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biological molecules Flashcards

1
Q

describe the evidence for evolution provided by biological molecules

A

all living things share the same biological molecules and have a similar biochemical basis (all organisms descended from one or a few common ancestors)

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2
Q

define what a monomer is

A

a simple, basic molecular unit from which larger molecules are made

e.g. monosaccharides, amino acids, and nucleotides

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3
Q

explain the difference between monomers and polymers

A

monomers are small, basic units, while polymers are large, complex molecules made up of repeating monomers joined together

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4
Q

what are condensation and hydrolysis reactions?

A

condensation reaction - joins two or more monomers together by forming a chemical bond, eliminating a water molecule.

hydrolysis reaction - separates two monomers by breaking a chemical bond, requires the addition of a water molecule

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5
Q

describe the composition and functions of carbohydrates

A

contain carbon, hydrogen, and oxygen, and their functions include energy storage and providing strength

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6
Q

explain what monosaccharides are

A

they are the simplest sugars and the monomers from which larger carbohydrates are made

e.g. glucose, fructose, and galactose

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7
Q

how are disaccharides formed?

A

two monosaccharides join together through a condensation reaction, creating a glycosidic bond and releasing a water molecule

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8
Q

list examples of disaccharides and their components

A

maltose = glucose + glucose
sucrose = glucose + fructose
lactose = glucose + galactose

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9
Q

how are polysaccharides formed?

A

when two or more monosaccharides join together via condensation reactions, releasing a water molecule for each glycosidic bond

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10
Q

describe the structure and function of starch

A

starch is made up of two polysaccharides of alpha glucose: amylose (unbranched) and amylopectin (branched)
it serves as a major energy source in diets and is found in plant storage organs

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11
Q

explain how the structure of starch relates to its function

A

it’s helical structure is compact for storage, it is insoluble which does not affect water potential, and its branched chains enable efficient hydrolysis for respiration

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12
Q

what is glycogen and its primary function?

A

glycogen is the main storage from of energy in animals, primarily stored in muscle and liver cells

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13
Q

describe the structure of glycogen and its functional significance

A

it is a polysaccharide of alpha glucose
has branched chains every 10 monomers
allows for rapid hydrolysis into glucose to meet cellular demands

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14
Q

explain teh role of cellulose in plants

A

provides structural strength in cell walls
allows them to withstand the turgor pressure due to many H bonds between parallel chains of microfibrils

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15
Q

how does the structure of cellulose contribute to its function?

A

straight chains of beta glucose
joined by 1-4 glycosidic bonds
H bonds formed between chains
provides collective strength to cell wall

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16
Q

compare the structures of starch, glycogen, and cellulose

A

starch - alpha glucose with helical and branched structures
glycogen - alpha glucose but more highly branced
cellulose - beta glucose forming straight, unbranched chains

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17
Q

describe the test for reducing sugars

A

add Benedict’s reagent to the sample and heat in water bath

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18
Q

describe the test for non-reducing sugars

A

add HCl and then add an alkali to neutralise to negative reducing sugar test
add Benedict’s solution
heat in water bath again

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19
Q

explain the positive result for the Benedict’s test

A

positive result indicated by colour change from blue to green, yellow, orange or brick red depending on the concentration of reducing sugars present

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20
Q

define the structure of triglycerides

A

one molecule of glycerol attached to three fatty acids

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21
Q

how are triglycerides formed

A

condensation reaction
H atom from hydroxyl group on glycerol joins with hydroxyl group on COOH of fatty acid
water molecule is released
ester bond is formed
process is repeated for two other fatty acids

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22
Q

what are the main functions of triglycerides?

A

energy storage

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23
Q

describe the properties of triglycerides

A

insoluble in water due to hydrophobic fatty acid tails facing inwards and glycerol outwards
long hydrocarbon tails that release energy when oxidised

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24
Q

explain the structure of phospholipids

A

one glycerol molecule, one phosphate group, and two fatty acid tails
head (phosphate and glycerol) is hydrophilic
tails are hydrophobic

