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biological molecules Flashcards

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1
Q
A
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2
Q

What are monomers?

A

Monomers are individual molecules that make up a polymer.

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3
Q

What are polymers?

A

Polymers consist of many monomers chemically bonded together.

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4
Q

What is a condensation reaction?

A

A condensation reaction removes a molecule of water from two monomers, forming a chemical bond between them.

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5
Q

What is a hydrolysis reaction?

A

A hydrolysis reaction inserts a molecule of water to break the bonds between two monomers.

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6
Q

What are the three types of carbohydrates?

A

Monosaccharides, Disaccharides, Polysaccharides.

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7
Q

What is glucose?

A

Glucose is a hexose sugar and a monosaccharide with the formula C6H12O6.

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8
Q

What are the two isomers of glucose?

A

α-Glucose and β-Glucose.

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9
Q

What is a disaccharide?

A

A disaccharide is formed when two monosaccharides are joined by a condensation reaction.

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10
Q

What are three common disaccharides?

A

Maltose, Sucrose, Lactose.

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11
Q

What is starch?

A

Starch is a storage polysaccharide in plants, made of α-glucose.

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12
Q

What is glycogen?

A

Glycogen is a storage polysaccharide in animals, also made of α-glucose.

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13
Q

What is cellulose?

A

Cellulose is a structural polysaccharide made of β-glucose, providing strength to plant cell walls.

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14
Q

What is the Benedict’s test used for?

A

The Benedict’s test is used to test for reducing sugars by changing color from blue to brick-red if present.

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15
Q

What test is used for non-reducing sugars?

A

Hydrolyse the sample with hydrochloric acid, neutralize it, then perform the Benedict’s test.

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16
Q

What is the iodine test for?

A

The iodine test is used to detect starch, changing from orange-brown to blue-black if present.

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17
Q

What is a triglyceride?

A

A triglyceride consists of one molecule of glycerol and three fatty acids.

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18
Q

What is a phospholipid?

A

A phospholipid consists of one glycerol, two fatty acids, and a phosphate group.

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19
Q

What is the emulsion test for?

A

The emulsion test detects lipids; a milky-white emulsion indicates a positive result.

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20
Q

What is an amino acid?

A

An amino acid is the monomer that forms protein polymers.

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21
Q

What bond forms between amino acids?

A

A peptide bond forms between amino acids.

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22
Q

What are the four structural levels of proteins?

A

Primary, Secondary, Tertiary, Quaternary.

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23
Q

What is the Biuret test for?

A

The Biuret test detects proteins, changing color from blue to lilac/purple.

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24
Q

What is an enzyme?

A

An enzyme is a tertiary-structured protein that speeds up reactions without being used up.

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25
Q

What is the active site of an enzyme?

A

The active site is the region where a substrate binds, forming an enzyme-substrate complex.

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26
Q

How do enzymes lower activation energy?

A

Enzymes lower activation energy by bending substrate bonds and bringing molecules together.

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27
Q

What is the lock and key theory of enzymes?

A

The lock and key theory states that the active site is a perfect fit for the substrate.

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28
Q

What is the induced fit theory of enzymes?

A

The induced fit theory suggests the active site changes shape to fit the substrate more tightly.

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29
Q

What is a competitive inhibitor?

A

A competitive inhibitor binds to the active site of an enzyme, blocking the substrate.

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30
Q

What is a non-competitive inhibitor?

A

A non-competitive inhibitor binds to a site away from the active site, altering the enzyme’s shape.

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31
Q

What is DNA made of?

A

DNA is made of nucleotides joined by phosphodiester bonds.

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32
Q

What is the structure of DNA?

A

DNA is a double helix formed by two polynucleotide strands joined by hydrogen bonds between bases.

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33
Q

What are the base pairs in DNA?

A

Adenine pairs with Thymine, and Cytosine pairs with Guanine.

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34
Q

What is RNA?

A

RNA is a single-stranded polynucleotide used in protein synthesis.

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35
Q

What are the types of RNA?

A

The three types of RNA are mRNA, tRNA, and rRNA.

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36
Q

What is the function of mRNA?

A

mRNA carries the genetic code from the DNA to the ribosome for protein synthesis.

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37
Q

What is the function of tRNA?

A

tRNA carries specific amino acids to the ribosome for polypeptide formation.

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38
Q

What is the function of rRNA?

A

rRNA combines with proteins to form ribosomes, the site of protein synthesis.

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39
Q

What is the difference between DNA and RNA?

A

DNA is double-stranded with Thymine, while RNA is single-stranded with Uracil.

