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Biology - Module 2 > Topic 2.2 Biological molecules > Flashcards

Topic 2.2 Biological molecules Flashcards

1
Q

Describe what the water molecule is

A

Water is a polar molecule due to the uneven distribution of charge within the molecule
– the oxygen atom attracts electrons more strongly than the hydrogen atoms. The
unequal sharing of electrons gives the water molecule a slightly negative charge near
its oxygen atom and a slightly positive charge near its hydrogen atoms.

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2
Q

List the features of water

A
  • solvent
  • high specific-heat capacity
  • high latent heat of vaporisation
  • strong cohesion of molecules
  • maximum density of water is 4 degrees
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3
Q

Expand on the high specific-heat capacity of water

A

It has a high specific-heat capacity meaning that a lot of energy is required to warm water up, therefore minimising temperature fluctuations in living things

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4
Q

Expand on the high latent heat of vaporisation of water

A

It also has a relatively high latent heat of vaporisation, meaning evaporation of water provides a cooling effect, with little wattle loss.

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5
Q

Explain how the strong cohesion of water molecules is useful.

A
  • enables efficient transport of water in tube-like transport cells as the strong cohesion supports columns of water.
  • the surface tension at the water-air boundary is high as a result of strong cohesion.
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6
Q

Expand on the maximum density of water.

A

The maximum density of water is at 4 degrees – this means that ice is less dense than water and floats on top of it creating an insulating layer, this increases the chance of survival of organisms in large bodies of water as it prevents them from freezing.

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7
Q

What are monomers?

A

Monomers are small units which are the components of larger molecules. Examples include monosaccharides, amino acids and nucleotides.

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8
Q

What are Polymers?

A

Polymers are molecules made from monomers joined together

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8
Q

What is a condensation reaction?

A

A condensation reaction is a reaction which joins monomers by chemical bonds, and it involves the elimination of a water molecule

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9
Q

What is a hydrolysis reaction?

A

Hydrolysis is the opposite of condensation, and it is when a water molecule is added to break a chemical bond between two molecules

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9
Q

What is a carbohydrate molecule made up of?

A

Carbohydrates are molecules made of carbon,hydrogen and oxygen

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10
Q

What are the three forms of Saccharides?

A
  • Monosaccharides
  • Disaccharides
  • Polysaccharides
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11
Q

How do Monosaccharides join to form the larger saccharides?

A

Through condensation reactions monosaccharides join by glycosidic bonds to form the larger saccharides.

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12
Q

Explain Glucose as a monosaccharide

A

Glucose is a monosaccharide containing six carbon atoms per molecule. As the main substrate for respiration, it is biologically essential.

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13
Q

What are the two isomeric forms of glucose?

A

• Alpha glucose
• Beta glucose

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14
Q

What is the difference between a hexose and a pentose monosaccharide

A

A hexose monosaccharide has 6 carbon atoms, whereas a pentose monosaccharide has 5 carbon atoms.

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15
Q

Give examples of a hexose monosaccharide

A

• glucose
• fructose
• galactose

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16
Q

Give examples of a pentose monosaccharide

A

• Ribose
• Deoxyribose

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17
Q

How do Disaccharides form?

A

A disaccharide is formed when two monosaccharides join together through a condensation reaction between the OH groups, which results in a glycosidic bonds forming.

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18
Q

How is maltose formed?

A

maltose is a disaccharide formed from two glucose molecules.

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18
Q

How is sucrose formed?

A

Sucrose is a disaccharide formed by condensation of glucose and fructose

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18
Q

How is lactose formed?

A

Lactose is a disaccharide formed by condensation of glucose and galactose.

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19
Q

What are polysaccharides?

A

Polysaccharides are formed by many glucose molecules joining together through condensation reactions forming glycosidic bonds.

