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Biological Molecule Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Structural characteristics of starch

A
  • compact
  • helical
  • insoluble, doesn’t affect water potential
  • large, cannot leave cell
  • 1-4 1-6 glycosidic bond
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2
Q

Structural characteristics of cellulose

A
  • long straight chains
  • 1-4 glycosidic bond
  • beta glucose
  • flip 180
  • form microfibrils
  • H bonds hold chains together= strength
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3
Q

Structural characteristics of glycogen

A
  • 1-4 1-6 glycosidic bond
  • made up of alpha glucose
  • highly branched ( more than starch) and coiled chains
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4
Q

methods used to measure quantity of reducing sugar

A
  • use colorimeter and calibration curve
  • (without using colorimeter) filter and dry precipitate, find mass or weight comparison
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5
Q

5 roles of lipids

A
  • make up cell membrane, e.g. phospholipid contribute to flexibility of membrane and transfer of lipid soluble substance across them
  • soucrce of energy
  • waterproofing
  • insulation
  • protection
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6
Q

Lipids role of waterproofing

A

insoluble, plants and insects have waxy lipid cuticle that conserves water. Mammals produce oil secretion from the sebaceous glands in skin

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7
Q

Lipids role as source of energy

A
  • when oxidised, lipids provide more than twice the energy as carbohydrates and release valuable water
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8
Q

Lipids role of insulation

A
  • fats are slow conductors of heat help retain body heat. Also act as electrical insulators in myelin sheath around nerve cells
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9
Q

Lipids role of protection

A
  • often store around delicate organs like kidney
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10
Q

Structure of lipids

A
  • made of CHO, greater ratio of H:O of 2:1and long hydrocarbon chains (R group)
  • not polymers because no repeating units, not a continuous chain
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11
Q

Saturated fatty acid

A
  • only with single C-C bond
  • typically more reactive
  • solid at room temperature
  • typically unhealthy fats
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12
Q

Unsaturated fatty acid

A
  • with one or more double C=C bond
  • one double bond is mono unsatured
  • two or more double bond is polyunsaturated
  • liquid in room temp, typically healthier oils
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13
Q

Triglycerides structure to functions

A
  • low mass to energy ratio so a good storage molecules because a lot of energy can store in a small volume
  • it is large, non polar molecules, insoluble so doesn’t affect osmotic balance or water potential
  • high ratio of H to O atoms, it release water when oxidised, provide a source of water
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14
Q

Phospholipids structure

A
  • 1/3 fatty acid replaced by a phosphate molecule
  • it has a hydrophilic head and hydrophobic tail
  • It is a polar molecule
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15
Q

Phospholipids structure to properties

A
  • in aqueous environment, it form a bilayer within cell surface membranes. So a hydrophobic barrier is formed between inside and outside of a cell
  • hydrophilic head help to hold the surface of cell surface membranes
  • allow to form glycolipids by combining carbohydrate within cell surface membranes. Glycolipids are important in cell recognition
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16
Q

Test for lipids

A
  • add 5cm3 ethanol in a 2cm3 sample, shake gently to let them dissolve. And water and shake again.
  • a cloudy white emulsion indicates the presence of lipids
17
Q

Why is ethanol test results in cloudy white? 🤍

A

Because lipids is being finely dispersed in the water to form emulsion. Light will be refracted when passing through from oil droplets to water droplets, making it appear cloudy

18
Q

Four groups attached with a central carbon atom

A
  • amino group NH2
  • hydrogen atom
  • carboxyl group COOH
  • R group( variety of different chemical groups, each amino acid has different R group)
19
Q

How is dipeptide formed?

A
  • condensation reaction of two amino acids with the form of peptide bonds
  • the water is made of OH in the carboxyl group of one and H in the amino group of the other
20
Q

Primary structure of a polypeptide

A
  • the sequence of amino acids of a polypeptide chain forms the primary structure of a protein
  • the sequence is determined by DNA, and it determines the ultimate shape and function of the protein
  • change in shapes will change the function of the protein
21
Q

Secondary structure of protein

A
  • the H in NH is positive and O of the C=O is negative so they readily form a weak hydrogen bonds , caused the long peptide bond to twist into 3D coil, α- helix shape or β pleated sheet
  • hydrogen bonds are easy to break
22
Q

Tertiary structure of protein

A
  • α- helix structure can be twisted and fold even more to give complex 3D shape
  • it is maintained by disulfide bridges, ionic bonds and more hydrogen bonds
  • this allows protein to be distinctive and can be recognised by other molecules
23
Q

Properties of different bonds form in protein

A

Disulfide bridges- very strong, not sure easy to break
Ionic bonds- formed between carboxyl and amino group, not involved in forming peptide bonds. Weaker than disulfide bridges, can easily break by change in PH
Hydrogen bonds- easily broken

24
Q

Quaternary structure of proteins

A
  • few polypeptide chains link together
  • sometimes non protein components are added e.g. iron of haem group to make haemoglobin
25
Q

Structure of haemoglobin

A
  • example of globular proteins
  • 2 alpha polypeptide chains
    2 beta polypeptide chains
    4 harm group
26
Q

Biuret test

A
  • for protein
  • biuret made of sodium hydroxide and very dilute copper(II) sulphate
  • from pale blue to lilac purple
27
Q

Functions of proteins

A
  • enzymes
    -antibodies, destroy invading cells and bacteria
  • transport proteins, transport materials across the body
  • structural proteins- gives structure for the body
28
Q

E.g. How does cellulose give cotton strength to make cloth ?

A
  • has long, straight unbranded chains
  • group together to form microfibrils
  • hydrogen bonds holding chains together
29
Q

E.g. What is the benefit of mitochondria having small width comparing to its length ?

A
  • short diffusion pathway= faster diffusion
  • large SA to volume ratio
30
Q

E.g. name of the different structures of alpha and beta glucose ?

A

Isomer

31
Q

E.g How does colorimeter identify the amount of sugar content ?

A
  • higher absorption = more sugar
  • lower transmission = more sugar

Biology (12 decks)

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