucose, containing two polymers - amylose and amylopectin.
10
Q
What is a glycosidic bond?
A
A C-O-C link between two sugar molecules formed by a condensation reaction. It is a covalent bond.
11
Q
What is amylose?
A
A polysaccharide in starch made of a-glucose joined by 1,4-glycosidic bonds that coils to form a helix.
12
Q
What is amylopectin?
A
A polysaccharide in starch made of a-glucose joined by 1,4 and 1,6-glycosidic bonds that has a branched structure.
13
Q
What is a condensation reaction?
A
A reaction that joins two molecules together with the formation of a chemical bond, involving the elimination of a molecule of water.
14
Q
What is a hydrolysis reaction?
A
A reaction that breaks a chemical bond between two molecules and involves the use of a water molecule.
15
Q
What are long, straight chains of B-glucose held together by?
A
Many hydrogen bonds.
16
Q
How is a triglyceride formed?
A
By the condensation of one molecule of glycerol and three molecules of fatty acids, forming 3 ester bonds.
17
Q
How is a phospholipid formed?
A
By the condensation of one molecule of glycerol and two molecules of fatty acid, held by two ester bonds, with a phosphate group attached to the glycerol.
18
Q
What is the induced-fit model?
A
The enzyme active site is not initially complementary to the substrate; the active site moulds around the substrate, putting tension on bonds and lowering the activation energy.
19
Q
What is a competitive inhibitor?
A
A molecule that is the same/similar shape as the substrate, binds to the active site, and prevents enzyme-substrate complexes from forming.
20
Q
What is a non-competitive inhibitor?
A
A molecule that binds to an enzyme at the allosteric site, causing the active site to change shape and preventing enzyme-substrate complexes from forming.
21
Q
What is the primary structure of a protein?
A
The sequence of amino acids on a polypeptide chain.
22
Q
What is the secondary structure of proteins?
A
The folding or coiling to create a ß pleated sheet or an a helix, held in place by hydrogen bonds.
23
Q
What is the tertiary structure of proteins?
A
The further folding to create a unique 3D shape, held in place by hydrogen, ionic and sometimes disulfide bonds.
24
Q
What is the quaternary structure of proteins?
A
More than one polypeptide chain in a protein.
25
What is a peptide bond?
A covalent bond joining amino acids together in proteins, formed by a condensation reaction.
26
What is the effect of temperature on enzyme-controlled reactions?
At low temperatures, there is not enough kinetic energy for successful collisions between the enzyme and substrate. At too high a temperature, enzymes denature, the active site changes shape and enzyme-substrate complexes cannot form.
27
What is the effect of pH on enzyme-controlled reactions?
Too high or too low a pH will interfere with the charges in the amino acids in the active site. This breaks the ionic and hydrogen bonds holding the tertiary structure in place, therefore the active site changes shape and the enzyme denatures. Different enzymes have a different optimal pH.
28
What is the effect of substrate concentration on enzyme-controlled reactions?
At low substrate concentrations, there will be fewer collisions between the enzyme and substrate. At high substrate concentrations, the rate plateaus because all the enzyme active sites are saturated.
29
What is the effect of enzyme concentration on enzyme-controlled reactions?
At low enzyme concentrations, there will be fewer collisions between the enzyme and substrate. At high enzyme concentrations, there are more enzymes than the substrate, resulting in many empty active sites.
30
What is an ester bond?
A chemical bond represented as -COO-, formed between glycerol and fatty acids.
31
What does hydrophilic mean?
The ability to mix, interact, or attract water.
32
What does hydrophobic mean?
The tendency to repel and not mix with water.
33
What is glucose?
A monosaccharide that exists as two isomers: B glucose and a glucose.
34
What is galactose?
An example of a monosaccharide that forms lactose.
35
What is fructose?
An example of a monosaccharide that forms sucrose.
36
What is an isomer?
Molecules with the same molecular formula but the atoms are arranged differently.
37
What is maltose?
A disaccharide formed by the condensation of two glucose molecules.
38
What is lactose?
Lactose is a disaccharide formed by the condensation of a glucose molecule and a galactose molecule.
39
What is sucrose?
Sucrose is a disaccharide formed by the condensation of a glucose molecule and a fructose molecule.
40
What is a polypeptide?
A polypeptide is a polymer chain of a protein made up of amino acids bonded together by peptide bonds following condensation reactions.
41
What is an amino acid?
An amino acid is the monomer of a protein formed from carbon, hydrogen, oxygen, and nitrogen (C.H.O.N) and contains a carboxyl group, an amine group, and an R group.
42
What is a carboxyl group?
A COOH group made up of a carbon (C) with a hydroxyl (OH) and a carbonyl (double-bonded O) group bonded to it.
## Footnote
Found in amino acids and fatty acids.
43
What is an amine group?
An NH2 group found on amino acids.
## Footnote
Example structure: H-R-C-H.
44
What is the R group on amino acids?
