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Biological Molecules Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Macronutrient

A

Organic compounds required in large amounts
- Proteins
- Lipids
- Carbohydrates

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2
Q

Protein

A

An organic macromolecule essential to life.
Formed from one or more polypeptides

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3
Q

Enzymes

A

Globular proteins that act as biological catalysts to increase the rate of reactions

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4
Q

Uses of protein

A

Enzymes which catalyse chemical reactions
- Forming muscle, bone and other structural features
- Emergency energy source

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5
Q

Elements in protein

A
  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Other elements like iron and sulphur
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6
Q

Condensation reaction

A

When 2 molecules join together, with water as a byproduct

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7
Q

Hydrolysis reaction

A

When 2 molecules break apart when water is added

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8
Q

Bonding of protein

A
  • Peptide bonds between amino acids
  • Regular covalent bonds within the amino acid
  • Ionic, hydrogen, disulfide, or hydrophobic bonds on secondary and tertiary levels
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9
Q

Hydrogen bond

A

A weak interaction between a negative ion and a positive hydrogen atom

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10
Q

Covalent bond

A

A strong interaction resulting in the sharing of electrons in the outer shell.
E.g. disulfide, phosphodiester, peptide, glycosidic

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11
Q

Cyclic form

A

The shape formed by a molecule where the final atom is attached to the first

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12
Q

Straight line form

A

The shape formed by a molecule where all the atoms are in a line

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13
Q

Amino acid

A

A monomer of proteins with 20 different types
- Amphoteric and a buffer
- Composed of the same basic structure, but with a unique R group

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14
Q

Amphoteric

A

A compound that is able to react with both bases and acids.
E.g. Amino acids, water, hydrogen carbonate ions

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15
Q

Peptide bond

A

A strong chemical bond between two amino acids, formed through a condensation reaction.
- When aqueous, the amino group goes from NH₂ to NH₃⁺ (+H⁺)
- The Carboxyl group goes from COOH to COO⁻ (-H⁺)
- The carboxyl and amino acids then bind, with water as a byproduct

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16
Q

Amino acid structure

A
  • Hydrogen group
  • Amino group
  • Carboxyl group
  • R group / side chain
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17
Q

Carboxyl group

A
  • COOH
  • Acidic
  • Found in single bonded monosaccharides
  • Found in amino acids
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18
Q

Dipeptide

A

Two amino acids that have combined together with a condensation reaction between the amino and carboxyl groups, resulting in the release of water

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19
Q

Polypeptide

A

A chain of multiple amino acids

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20
Q

Primary structure

A

The order of amino acids in a protein.
Has peptide bonds between amino and carboxyl groups

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21
Q

Secondary structure

A

When chains of amino acids coil or fold
36 amino acids per 10 turns
- Two different types: α-helix, β-pleated sheet
- Lots of hydrogen bonds between -NH group and -CO group further down the chain
- Stable at optimal temperatures

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22
Q

Alpha helix

A

A form of secondary structure of amino acids where the amino acids that bind are 4 places apart. Resulting in a twirl shape

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23
Q

Beta pleated shee

A

A form of secondary structure where a zig-zag structure is formed as the chains folds over itself

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24
Q

Tertiary structure

A

When coiled chains of amino acids are folded into precise shapes, usually either supercoiled or spherical.
Mostly exhibited in globular proteins, with fibrous proteins often stopping at secondary structure
- Variety of bonds, including ionic, hydrogen,hydrophilic, hydrophobic, disulfide

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25
Q

Ionic bonds

A

Bonds formed between oppositely charged groups on amino acids. Formed in tertiary structures

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26
Q

Disulfide bonds

A

A bond between the sulfide components of the R-group of cysteines.
A form of strong covalent bonds

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27
Q

Quaternary structure

A

A combination of multiple polypeptide chains.
Almost exclusively found in globular proteins

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28
Q

Fibrous proteins

A

A form of tertiary structure of proteins where the chains of amino acids are arranged in long patterns.
Usually insoluble in water

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29
Q

Examples of fibrous proteins

A
  • Keratin
  • Collagen
  • Elastin
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29
Q
A
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30
Q

Collagen

A

A fibrous protein where every 3rd amino acid is glycine, giving strength due to the small size of glycine.
- Composed of 3 chains of around 1000 amino acids each. Bonded with hydrogen bonds
- Structural protein that gives strength to skin, bones, tendons and forms cartilage.
- Found in artery walls, bones, and connective tissue

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31
Q

Keratin

A

A fibrous protein rich in cysteine, with lots of disulfide bridges
- Strong, waterproof, barrier
- Found in hair, nails, claws, hoofs

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32
Q

Elastin

A

A fibrous protein with many cross-links and coils to give strength and elasticity
- Found in skin, lungs, bladder, blood vessels

