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AS Biology > Biological Molecules EFi > Flashcards

Biological Molecules EFi Flashcards

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1
Q

What is the active site?

A

An indent/cleft on the surface of the molecule.

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2
Q

Why is a enzyme highly specific?

A

Only corresponding molecule will fit

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3
Q

How do enzymes work?

A

Lower activation energy of a reaction making it more efficient. Also controls reaction and ensures doesn’t occur spontaneously. Does not produce unwanted by-products.

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4
Q

Where can enzyme action occur?

A

Intracellular (in cells) or Extracellular

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5
Q

Give an example of where Extracellular Enzyme action may occur.

A

Blood

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6
Q

What are enzymes?

A

Biological catalysts that speed up metabolic reactions in living organisms

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7
Q

What is the equation for Adenosine Triphosphate being broken down into Adenosine Diphosphate?

A

ATP → ADP + Pi (Phosphate)

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8
Q

What type of reaction is ATP being converted into ADP?

A

Exergonic (release of energy), Hydrolysis

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9
Q

What enzyme is used to convert ATP into ADP?

A

ATP Hydrolase. Catabolic - Hydrolysis Reaction

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10
Q

What type of reaction is ADP being phosphorylated into ATP?

A

Endogonic (absorption of energy), Condensation

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11
Q

What enzyme is used to phosphorylate ADP into ATP?

A

ATP Synthase. Anabolic - Condensation Reaction

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12
Q

Why is ATP used for energy?

A

Small molecule so easily transported across membranes

Allows energy to be released in small usable, controlled amounts where required

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13
Q

What is ATP?

A

Adenosine Triphosphate is an energy containing molecule providing energy for ALL metabolic reactions in ALL organisms

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14
Q

What is ATP a product of? (AS Level)

A

Respiration

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15
Q

Where is Adenosine Triphosphate formed?

A

Mitochondrion/Mitochondria

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16
Q

What is the polypeptide primary structure?

A

The order of the amino acids

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17
Q

What is the polypeptide secondary structure?

A

β-pleats - folded

α-Helix - coiled

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18
Q

What is the polypeptide tertiary structure?

A

How the secondary structure is subsequently folded due to variable chemical properties of the R group

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19
Q

What is the quaternary structure of a polypeptide?

A

How multiple polypeptide chains fit together to form a complex protein. Might include a prosthetic group such as Iron (II) (Fe2+) in Haemoglobin

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20
Q

What are the 3 bond types in polypeptides?

A

Increasing bond strength as going down:
Hydrogen Bonds
Ionic Bonds
Disulphide Bridges

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21
Q

How many amino acids cannot be produced by our bodies and have to come from our diet?

A

9

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22
Q

How many amino acids are there?

A

20 (22 including the 2 STOP Amino Acids)

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23
Q

What are proteins made from?

A

Amino Acids

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24
Q

Why do phospholipids make up membranes?

A

Phosphate is polar and soluble in water (Hydrophilic) - Acts as heads in water

Fatty Acid Chains are non-polar and hydrophobic - tails out of the water

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25
Q

What do phospholipids make up?

A

Membranes, e.g. Phospholipid Bi-layer

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26
Q

What is the difference between a saturated and unsaturated fatty acid?

A

Saturated has no C=C double bond, so is carrying as much hydrogen as possible. Straight Chain

Unsaturated has C=C double bonds which can create a bend in the chain so pack less closely. More fluid @ room temp. Not carrying full hydrogen

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27
Q

What are the properties of a triglyceride molecule?

A

Insoluble in water
Non-polar
Large

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28
Q

What type of bond is formed b/w a Glycerol and a Fatty Acid?

A

Ester Bond

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29
Q

What is a Triglyceride?

A

A glycerol bonded w/ 3 Fatty Acids

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30
Q

What are the functions of lipids?

A 
Insulation
Long-term energy storage
Protection
Steroid Hormone Synthesis
Waterproofing
Source of Energy
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31
Q

How is cellulose suited to its function?

A

Made of β-glucose chains - long, straight, unbranched chains

Chains run parallel to one another and are cross-linked by hydrogen bonds which add collective strength

These are grouped to form microfibrils which are grouped to form fibres which provides even more strength

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32
Q

What happens between cellulose chains?

A

Hydrogen bonds are formed between adjacent cellulose chains. The sheer overall number makes it a lot stronger

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33
Q

Which is found in animal cells? Starch or Glycogen

A

Glycogen

It is found in animals and bacteria

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34
Q

What type of reaction occurs when starch is formed?

