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Biology A level > Topic 2 - Biological molecules > Flashcards

Topic 2 - Biological molecules Flashcards

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1
Q

What type of bonding is present between the oxygen and hydrogens in a water molecule

A

Covalent bonding

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2
Q

Why is a water molecules considered polar

A

the oxygen nucleus pulls the shared electrons away from the hydrogen nuclei. Giving the oxygen nuclei a δ- charge, and the hydrogen nuclei a δ+ charge.

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3
Q

The polarity of water causes attraction between water molecules. What is the force of attraction between water molecules

A

Hydrogen bonds from the H to the lone pair of O

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4
Q

Why is liquid medium a useful property of water

A

​Provides habitats for aquatic organisms, medium for chemical reactions & used for transport

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5
Q

Why is important metabolite a useful property of water

A

Used in hydrolysis & condensation reactions

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6
Q

Why is high specific heat capacity a useful property of water

A

​Keeps aquatic & cellular environments stable

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7
Q

Why is high latent heat of vaporisation a useful property of water

A

Evaporation has a cooling effect on organisms

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8
Q

Why is cohesion of molecules a useful property of water

A

​Water is drawn up the xylem

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9
Q

Why is surface tension a useful property of water

A

​Allows pond-skaters to walk on the surface

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10
Q

Why is good solvent and transport medium a useful property of water

A

​Dissolves ionic and polar molecules, allowing them to easily be transported

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11
Q

Why is good reaction medium a useful property of water

A

The cytoplasm in cells is an aqueous solution where many chemical reactions happen

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12
Q

Why is incompressible a useful property of water

A

​Can prevent plants from wilting & act as a hydrostatic skeleton for invertebrates

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13
Q

What are monomers

A

Monomers are individual molecules that make up a polymer.

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14
Q

What are polymers

A

Polymers are long chains that are composed of many individual monomers that have been bonded together in a repeating pattern.

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15
Q

What is a condensation reaction

A

When two molecules combine to form a more complex molecule with the removal of water

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16
Q

What is a hydrolysis reaction

A

When larger molecules are broken down into smaller molecules with the addition of water

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17
Q

What are the simplest carbohydrates (and name the 3)

A

Monosaccharides are the simplest carbohydrates, consisting of only one sugar molecule

Glucose, Fructose & Galactose

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18
Q

What are pentose sugars

A

Pentose sugars = ribose sugars
Found in many important biological molecules such as ribonucleic acid (RNA), ATP, NAD

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19
Q

What type of sugar is glucose

A

Hexose

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20
Q

How many isomers does Glucose have

A

2

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21
Q

Draw alpha glucose

A

O-C-C-C-C-CH2OH

OH: down, down, up, down

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22
Q

Draw beta glucose

A

O-C-C-C-C-CH2OH

OH: up, down, up, down

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23
Q

What are disaccharides and what kind of bond is there

A

Disaccharides are sugars that are composed of two monosaccharides joined together in a condensation reaction, forming a glycosidic bond.

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24
Q

What monosaccharides are maltose made up of

A

2 x alpha glucose

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25
Q

What monosaccharides are sucrose made up of

A

alpha glucose and fructose

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26
Q

What monosaccharides are lactose made up of

A

beta glucose and galactose

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27
Q

What is the main polysaccharide energy store in plants and what is it composed of

A

amylopectin (starch) is the main polysaccharide energy store in plants, is composed of α-glucose.

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28
Q

What is the difference between amylose and amylopectin

A

Amylose is a straight chain polymer of glucose units vs amylopectin is a branched chain polymer of glucose units

29
Q

What is the polysaccharide energy store in animals called and what is it composed of

A

glycogen is the main polysaccharide energy store in animals, is composed of α-glucose.

30
Q

What is the structural component of plant cell walls and what is it composed of

A

Cellulose is a structural component of plant cell walls, composed of long unbranched chains of b-glucose.

31
Q

What is a saturated fatty acid

A

there are no C=C bonds and the molecule has as many hydrogen atoms as possible.

32
Q

What is an unsaturated fatty acid

A

there is at least one C=C bond, therefore the molecule contains fewer hydrogen atoms than is maximally possible.

33
Q

How is a triglyceride molecule formed

A

A triglyceride molecule is formed by joining one molecule of glycerol to three fatty acids through three condensation reactions, forming ester bonds.

34
Q

What key roles do triglycerides have

A

Triglycerides have key roles in respiration and energy storage

35
Q

Why so triglycerides have key roles in respiration and energy store

A

due to its insolubility and high carbon to hydrogen ratio

36
Q

How is a phospholipid formed

A

Phospholipids replace one of the fatty acid chains in triglycerides with a phosphate molecule.

37
Q

What property enables phospholipids to form phospholipid bilayers

A

Hydrophobic tails and hydrophilic heads

38
Q

What is the monomer unit in proteins

A

Amino acids

39
Q

What do the 20 naturally occurring amino acids differ by

A

R groups

40
Q

Draw an amino acid (structural formula)

A

NH2 (amino group) to a C (bonded to an H and R group) and then bonded to a carboxyl group

41
Q

How are dipeptides formed

A

Dipeptides are formed when two amino acids are joined together by a condensation reaction, forming a peptide bond.