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33
Q

Globular protein

A

A protein of a roughly spherical shape.
- Hydrophobic parts are towards the centre, and hydrophilic towards the surface, making the protein water soluble.
- Often have very specific shapes

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34
Q

Examples of globular proteins

A
  • Haemoglobin
  • Insulin
  • Pepsin
  • Most enzymes
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35
Q

Conjugated protein

A

A protein to which another chemical is attached
E.g. glycoprotein, lipoprotein

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36
Q

Haemoglobin

A

A globular protein formed from 2 alpha and 2 beta chains, each with a haem group attached.
- Held together in a specific shape

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37
Q

Insulin

A

A globular protein made of 2 polypeptide chains, with both alpha and beta folding
- Soluble to water
- Increases the uptake of glucose in the liver

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38
Q

Pepsin

A

A globular protein made up of a single polypeptide chain of 327 amino acids
- Able to work in acidic conditions due to the high proportion of acidic R groups compared to basic R groups
- Breakdowns enzymes in the stomach

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39
Q

ab

A
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40
Q

com

A
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41
Q

Biuret test

A

A qualitative test for proteins

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42
Q

Carbohydrate

A

A compound made of carbon, hydrogen and oxygen. Also a form of macronutrient that is the primary energy source for humans

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43
Q

Elements in carbohydrates

A
  • Carbon
  • Oxygen
  • Hydrogen
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44
Q

Uses of carbohydrates

A
  • Primary energy source of humans
  • Structural units
  • Energy store
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45
Q

Bonding in carbohydrates

A
  • Glycosidic bonds between monosaccharides
  • Hydrogen bonds between carbon and hydrogen
46
Q

Sugar

A

Small, water soluble carbohydrates that taste sweet. Either monosaccharides or disaccharide

47
Q

Monosaccharide

A

A singular sugar molecule that forms the basis for polysaccharides

48
Q

Examples of monosaccharides

A
  • Glucose (C₆H₁₂O₆)
  • Fructose (C₆H₁₂O₆)
  • Galactose (C₆H₁₂O₆)
  • Ribose (C₅H₁₀O₅)
  • Deoxyribose (C₅H₁₀O₄)
49
Q

Isomer

A

A compound with the same formula but different structure

50
Q

Alpha glucose

A

A hexose sugar that’s a form of glucose where the
-OH molecule is on the bottom.
C₆H₁₂O₆
Energy source, component of glycogen and starch
- Large portion of bonds broken during respiration
- OH groups forms hydrogen bonds, making it water soluble

51
Q

Beta glucose

A

A hexose sugar that’s a form of glucose where the
-OH molecule is on the top
C₆H₁₂O₆
Energy source, component of cellulose
- Forms hydrogen bonds with other identical molecules to become insoluble
- Alternate shape gives chains strength and prevents spiralling

52
Q

Ribose

A

A pentose sugar that’s a component of RNA, ATP and NAD
C₅H₁₀O₅

53
Q

Deoxyribose

A

A pentose sugar that’s a component of DNA
C₅H₁₀O₄

54
Q

Disaccharide

A

A form of sugar that is formed when two monosaccharides undergo a condensation reaction, producing a water by-product

  • Cellobiose (β glucose + β glucose)
  • Maltose (α glucose + α glucose)
  • Lactose (α glucose + galactose)
  • Sucrose (α glucose + fructose)
55
Q

Cellobiose

A

Disaccharide formed from 2 β-glucose monomers.
Used as an indicator for Crohn’s disease

56
Q

Maltose

A

Disaccharide formed from 2 α-glucose monomers.
Has 1-4 glycosidic bond
Formation triggers germination

57
Q

Lactose

A

Disaccharide formed from α-glucose and galactose monomers.
Provides energy for infant mammals
- Fed to infant mammals to provide gradual release of monosaccharides

58
Q

Sucrose

A

Disaccharide formed from α-glucose and fructose monomers.
Produced by photosynthesis
Primary sugar in plants

59
Q

Polysaccharide

A

A carbohydrate polymer formed by more than two monosaccharides

60
Q

Homopolysaccharide

A

A polysaccharide made up of all the same type of monosaccharide monomer
E.g. cellulose, starch, glycogen, amylose

61
Q

Advantages of polysaccharides as energy stores

A
  • Compact
  • Easily ‘snipped off’ when monosaccharides are required for respiration
  • Branching allows for quick release of lots of energy
  • Less water soluble than monosaccharides, preventing cytolysis
62
Q

Glycosidic bond

A

A type of covalent bond formed by a condensation reaction between two monosaccharides

63
Q

Amylose

A

A single long chain of α-glucose with 1-4 glycosidic bonds.
– Hydrogen bonds between units to form coil
- Not water soluble due to hydroxyl groups on carbon 2 situated inside the coil
- Multiple chains make up starch

