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Biomolecules Flashcards

1
Q

Describe the structure of a water molecule

A

An oxygen atoms covalently bonded to 2 hydrogen atoms. Non-linear shape.

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2
Q

Name the bond that can link two water molecules together

A

Hydrogen bond

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3
Q

What is a hydrogen bond? What types of atoms can it join together and where do they occur in biology?

A

A hydrogen bond is a weak interaction that can occur whenever molecules contain a slightly negative charged atom bonded to a slightly positively charged hydrogen.

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4
Q

Define ‘polar’

A

Has 2 poles, one slightly positive and the other slightly negative.

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5
Q

Why is a water molecule polar?

A

Water is a polar molecule because the oxygen atom is more attracted to electrons than hydrogen so it pulls shared electrons towards it. This causes the O to be slight negative and the Hs to be positive. (O is delta negative and Hs are delta positive).

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6
Q

Define the term ‘electronegativity’

A

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons.

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7
Q

Define the term ‘dipole’

A

A dipole is a molecule in which a concentration of positive electric charge is separated from a concentration of negative charge.

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8
Q

List the roles water plays in life

A
  • Solvent transport medium
  • Solvent
  • Habitat
  • Reactant
  • Thermal stability
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9
Q

Explain why the polar nature of water allows it to be a useful solvent

A

It dissolves polar and charged molecules as charges interact with polar water molecules which cluster around them, keeping them apart.

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10
Q

Explain why the polar nature of water allows it to be a useful transport medium.

A

Water remains liquid over a large temperature range as H bonds require lots of energy to break. It also dissolves many molecules.

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11
Q

Explain why the polar nature of water allows it to be a useful coolant

A

Water has a high specific heat capacity as H bonds require lots of energy to break

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12
Q

Explain why the polar nature of water allows it to be a useful habitat.

A
  • Water maintains a constant temp. due to the energy required to break the H bonds (high latent heat of vaporisation).
  • Solid water (ice) is less dense than liquid water which protects species beneath the ice and provides a habitat for animals above ice.
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13
Q

Define ‘hydrophilic’

A

The physical property of a molecule that is attracted to water.

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14
Q

Define ‘hydrophobic’

A

The physical property of a molecule that is repelled by water.

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15
Q

Define ‘cohesion’

A

Water molecules attracted to one another.

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16
Q

Define ‘adhesion’

A

Water molecules attracted to other substances.

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17
Q

Describe any other properties of water (not related to its polar nature) that makes it useful for life.

A

Transparent to light — plants growing under water can get light for photosynthesis and aquatic animals can see underwater.

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18
Q

List 8 examples of how water is used from across the whole diversity of life.

A
  1. Supports — keeping plant cells turgid, the hydrostatic skeletons of earthworms.
  2. Lubrication — Joints such as elbow (synovial joints) have sac of synovial fluid which stops bones rubbing against each other.
  3. Buoyancy — Whales couldn’t be so big etc.
  4. Swimming — When something pushes against water, there is an equal reactive fore propelling forward.
  5. Reactions — Photosynthesis, hydrolysis
  6. High surface tension allows organisms to suspend themselves at/on the surface e.g. pond skaters.
  7. Ice floats as less dense so insulates the water underneath where organisms can survive.
  8. Regulating temperature and reaction conditions etc. — sweating as well as high heat capacity.
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19
Q

Using the ‘polar nature of water’, explain how water can dome above the level of the glass container it is in, the shape of the meniscus in a glass measuring cylinder, and capillary action in a narrow glass tube.

A

Dome: Cohesion between water molecules causing surface tension due to hydrogen bonds.

Meniscus: Adhesion to sides of container draws molecules up.

Capillarity: Cohesion between water molecules and adhesion to other molecules explains why water moves up narrow spaces. Important for water in xylem vessels.

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20
Q

Define ‘monomer’ and ‘polymer’

A

Monomer — Individual molecules that make up a polymer.

Polymer — Long-chain molecules composed of linked (bonded) multiple individual molecules (monomers) in a repeating pattern.

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21
Q

Define ‘macromolecule’

A

Large complex molecules with large molecular masses.

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22
Q

Define ‘dimer’

A

A molecule consisting of two identical molecules linked together.

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23
Q

Define ‘oligomer’

A

A polymer whose molecules consist of relatively few repeating units.

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24
Q

Define ‘condensation reaction’

A

A reaction between two molecules to form a larger molecule and the release of a water molecule (opposite to hydrolysis).

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25
Q

Define ‘hydrolysis’ reaction

A

The breakdown of a molecule into two smaller molecules requiring the addition of a water molecule (opposite to condensation).

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26
Q

Define ‘metabolism’

A

The chemical processes that occur within a living organism in order to maintain life.

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27
Q

Define ‘catabolic reaction’

A

Reactions of metabolism that break molecules down into smaller units. These reactions release energy.

