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Biology Paper 1/2 > Biological Molecules 1 > Flashcards

Biological Molecules 1 Flashcards

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1
Q

Define monomers and polymers and what is the process called when monomers form polymers

A

Monomers - Small, basic molecular unit
Polymers - large, complex molecules made from long chains of monomers bonded together

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2
Q

Give some example of monomers

A

Monosaccharides
Amino acids
Nucleotides

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3
Q

Define condensation reaction
Define hydrolysis reaction

A

Condensation reaction- Monomers join together to produce a polymer and water
Hydrolysis reaction- Use water to break down a polymer into monomers

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4
Q

Glucose + Glucose -> —— + water

A

Maltose

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5
Q

What conditions are needed for hydrolysis reaction

A

Enzyme(catalyse reactions)
Optimum pH levels
Optimum temperature

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6
Q

Why are Hydrogen bonds not in biomolecules
What are polar molecules

A

Hydrogen bonds are weak
Molecules with a partial charge due to uneven distribution of electrons in the atom

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7
Q

Ionic bond and covalent bond
Does or doesn’t dissolve in water

A

Ionic bond does dissolve in water
Covalent bond doesn’t dissolve in water

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8
Q

What properties of a molecule is affected by the bond type

A

Boiling point
Melting point
Malleability
Solubility

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9
Q

What is the polymers of glucose amino acid and nucleotide

A

Starch Cellulose Glycogen
Protein
DNA RNA

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10
Q

What 3 elements do all carbohydrates contain?
Name 3 types of carbohydrates
Give 3 examples of each one

A

Carbon Hydrogen Oxygen
Monosaccharides Disaccharides Polysaccharides
Monosaccharides: Glucose, Fructose, Galactose
Disaccharides: Sucrose, Maltose, Lactose
Polysaccharides: Starch, Cellulose, Glycogen

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11
Q

What is found in all 3 Polysaccharides

A

Glucose

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12
Q

What does ATP and ADP stand for

A

Adenosine Triphosphate
Adenosine Diphosphate

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13
Q

Why is ATP a derivative of a nucleotide

A

It is also made of a sugar, base and Phosphorus

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14
Q

What is the Phosphate, base and sugar in ATP

A

Phosphate-Triphosphate
Sugar: Ribose/Pentose
Base: Adenine

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15
Q

What is the word equation for aerobic respiration and where does the energy come from

A

Oxygen + Glucose -> Carbon dioxide + water + Energy(ATP)
Energy comes from bonds in glucose

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16
Q

What is the reaction when ATP releases energy
what is the word equation
What enzyme is needed

A

Hydrolysis
ATP + H2O -> ADP + Pi + Energy
ATP hydrolase

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17
Q

What is the reaction for the resynthesis of ATP
What is the word equation
What enzyme is needed
Where does this process take place

A

Condensation
ADP + Pi -> ATP
ATP synthase
Takes place during photosynthesis or respiration

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18
Q

What is the word for adding phosphorus and removing phosphorus

A

Phosphorylation
Dephosphorylation

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19
Q

What are the 3 ways ATP is synthesised

A

Oxidative phosphorylation (aerobic respiration in plant and animal cells)
Photophosphorylation (Photosynthesis in chlorophyll)
Substrate level phosphorylation (free phosphorus + ADP in plant/animal cell)

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20
Q

Give a few examples of the role of ATP in biological systems

A

Active transport(movement against the concentration gradient)
Protein synthesis
Muscle contraction(requires energy for the filaments to work)
Metabolic processes(build macromolecules)
Secretion(required to form lysosomes)
Activating molecules(Phosphate released from the hydrolysis of ATP can be used to activate other key biological molecules)

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21
Q

Why does ATP have a short term energy supply

A

-Weak bonds between Phosphate group
-Energy is released in a single step (adding water)
-Releases less energy compared to glucose

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22
Q

What is the function of ATP and why is it important for metabolic reactions in cells

A

An immediate source of energy for biological processes
Metabolic reactions in cells must have a constant, steady supply of ATP

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23
Q

Why are Phosphate groups inorganic

A

They do not contain any carbon atoms

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24
Q

Why is ATP an immediate source of energy

A

Only one bond needs to be hydrolysed to release energy

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25
Q

What is phosphorylation and give an example

A

The inorganic Phosphate released during the hydrolysis of ATP can be bonded onto different Compounds to make them more reactive
This happens to glucose ar the start of respiration to make it more reactive

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26
Q

What makes ATP a suitable immediate source of energy(explain properties)