64
Q

Amylopectin

A

A single long chain of α-glucose with 1-4 glycosidic bonds, with other chains coming off it with 1-6 glycosidic bonds
- Coiled into a spiral shape, with branches coming off it

65
Q

Cellulose

A

A form of polysaccharide made from β-glucose’ with 1-4 glycosidic bonds.
- Forms long and straight molecules.
- Hydrogen bonds between bundles
- Not water soluble
- Forms cell walls in plant cells
- Difficult to digest
- High tensile strength

66
Q

Glycogen

A

A form of polysaccharide made from α-glucose with 1-4 glycosidic bonds; with other chains coming off it with 1-6 glycosidic bonds.
- Shorter branches than amylopectin, but with more branches
- Some hydrogen bonds in between units
- Not water soluble

67
Q

Starch

A

A polysaccharide used for storing glucose in plants
(C₆H₁₂O₅)ₙ

68
Q

Features of plant cell walls

A
  • Enough strength to support the whole plant
  • Space for flow of water and ions
  • Permeable
  • High tensile strength
  • Able to be reinforced by other substances
69
Q

Peptidoglycan

A

A polysaccharide that forms the basis of bacterial cell walls

70
Q

Reducing sugar

A

All monosaccharides and some disaccharides
- Can give electrons to other molecules
- Can be tested for with Benedict’s reagent

71
Q

Non-reducing sugar

A

Cannot be easily oxidised
- A sugar that accepts electrons from other chemicals
- Made up of ‘reducing groups’ i.e. can be broken down into reducing sugars
- Usually more more complex disaccharides E.g. sucrose

72
Q

Benedict’s test

A

A semi-qualitative test for reducing and non-reducing sugars

73
Q

Reagent strips

A

Qualitative test for reducing sugars (used as urine test for glucose)

74
Q

Iodine test

A

Qualitative test for starch

75
Q

Lipid

A

A molecule formed from fatty acids and glycerol.
Includes triglycerides, phospholipids, glycolipids, and cholesterol

76
Q

Elements in lipids

A
  • Carbon
  • Hydrogen
  • Oxygen
  • Sometimes phosphorus, nitrogen, sulphur, etc
77
Q

Uses of lipids

A

Energy store / source
- Insulation and protection
- Source of nutrients
- Cell membranes
- Buoyancy

78
Q

Energy store / source
- Insulation and protection
- Source of nutrients
- Cell membranes
- Buoyancy

A

The alcohol group in glycerol and the carboxyl group in fatty acids bond to form the lipid, known as ester bonds
- Hydrogen bonds between carbons

79
Q

Triglyceride

A

Triglyceride
A lipid formed from three fatty acids bonded to a glycerol molecule.
Bonded through esterification
Unsaturated versions are liquid, saturated versions are solid
- Insoluble in water

80
Q

Esterification

A

The condensation reaction between an alcohol group and carboxyl group, resulting in an ester.
A water molecule is also released

81
Q

Glycerol

A

A type of alcohol with three carbon atoms. It forms the basis of most lipids
- Has 3 free -OH groups, for fatty acids to attach to
- Water soluble

82
Q

Fatty acids

A

A carboxyl group attached to a hydrocarbon tail.
2-20 carbons long
- Ionises to release H⁺, making it an acid

83
Q

Saturated fatty acids

A

Fatty acids that contain the maximum amount of hydrogen atoms as possible (only C-C single bonds)
- High melting point, solid at room temp
- No double bonds in hydrocarbon
- Straight hydrocarbon chains
- Increases risk of heart disease

84
Q

Unsaturated fatty acids

A

Fatty acids that do not contain the maximum amount of hydrogen atoms (contains C=C double bonds).
- Kink in the structure makes it more fluid
- Low melting point, liquid at room temp
- One or more double bonds in hydrocarbon
- Kink in hydrocarbon chains
- Doesn’t increase risk of heart disease

85
Q

Polyunsaturated fatty acids

A

Fatty acids that do not contain the maximum amount of hydrogen atoms (contains multiple C=C double bonds).