42
Q

What is a polypeptide

A

A polypeptide is a polymer made of many amino acids joined together by peptide bonds.

43
Q

How many polypeptide chains are in proteins

A

A protein may contain one or more polypeptide chains

44
Q

Definition of a primary protein and bond type

A

​The specific sequence of amino acids in a polypeptide chain

Peptide bonds

45
Q

Definition of a secondary protein and bond type

A

The curling or folding of the polypeptide chain into α-helices and β-pleated sheets due to the formation of hydrogen bonds

Hydrogen bonds

46
Q

Definition of a tertiary protein and bond type

A

The overall specific 3-D shape of a protein, which is determined by interactions between R groups and the properties of R groups

Hydrogen bonds, ionic bonds and disulphide bridges

47
Q

Definition of a quaternary protein and bond type

A

​The specific 3-D shape of a protein that is determined by the multiple polypeptide chains and/or prosthetic groups bonded together

Hydrogen bonds, ionic bonds and disulphide bridges

48
Q

What are inorganic ions

A

Inorganic ions are atoms or molecules with an electric charge, containing no carbon.

49
Q

What are cations

A

Positively charged ions

50
Q

What are anions

A

Negatively charged ions

51
Q

Where do inorganic ions occur in solution

A

Inorganic ions occur in solution in the cytoplasm and body fluids of organisms, some in high concentrations and others in very low concentrations

52
Q

Role of hydrogen ions

A

Hydrogen ions determine the pH of bodily fluids. The higher the concentration, the lower the pH

53
Q

Role of sodium ions

A

Sodium ions are used in the co-transport of glucose and amino acids across cell membranes and transmission of nervous impulses

54
Q

Role of phosphate ions

A

Phosphate ions are essential components of DNA, RNA, nucleotides & ATP

55
Q

Role of calcium ions

A

Calcium ions regulate protein channels, impulse transmission and harden body parts like teeth.

56
Q

Role of potassium ions

A

Potassium ions play a role in muscle contraction, nervous transmission. active transport and maintaining turgidity in plant cells.

57
Q

Role of ammonium ions and nitrate ions

A

Ammonium ions and Nitrate ions are part of the nitrogen cycle and a source of nitrogen for biological molecules

58
Q

Role of hydrogen carbonate ions

A

Hydrogencarbonate ions are formed when carbon dioxide dissolves in blood. They are important in the transport of carbon dioxide in the blood and the regulation of blood pH

59
Q

How do you test for reducing sugars and state the results

A

Benedict’s reagent -> heat
Blue to Red/orange ppt

Reagent test strip
Compare with calibration card

60
Q

How do you test for non reducing sugars and state the results

A

Hydrochloric acid -> heat
Sodium hydrogen carbonate
Benedict’s reagent -> heat

Red/orange ppt

61
Q

How do you test for starch and state the results

A

Iodine in potassium iodide solution
Yellow to blue/black

62
Q

How do you test for proteins and state the results

A

sodium hydroxide
Copper (II) sulphate
Blue to purple

63
Q

How do you test for lipids and state the results

A

Ethanol
Water -> shake
Cloudy white

64
Q

What is a globular protein

A

a protein with a spherical shape that is soluble in water; they typically have metabolic roles

65
Q

What are the important properties of globular proteins

A

They are roughly spherical in shape, with hydrophobic R groups on the inside and hydrophilic R groups on the outside. They are therefore soluble in water

They have very specific shapes; this allows them to carry out very specific functions

66
Q

Give three examples of globular proteins and state their bonds types and roles

A

Haemoglobin is a conjugated globular protein, made of 4 polypeptide chains and 4 haem prosthetic groups which contain Fe2+.

Insulin is composed of two polypeptide chains, joined together by disulphide links. The specificity of the shape allows binding to cell membrane receptors.

Pepsin has hydrogen bonds, disulphide link and few basic R groups to keep it functional in low pH stomach acid.

67
Q

State three properties of fibrous proteins

A

They contain long polypeptide chains with repeating sequences of amino acids

The amino acids have non-polar R groups, so the proteins are insoluble in water

The polypeptide chains are able to form fibres which make the proteins stronger

68
Q

Give three examples of fibrous proteins as well as their bond type and their use

A

Collagen is used to make bones, tendons and are found in artery walls to help resist the high pressure

Keratin contains high amounts of cysteine, resulting in disulphide links forming between the two polypeptide chains, which makes the molecule very hard and strong. It is found in fingernails, hooves and horns.

Elastin has the ability to stretch and recoil. Elastin is stretchy due to coiling of the elastin molecules and cross-links that keep the molecules together. It is found in the lungs, bladder and blood vessel walls.

Biology A level (32 decks)

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