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28
Q

Define ‘anabolic reactions’

A

Reactions of metabolism that construct molecules from smaller units. These reactions require energy from the hydrolysis of ATP.

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29
Q

List the main 4 categories of biological molecules.

A
  • Carbohydrates
  • Lipids
  • Proteins
  • Nucleic acids
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30
Q

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule (and whether it is a polymer), the name of the bonds that links the building blocks together, the name of the reaction that breaks the macromolecules apart, examples of the functions of the molecules and the elements that make up the molecules for carbohydrates.

A
  • Monosaccharides, disaccharides, polysaccharides
  • They are polymers
  • Glycosidic bond
  • Condensations reaction
  • Hydrolysis
  • Respiration, sell signalling, cell wall
  • C, H, O
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31
Q

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule (and whether it is a polymer), the name of the bonds that links the building blocks together, the name of the reaction that breaks the macromolecules apart, examples of the functions of the molecules and the elements that make up the molecules for lipids.

A
  • Fatty acids and glycerol, (monoglyceride, diglyceride) and triglyceride
  • Not a polymer
  • Ester bond
  • Condensation
  • Hydrolysis
  • Source of energy, membrane structure, hormones
  • C, H, O
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32
Q

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule (and whether it is a polymer), the name of the bonds that links the building blocks together, the name of the reaction that breaks the macromolecules apart, examples of the functions of the molecules and the elements that make up the molecules for proteins.

A
  • Amino acids
  • Dipeptide and polypeptide
  • They are polymers
  • Peptide bond
  • Condensation
  • Hydrolysis
  • Transport molecules, enzymes, antibodies
  • C, H, O, N
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33
Q

Summarise the name of the building blocks, the name of the dimer, the name of the macromolecule (and whether it is a polymer), the name of the bonds that links the building blocks together, the name of the reaction that breaks the macromolecules apart, examples of the functions of the molecules and the elements that make up the molecules for nucleic acids.

A
  • Nucleotides, dinucleotide, polynucleotide
  • They are polymers
  • Phosphodiester bond
  • Condensation
  • Hydrolysis
  • Genetic material, protein synthesis
  • C, H, O, N, P
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34
Q

Define ‘single bond’ and ‘double bond’

A

Single bond: A chemical bond in which one pair of electrons is shared between two atoms.

Double bod: A chemical bond in which two pairs of electrons are shared between two atoms.

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35
Q

State the elements present in carbohydrates.

A

C, H, O

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36
Q

State the general formula of carbohydrates.

A

(CH2O)n

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37
Q

Define ‘monosaccharide’, ‘disaccharide’, and ‘polysaccharide’

A

Monosaccharide: A single sugar molecule.

Disaccharide: A molecule comprised of two monosaccharides joined by a glycosidic bond.

Polysaccharide: A polymer made of many sugar monomers (monosaccharides).

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38
Q

Define ‘pentose sugar’ and ‘hexose sugar’

A

Pentose: A monosaccharide composed of 5 carbons.

Hexose: A monosaccharide composed of 6 carbons.

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39
Q

Define ‘triose sugar’ and name an example

A

Triose: Monosaccharide composed of 3 carbons e.g. glyceraldehyde.

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40
Q

Define ‘furanose ring’ and ‘pyranose ring’

A

Furanose ring: 5 membered ring e.g. fructose

Pyranose ring: 6 membered ring e.g. glucose

41
Q

Define ‘isomer’

A

Molecules with the same molecular formulae but different structural formulae (same atoms but arranged differently).

42
Q

Describe the difference between alpha- and beta-glucose.

A

In alpha glucose, the hydroxyl group is attached facing down and away from the main structure, while in the beta glucose, the hydroxyl group is attached above the ring and on the first carbon.

43
Q

Describe the differences between alpha glucose and ribose.

A
  1. Glucose is pyranose but ribose is furanose.
  2. Glucose is used in starch and glycogen, ribose is used in RNA.
44
Q

List 3 examples of disaccharides and for each state which monosaccharides they are composed of.

A
  1. Sucrose — Alpha-glucose and fructose
  2. Maltose — 2 Alpha-glucose
  3. Lactose — Alpha glucose and galactose
45
Q

What is sucrose composed of?

A

Alpha-glucose and fructose

46
Q

What is maltose composed of?

A

2 alpha-glucose

47
Q

What is lactose composed of?

A

Alpha-glucose and galactose

48
Q

State the properties and functions of glucose, fructose, galactose, maltose, sucrose, and lactose. For each also state where they occur.

A
  1. Glucose — Monosaccharide used in respiration and to make polymers such as starch.
  2. Fructose — Hexose sugar commonly found in fruit.
  3. Galactose — Hexose sugar
  4. Maltose — Found in barley
  5. Sucrose — Found in sugar cane and beet
  6. Lactose — Found in milk
49
Q

Explain why alpha-glucose links together to form starch whereas beta-glucose links together to from cellulose.