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40
Q

What is DNA replication?

A

DNA replication is the process of copying DNA before cell division.

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41
Q

What enzymes are involved in DNA replication?

A

DNA Helicase and DNA Polymerase.

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42
Q

What is semi-conservative replication?

A

Semi-conservative replication means each new DNA molecule contains one original strand and one new strand.

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43
Q

What is ATP?

A

ATP is a phosphorylated macromolecule that provides energy for cellular processes.

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44
Q

What is the function of ATP?

A

ATP releases energy when hydrolyzed into ADP and an inorganic phosphate.

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45
Q

What is the structure of ATP?

A

ATP consists of adenine, ribose, and three phosphate groups.

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46
Q

What are the properties of water that are important for life?

A

Water is a solvent, has high cohesion, high heat capacity, and is a metabolite.

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47
Q

What is an ion?

A

An ion is a charged particle that has gained or lost electrons.

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48
Q

What is the function of sodium ions (Na+)?

A

Sodium ions are used in the co-transport of glucose and amino acids in the small intestine.

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49
Q

What is the function of hydrogen ions (H+)?

A

Hydrogen ions control pH and are used in creating electrochemical gradients for ATP production.

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50
Q

What is the function of iron ions (Fe2+)?

A

Iron ions are a component of hemoglobin, helping transport oxygen in the blood.

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51
Q

What is the function of phosphate ions (PO4^3-)?

A

Phosphate ions are important in the production of ATP and nucleic acids.

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52
Q

What are the three main polysaccharides?

A

Starch, glycogen, and cellulose.

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53
Q

What is the function of amylose in starch?

A

Amylose has a helical structure making it compact for energy storage in plants.

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54
Q

What is the role of amylopectin in starch?

A

Amylopectin is highly branched, allowing quick hydrolysis for energy release in plants.

55
Q

Why is glycogen highly branched?

A

Glycogen is highly branched to allow rapid glucose release for energy in animals.

56
Q

What is cellulose’s role in plants?

A

Cellulose provides structural support in plant cell walls by forming strong microfibrils.

57
Q

What are reducing sugars?

A

Reducing sugars can donate electrons to reduce other molecules, detectable with Benedict’s reagent.

58
Q

What is the principle behind the Benedict’s test?

A

Benedict’s reagent changes color (from blue to brick-red) in the presence of reducing sugars after heating.

59
Q

How do you test for non-reducing sugars?

A

First, hydrolyze the sample with acid, neutralize it, then test with Benedict’s reagent.

60
Q

Why are lipids not considered polymers?

A

Lipids are not polymers because they are not made of repeating monomer units.

61
Q

What is a saturated fatty acid?

A

A saturated fatty acid contains no carbon-carbon double bonds, only single bonds.

62
Q

What is an unsaturated fatty acid?

A

An unsaturated fatty acid contains at least one carbon-carbon double bond.

63
Q

What bonds are formed in triglycerides?

A

Ester bonds form between the glycerol and fatty acids in triglycerides.

64
Q

What is the significance of phospholipids in cell membranes?

A

Phospholipids form a bilayer with hydrophilic heads facing out and hydrophobic tails facing inward, creating a barrier.

65
Q

How do unsaturated fatty acids affect membrane fluidity?

A

Unsaturated fatty acids increase membrane fluidity by preventing phospholipids from packing tightly together.

66
Q

What is a globular protein?

A

Globular proteins are soluble proteins with biochemical roles, such as enzymes and hormones.

67
Q

What is a fibrous protein?

A

Fibrous proteins are insoluble and have structural roles, such as keratin in nails and collagen in connective tissue.

68
Q

What is the quaternary structure of proteins?

A

The quaternary structure is formed when two or more polypeptide chains join together.

69
Q

What is the role of hydrogen bonds in protein structure?

A

Hydrogen bonds stabilize the secondary structure of proteins (alpha helices and beta sheets).

70
Q

What is the Biuret test used for?

A

The Biuret test detects proteins, turning lilac/purple if proteins are present.

71
Q

What is the difference between competitive and non-competitive inhibition?

A

Competitive inhibitors bind to the active site, while non-competitive inhibitors bind elsewhere, altering the enzyme’s shape.

72
Q

How do enzymes lower activation energy?

A

Enzymes lower activation energy by stressing substrate bonds or bringing substrates closer together.

73
Q

What are the optimal conditions for enzyme activity?

A

Enzymes function best at their optimal temperature and pH, beyond which they may denature.

74
Q

How do you calculate the rate of reaction in enzyme activity?