A

-ATP releases energy in small, manageable amounts so no energy is wasted(cells do not heat from wasted hear energy and cells are less likely to run out of resources. Glucose would release large amounts of energy which results in wasted energy)
-Small and soluble so easily transported around the cell(can dissolve in cytoplasm, common with glucose)
-Only one bond needs to be hydrolysed to release energy(Glucose needs several bonds to be broken to release all its energy)
-It can transfer energy to another molecule by transferring one of its Phosphate groups(can able phosphorylation, glucose can’t as it doesn’t have any Phosphate groups)
-ATP can’t pass out of the cell so the cell always has an immediate supply of energy, cell can run out of glucose

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27
Q

Compare the strength of the bond between covalent and ionic
What is the electrostatic attraction between opposite charged ions called

A

Covalent- more stable molecule formed
Ionic- weaker than covalent bonds
Ionic bond

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28
Q

What are 5 examples of biomolecules

A

Nucleic acids
Polysaccharides
Lipids
Proteins
Water

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29
Q

Describe Hydrogen, covalent and ionic bonds

A

HYDROGEN: Electrons tend to position at one side which causes molecule to become polarised. Negatively charged region attracts positively charged region of another molecule. Individually, these bonds are weak but collectively become important forces to define the molecules properties
COVALENT: Shared pair of electrons. Filled outer shell of electrons for both atoms. More stable molecule is formed
IONIC: Oppositely charged ions attract eachother. Electrostatic attraction between them is known as the ionic bond. Weaker than covalent bonds

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30
Q

Where does initial energy come from

A

-The sun
-Photosynthesis occurs in plants where carbon dioxide and water react to release oxygen and glucose
-Respiration occurs where glucose is oxidised to make ATP

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31
Q

Why are ——— bonds are broken in ATP easily

A

Phosphodiester bonds
They have a low activation energy

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32
Q

What can the Phosphate bring produced in the hydrolysis of ATP be used for

A

To phosphorylate compounds by binding on to them to make them more reactive
To provide energy to energy requiring cellular reactions

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33
Q

Why is ATP not a good long term source of energy

A

Easily be hydrolysed into ADP
Fats and Carbohydrates are better stores of long term energy(glycogen and starch)

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34
Q

Glucose is an isomer
Define isomer

A

Same molecular formula but a different structure

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35
Q

Glucose is an isomer
Define isomer

A

Same molecular formula but a different structure

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36
Q

Samsung notes (glucose)

A

Yay

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37
Q

What is a molar solution

A

1 mole is in a litre of solvent

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38
Q

Name two lipids and describe their structures

A

TRIGLYCERIDES: 1 Glycerol and 3 fatty acids
PHOSPHOLIPIDS: 1 glycerol, 2 fatty acids, 1 Phosphate group

39
Q

What is the reaction that forms Triglycerides and Phospholipids and what bonds are formed and what molecule is also formed

A

Condensation reaction
Ester bond
Water molecules

40
Q

Define Saturated fatty acids and Unsaturated fatty acids

A

The hydrocarbons chain only has single bonds between carbons
The hydrocarbon chain consists of atleast one double bond between carbons

41
Q

What are the 4 properties of Triglyceride and explain them

A

ENERGY STORAGE Large ratio of energy storing carbon Hydrogen bonds compared to the number of carbon atoms
METABOLIC WATER SOURCE High ratio of Hydrogen to oxygen atoms, triglycerides can be oxidised to release water
INSOLUBLE IN WATER Large and hydrophobic and do not affect water potentials and osmosis
LOW MASS Lots can be stored without increasing the mass by a lot and preventing movement

42
Q

Describe the emulsion test for lipids

A

Dissolve the sample in ethanol
Add Distilled water
Lipid is present if a white emulsion forms

43
Q

Describe the fatty acid and Phosphate in phospholipids and how they react to water
What is this type of molecule called

A

Fatty acids are hydrophobic and repel water because they have no charge, but it reacts with lipids
Phosphates are hydrophilic and attract water because its charged
Amphipatic

44
Q

Why are phospholipids polar molecules

A

They have 2 charged regions

45
Q

Describe how phospholipids are positioned in water

A

Heads (phosphate) is exposed to water and tails are not(fatty acid)

46
Q

What are the functions of Proteins

A

Structure
Immunological functions(antibodies)
Catalytic functions(enzymes)
Signalling/Identification(antigens)

47
Q

Name the 3 groups in an amino acid monomer

A

Amino group
Variable group (R group)
Carboxyl group

48
Q

What molecule is formed when 2 amino acids react together
What bond is formed

A

Dipeptide
Peptide bond

49
Q

What is the bond formed between glucose

A

Glycosidic

50
Q

What method should you use to seperate the different amino acids

A

Chromatography

51
Q

Explain the 4 structures of Proteins in all 4 stages

A

PRIMARY STRUCTURE : The order of amino acids in the polypeptide chain(Peptide bonds holds all the amino acids together in the polypeptide chain)
SECONDARY STRUCTURE : The sequence of amino acids causes parts of protein molecule to bend into an alpha helix or fold into beta pleated sheets (Hydrogen bonds hold together the secondary structure - Hydrogen bonds form between the C=O groups of the carboxyl group (especially O) of one amino acid and the H in the amino group of another amino acid
TERTIARY STRUCTURE : The further folding of the secondary structure to form a unique 3D shape, 3D structure is held in place by ionic, Hydrogen and disulfide bonds(The ionic and disulfide bonds form betweeb R groups of different amino acids)(Disulphide bonds only occur if there is an amino acid with a sulfur in its R group)
QUARTERNARY STRUCTURE : A protein made up of more than 1 polypeptide chain