A
  • It’s due to the arrangement of the hydrogen and hydroxyl groups on carbon 1.
  • The 1-4 glycosidic bonds using alpha mean all the monomers are the same way up, but with beta each is rotated 180 degrees from the last.
50
Q

List two different polysaccharides that make up starch.

A
  • Amylose (1-4 bonds only)
  • Amylopectin (mainly 1-4 but some 1-6)
51
Q

Describe the structure of a cellulose fibre.

A
  • Several cellulose molecules produce a microfibril.
  • Several microfibrils hydrogen bonded together to produce a macro-fibril.
  • Macro-fibrils are laid down in layers to form a cell wall etc.
52
Q

Describe and explain the properties and functions of starch.

A
  • Coils into helix
  • Amylase unbranched and amylopectin branched
  • Compact and insoluble so ideal for storage — food stores in plants.
53
Q

Describe and explain the properties and functions of glycogen.

A
  • More branched than amylopectin
  • Coils into helix
  • Compact and insoluble so ideal for storage — animals and fungi
54
Q

Describe and explain the properties and functions of cellulose.

A
  • Unbranched
  • Does not form helix but forms layers of fibres to give great strength to cell wall.
55
Q

State the elements present in lipids (and the additional element needed to make phospholipids).

A

C, H, O, P

56
Q

State the 3 categories of lipids

A
  1. Triglycerides
  2. Steroids
  3. Phospholipids
57
Q

Explain why saturated triglycerides tend to be solid (fats) at room temp. whereas unsaturated triglycerides tend to be liquid (oils).

A
  • Saturated fatty acids can pack more tightly as they don’t have kinks and therefore have higher melting points than unsaturated fats which are more spread out so melt at a lower temp.
58
Q

State the difference between the triglyceride found in non-fish animals and those in plants/fish.

A

Plant and fish triglycerides tend to be unsaturated whereas other animals fats tend to be saturated.

59
Q

State the property that each end of the phospholipid has.

A
  • Hydrophilic head
  • Fatty acid tails are hydrophobic
60
Q

Describe the difference between a triglyceride and a phospholipid.

A
  • Phospholipids have a phosphate group in place of one of the fatty acids.
61
Q

What bonds holds the building blocks of a triglyceride together?

A

Ester bond

62
Q

Explain how an ester bond is formed between a glycerol and a fatty acid.

A
  • Called esterification
  • Reaction between hydroxyl of glycerol and Carboxyl of fatty acid, expelling water.
63
Q

State the number of water molecules produced in the production of one triglyceride.

A

3

64
Q

State the products of digestion or a triglyceride (include partial digestion) and state what would happen to the pH of the solution (and why).

A
  • Produces fatty acids and glycerol or partially only removes some of the fatty acids to produce a monoglyceride etc.
  • Due to fatty acids, pH would decrease and become more acidic.
65
Q

What are triglycerides composed of?

A

Three fatty acids linked by one glycerol molecule.

66
Q

Describe the structure of sterols/cholesterol.

A
  • Base nucleus of 4 connected organic rings.
  • They differ from each other due to different side groups.
67
Q

List 5 functions of triglycerides.

A
  1. Energy store
  2. Thermal insulation
  3. Cushioning for internal organs
  4. Buoyancy
  5. Waterproofing
68
Q

List 2 functions of phospholipids.

A
  1. Membranes
  2. Myelin sheaths
69
Q

List 2 functions of cholesterol.

A
  1. Membranes
  2. Hormones (made by adding different side groups).
70
Q

Explain why triglycerides store more energy per gram than carbohydrate.

A
  • They require more oxidation to be broken down into CO2 and O2 so release more energy (although it takes much longer).
71
Q

Explain how phospholipids form a membrane.

A
  • Phospholipid bilayer
  • Two layers with the hydrophobic fatty acid tails sandwiched on the inside and the hydrophilic heads on the outside.
72
Q

Describe how the presence of cholesterol affects the properties of cell membranes.

A

Regulates membrane fluidity.

73
Q

How many amino acids occur in life?

A

20

74
Q

Describe the difference types of amino acids in life.

A
  1. Non-polar hydrophobic
  2. Polar hydrophilic
  3. Polar hydrophilic basic (positively charged)
  4. Polar hydrophilic acidic (negatively charged)
75
Q

Explain how the variety of amino acids lead to a wide range of dipeptides and very quickly lead to an incredible variety of polypeptide chains.

A
  • 20 amino acids and therefore 400 dipeptides as the order does change the molecule.
  • There are 20^w3 tripeptides and so give rise to incredible variation in polypeptides.
76
Q

Define ‘polypeptide chain’

A

Chain of thee or more amino acids

77
Q

Define ‘protein’

A

One or more polypeptides arranged as a macromolecule.