The variable group that is the part of each of the 20 amino acids that is different.
45
What is a secondary structure in proteins?
A coiled shape held in place by hydrogen bonds.
46
What is an alpha helix?
A type of secondary structure in proteins characterized by a coiled shape.
47
What is a secondary structure in proteins?
A folded, pleated shape held in place by hydrogen bonds.
48
What are hydrogen bonds?
Weak bonds that form between H and O in many biological molecules e.g. proteins, water, DNA, tRNA.
49
What are ionic bonds?
Bonds that form between the R groups of different amino acids in the tertiary structure of proteins.
50
What are disulfide bonds?
Strong covalent bonds between two sulfur atoms in the R groups of different amino acids in the tertiary structure of proteins.
51
What is the unique-shaped part of an enzyme that the substrate binds to?
Active site
52
What is the minimum amount of energy required for a reaction to occur?
Activation energy
53
What forms when an enzyme and substrate collide and bind?
Enzyme-substrate complex
## Footnote
This results in a lowered activation energy.
54
What happens when the active site changes shape so the substrate can no longer bind?
Denature
55
What is an enzyme-inhibitor complex?
The structure that forms when an enzyme and inhibitor collide and bind.
## Footnote
It prevents enzyme-substrate complexes from forming.
56
What is a saturated fatty acid?
A long hydrocarbon chain with a carboxyl group at one end and only single bonds between carbon atoms.
57
What is an unsaturated fatty acid?
A long hydrocarbon chain with a carboxyl group at one end and at least one double bond between carbon atoms.
58
What is a polar molecule?
A molecule that has an uneven distribution of charge.
59
What is a phospholipid bilayer?
Phospholipids have two charged regions and in water, they are positioned so that the heads are exposed to water and the tails are not.
60
What is the function of the plasma membrane?
The plasma membrane consists of a phospholipid bilayer and is found in cell surface membranes and organelle membranes.
61
What is a reducing sugar?
Reducing sugars can reduce cations in Benedict's reagent to cations in the form of copper (I) oxide, which forms a brick-red precipitate.
62
How do you test for reducing sugar?
Add Benedict's reagent, heat, and observe for green/yellow/orange/brick red precipitate.
63
How does the structure of a triglyceride relate to its function?
Triglycerides have a large ratio of energy-storing carbon-hydrogen bonds compared to the number of carbon atoms, allowing them to store a lot of energy. They also have a high ratio of hydrogen to oxygen atoms, acting as a metabolic water source, do not affect water potentials and osmosis, and have a relatively low mass.
64
How does the structure of a phospholipid relate to its function?
Phospholipids have two charged regions, making them polar. In water, they are positioned so that the heads are exposed to water and the tails are not, forming a phospholipid bilayer that makes up the plasma membrane around cells.
65
How does the structure of a triglyceride and phospholipid differ?
A phospholipid has one fewer fatty acid chain, which is replaced by a phosphate group.
66
What is the difference between saturated and unsaturated fatty acids?
A saturated fatty acid has no double bonds between carbon atoms, whereas unsaturated fatty acids have at least one double bond between carbon atoms.
67
What is a non-reducing sugar?
A sugar unable to reduce Cu*; the glycosidic bond must be hydrolysed to expose the reducing group.
## Footnote
Example: sucrose.
68
How to test for non-reducing sugar?
1. Following a negative Benedict's test, boil sample in acid and then neutralise with alkaline. 2. Add Benedict's reagent and heat. 3. Observe orange/brick red colour. 4. Add iodine; it turns blue/black.
69
How to test for starch?
Refer to specific starch testing methods.
70
How to test for lipids?
Add ethanol and shake to dissolve; then add water. White emulsion forms.
71
What is the test for protein?
Add biuret; it turns purple.
72
What is a nucleotide?
The monomer of DNA and RNA; it contains a pentose sugar, a phosphate group, and a nitrogenous base.
73
What are the components of a nucleotide?
A pentose sugar, a phosphate group, and a nitrogenous base.
74
What is a nitrogenous base?
Part of a nucleotide; examples include adenine, guanine, cytosine, thymine, and uracil.
75
What is a DNA nucleotide?
The monomer of DNA; it contains a deoxyribose sugar, a phosphate group, and a nitrogenous base.
76
What sugar is found in DNA nucleotides?
Deoxyribose.
77
What is the test for protein?
Add biuret; it turns purple.
78
What is a nucleotide?
The monomer of DNA and RNA; it contains a pentose sugar, a phosphate group, and a nitrogenous base.
79
What are the components of a nucleotide?
A pentose sugar, a phosphate group, and a nitrogenous base.
80
What is a nitrogenous base?
Part of a nucleotide; examples include adenine, guanine, cytosine, thymine, and uracil.
81
What is a DNA nucleotide?
The monomer of DNA; it contains a deoxyribose sugar, a phosphate group, and a nitrogenous base.
