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A level Biology > Chapter 2 - Biological Molecules > Flashcards

Chapter 2 - Biological Molecules Flashcards

(90 cards)

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1
Q

How many bonds can a carbon atom form?

A

4 bonds

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2
Q

How many bonds can a nitrogen atom form?

A

3 bonds

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3
Q

How many bonds can an oxygen atom form?

A

2 bonds

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4
Q

How many bonds can a hydrogen atom form?

A

1 bond

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5
Q

What is an electrolyte?

A

Ions in a solutions, these often have important roles in living organisms

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6
Q

What atoms is water formed from?

A

2 Hydrogen and 1 Oxygen

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7
Q

How does surface tension affect water?

A

It causes it to behave like a plastic sheet
It is caused by intermolecular attraction
It isn’t affected by molecules around them so it pulls more strongly
Means it can become a habitat for other lovings things.

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8
Q

What causes surface tension of water?

A

Hydrogen bonds
Which occurs between hydrogen atoms to oxygen atoms of other molecules
e.g another water molecule

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9
Q

Why is it important that water is colourless?

A

It means that it is transparent to light as a result, sunlight can reach cells in a plant to allow photosynthesis to occur

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10
Q

What is cohesion?

A

Cohesion is strong attraction to eachother making water a sticky liquid, which causes surface tension.

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11
Q

What does it mean by water is polar?

A

It has regions of positivity and negativity

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12
Q

Describe the specific heat capacity of water.

A

It is the energy required to raise 1kg of water by 1 °C
It is important that it is high so body temperature doesn’t raise too quickly otherwise homeostasis can’t function properly and enzymes would denature

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13
Q

Describe the latent heat of water.

A

It is relatively large meaning evaporation of water provides a cooling effect with little water loss

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14
Q

Describe the density of water.

A

The density of water decreases as it freezes.
This is because it expands as it freezes by forming a rigid structure with more space in between them compared to as a liquid.
This is why ice floats on water.

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15
Q

How is water a solvent?

A

Water is polar, as a result it forms electrostatic interactions with other charged particles (hydrophilic)
As a result many metabolic reactions are able to occur

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16
Q

What is a carbohydrate?

A

Consists of carbon, hydrogen and oxygen and are long chains of sugar units called saccharides.
It is an important energy source for plants and animals.

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17
Q

What is the ratio of carbon, hydrogen and oxygen atoms in a carbohydrates?

A

C : 2H : O

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18
Q

What are the three main types of carbohydrates?

A

Monosaccharides, Disaccharides and Polysaccharides

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19
Q

What is a monosaccharide?

A

It is a single sugar unit

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20
Q

What is a disaccharide?

A

It is a two sugar units bonded by a glycosidic bond

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21
Q

What is a polysaccharide?

A

Three or more sugar units bonded together in a chain by glycosidic bonds and are joined together by condensation reactions

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22
Q

How do saccharides bond together?

A

By condensation reactions

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23
Q

What are the 6 properties of water?

A
  1. It is a metabolite in many metabolic reactions
  2. It is the solvent where metabolic reactions occur
  3. Relatively high heat capacity
  4. Relatively large latent heat of vaporisation
  5. Strong cohesion between water molecules
  6. Ice is less dense than water
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24
Q

What is a monomer?

