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Biology A level > Topic 2 - Biological molecules > Flashcards

Topic 2 - Biological molecules Flashcards

(68 cards)

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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
What monosaccharides are sucrose made up of
alpha glucose and fructose
26
What monosaccharides are lactose made up of
beta glucose and galactose
27
What is the main polysaccharide energy store in plants and what is it composed of
amylopectin (starch) is the main polysaccharide energy store in plants, is composed of α-glucose.
28
What is the difference between amylose and amylopectin
Amylose is a straight chain polymer of glucose units vs amylopectin is a branched chain polymer of glucose units
29
What is the polysaccharide energy store in animals called and what is it composed of
glycogen is the main polysaccharide energy store in animals, is composed of α-glucose.
30
What is the structural component of plant cell walls and what is it composed of
Cellulose is a structural component of plant cell walls, composed of long unbranched chains of b-glucose.
31
What is a saturated fatty acid
there are no C=C bonds and the molecule has as many hydrogen atoms as possible.
32
What is an unsaturated fatty acid
there is at least one C=C bond, therefore the molecule contains fewer hydrogen atoms than is maximally possible.
33
How is a triglyceride molecule formed
A triglyceride molecule is formed by joining one molecule of glycerol to three fatty acids through three condensation reactions, forming ester bonds.
34
What key roles do triglycerides have
Triglycerides have key roles in respiration and energy storage
35
Why so triglycerides have key roles in respiration and energy store
due to its insolubility and high carbon to hydrogen ratio
36
How is a phospholipid formed
Phospholipids replace one of the fatty acid chains in triglycerides with a phosphate molecule.
37
What property enables phospholipids to form phospholipid bilayers
Hydrophobic tails and hydrophilic heads
38
What is the monomer unit in proteins
Amino acids
39
What do the 20 naturally occurring amino acids differ by
R groups
40
Draw an amino acid (structural formula)
NH2 (amino group) to a C (bonded to an H and R group) and then bonded to a carboxyl group
41
How are dipeptides formed
Dipeptides are formed when two amino acids are joined together by a condensation reaction, forming a peptide bond.
42
What is a polypeptide
A polypeptide is a polymer made of many amino acids joined together by peptide bonds.
43
How many polypeptide chains are in proteins
A protein may contain one or more polypeptide chains
44
Definition of a primary protein and bond type
​The specific sequence of amino acids in a polypeptide chain Peptide bonds
45
Definition of a secondary protein and bond type
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
Definition of a tertiary protein and bond type
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
Definition of a quaternary protein and bond type
​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
What are inorganic ions
Inorganic ions are atoms or molecules with an electric charge, containing no carbon.
49
What are cations
Positively charged ions
50
What are anions
Negatively charged ions
51
Where do inorganic ions occur in solution
Inorganic ions occur in solution in the cytoplasm and body fluids of organisms, some in high concentrations and others in very low concentrations
52
Role of hydrogen ions
Hydrogen ions determine the pH of bodily fluids. The higher the concentration, the lower the pH
53
Role of sodium ions
Sodium ions are used in the co-transport of glucose and amino acids across cell membranes and transmission of nervous impulses
54
Role of phosphate ions
Phosphate ions are essential components of DNA, RNA, nucleotides & ATP
55
Role of calcium ions
Calcium ions regulate protein channels, impulse transmission and harden body parts like teeth.
56
Role of potassium ions
Potassium ions play a role in muscle contraction, nervous transmission. active transport and maintaining turgidity in plant cells.
57
Role of ammonium ions and nitrate ions
Ammonium ions and Nitrate ions are part of the nitrogen cycle and a source of nitrogen for biological molecules
58
Role of hydrogen carbonate ions
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
How do you test for reducing sugars and state the results
Benedict's reagent -> heat Blue to Red/orange ppt Reagent test strip Compare with calibration card
60
How do you test for non reducing sugars and state the results
Hydrochloric acid -> heat Sodium hydrogen carbonate Benedict's reagent -> heat Red/orange ppt
61
How do you test for starch and state the results
Iodine in potassium iodide solution Yellow to blue/black
62
How do you test for proteins and state the results
sodium hydroxide Copper (II) sulphate Blue to purple
63
How do you test for lipids and state the results
Ethanol Water -> shake Cloudy white
64
What is a globular protein
a protein with a spherical shape that is soluble in water; they typically have metabolic roles
65
What are the important properties of globular proteins
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
Give three examples of globular proteins and state their bonds types and roles
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
State three properties of fibrous proteins
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
Give three examples of fibrous proteins as well as their bond type and their use
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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