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20
Q

Give examples of polysaccharides

A
  • Starch
  • Glycogen
  • Cellulose
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21
Explain what Amylose is (polysaccharide)
Amylose is a linear polymer of alpha glucose molecules linked by alpha(1-4) glycosidic bonds, forming a helical structure.
21
Explain what cellulose is (polysaccharide)
Cellulose is a linear polymer of beta-glucose molecules linked by beta(1-4) glycosidic bonds, resulting in straight chains that form rigid structures through hydrogen bonding between adjacent chains.
22
Explain what Amylopectin is (polysaccharide).
Amylopectin is a branched polymer of an alpha glucose with alpha(1-4) glycosidic bonds in the linear sections and alpha(1-6) bonds at the branch points.
23
Explain what glycogen is (polysaccharide)
Glycogen is a highly branched polymer of alpha-glucose, similar to amylopectin but with more frequent alpha(1-6) branching making it more compact
24
Explain the relationship between glucoses structure and function
Glucose is small, soluble monosaccharide that serves as a primary energy source in cellular respiration due to its ease of transport and rapid metabolism.
25
Explain the relationship between starch's structure and function
The helical structure of amylose and the branched form of amylopectin make starch compact and insoluble, ideal for energy storage in plants without affecting osmotic balances
26
The relationship between structure and function for Glycogen
Its highly branched structure allows for rapid release of glucose units, meeting the high metabolic demands of animals. Its compact form facilitates efficient energy storage in liver and muscle tissues.
27
What are the two types of lipids
- Saturated lipids - Unsaturated lipids
27
The relationship between structure and function for Cellulose
The straight, unbranched chains of beta-glucose form strong fibres through extensive hydrogen bonding. This provides structural support in plant cell walls, contributing to their rigidity and strength.
27
Define saturated lipids
Saturated lipids do not contains a carbon-carbon double bond.
28
Define unsaturated lipids
Unsaturated lipids contain a carbon-carbon double bond, and melt at lower temperatures.
29
List the biological roles of lipids
- membrane formation and the creation of hydrophobic barriers. - hormone production - electrical insulation necessary for impulse transmission - waterproofing, for example in birds’ feathers and on plant leaves
29
List the important roles of lipids, triglycerides in particular, in long-term energy storage
- thermal insulation to reduce heat loss, for example in penguins - cushioning to protect vital organs such as the heart and kidneys - buoyancy for aquatic animals like whales.
30
What do triglycerides consist of?
- glycerol molecule - three fatty acids -ester bonds formed during condensation reaction link fatty acids to glycerol backbone
31
Explain how triglycerides are helpful.
Triglycerides are hydrophobic, making them ideal for energy storage. They are compact and energy-dense, releasing energy when metabolised.
32
What do phospholipids consist of?
A phospholipid contains one glycerol molecule, two fatty acids, and a phosphate group.
33
How is the amphipathic nature valuable for cell membranes?
It allows phospholipids to form bilayers, which are the basis of cell membranes. The centre of the bilayer is hydrophobic, so water-soluble substances can not pass through.
34
Explain how a phospholipid is an amphipathic molecule.
The fatty acids tails are hydrophobic, while the phosphate group head is hydrophilic, leading to an amphipathic molecule
35
Where are inorganic ions found?
Inorganic ions occur in solution in the cytoplasm and body fluid of organisms, some in high concentrations and others in really low concentrations.
36
List some of the essential ions:
- hydrogen ions - iron ions - sodium ions - phosphate ions
37
Explain the importance of hydrogen ions?
Hydrogen ions determine the pH of substances such as blood - the higher the conc of hydrogen ions the lower the pH
38
Explain the importance of iron ions.
Iron ions are component of haemoglobin which is an oxygen carrying molecule in red blood cells.
38
Explain the importance of sodium ions.
Sodium ions are involved in the co-transport of glucose and amino acids.
39
Explain the importance of phosphate ions
Phosphate ions are a component of DNA and ATP.
40
What are amino acids?
Amino acids are the monomers from which proteins are made.
41
What are peptides?
Peptides are polymers made up of amino acid molecules.
41
What do proteins consist of
Proteins consist of the elements carbon, hydrogen, oxygen, and nitrogen. They contain of one or more polypeptides arranged as complex macromolecules.
42
What do amino acids contain?
Amino acids contain an amino group - NH2, a carboxylic group and a variable R group which is a carbon-containing chain.
43
How are amino acids joined?
Amino acids are joined by peptide bonds formed in condensation reactions.
44
