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Biology > 2.1.2 - BIOLOGICAL MOLECULES > Flashcards

2.1.2 - BIOLOGICAL MOLECULES Flashcards

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1
Q

What is a monomer?

A

Monomers are small units which are components of larger molecules (e.g. monosaccharides, amino acids and nucleotides)

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2
Q

What is a polymer?

A

Molecules made from monomers joined together

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3
Q

What is a condensation reaction?

A

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

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4
Q

What is a hydrolysis reaction?

A

The opposite of condensation and it’s when water is added to break a chemical bond between two molecules

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5
Q

What are the properties/functions of water?

A
  • Water is a reactant in many chemical reactions, including hydrolysis reactions
  • Water is a solvent: some substances dissolve in it
  • Water transports substances: can transport glucose + oxygen around an organism
  • Water helps with temperature control: high specific heat capacity + high latent heat of vaporisation
  • Water is a habitat: helps with temp. control, is a solvent and becomes ice when it freezes (means organisms can live in it)
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6
Q

Describe the structure of water.

A
  • A molecule of water is one atom of oxygen (O) joined to two atoms of hydrogen (H) by shared electrons
  • Shared negative H electrons are pulled toward O atom so other side of each hydrogen atom is left with a slight positive charge
  • The unshared negative electrons on the O atom give a slight negative charge
  • This makes it a polar molecule — has a partial negative charge on one side and a partial positive charge on the other
  • Slightly negative oxygen atoms attract slightly positive hydrogen atoms from other water molecules
  • This attraction is called hydrogen bonding
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7
Q

What is Specific Heat Capacity?

A

The energy required to raise the temperature of 1 gram of a substance by 1 degree Celsius

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8
Q

What is Latent Heat of Evaporation?

A

The amount of energy required to turn 1g of liquid water into steam

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9
Q

How does water’s polarity benefit it?

A
  • Makes it very cohesive: attraction between molecules of the same type (e.g. 2 water molecules)
  • Makes it a good solvent: many important substance sin biological reactions are ionic (meanings they are made from one positively atom or molecule and on negatively charged atom or molecules
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10
Q

What molecules do carbohydrates consist of?

A
  • Carbon
  • Hydrogen
  • Oxygen
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11
Q

What are the monomers that make up carbohydrates called?

A

Monosaccharides

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12
Q

What is glucose (in terms of structure)?

A

Made up of SIX carbon atoms (HEXOSE MONOSACCHARIDE)

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13
Q

What is ribose (in terms of structure)?

A

Made up of FIVE carbon atoms (PENTOSE MONOSACCHARIDE)

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14
Q

What is glucose (in terms of function)?

A
  • Main substrate for respiration
  • Made up of two isomers: α-glucose and β-glucose
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15
Q

Name three monosaccharides.

A
  • Glucose
  • Galactose
  • Fructose
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16
Q

Name three disaccharides.

A
  • Maltose
  • Lactose
  • Sucrose
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17
Q

What is the word equation for Maltose?

A

Glucose + Glucose ⇌ Maltose

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18
Q

What is the word equation for Lactose?

A

Glucose + Galactose ⇌ Lactose

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19
Q

What is the word equation for Sucrose?

A

Glucose + Fructose ⇌ Sucrose

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20
Q

What is a glycosidic bond?

A

Bonds between monosaccharides that make disaccharides or polysaccharides
Formed in condensation reactions

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21
Q

Name three polysaccharides.

A
  • Cellulose
  • Starch
  • Glycogen
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22
Q

What is Amylose?

A
  • Unbranched chain of α-glucose molecules
  • Joined by 1,4 glycosidic bonds (COILED + COMPACT)
  • ∴ can store a lot of energy
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23
Q

What is Amylopectin?

A
  • Branched chain of α-glucose molecules
  • Joined by 1,4 and 1,6 glycosidic bonds
  • Side branches mean enzymes can digest easily + energy release quickly
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24
Q

What is starch?

A

Starch stores energy in plants + is made of polysaccharides Amylose + Amylopectin
- Insoluble in water

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25
Q

What is glycogen?

A

Main energy storage molecule in animals

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26
Q

Describe the structure of glycogen

A
  • Formed by many α-glucose molecules
  • Joined by 1,4 + 1,6 glycosidic bonds
  • Large number of branches –> glucose + energy released quickly
  • Large but compact –> maximises amount of energy stored
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27
Q

What is cellulose?

A

Component of cell walls in plants

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28
Q

Describe the structure of cellulose.

A
  • Composed of long, unbranched chains of β-glucose joined by glycosidic bonds
  • Cellulose chains linked by hydrogen bonds to form strong fibres (microfibrils)
  • Microfibrils mean cellulose provides structural support for cells
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29
Q

Describe how glycosidic bonds are formed and broken in living organisms.