A

A monomer is a small unit that makes up larger molecules

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25
What is a polymer?
Large molecules made of a large chain of monomers
26
How are polymer bonds broken?
Hydrolysis using a water molecule
27
What elements are carbohydrates made from?
Carbon, Hydrogen and Oxygen
28
What elements are lipids made from?
Carbon, Hydrogen and Oxygen
29
What elements are proteins made from?
Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur
30
What elements are nucleic acids made from?
Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus
31
Which saccharides form maltose?
Glucose and glucose
32
What saccharides make sucrose?
Glucose and fructose
33
What saccharides make lactose?
Glucose and galactose
34
What is starch?
Polysaccharide Made up of alpha glucose molecules Non-soluble
35
What are the two types of starch?
Amylose and amylopectin
36
What is amylose?
Starch No branches and forms a coil Straight chain 1-4 glycosidic bonds
37
What is amylopectin?
Starch Forms a coil and has branches at regular intervals (around every 23 subunits) Branches allow it to be stored 1-4 and 1-6 (branches) glycosidic bonds
38
What is glycogen?
It is the way alpha glucose is stored in animals and fungi More branched than amylopectin More compact for storage so it can be broken down quicker
39
How can you bond two B-glucose molecules?
Flip alternate molecules 180 degrees so the OHs are next to each other in order to bond
40
What is cellulose made up of?
Long chains of B-glucose molecules (1000-10000)
41
Describe the structure of a cellulose chain.
It is a long straight chain due to the molecules alternating by flipping 180 degrees each time
42
What is glucose?
Hexose monosaccharide with a ring structure Soluble molecule that is used for respiration, stored as glycogen or starch as energy reserves, or used in structural molecules
43
What is the chemical test for proteins?
Biuret test is added to the sample in solution. Set timer for 5 mins then record observations. Positive result is purple. Compare to a control such as distilled water
44
What if the function of Calcium ions (Ca 2+)?
Nerve impulse transmission Muscle contraction
45
What is the function of Sodium ions (Na +)?
Nerve impulse transmission Kidney function
46
What was the function of Potassium ions (K +)?
Nerve impulse transmission Stomatal opening
47
What is the function of ammonium ions (NH4 +)?
Production of nitrate ions by bacteria
48
What is the function of hydrogen ions (H +)?
Catalysis of reactions pH determination
49
What is the function of nitrate ions?
Nitrogen supply to plants for amino acids and protein formation
50
What is the function of hydrogen carbonate ions?
Maintenance of blood pH
51
What is the function of Chloride ions?
Balance positive charge of sodium and potassium ions in cells
52
What is the function of Phosphate ions?
Cell membrane formation Nucleic acid and ATP formation Bone formation
53
What is the function of Hydroxide ions?
Catalysis of reactions pH determination
54
How are polymer bonds formed?
Condensation reactions Produces water
55
How do you test for starch?
Iodine test Add a few drops to substance Orange-brown = no presence Blue-black = presence
56
How do you test for reducing sugars?
Benedicts test for reducing sugars Place sample into boiling tube Add equal volume of benedicts regent Heat gently in a boiling water bath for 5 mins. Blue -> Green -> Yellow -> Orange -> Red Blue = no reducing sugars Red = high concentration of reducing sugars OR Regent test strips can be used for semi-quantitative results
56
How do you test for non-reducing sugars?
Benedicts test for non-reducing sugars Benedicts regent doesn't react directly with non-reducing sugars Substance boiling with dilute HCl Then warm with benedicts regent Blue -> Green -> Yellow -> Orange -> Red Blue = None Red = High concentration
57
What is a lipid?
Non-polar Not soluble in water Large complex molecules known as macromolecules
58
What is a triglyceride?
One glycerol (alcohol) Three fatty acids (carboxyl) Ester bonds
59
What is a saturated fatty acid chain?
Fatty acid with no double bonds between carbon atoms
60
What is a mono-unsaturated fatty acid chain?
Fatty acid with one double bond between carbon atoms
61
What is a polyunsaturated fatty acid chain?
Fatty acid with more than one double bond between carbon atoms
62
What is a phospholipid?
Modified triglyceride Found in cytoplasm of every cell Phosphate group hydrophilic head (charged) Two fatty acid hydrophobic tails (non polar)
63
Describe the structure of phospholipids in the plasma membrane.
Form the phospholipid bilayer Tails face inwards touching each other Heads face outwards Layer of two phospholipids
64
What is a sterol?
Steroid alcohol Complex alcohols Four carbon ring structure with a hydroxyl (OH) group at one end e.g. Cholesterol
65
Describe cholesterol.
Sterol Important in formation of cell membranes
66
What are the roles of lipids?
Membrane formation and creation of hydrophobic barriers Hormone production Electrical insulation of impulse transmission Waterproofing
67
What are specific roles of triglycerides?
Thermal insulation to reduce heat loss Cushioning to protect vital organs Buoyancy for aquatic animals
68
Describe the general structure of amino acids.
Amine group R-group Carboxyl group
69
How are amino acids synthesized?
By the amine and carboxylic acid groups R-group not involved Peptide bonds Condensation reaction to bond Hydrolysis reaction to break bonds
70
What is a dipeptide?
Two amino acids joined together by a peptide bond
71
What is a polypeptide?
Many amino acids joined together by a peptide bond
72
Describe the primary structure of a protein.
Sequence where amino acids are joined Only involved peptide bonds Determines the structure of the polypeptide and further levels of protein structure Encoded by DNA and mRNA
73
Describe the secondary structure of a protein.
Hydrogen bonds may form within the amino acid chain Can form an alpha helix or beta pleated sheet
74
Describe the tertiary structure of a protein.
Folding of protein into final shape Secondary structure brings R-groups close enough together to interact causing the folding
75
What are the interactions between R-groups?
Hydrophobic and hydrophilic interactions Hydrogen bonds Ionic bonds Disulfide bonds
76
Describe hydrophobic and hydrophilic interactions.
Weak interactions between polar and non-polar R-groups.
77
Describe hydrogen bonds.
Weakest bonds Formed between hydrogen and oxygen atoms
78
Describe ionic bonds.
Stronger than hydrogen bonds and form between oppositely charged R-groups
79
Describe disulfide bonds.
Covalent and strongest of the bonds but only form between R-groups that contain sulfur atoms
80
Describe the quaternary structure of a protein.
Similar interactions to the tertiary structure except it is between different protein subunits
81
What is a globular protein?
Spherical shape Water soluble as they have R-groups on the inside that are hydrophobic and hydrophilic ones on the outside Involved in metabolic processes
82
What is haemoglobin?
Globular protein Carries oxygen Conjugated protein Made of four polypeptide chains and four haem prosthetic groups that contain iron
83
What is insulin?
Globular protein Involved in carrying blood glucose Made of two polypeptide chains which are joined by disulfide bonds Specific to the shape of cell membrane receptors
84
What is pepsin?
Globular protein Enzyme that functions in the stomach Has a few basic R-groups, hydrogen bonds and a disulfide bond.
85
What is a fibrous protein?
Usually made of long polypeptide chains that form fibers Insoluble as they have amino acids with hydrophobic R-groups Very strong, yet flexible
86
What is collagen?
Fibrous protein Found in bones and tendons Withstand large pulling forces Found in artery walls to help withstand high pressure
87
What is keratin?
Fibrous protein Strong molecule Large number of cysteine amino acids and many disulfide bonds Found in hooves, horns and fingernails
88
What is elastin?
Fibrous protein Elastic Found in walls of blood vessels, lungs and bladder
89
What is the calculation for Rf value?
Rf = distance moved by solute / distance moved by solvent

A level Biology (25 decks)

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