52
Q

What happnes when a protein is denatured

A

The bonds that hold the tertiary and secondary structure in shape are broken and the unique 3D shape is lost

53
Q

What conditions denature a protein

A

-Too high temperature(Too much kinetic energy)
-Too high/low pH (Too many H+ or OH-)

54
Q

Why is the primary structure of a protein very important

A

If one amino acid in the sequence is different, it will cause the ionic/hydrogen/ disulfide bond to form in a differnt location, this results in a different 3D shape, this changes the shape of the active site(enzyme will not function)

55
Q

What happens if carrier proteins are denatured

A

Their binding site changes shape so the molecules are no longer complementary and cannot be transported across membranes

56
Q

What does biuret solution contain

A

Sodium hydroxide and Copper II

57
Q

What structure are enzymes and what kind of proteins are they

A

Tertiary structure
Globular proteins

58
Q

Sucrose + water ->
Lactose + Water ->
Maltose + Water ->

A

Sucrose + water -> Glucose + Fructose
Lactose + Water -> Glucose +Galactose
Maltose + Water -> Glucose + Glucose

59
Q

Why does the acitive site of an enzyme have a specific, unique shape

A

Due to the specific folding and bonding in the tertiary structure of the protein
Unique 3D structure determines the shape of the active site.

60
Q

What are the 2 models of enzyme action

A

Lock and key model
Induced fit model

61
Q

Explain the lock and key model

A

The enzyme active site is a fixed shape and random collisions cause the substrate to collide and attach fk the enzyme which forms an enzyme substrate complex
-The substrate then distorts which lowers the activation energy - products are released - enzymes active site is empty - enzyme can be reused

62
Q

Explain the induced fit model

A

Enzyme’s active site is induced (chnages shape slightly) to mould around the substrate - puts strain on bonds in substrate and weakens them - lowers activation energy - products are removed -> active site returns to original shape

63
Q

What factors affect enzyme action

A

Temperature
pH level
Enzyme concentration
Substrate concentration
Inhibitors

64
Q

Explain temperature in rate of reaction

A

-If the temperature is low, there is not enough kinetic energy for successful collisions between enzyme and substrate
-As the temperature increases, the kinetic energy increases so more frequent, successful collisions betweeb enzyme and substrate so rate of reacrion increases
-When the temperature is too high, the enzymes denatured and active sites chnage shape as the bond holding together the amino acids in the fixed, 3D tertiary structure are broken so enzyme substrate complexes can’t form

65
Q

Explain pH in rate of reaction

A

-If the pH is too high(too many hydroxide ions) or too low (too many Hydrogen ions), this will Interfere with the charges in the amino acids in the active site and breaks down the bonds holding together the amino acids in the tertiary structure, active site chnages shape and enzyme denatured so less enzyme substrate complexes form

66
Q

Explain substrate concentration in rate of reaction

A

-At low substrate concentration, the rate of reaction is low so substrate concentration is the limiting factor as there are few successful collisions between the enzyme and substrate so less enzyme substrate complexes form
-As the substrate concentration increases, the frequency of collisions between the enzyme and substrate increases do the rate of reaction increases
- When you keep increases the substrate concentration, the rate of reactions starts to become constant as the enzyme active sites are Saturated(new limiting factor is enzyme concnetration)

67
Q

Explain enzyme concentration in rate of reaction

A

-At low enzyme concentration, the rate of reaction is low as enzyme active sites are saturated, so enzyme concentration is the limiting factor
-As the enzyme concentration increases, there are more frequent and successful collisions between the enzyme and substrate, so the rate of reaction increases
-As enzyme concentration increases, rate of reaction stays constant as substrates are used up so no collisions between enzyme and substrate and now enzyme substrate complexes form

68
Q

EQ: Describe bow the structure of a protein depends on the amino acids it contains

A
  • Structure is determined by position of amino acid
  • Primary structure is sequence kf amino acids
    -Secondary structure is formed by Hydrogen bonding
    -Tertiary structure is formed by interactions
    -Creates active sites in enzymes
    -Quarternary structure contains more than one polypeptide chain
69
Q

Describe the structure of proteins

A

Polymer of amino acids
Joined by peptide bonds
Formed by condensation
Primary structure is order of amino acids
Secondary structure is folding of polypeptide chain due to Hydrogen bonding
Tertiary structure is 3D folding due to Hydrogen bonds and ionic bonds
Quarterbary structure is two or more polypeptide chains