A
  • During synthesis, a hydrogen atom on one monosaccharide bonds to a hydroxyl (OH) group on the other monosaccharide, releasing a water molecule (CONDENSATION REACTION)
  • A water molecule reacts with the glycosidic bond, breaking it apart (HYDROLYSIS REACTION)
30
Q

What molecules do lipids consist of?

A
  • Carbon
  • Hydrogen
  • Oxygen
31
Q

What are lipids?

A

Molecules that are only soluble in organic solvents (e.g. alcohol)

32
Q

What are the two types of lipids/fatty acids?

A
  • Saturated
  • Unsaturated
33
Q

What is a saturated fatty acid?

A
  • No double bonds between carbon atoms
  • Saturated with hydrogen
34
Q

What is an unsaturated fatty acid?

A
  • At least one double bond between carbon atoms (causing chain to kink)
  • Melt at lower temperatures than saturated fatty acids
35
Q

What are triglycerides?

A
  • Macromolecules - complex molecules with a relatively large molecular mass
  • Non-polar, hydrophobic molecules
36
Q

Describe the structure of a triglyceride

A
  • One glycerol molecule + Three fatty acids
  • Fatty acids have hydrophobic tail and hydrophilic head
37
Q

What are phospholipids?

A
  • A type of lipid, formed from the monomers glycerol and fatty acids
  • Found in the cell membranes of all eukaryotes and prokaryotes (makes up PHOSPHOLIPID BILAYER)
    ^–Cell membranes control what enters and leaves a cell
38
Q

Describe the structure of a phospholipid.

A
  • One glycerol molecule + Two fatty acids + One phosphate head
  • As the phosphate is polar it is soluble in water (hydrophilic)
  • The fatty acid ‘tails’ are non-polar and therefore insoluble in water (hydrophobic)
39
Q

How are triglycerides formed?

A

Ester bonds

40
Q

What is an ester bond?

A
  • Triglycerides are formed by esterification
  • Ester bonds formed when a hydroxyl group from the glycerol bonds with the carboxyl group of the fatty acid
  • Ester bond formation is a condensation reaction
  • In forming a triglyceride, three water molecules are released
41
Q

What are the functions of a triglyceride?

A
  • Energy storage
  • Insulation
  • Buoyancy
  • Protection
42
Q

Explain buoyancy as a function of triglycerides.

A

The low density of fat tissue increases the ability of animals to float more easily

43
Q

Explain insulation as a function of triglycerides.

A
  • Triglycerides are part of the composition of the myelin sheath that surrounds nerve fibres
  • The myelin sheath provides insulation which increases the speed of transmission of nerve impulses
  • Triglycerides compose part of the adipose tissue layer below the skin which acts as insulation against heat loss (e.g. blubber of whales)
44
Q

Explain protection as a function of triglycerides.

A

The adipose tissue in mammals contains stored triglycerides and this tissue helps protect organs from the risk of damage

45
Q

What is an ion?

A

An atom (or group of atoms) that has an electric charge
- Cation: Positive charge
- Anion: Negative charge

46
Q

What is an inorganic ion?

A
  • An ion that doesn’t contain carbon (but there are a few exceptions)
  • Important in biological processes
47
Q

Name the essential ions, their chemical symbols, and the type of ion they are.

A

CATION | ANION
- Calcium - Ca²⁺
- Sodium - Na⁺
- Potassium - K⁺
- Hydrogen - H⁺
- Ammonium - NH₄⁺

  • Nitrate - NO₃⁻
  • Hydrogencarbonate - HCO₃⁻
  • Chloride - Cl⁻
  • Phosphate - PO₄³⁻
  • Hydroxide - OH⁻
48
Q

What molecules do proteins consist of?

A
  • Carbon
  • Hydrogen
  • Oxygen
  • Nitrogen
  • Sulfur
49
Q

What are the monomers in proteins?

A

Amino acids

50
Q

What are the polymers in proteins?

A
  • Dipeptides (two amino acids join together)
  • Polypeptides (more than two amino acids join together)
  • Proteins are made of one or more polypeptides
51
Q

Name the four levels of a protein’s structure.

A
  • Primary Structure
  • Secondary Structure
  • Tertiary Structure
  • Quaternary Structure
52
Q

How many amino acids are found in proteins in living organisms?

A

There are 20 common to living organisms

53
Q

What is the name of the bonds that join amino acids together?

A
  • Peptide bonds
  • This is a condensation reaction, releasing water
54
Q

Explain the primary structure of a protein.