Explain the secondary structure of a protein.
The secondary structure is the shape that the chain of amino acids takes- either alpha helix or beta pleated sheet. The shape is determined by the hydrogen bonding. Hydrogen bonds form between the oxygen of one peptide bond and the hydrogen bond of another, stabilising the alpha-helix and beta-pleated formations.
45
What are the four types of protein structures?
- primary structure - secondary structure - tertiary structure - quaternary structure
45
Explain the primary structure of a protein
The primary structure of a protein is the sequence of amino acids in polypeptide chain, linked by peptide bonds. It determines the protein's unique characteristics and dictates higher-level structures. The only bonds involved in the primary structure of a protein are peptide bonds.
46
Explain the tertiary structure of a protein.
The tertiary structure is the overall 3D shape of a singly polypeptide chain, resulting from interactions among R-groups. The following interactions and bonds occur: - Hydrogen bonds form between polar R-groups, contributing to the protein’s stability. - Ionic bonds form between oppositely charged R-groups. - Disulfide bonds - these are covalent and strongest of the bonds - Hydrophobic and hydrophilic interactions - weak interactions between polar and non-polar R-groups.
47
Explain the quaternary structure of protein.
The quaternary structure is the arrangement and interaction of multiple polypeptide subunits in a multi-subunit protein. Similar to tertiary structure, it includes hydrogen, ionic, and disulfide bonds, and hydrophobic interactions, facilitating the assembly and stability of the multi-subunit complex.
48
What are Globular proteins?
Globular proteins are spherical and water-soluble due to their tertiary structure , where hydrophobic R-groups are oriented inward and hydrophilic R-groups outward.
49
What roles to globular proteins take part in due to their solubility and diverse structures?
enzymatic catalysis, transport and regulation.
50
What are conjugated proteins?
Conjugated proteins are globular proteins that contain a non-protein component called a prosthetic group
51
Give the structure and function of haemoglobin as an example of a conjugated protein.
Structure: Haemoglobin is a globular protein with a quaternary structure composed of four polypeptide chains, each containing a haem prosthetic group. Function: The haem groups bind oxygen molecules, allowing haemoglobin to transport oxygen from the lungs to tissues efficiently.
52
Give the structure and function of insulin as an example of a globular protein.
Structure: Insulin is a globular protein consisting of two polypeptide chains linked by disulfide bonds, forming a specific three-dimensional shape. Function: As a hormone, insulin regulates blood glucose levels by facilitating cellular glucose uptake, and maintaining homeostasis.
53
Give the structure and function of enzymes as an example of a globular protein.
Structure: Enzymes like amylase are globular proteins with an active site formed by their tertiary structure, allowing substrate specificity. Function: Amylase catalyses the hydrolysis of starch into sugars, playing a crucial role in digestion.
54
Give the features of a fibrous protein
Fibrous proteins are insoluble in water, due to the hydrophobic nature of their amino acids. They are strong and durable providing mechanical strength and support. They are long, linear polypeptide chains arranged in fibres or sheets.
55
Explain the properties and functions of collagen, as an example of fibrous proteins.
Properties: High tensile strength, flexible. Functions: Found in connective tissues such as tendons, ligaments, skin, and bone. Provides structural support and resists pulling forces.
56
Explain the properties and functions of Keratin, as an example of a fibrous protein.
Properties: Tough and rigid (in hard keratin-like nails) or flexible (in soft keratin-like skin). Functions: Makes up hair, nails, skin, and animal horns. Provides protection and structural integrity.
57
Explain the properties and functions of elastin, as an example of fibrous protein.
Properties: Elastic and flexible, allowing tissues to return to their original shape after stretching. Functions: Found in elastic tissues such as skin, lungs, and blood vessel walls. Enables elasticity and stretchability.
58
Explain the biuret test for proteins
Add an equal amount of NaOH to the sample. After that add a few drops of dilute copper(II) sulfate. If protein is present the solution turns lilac/purple. In the absence of protein the solution remains blue.
59
Explain the emulsion test for lipids
Add ethanol to the sample and shake to mix well. Then add a few ml of water and mix. If the solution turns cloudy, a lipid a present
60
Explain the Iodine test for starch.
Iodine solution is added to the sample If starch is present, the colour of the potassium iodide solution turns from yellow to blue/black.

Biology - Module 2 (6 decks)

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