A

The rate of reaction can be calculated by measuring product formation or substrate usage over time.

75
Q

What effect does temperature have on enzyme activity?

A

Increased temperature raises kinetic energy, increasing collisions, but too high temperatures cause denaturation.

76
Q

What is the effect of pH on enzyme activity?

A

Deviation from the optimal pH alters ionic bonds in the enzyme, changing its active site and reducing activity.

77
Q

How does enzyme concentration affect reaction rate?

A

Increasing enzyme concentration increases the rate until the substrate becomes the limiting factor.

78
Q

What is the role of DNA Helicase in replication?

A

DNA Helicase unwinds the DNA double helix and breaks hydrogen bonds between bases.

79
Q

What is the role of DNA Polymerase in replication?

A

DNA Polymerase joins nucleotides together to form the sugar-phosphate backbone during replication.

80
Q

What is the semi-conservative model of DNA replication?

A

Semi-conservative replication means that each new DNA molecule contains one original and one new strand.

81
Q

What did the Meselson-Stahl experiment demonstrate?

A

The Meselson-Stahl experiment confirmed that DNA replicates in a semi-conservative manner.

82
Q

Why is ATP known as the universal energy currency?

A

ATP is used by all cells to provide energy for biological processes through hydrolysis.

83
Q

What is the role of ATP Synthase?

A

ATP Synthase catalyzes the formation of ATP from ADP and inorganic phosphate during respiration.

84
Q

How does water’s high specific heat capacity benefit organisms?

A

Water’s high specific heat capacity stabilizes temperatures in organisms and aquatic environments.

85
Q

How does water’s cohesion support life?

A

Cohesion allows water to form continuous columns in xylem vessels and creates surface tension for small organisms.

86
Q

Why is water a good solvent?

A

Water is polar, allowing it to dissolve ions and polar molecules, facilitating transport and reactions in cells.

87
Q

How is sodium (Na+) involved in transport across membranes?

A

Sodium ions are involved in co-transport of glucose and amino acids in the small intestine.

88
Q

What is the function of hydrogen ions (H+)?

A

Hydrogen ions affect pH and create proton gradients for ATP production in cellular respiration.

89
Q

What is the function of iron ions (Fe2+)?

A

Iron ions are a component of hemoglobin, aiding oxygen transport in the blood.

90
Q

What is the function of phosphate ions (PO4^3-)?

A

Phosphate ions are essential for the formation of ATP and DNA/RNA nucleotides.

91
Q

What is the structure of α-glucose?

A

In α-glucose, the hydroxyl (OH) group is below Carbon 1, and the hydrogen (H) is above Carbon 1.

92
Q

What is the structure of β-glucose?

A

In β-glucose, the hydroxyl (OH) group is above Carbon 1, and the hydrogen (H) is below Carbon 1.

93
Q

How do two α-glucose molecules form maltose?

A

Two α-glucose molecules undergo a condensation reaction, forming a glycosidic bond and releasing water.

94
Q

Why is starch a good energy storage molecule?

A

Starch is compact (due to amylose’s coiled structure) and insoluble, so it doesn’t affect water potential in cells.

95
Q

What role does glycogen play in animal cells?

A

Glycogen stores glucose in animal cells, releasing it quickly for energy through its branched structure.

96
Q

How does cellulose provide structural support?

A

Cellulose chains form microfibrils, which provide strength and rigidity to plant cell walls.

97
Q

What is the function of microfibrils in cellulose?

A

Microfibrils formed by cellulose chains provide tensile strength in plant cell walls.

98
Q

What happens when a polysaccharide is hydrolyzed?

A

The glycosidic bonds are broken, releasing monosaccharides.

99
Q

What is the significance of hydrogen bonds in cellulose?

A

Hydrogen bonds between cellulose molecules strengthen plant cell walls.

100
Q

Why can’t glucose be stored in its monosaccharide form in cells?

A

Glucose is soluble and would affect the water potential, causing water to enter the cell and potentially burst it.

101
Q

What is the main difference between amylose and amylopectin?

A

Amylose is unbranched and coiled, while amylopectin is branched and more easily hydrolyzed.

102
Q

What is a reducing sugar?

A

A reducing sugar is one that can donate electrons to another molecule, like glucose or maltose.

103
Q

What does Benedict’s reagent test for?

A

Benedict’s reagent tests for reducing sugars; it changes color from blue to brick-red if present.

104
Q

What is the outcome of a positive iodine test for starch?

A

The iodine solution turns from orange-brown to blue-black in the presence of starch.