78
Q

Describe how one end of a polypeptide chain differs from the other end.

A
  • One end is the C terminal which the Carboxyl end.
  • The other is the N terminal, the amine group.
79
Q

Describe the ‘primary structure’ of a protein and how it is held together.

A
  • The number and sequence of amino acids in a polypeptide is its primary structure.
  • Each amino acid is bonded to the next by peptide bonds.
80
Q

Define ‘secondary structure’ of a protein, describe two different types and how the secondary structure is held in place.

A
  • All or part of primary structure may fold into a secondary structure and most commonly they are alpha-helix or beta-pleated sheets.
  • To produce on of these, there must be a regular repeating pattern of amino acids.
  • The structures are held together by hydrogen bonds between N-H groups and C=Os.
81
Q

Define ‘tertiary structure’ of a protein and how it’s held in place.

A
  • The compact 3D shape adopted by most polypeptides.
  • These molecules are called globular.
  • The R groups form the bonds that hold the structure in place.
82
Q

What are the different bonds that can form between the R groups in a tertiary protein?

A
  1. Hydrogen bonds — Form between slightly charged R groups.
  2. Ionic bonds — Form between R groups carrying opposite charges.
  3. Disulphide bonds/bridges — Form between the sulphur containing R groups of two cysteine amino acids - strong covalent bond.
  4. Hydrophobic interactions — Proteins folds so that hydrophobic R groups lie in centre of the molecule away from the aqueous environment.
83
Q

Explain how the primary structure of a protein determines its tertiary structure.

A
  • Tertiary structure depends on the R groups and therefore which amino acids are present, and in which order it is is highly dependant on primary structure.
84
Q

Define ‘quaternary structure’ of a protein, and describe how it’s held in place.

A
  • A protein with a quaternary structure contains two or more polypeptide chains bonded together which have no function on their own, and only form a functional molecule when bonded.
85
Q

What are the bonds that hold together quaternary proteins?

A
  1. Hydrogen bonds
  2. Ionic bonds
  3. Disulphide bridges
  4. Hydrophobic interactions
86
Q

Define ‘globular protein’ and ‘fibrous protein’

A

Globular protein: Spherical, water soluble proteins

Fibrous protein: Long, insoluble, structural proteins

87
Q

Define ‘prosthetic group’ and ‘conjugated protein’

A

Prosthetic group: Non-protein component of a conjugated protein.

Conjugated protein: A protein that is joined to a non-protein group (prosthetic group).

Both parties are needed to function.

88
Q

Describe an example of a conjugated protein. Identify key structural components, properties, and functions.

A

Haemoglobin: Each of the four polypeptide chains is bonded to a haem group. It carries oxygen.

89
Q

Describe an example of an enzyme. Identify key structural components, properties, and functions.

A

Catalase: Quaternary protein with 4 haem groups. The presence of iron II ions allow it to catalyse break down of hydrogen peroxide which is a harmful waste product of metabolism.

90
Q

Describe an example of a peptide hormone. Identify key structural components, properties, and functions.

A

Antidiuretic hormone: Regulates the body’s retention of water by increasing water absorbing of kidney’s collection duct.

91
Q

Give 3 examples of fibrous proteins.

A
  1. Keratin
  2. Elastin
  3. Collagen
92
Q

Describe the structure, properties, location, and functions of collagen.

A
  • Polypeptides wound together to form a rope like structure.
  • Connective tissue found in skin, tendons, ligaments and the nervous system.
93
Q

Describe the structure, properties, location, and functions of keratin.

A
  • Many sulphur containing amino acids mans many disulphide bridges which make it very strong.
  • Less flexible
  • Hair, skin, and nails
94
Q

Describe the structure, properties, location, and functions of elastin.

A
  • Made by linking many soluble tropelastin protein molecules which act as little springs together to form an insoluble macromolecule.
  • Found in elastic fibres in blood vessels and alveoli which allow them to expand and return to normal as needed.
95
Q

Describe the structure, properties, location, and functions of globular proteins.

A
  • Spherical
  • Water soluble due to folding so that the hydrophobic regions are inside, and the hydrophilic regions are on the outside.
96
Q

Describe the structure, properties, location, and functions of fibrous proteins.

A
  • Long, strong, and insoluble molecules.
  • Tend to contain a limited range of amino acid with small R groups.
  • Arranged in a pretty regular pattern containing many hydrophobic amino acids.
97
Q

Define ‘inorganic’

A

Relating to or denoting compounds which aren’t organic (broadly, compounds not containing carbon).

98
Q

Define ‘cation’

A

Positive ion

99
Q

Define ‘anion’

A

Negative ion

Biology (25 decks)

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