82
What sugar is found in DNA nucleotides?
Deoxyribose.
83
What is a polynucleotide?
A polynucleotide is a DNA polymer made up of many nucleotides joined together via a condensation reaction.
## Footnote
Joined by phosphodiester bonds.
84
What is a phosphodiester bond?
A phosphodiester bond is the bond that joins two nucleotides together, forming between a phosphate group and the pentose sugar.
85
What are complementary base pairs?
Complementary base pairs are the base pairs that align opposite each other and form hydrogen bonds.
## Footnote
Examples include adenine and thymine/uracil, guanine and cytosine.
86
What is ribose?
Ribose is a pentose sugar found in RNA nucleotide and ATP.
87
What is Uracil?
A nitrogenous base found in RNA instead of thymine.
88
What is mRNA?
Messenger RNA, a copy of a gene and a single-strand polymer of RNA.
89
Where is mRNA found?
Found only in the cytoplasm.
90
What is the structure of mRNA?
Single-stranded but folded to create a shape that looks like a cloverleaf, held in place by hydrogen bonds.
91
What is tRNA?
Transfer RNA, involved in protein synthesis.
92
What is rRNA?
Ribosomal RNA, which combines with protein to make ribosomes.
93
What is a DNA template strand?
A DNA strand that is used to make a new DNA copy from. Both DNA strands in the double helix are used as templates in DNA replication.
94
What is DNA polymerase?
An enzyme in DNA replication that joins together adjacent nucleotides.
95
What is semi-conservative replication?
DNA replication is semi-conservative replication, where one strand is from the parental DNA and one strand is newly synthesised.
96
What is DNA helicase?
An enzyme that breaks hydrogen bonds between the two chains of DNA in a double helix, causing the two strands to separate. It is involved in DNA replication and transcription.
97
What is a DNA template strand?
A DNA strand that is used to make a new DNA copy from. Both DNA strands in the double helix are used as templates in DNA replication.
98
What is DNA polymerase?
An enzyme in DNA replication that joins together adjacent nucleotides.
99
What is semi-conservative replication?
DNA replication is semi-conservative replication, where one strand is from the parental DNA and one strand is newly synthesised.
100
What is DNA helicase?
An enzyme that breaks hydrogen bonds between the two chains of DNA in a double helix, causing the two strands to separate. It is involved in DNA replication and transcription.
101
What is the large latent heat of vaporisation?
A lot of energy is required to convert water from its liquid state to a gaseous state.
## Footnote
This is due to the hydrogen bonds, as energy is needed to break these to turn it into a gas. This means water can provide a cooling effect.
102
What is high specific heat capacity?
A lot of energy is required to raise the temperature of water.
## Footnote
Some of the heat energy is used to break the hydrogen bonds between water molecules, which is important so water can act as a temperature buffer.
103
What is a metabolite in relation to water?
Water is involved in many reactions.
## Footnote
Such as photosynthesis, hydrolysis, and condensation reactions.
104
Why is water considered a good solvent?
Water is a good solvent, meaning many substances dissolve in it.
## Footnote
Polar (charged) molecules dissolve readily in water due to the fact water is polar.
105
What is strong cohesion in water?
Water molecules 'stick' together due to hydrogen bonds.
## Footnote
This results in water moving up the xylem as a continuous column of water and provides surface tension, creating a habitat on the surface of the water for small invertebrates.
106
What is ATP synthase?
An enzyme that catalyses the synthesis of ATP from ADP + Pi.
107
What is ATP hydrolase?
An enzyme that catalyses the hydrolysis of ATP into ADP + Pi.
108
What is phosphorylation?
The addition of a phosphate group to a molecule.
## Footnote
This process makes the molecule more reactive and it gains energy.
109
What is the structure of water?
Water is a polar molecule. The oxygen atom is slightly negative, and the hydrogen atoms are slightly positive.
110
What is a dipeptide?
A dipeptide is two amino acids bonded together by a peptide bond, formed by a condensation reaction.
111
What is an RNA nucleotide?
An RNA nucleotide is a monomer of RNA composed of a phosphate group, ribose, and a nitrogenous base. It has the base uracil instead of thymine.
112
What is the role of hydrogen ions?
Hydrogen ions determine the pH. The more hydrogen ions, the more acidic the conditions are. They play an important role in chemiosmosis in respiration and photosynthesis.
113
What is the role of iron ions?
Iron ions are a compound of haemoglobin and are involved in oxygen transport.
114
What is the role of sodium ions in co-transport?
Sodium ions are involved in co-transport for the absorption of glucose and amino acids in the ileum.
115
What is the role of phosphate ions?
Phosphate ions are components of DNA, RNA, and ATP.
## Footnote
The phosphodiester bond in DNA and RNA forms between the phosphate group and the pentose sugar.
116
What is the structure of fatty acids?
Fatty acids consist of a carboxyl group and a long hydrocarbon chain, and they can be saturated or unsaturated.