A

Condensation

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35
Q

Why is starch suited to be a store of energy? (Same for glycogen)

A

Insoluble - doesn’t affect water potential
Large and insoluble - doesn’t diffuse out of cells
Compact - can be stored in a small place
Branched form has many ends which can be acted on by enzymes to quickly release glucose monomers

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36
Q

What is starch made from?

A

α-Glucose

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37
Q

What is cellulose made from?

A

β-Glucose

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38
Q

What is formed when Glucose is bonded with Galactose?

A

Lactose

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39
Q

What is formed when glucose is bonded with Fructose?

A

Sucrose

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40
Q

What is formed when two glucose are bonded together?

A

Maltose

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41
Q

What enzyme is used to hydrolyse Lactose?

A

Lactase

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42
Q

What enzyme is used to hydrolyse Sucrose?

A

Sucrase

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43
Q

What enzyme is used to hydrolyse Maltose?

A

Maltase

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44
Q

What happens when you heat Sucrose with dilute acid?

A

It is broken down into α-Glucose and Fructose

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45
Q

What is Benedict’s Solution?

A

Alkaline solution of Copper (II) Sulphate

46
Q

What happens when Benedict’s Solution is mixed and heated with a reducing sugar?

A

Cu2+ ions in the solution are reduced to Cu+ ions

47
Q

What happens when a Reducing Sugar is mixed and heated with Benedict’s Solution? (colour/ppt)

A

Orange Precipitate (ppt) is formed

48
Q

What are reducing sugars?

A

ALL Monosaccharides
&
SOME Disaccharides

49
Q

What is a reducing sugar?

A

Any sugar that is capable of acting as a reducing agent because it has a free aldehyde or ketone group

50
Q

Give an example of a polysaccharide

A

Cellulose
Starch
Glycogen

51
Q

What is the name of the bond formed between monosaccharides?

A

Glycosidic Bond

52
Q

What is the term for two monosaccharides bonded together?

A

Disaccharide (Di=2)

53
Q

What is the general formula for ALL Monosaccharides?

A

(CH2O)n (n= number of carbons)

54
Q

What is the term for a single monomer?

A

Monosaccharide

55
Q

What is catabolism?

A

Breaking larger molecules into smaller units by Hydrolysis Reaction

Polymer → Monomer

56
Q

What is Anabolism?

A

Synthesis of complex molecules in living organisms from simpler ones together with strong energy

Monomer → Polymer

57
Q

What is the collective term for all chemical processes that occur in living organisms?

A

Metabolism

58
Q

Give an example of a Hydrolysis Reaction

A 
Nucleic Acids → Nucleotides
Carbohydrates → Monosaccharides
Lipids → Fatty Acids
           → Glycerol
Proteins → Amino Acids
59
Q

Give an example of a Condensation Reaction

A

Nucleotides → Polynucleotides (Nucleic Acids)
Monosaccharide → Polysaccharide (Carbohydrate)
Fatty Acids → Lipids
Glycerol → Lipids
Amino Acids → Polypeptides (Proteins)

60
Q

What is the name for a type of reaction that USES water to break bonds?

A

Hydrolysis
Hydro = Water
Lysis = Splitting

61
Q

What is the name for a type of reaction that PRODUCES water?

A

Condensation Reaction

62
Q

What is the name of the process in which a monomer becomes a polymer?

A

Polymerisation

63
Q

Name a Carbohydrate Monomer (Monosaccharide)

A

Glucose
Galactose
Fructose

64
Q

What are the properties of Ionic Bonding?

A 
Stronger than Hydrogen and Covalent. (Chemistry)
Donation of electron
Weaker than Covalent bonds (Biology)
e.g.
Na+ + Cl- → NaCl
65
Q

What do Ionic Bonds form between?

A

A metal and a non-metal

66
Q

What are the properties of Covalent Bonding?

A

Strong. The main bonds holding atoms together in organic molecules.
Can only be broken with a lot of energy and presence/action of enzyme
Atoms share a pair of electrons in their outer shells

67
Q

What do Covalent Bonds form between?

A

Non-metals only

68
Q

Summarise Hydrogen Bonding

A

Weak electrostatic bond formed between two polar molecules at the negatively charged and positively charged area on the other molecule

69
Q

What are the properties of Hydrogen Bonding?