A
  • The sequence and number of amino acids in a protein/polypeptide chain
  • Different proteins have different sequences of amino acids in their primary structure
55
Q

Explain the secondary structure of a protein.

A
  • The polypeptide chain doesn’t remain straight
  • Hydrogen bonds formed between nearby amino acids
  • It either coils into an α helix or folds into a β-pleated sheet
56
Q

Explain the tertiary structure of a protein.

A
  • Coiled or folded chain of amino acids often further coils or folds
  • More bonds form
  • This is the final 3D structure for proteins made from a single polypeptide chain
57
Q

Explain the quaternary structure of a protein.

A
  • Some proteins are made from multiple polypeptide chains held together by bonds
  • The quaternary structure is the way these polypeptide chains are held together (e.g. haemoglobin is made of four polypeptide chains, bonded together)
  • This structure is the final 3D structure for proteins made from multiple polypeptide chains
58
Q

What bonds hold together the different levels of the proteins structures?

A
  • Primary structure: Peptide bonds
  • Secondary structure: Hydrogen bonds
  • Tertiary structure: Ionic bonds, Disulfide bonds, Hydrophobic and Hydrophilic interactions, Hydrogen bonds
  • Quaternary structure: Determined by the tertiary structure
59
Q

Describe the structure of a globular protein.

A
  • compact, roughly spherical (circular) in shape and soluble in water
  • non-polar hydrophobic R groups are orientated towards the centre of the protein away from the aqueous surroundings
  • their polar hydrophilic R groups orientate themselves on the outside of the protein
  • orientation causes solubility as H₂O molecules can surround the polar hydrophilic R groups
  • irregular and wide range of R groups in amino acid sequence
  • physiological and functional in function
60
Q

Describe the structure of a fibrous protein

A
  • Long strands of polypeptide chains that have cross-linkages due to hydrogen bonds
  • These proteins have little or no tertiary structure
  • Insoluble and strong. structural in their functions
  • Large no. of hydrophobic R groups, so insoluble
  • Repetitive amino acid sequence with a limited range of R groups
61
Q

State three examples of globular proteins and explain them.

A
  • Haemoglobin - Carries oxygen around the body in red blood cells. CONJUGATED PROTEIN. The 4 polypeptide chains have a prosthetic group called a haem (contains iron which oxygen binds to)
  • Insulin - Hormone secreted by pancreas. Helps regulate blood glucose level. SOLUBLE so can be transported in blood
  • Amylase - Enzyme that catalyses breakdown of starch in the digestive system. Made of single amino acid chain. Secondary structure contains α helix + β-pleated sheet
62
Q

State three examples of fibrous proteins and explain them.

A
  • Collagen - found in animal connective tissues (e.g. bones, skin + muscle). Very strong. Molecules can bind to it to increase rigidity (e.g. bone)
  • Keratin - found in many external structures of animals (e.g. skin, hair, nails, feathers + horns). Can be flexible (skin) or tough (nails)
  • Elastin - found in elastic connective tissue (e.g. skin, large blood vessels + some ligaments). Elastic, so allows tissue to return to original shape
63
Q

What is a reducing sugar?

A

Can donate electrons (carboxyl group becomes oxidised), the sugars become the reducing agent

64
Q

What is a non-reducing sugar?

A

Cannot donate electrons - cannot be oxidised

e.g. Sucrose

65
Q

Describe the structure of cholesterol

A

Has hydrophobic and hydrophilic regions

66
Q

What are the functions of cholesterol?

A
  • Synthesised in the liver and transported via blood
  • Affects fluidity and permeability in the cell membrane
  • Disrupts close packing of cells membrane - increases rigidity (makes membrane less flexible)
  • Barrier - prevents water soluble substances from diffusing across the membrane
  • Used to produces steroid-based hormones (oestrogen, testosterone, progesterone)
67
Q

Describe the structure of an amino acid

A

C atom bonded to:

  • amine group - NH₂
  • carboxylic acid group
  • H atom
  • R group
68
Q

What is an R group?

A

How each amino acid differs + why amino acid properties differ (e.g. if acidic or basic, polar or no polar)

69
Q

How is a peptide bond formed?

A
  • A hydroxyl (-OH) is lost from the carboxylic group of one amino acid and a hydrogen is lost from the amine group of another amino acid
  • Remaining C atom (with double bonded oxygen) from the first amino acid bonds to the nitrogen atom of the second amino acid
70
Q

How is a peptide bond broken?

A
  • Hydrolysis reaction
  • Addition of water breaks the peptide bonds resulting in polypeptides being broken down to amino acids
71
Q

What is a conjugated protein?

A

Globular proteins that contain a prosthetic group

e.g. haemoglobin which contains a prosthetic haem group

Biology (26 decks)

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