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25
what is the function of phospholipids in biological membranes?
form the phospholipid bilayer acts as a barrier in cell membranes to water-soluble molecules, ions, and polar molecules
26
describe the formation of phospholipds
condensation reaction between glycerol and phosphate group forming phosphate ester bond condensation reaction between glycerol and fatty acids forming ester bonds releasing water molecules
27
what are the properties of phospholipids?
hydrophilic heads which attract water hydrophobic tails which repel water forms a bilayer that shields the tails and provides stability and fluidity to membrane
28
define fatty acids and their structure
a hydrocarbon chain which contains a carboxyl group and can vary in length and saturation
29
explain the difference between saturated and unsaturated fatty acids
saturated - no C=C double bond and each C is saturated with hydrogens unsaturated - one or more C=C double bonds causing the chain to kink
30
describe the method for testing lipids
add ethanol to sample, add water, and shake milky emulsion layer will form if positive
31
what are the hazards associated with testing lipids using ethanol
ethanol is flammable, testing should not be conducted near open flames
32
describe the structure of an amino acid
consists of an amine group (NH2), a carboxyl group (COOH), and a variable group (R) that differs among the 20 amino acids
33
explain how dipeptides and polypeptides are formed
dipeptides are formed through a condensation reaction between the hydroxyl group of the carboxyl group of one amino acid and the hydrogen of the amine group of another, releasing a water molecule polypeptide is two or more amino acids linked by peptide bonds
34
what determines the primary structure of a protein?
the sequence of amino acids in a polypeptide chain, which is instructed by the DNA of a cell
35
describe the significance of the primary structure of proteins
specific for each protein it determines the protein’s shape and function by where the H bonds form
36
explain the secondary structure of proteins
formation of H bonds between amino acids, leading to structures such as alpha helices and beta pleated sheets
37
explain the tertiary structure proteins
further folding hydrogen bonds, disulphide bridges, and ionic bonds forms a 3D structure
38
define quaternary structure in proteins
multiple polypeptide chains bonded together
39
explain how a change in DNA base sequence can affect enzyme reactions
change in bases = change in primary structure bonds will form in different places in tertiary structure changes enzymes active site can no longer form ESCs
40
describe the characteristics of globular proteins
soluble with their R groups folded inwards often involved in metabolic processes
41
what are fibrous proteins and their properties?
insoluble with their R groups exposed provides structural support and strength
42
define the role of enzymes in biological reactions
biological catalysts that speed up the rate of chemical reactions without being consumed by providing an alternate pathway with a lower activation energy
43
explain the difference between intracellular and extracellular enzymes
intracellular - catalyse reactions inside cells extracellular - catalyse reactions outside of cells
44
describe the lock and key model of enzyme action
it suggests that the active site of an enzyme has a fixed shape that is complementary to the substrate, allowing them to bind and form an ESC
45
what is the induced fit model of enzyme action?
it suggests that the active site of an enzyme,e is not completely complementary to the substrate initially, but upon binding, the enzymes active site changes shape to fit the substrate to form an ESC
46
explain enzyme specificity
only one specific enzyme can catalyse one reaction as only one substrate is complementary to its active site
47
how can mutations affect enzyme function?
changes base sequence which changes the primary structure of the protein bonds will form in different places in tertiary structure enzymes active site changes shape changes enzyme function
48
what is the Biuret test used for?
detects the presence of proteins positive = blue to purple
49
describe the effect of temperature on enzyme activity
temp increases, kinetic energy increases, increase in more frequent collisions, increase in ESCs formed rate of reaction increases until optimum temperature where the active site denatures by breaking of H bonds
50
explain how pH affects enzyme activity
deviation from optimum pH of an enzyme can lead to denaturing of H+ and OH- ions disrupt the H and ionic bonds that maintain the tertiary structure
51
define competitive inhibitors and their effect on enzyme activity
competitive inhibitors have similar shape to substrate and competes for binding to the enzyme’s active site blocks active site reducing ESC formation, decreasing rate of reaction increasing substrate concentration can mitigate this effect
52
how does enzyme concentration influence the rate of reaction?
53
What do all living things share that supports the theory of evolution?