86
Q

Condensation reactions in triglycerides

A
  • Glycerol and 3 fatty acids join
  • Releases 3H₂O
  • Creates 3 ester bonds
87
Q

Hydrolysis reactions in triglycerides

A
  • Molecule breaks apart
  • Requires 3H₂O
  • Breaks 3 ester bonds
88
Q

Phospholipids

A

A form of lipid that consists of glycerol, two fatty acids (1 saturated, 1 unsaturated) and a phosphate group.
- Hydrocarbon tails are usually 16-18 carbons long
- Cell membranes are formed from a double layer of this
- Amphipathic: hydrophobic tail, hydrophilic head
- Forms micelles when submerged in water
- Insoluble in water

89
Q

Amphipathic

A

A molecule with both hydrophobic and hydrophilic parts

90
Q

Micelles

A

Tiny balls of phospholipids with the tails in the centre, and the heads sticking out

91
Q

Phospholipid bilayer

A

A dual layer of phospholipids with the tails facing towards each other, and the heads facing away
Forms the backbone of cell membranes
- Selectively permeable, only small non-polar molecules can pass through

92
Q

Cholesterol

A

A type of lipid sterol (steroid alcohol).
Consists of 4 carbon-rings called isoprene units
- Small and hydrophobic, it often sits between the phospholipids of a membrane, giving stability, preventing it from becoming too stiff or fluid.
- Mainly made in the liver
- Insoluble in water

93
Q

Uses of cholesterol

A
  • Membranes
  • Makes up oestrogen
  • Makes up testosterone
  • Makes up Vitamin D
94
Q

Emulsion test

A

Qualitative test for lipids

95
Q

Inorganic ion

A

A charged molecule that is not carbon based but still essential to bodily functions
- Cations or anions

96
Q

Cation

A

A positively charged ion (less electrons)
- Ca²⁺
- Na⁺
- K⁺
- H⁺
- NH₄⁺

97
Q

Anion

A

A negatively charged ion (more electrons)
- NO₃⁻
- HCO₃⁻
- Cl⁻
- PO₄³⁻
- OH⁻

98
Q

Calcium

A

Essential cation
- Increases rigidity of bone, teeth and cartilage
- Component on exoskeleton of crustaceans
- Enzyme activator
- Stimulates muscle contraction
- Regulates nerve transmission
- Regulates membrane permeability
- Cell wall development
- Triggers exocytosis
- Moves vesicles to the cell membrane

99
Q

Sodium

A

Essential cation
- Osmotic pressure regulation
- Water level regulation
- Buffer
- Carbohydrate absorption
- Muscle contraction
- Maintains turgidity in plants
- Nerve transmission

100
Q

Potassium

A

Essential cation
- Control of water levels
- Active transport
- Protein and glycogen synthesis
- Flower and leaf health
- Nerve transmission
- Muscle contraction
- Turgidity in plants

101
Q

Ammonium and nitrate

A

Essential ions, one cation and one anion
NH₄⁺ and NO₃⁻
- Component of amino acids, vitamins, chlorophyll
- Component of protein-based hormones
- Essential in nucleic acids
- Buffer
- Component of nitrogen cycle

102
Q

Hydrogencarbonate

A

Essential ion
HCO₃⁻
- Buffer
- Transport of carbon dioxide

103
Q

Chloride

A

Essential ion
- Production of urine
- Transport of carbon dioxide
- Haemoglobin regulation
- Buffer
- Production of HCl

104
Q

Phosphate

A

Essential ion
PO₄³⁻
- Bone, teeth and cartilage regulation
- Component of exoskeletons in crustaceans
- Buffer
- Root growth in plants
- ATP

105
Q

Uses of water

A
  • Solvent
  • Transport medium
  • Reactant in metabolic reactions
  • Maintain turgidity of cells
  • Lubricant
  • Soften skin
  • Cushion joints
  • Adhesion / cohesion
106
Q

Cohesion

A

Attraction of 2 molecules of the same type

107
Q

Adhesion

A

Attraction of 2 molecules of different types

108
Q

Specific heat capacity

A

The amount of energy needed to raise the temperature of 1kg of a substance by 1°c

109
Q

Properties of water

A
  • Polar
  • High specific heat capacity
  • Solvent
  • Unique density (solid < liquid)
  • Forms surface tension
  • Cohesiveness in xylem
  • Resists changes in heat
110
Q

Density of water

A

Due to the structure of water molecules, ice is less dense than liquid water. This means that ice floats on top of water.
- This provides stable aqueous environments
- Bodies of water become insulated by the layer of ice

111
Q

Solvency of water

A

The polarity of water attracts both positive and negative parts of solutes, increasing the range of molecules it can dissolve.
- This allows molecules and ions to react within water
- Means water can act as a transport medium
- Means water can act as a medium for metabolic reactions
- Allows water to dilute toxic substances
- Allows separation of ionic compounds
- Means organisms can take in minerals / ions / gas / food

112
Q

Cohesiveness of water

A

Hydrogen bonds keep the molecules together, increasing their attractiveness to each other, rather than other molecules like air
- Creates surface tension
- Chains of water molecules can move up xylem vessels in plants
- Allows some insects to walk on water

113
Q

Stable temperature of water

A

High specific heat capacity (4.2kJ/kg) creates a stable environment for life, both aqueous and not

High Latent heat allows water to stabilise temperatures and cool things down
- Useful in temperature regulation systems

Biology (18 decks)

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