A

Very Weak
Gives Water Surface Tension
Formed Between Atom with a slight positive and slight negative charge
Form spontaneously at temperatures found in living cells so don’t require enzymes

70
Q

Name a Non-Organic (Biological) Compound

A

Iron - Haemoglobin (Hb)
Water
Minerals

71
Q

Name an Organic (Biological) Compound

A 
Carbohydrates
Proteins
Nucleic Acids - Adenosine Triphosphate (ATP), Deoxyribonucleic Acid (DNA)
Lipids - Fats
Vitamins
All Have Carbon-Carbon Bonds
72
Q

Why is water important for metabolism?

A

Water is used to break down many complex molecules by hydrolysis, e.g. proteins to amino acids. Water is also produced in condensation reaction
Chemical reactions take place in an aqueous medium
Water is a major raw material in photosynthesis

73
Q

Why is water important as a solvent?

A

Water readily dissolves other substances:
Gases such as Oxygen and Carbon Dioxide
Waste such as Ammonia and Urea
Inorganic ions and small hydrophilic molecules such as amino acids, monosaccharides and ATP
Enzymes, whose reactions take place in solution

74
Q

What are other important features of water?

A

Its evaporation cools organisms and allows them to control their temperature
It is not easily compressed and therefore provides support, for example the hydrostatic skeleton of animals such as the earthworm and turgor pressure in herbaceous plants
It is transparent and therefore aquatic plants can photosynthesise and also light rays can penetrate the jelly-like fluid that fills the eye and so reaches the retina

75
Q

What percentage of a mammal is typically water?

A

65%

76
Q

What percentage of a jellyfish is water?

A

98%

77
Q

What is the term for when water is pulled back to the body of water rather than escaping from it?

A

Surface Tension

This means that the water surface acts like a skin and is strong enough to support small organisms such as Pond Skaters

78
Q

Why does water have a large cohesive force?

A

Due to its Hydrogen Bonding. These allow water to be pulled up through a tube such as a Xylem Vessel

79
Q

What is the term for the tendency of molecules to stick together?

A

Cohesion

80
Q

What is the Latent Heat of Vaporisation of Water?

A

The energy required for to evaporate 1g of water.
Evaporation of water such as sweat in mammals is therefore a very effective means of cooling because body heat is used to evaporate the water

81
Q

Why does water have a high specific heat capacity? (Biological Explanation)

A

Water molecules stick together due to hydrogen bonding
Without Hydrogen bonding, water would be a gas at common temperatures on Earth
Therefore it takes more energy to heat a given mass of water
Water therefore acts as a buffer against sudden temperature variations, making the aquatic environment a temperature-stable one

82
Q

Why is water described as ‘Dipolar’?

A

Oxygen atom is slightly negative

Hydrogen atoms are slightly positive

Water has both positive and negative poles and is therefore described as Dipolar

83
Q

Name some of the energy-requiring uses of Adenosine Triphosphate in Cells?

A 
Metabolic Processes
Movement
Active Transport
Secretion
Activation of Molecules
84
Q

What are the 3 ways in which ATP is synthesised from ADP? Simplified Terms

A

1) Phosphorylation
2) Oxidative Phosphorylation
3) Substrate-level Phosphorylation

85
Q

What are the 3 ways in which the Synthesis of ATP from ADP occurs?

A

1) In Chlorophyll-containing plant cells during Photosynthesis (Photophosphorylation)
2) In plant and animal cells during respiration (Oxidative Phosphorylation)
3) In plant and animal cells when phosphate groups are transferred from donor molecules to ADP (Substrate-level Phosphorylation)

86
Q

What are the 5 stages of Semi-conservative Replication?

A

1) DNA Helicase breaks the hydrogen bonds linking base pairs
2) Double helix separates as a result into 2 strands and unwinds
3) Each exposed polynucleotide chain acts as a template to which complementary free nucleotides bind by specific base pairing
4) Nucleotides are joined together in a condensation reaction by the enzyme DNA polymerase to form the ‘missing’ polynucleotide strand on each of the two strands of DNA
5) Each of the new DNA molecules contains one of the original DNA strands, that is, half the original DNA has been saved and built into each of the new DNA molecules

87
Q

What are the 4 main requirements for Semi-Conservative Replication to Occur?

A

1) The 4 types of nucleotides, each with their bases of A, C, G or T must be present
2) Both strands of the DNA molecule act as a template for the attachment of these nucleotides
3) The enzyme DNA Polymerase
4) Source of Chemical Energy is required to drive the process

88
Q

What are the 2 main stages of cell division?