The same biological molecules ## Footnote This indicates a common biochemical basis for all organisms.
54
What is a monomer?
A simple, basic molecular unit from which larger molecules/polymers are made ## Footnote Examples include monosaccharides, amino acids, and nucleotides.
55
What is a polymer?
A large, complex molecule made up of repeating monomers joined together ## Footnote Examples include starch, glycogen, cellulose, polypeptides, DNA, and RNA.
56
What type of reaction joins two monomers together?
Condensation reaction ## Footnote This reaction forms a chemical bond and releases a water molecule.
57
What type of reaction separates two monomers?
Hydrolysis reaction ## Footnote This reaction requires the addition of a water molecule.
58
What are the main elements contained in carbohydrates?
Carbon, hydrogen, and oxygen.
59
What are monosaccharides?
Simplest sugars, monomers from which larger carbohydrates are made ## Footnote Examples include glucose, fructose, and galactose.
60
What is the formula for monosaccharides like glucose?
C6H12O6.
61
What forms when two monosaccharides join together?
Disaccharides ## Footnote They are formed by a condensation reaction, creating a glycosidic bond.
62
Give examples of disaccharides.
* Maltose (glucose + glucose) * Sucrose (glucose + fructose) * Lactose (glucose + galactose) * Lactulose (galactose + fructose)
63
What are polysaccharides?
Formed when more than 2 monosaccharides join together via condensation reactions ## Footnote Examples include starch, glycogen, and cellulose.
64
What is the function of starch?
Energy storage ## Footnote It is found in many parts of a plant, especially in seeds and storage organs.
65
What are the two types of polysaccharides that make up starch?
* Amylose (unbranched) * Amylopectin (branched)
66
What is the main storage form of energy in animals?
Glycogen.
67
What is the primary function of cellulose?
Provides structural strength in the cell walls of plants.
68
What type of bond is found in cellulose?
C1-4 glycosidic bonds.
69
How can reducing sugars be tested?
By using Benedict’s reagent and heating in a boiling water bath.
70
What is a positive result for reducing sugars in a Benedict’s test?
Blue → green, yellow, orange, brick red.
71
What elements do lipids contain?
Carbon, hydrogen, and oxygen.
72
What is the structure of triglycerides?
1 molecule of glycerol attached to 3 fatty acids.
73
What is the main function of triglycerides?
Storage molecules.
74
What is the structure of phospholipids?
1 glycerol, 1 phosphate group, and 2 fatty acid tails.
75
What is the test for lipids?
Ethanol and water test.
76
What is a positive result for lipids in the ethanol and water test?
White/milky emulsion.
77
What are proteins made of?
Amino acids.
78
What determines the primary structure of proteins?
The sequence of amino acids in a polypeptide chain.
79
What is the secondary structure of proteins characterized by?
Hydrogen bonds forming alpha helices or beta-pleated sheets.
80
What types of bonds are found in the tertiary structure of proteins?
* Hydrogen bonds * Disulfide bridges * Ionic bonds * Hydrophobic interactions
81
What is the quaternary structure of proteins?
The way polypeptide chains are assembled.
82
What does enzyme specificity mean?
Enzymes only catalyze one reaction as only one substrate is complementary to the active site.
83
What factors affect enzyme activity?
* Temperature * pH * Enzyme concentration * Substrate concentration * Competitive inhibitors * Non-competitive inhibitors
84
What happens to enzymes when temperature exceeds the optimum?
Enzymes denature as the active site changes shape.
85
What is a positive result for proteins in the Biuret test?
Blue → purple.
86
What increases the likelihood of forming enzyme-substrate complexes?
More enzymes are available ## Footnote This means that with more enzymes, there are more opportunities for substrates to collide and form complexes.
87
What happens to the rate of reaction as substrate concentration increases?
It increases up to the saturation point ## Footnote At saturation, all enzyme active sites are occupied, and further increases in substrate concentration do not affect the rate.
88
What is the effect of competitive inhibitors on enzyme activity?
They compete with substrates to bind to the enzyme's active site ## Footnote This reduces the number of enzyme-substrate complexes formed.
89
True or False: Increasing substrate concentration always reduces the effect of competitive inhibitors.
True ## Footnote At higher substrate concentrations, there are more collisions between substrates and active sites.
90
How do non-competitive inhibitors affect enzyme activity?
They bind to an allosteric site, causing a conformational change ## Footnote This change prevents substrates from binding to the active site.
91
What is the structure and function of DNA?
Stores genetic information and hereditary material ## Footnote DNA is composed of 3.2 billion base pairs in a typical mammalian cell.
92
What are the components of a nucleotide?
Phosphate group, pentose sugar, nitrogenous base ## Footnote The nitrogenous bases can be A, T, C, G (in DNA) or A, U, C, G (in RNA).
93