105
Q

Why are lipids important for energy storage?

A

Lipids store more energy per gram than carbohydrates and are used for long-term energy storage.

106
Q

How do phospholipids contribute to membrane structure?

A

Phospholipids form a bilayer in cell membranes, with hydrophilic heads facing outward and hydrophobic tails inward.

107
Q

Why do triglycerides provide more energy than carbohydrates?

A

Triglycerides contain more hydrogen-carbon bonds, which release more ATP during oxidation.

108
Q

What is an ester bond?

A

An ester bond forms between the hydroxyl group of glycerol and the carboxyl group of fatty acids in lipids.

109
Q

What is the difference between saturated and unsaturated fats?

A

Saturated fats have no double bonds between carbon atoms, while unsaturated fats have at least one double bond.

110
Q

What effect does a high concentration of unsaturated fatty acids have on membrane fluidity?

A

Unsaturated fatty acids increase membrane fluidity by preventing tight packing of phospholipids.

111
Q

How does a competitive inhibitor affect enzyme activity?

A

A competitive inhibitor competes with the substrate for the active site, reducing the rate of reaction.

112
Q

How does a non-competitive inhibitor affect enzyme activity?

A

A non-competitive inhibitor binds to a site away from the active site, changing the enzyme’s shape and reducing activity.

113
Q

Why is the tertiary structure important for enzyme function?

A

The tertiary structure determines the shape of the active site, which is specific to the substrate.

114
Q

How does enzyme concentration affect the rate of reaction?

A

Increasing enzyme concentration increases the rate of reaction until the substrate becomes the limiting factor.

115
Q

What happens to enzyme activity at high temperatures?

A

At high temperatures, enzymes denature as the hydrogen bonds in the tertiary structure break, altering the active site.

116
Q

What happens to enzyme activity at low pH?

A

At low pH, ionic bonds in the enzyme’s tertiary structure are disrupted, changing the shape of the active site.

117
Q

What happens during DNA replication?

A

DNA Helicase unwinds the double helix, and DNA Polymerase joins complementary nucleotides to the original strands.

118
Q

What is the purpose of DNA Helicase?

A

DNA Helicase unwinds the DNA and breaks hydrogen bonds between bases during replication.

119
Q

What is the purpose of DNA Polymerase?

A

DNA Polymerase joins adjacent nucleotides during DNA replication, forming phosphodiester bonds.

120
Q

What is meant by complementary base pairing?

A

In DNA, adenine pairs with thymine and cytosine pairs with guanine through hydrogen bonds.

121
Q

What is the role of mRNA in protein synthesis?

A

mRNA carries the genetic code from the DNA to the ribosome, where it is translated into a polypeptide.

122
Q

What is the function of tRNA?

A

tRNA carries specific amino acids to the ribosome, where they are added to the growing polypeptide chain.

123
Q

What is rRNA and its role?

A

rRNA combines with proteins to form ribosomes, the site of protein synthesis.

124
Q

What is ATP and why is it important?

A

ATP is a molecule that provides energy for cellular processes through the hydrolysis of its terminal phosphate bond.

125
Q

How is ATP synthesized?

A

ATP is synthesized from ADP and inorganic phosphate (Pi) by ATP Synthase during respiration or photosynthesis.

126
Q

Why is water’s high latent heat of vaporization important?

A

Water’s high latent heat of vaporization allows organisms to cool down through sweating or transpiration without losing too much water.

127
Q

How does water’s cohesion benefit plants?

A

Water’s cohesion allows it to be drawn up the xylem in a continuous stream, supporting transpiration.

128
Q

How does water’s high specific heat capacity support life?

A

Water’s high specific heat capacity buffers temperature changes, stabilizing environments for aquatic life.

129
Q

Why is water a good solvent?

A

Water is polar, allowing it to dissolve ions and polar molecules, facilitating biochemical reactions.

130
Q

What role does sodium (Na+) play in the body?

A

Sodium is involved in generating nerve impulses and transporting glucose and amino acids across cell membranes.

131
Q

How do hydrogen ions (H+) affect biological systems?

A

Hydrogen ions determine the pH of solutions, affecting enzyme activity and other biochemical processes.

132
Q

Why are iron ions (Fe2+) important in the body?

A

Iron ions are a component of hemoglobin, which binds to oxygen and transports it in the bloodstream.

133
Q

What role do phosphate ions (PO4^3-) play in cells?

A

Phosphate ions are essential for ATP synthesis and the formation of DNA and RNA.

A Level Biology (10 decks)

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