A

1) Nuclear Division - Process by which the nucleus divides. Two main types: Mitosis and Meiosis
2) Cytokinesis - Follows Nuclear Division and is the process by which the whole cell divides

89
Q

How is the DNA molecule adapted to carry out its functions?

A

Very stable structure which normally passes from generation to generation without change. Only rarely does it mutate

Two separate strands joined only with Hydrogen Bonds which allow them to separate in DNA replication

Extremely large molecule and therefore carries immense amount of genetic information

By having base pairs within the helical cylinder of the deoxyribose-phosphate backbone, the genetic information is to some extent protected from being corrupted by outside chemical and physical factors

Base pairing leads to DNA being able to replicate and to transfer information as mRNA

90
Q

Why is DNA a stable molecule?

A

Phosphodiester backbone protects the more chemically reactive organic bases inside double helix

Hydrogen bonds link the organic base pairs forming bridges (rungs) between the phosphodiester uprights.

As there are more Hydrogen bonds between Cytosine and Guanine (C and G), the higher the proportion of C-G pairings, the more stable the DNA molecule

91
Q

How many hydrogen bonds between Cytosine and Guanine?

A

3

92
Q

How many Hydrogen bonds between Adenine and Thymine?

A

2

93
Q

What different types of RNA is there?

A 
mRNA (messenger)
regulatory RNA
μRNA (micro)
rRNA (ribosomal)
tRNA (transfer)
mtRNA (mitochondrial)
94
Q

What are Nucleotides held together by?

A

Phosphodiester Linkage/Bond

95
Q

What nucleotides are present in RNA?

A

Adenine and Uracil

Cytosine and Guanine

96
Q

Which nucleotides are present in DNA?

A

Adenine and Thymine

Cytosine and Guanine

97
Q

Which carbon is the Phosphate group attached to?

A

Carbon No. 5

98
Q

Which Carbon is the Nitrogenous base attached to?

A

Carbon No. 1

99
Q

What is the sugar present in RNA?

A

Ribose (RiboNucleic Acid)

100
Q

What is the sugar present in DNA?

A

Deoxyribose (DeoxyriboNucleic Acid)

101
Q

What are Nucleic Acids?

A

Long chains created by the joining of monomers, which are the nucleotides

Nucleotides are building blocks of nucleic acids

Small molecules composed of 3 sub-units:
A Nitrogenous Base
5 Carbon Sugar and
A Phosphate Group

102
Q

What is Non-Competitive Inhibition?

A

Where inhibitor binds to Allosteric Site

In binding, they alter the shape of the enzyme tertiary site

This disrupts the shape of the active site so that the substrate can no longer bind to the enzyme

IRREVERSIBLE

103
Q

What does level of inhibition depend on?

A

Concentration of Substrates

104
Q

What is an Irreversible Inhibitor called?

A

An Inactivator

105
Q

What is Competitive Inhibition?

A

Inhibition by competitive inhibitors, mostly reversible

Could be overcome by increasing the amount/concentration of substrate

By increasing the substrate, it would reduce the effect of REVERSIBLE competitive inhibition

106
Q

Are Enzyme Inhibitors Permanent or Temporary?

A

Either

107
Q

How do Enzyme Inhibitors work?

A

They bind with enzyme molecule in a way that influences how the substrate binds to the enzyme so affects its turnover rate

Can either:
Block Active Site
Alter turnover rate of the enzyme

108
Q

What are enzyme inhibitors?

A

Inhibitors are substances that reduce the activity of an enzyme

109
Q

What is the effect of pH on Enzyme Action?

A

Change in pH alters charge on the amino acids that make up the active site. As a result, substrate can no longer bind

Depending on level of pH change, it can break the bonds responsible for maintaining the tertiary structure of the enzyme

The enzyme therefore changes shape

110
Q

Summarise the effect of temperature on Enzymes

A 
Heat causes vibration
Vibrations break bonds
Broken bonds disrupt Tertiary Structure
This changes the shape
Temp too high = irreversible
111
Q

What is the effect of temperature on enzymes?

A

Heat causes molecules to vibrate

This may break some of the weak hydrogen bonds and weak ionic bonds holding tertiary structure in place

Changing the shape means that substrate can no longer bind to the active site

With too high a temperature the active site is irreversibly changed

The enzyme is DENATURED and the enzyme no longer works

112
Q

What is Induced Fit?

A

Substrates induces a change in the enzyme that makes it fit

Enzyme when it contacts, will mould around substrate

Confirmation change so that the enzyme moulds to fit the substrate

This forms an enzyme-substrate complex

AS Biology (10 decks)

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