What type of bond is formed between nucleotides in DNA?
Phosphodiester bond ## Footnote This bond forms during a condensation reaction between the phosphate group and the pentose sugar.
94
Describe the structure of DNA.
Double helix with two polynucleotide strands ## Footnote Strands are held together by hydrogen bonds between complementary bases.
95
What is the significance of complementary base pairing in DNA?
Enables accurate replication and reduces mutation chances ## Footnote Each base has a specific partner: A pairs with T/U and C pairs with G.
96
What is the main difference between DNA and RNA?
DNA is double-stranded; RNA is single-stranded ## Footnote DNA contains deoxyribose, while RNA contains ribose.
97
What is the role of DNA helicase during replication?
Unzips the DNA by breaking hydrogen bonds ## Footnote This allows the two strands to separate and serve as templates.
98
What is the purpose of DNA ligase in DNA replication?
Joins Okazaki fragments on the lagging strand ## Footnote DNA polymerase synthesizes DNA in short segments on the lagging strand.
99
What was the conclusion of the Meselson and Stahl experiment?
DNA replicates by semi-conservative replication ## Footnote This was proven using nitrogen isotopes to trace DNA replication.
100
What is ATP and its role in the cell?
A nucleotide derivative that stores energy ## Footnote ATP is broken down to release energy for cellular processes.
101
Why is ATP more useful than glucose for energy transfer?
ATP is smaller and can be used more easily ## Footnote Glucose is larger and requires more steps to release energy.
102
What is the process of ATP hydrolysis?
ATP is broken down into ADP and Pi, releasing energy ## Footnote This reaction is catalyzed by ATP hydrolase.
103
What is the importance of water in biological systems?
Acts as a solvent, participates in metabolic reactions ## Footnote Water has high specific heat capacity and is cohesive.
104
What type of bonding occurs between water molecules?
Hydrogen bonding ## Footnote This occurs between the slightly positive hydrogen atoms and the slightly negative oxygen atoms.
105
What is the charge distribution in a water molecule?
Slight (partial) negative charge on one side and a slight (partial) positive charge on the other.
106
What type of bond forms between a hydrogen atom and an oxygen atom in water?
Hydrogen bonds
107
What is a hydrolysis reaction?
A reaction that requires a molecule of water to break a bond.
108
What is a condensation reaction?
A reaction that releases a molecule of water as a new bond is formed.
109
How is energy released from ATP?
Through a hydrolysis reaction.
110
What is a metabolite?
A substance involved in a metabolic reaction.
111
Define a solvent.
A substance capable of dissolving another substance.
112
Why is water considered a good solvent?
Because it is polar and can surround ions, allowing them to dissolve.
113
What is latent heat?
The heat energy needed to change a substance from one state to another.
114
What does high latent heat of vaporisation mean for water?
A lot of energy is used to change it from a liquid to a gas.
115
How does water evaporation help organisms?
It cools them down without losing too much water.
116
What is specific heat capacity?
The energy needed to raise the temperature of 1kg of a substance by 1 °C.
117
What role do hydrogen bonds play in water's high specific heat capacity?
A lot of heat energy is used to break the hydrogen bonds, limiting temperature increase.
118
Why is stable temperature important for living organisms?
It helps maintain a constant internal body temperature, affecting enzyme activity.
119
Define cohesion in the context of water.
The attraction between molecules of the same type.
120
What is the significance of water's cohesion?
It helps water flow and contributes to high surface tension.
121
What is an inorganic ion?
An ion that doesn’t contain carbon.
122
What is the role of iron (Fe3+) in the body?
It is a component of hemoglobin that carries oxygen in red blood cells.
123
What is the function of phosphate (PO4^3-) in biological molecules?
It is involved in phosphorylation and is present in DNA, RNA, and ATP.
124
How do hydrogen ions (H+) affect pH?
More H+ present leads to lower pH and a more acidic environment.
125
What is co-transport in the context of sodium ions (Na+)?
It is the process of transporting glucose or amino acids into a cell alongside sodium ions.
126
How does a change in DNA base sequence affect enzyme reactions?
It alters the sequence of amino acids, affecting the enzyme's tertiary structure and active site.
127
What are the monomers of carbohydrates?
Monosaccharides
128
What bond type is found in carbohydrates?
Glycosidic bonds
129
What is the test for carbohydrates?
Benedict's test
130
What are the components of lipids?
Fatty acid + glycerol + phosphate group
131
What bond types are found in lipids?
Ester/phosphoester bonds
132
What is the test for proteins?
Biuret test
133
What are the monomers of nucleic acids?
Nucleotides
134
What bond type is found in nucleic acids?
Phosphodiester bonds

biology (10 decks)

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