70
Q

EQ Describe how proteins are digested in the human gut

A

Hydrolysis of peptide bonds
Endopeptidases break polypeptide into smaller peptide chains
Exopeptidases remove terminal amino acids
Dipeptidases break down dipeptides into amino acids

71
Q

What do inhibitors do
What are two types of inhibitors and explain them

A

They prevent the formation of enzyme substrate complexes
Competitive inhibitor: Inhibitors has a similar shape to substrate. Inhibitors can bind to active site. Enzyme substrate complex unable to form.
Non competitive inhibitors: Inhibitor binds to enzyme away from the active site. Forces the active site to change shape. Substrate can no longer bind to active site. Enzyme substrate complexes do not form

72
Q

Biomolecules Samsung notes

A

🪷

73
Q

MONOSACCHARIDES
Explain fructose, glucose, galactose

A

Fructose: Sugar found naturally in fruits vegetables and honey
Glucose: Main sugar used for respiration. Absorbed and transported in bloodstream to cells
Galactose: Mainly in our diet as part of Lactose dissacharide

74
Q

How can you differentiate alpha glucose and beta glucose

A

In alpha glucose, the hydroxyl group is below Carbon 1
In beta glucose, the hydroxyl group is above Carbon 1

75
Q

STARCH
Monomers?
Bonds between monomers?
Function?
Location?
Structure?
Explanation of how the structure leads to the function?

A

MONOMERS: Alpha glucose
BONDS BETWEEN MONOMERS: 1-4 glycosidic bonds in amylase, 1-4 and 1-6 glycosidic bonds in amylopectin
FUNCTION: Insoluble store of glucose
LOCATION: Plant cells(e.g. starch grains in chloroplast)
STRUCTURE: Amylase is a long, unbranched chain that forms a helix
Amylopectin is a branched molecule
EXPLANATION OF HOW THE STRUCTURE LEADS TO THE FUNCTION
Forms a helix that is compact so it can fit a lot of glucose in a small space
Branched structure which increases surface area for rapid hydrolysis back into glucose
Insoluble so doesn’t affect water potential

76
Q

GLYCOGEN
Monomers?
Bonds between monomers?
Function?
Location?
Structure?
Explanation of how the structure leads to the function?

A

MONOMERS: Alpha glucose
BONDS BETWEEN MONOMERS: 1-4 and 1-6 glycosidic bonds(more 1-6 glycosidic bonds than amylopectin)
FUNCTION: Insoluble store of glucose
LOCATION: In liver and muscle cells in animals
STRUCTURE: Highly branched molecule
EXPLANATION OF HOW THE STRUCTURE LEADS TO THE FUNCTION
Branched structure increases surface area for rapid hydrolysis back to glucose
Insoluble so won’t affect water potential

77
Q

What reaction forms polysaccharides

A

Condensation reaction

78
Q

CELULLOSE
Monomers?
Bonds between monomers?
Function?
Location?
Structure?
Explanation of how the structure leads to the function?

A

Beta glucose
1-4 glyscosidic bonds
Structural strength for cell walls
Plants in cell wall
Polymers form long, straight, unbranched chains. Chains are parallel to eachother and are held together by Hydrogen bonds which form cross links between adjacent chains, this forms fibrils. Subsequent beta glucoses are rotated by 180°
Many Hydrogen bonds provide collective strength
Insoluble so does not affect water potential

79
Q

Explain how cellulose molcules are adapted for their function in plants cells

A
  • Long unbranched straight chains provide rigidity that is required to support the plant
  • Hydrogen bonds form cross links between adjacent and chains which provides strength
    -Cellulose has high tensile strength
    -Cellulose fibres provide extra strength to the cell walls
80
Q

Describe the test for starch

A

Add iodine
If the solution changes colour from orange to blue-black, starch is present

81
Q

Name some reducing sugars

A

Glucose, Fructose, Galactose, Lactose, Maltose

82
Q

Name some non reducing sugars

A

Sucrose

83
Q

Describe the test for reducing sugars

A

Add benedicts solution and hear in a Waterbath
Colour change from blue to green/yellow/brick red

84
Q

In the Benedicts test, what do the colours green, yellow and brick red indicate

A

GREEN: Low concentration of non/reducing sugars
YELLOW: Moderate concentration of non/reducing sugars
BRICK RED: High concentration of non/reducing sugars

85
Q

In a benedicts test, why does the colour change at the top of the solution first?

A

Convection currents cause hotter particles in the solution to rise to the top. They have lots of kinetic energy, so they have lots of successful collisions so the reaction is faster and colour chnage happens first at the top

86
Q

Explain the test for non reducing sugars

A

Add acid to the non reducing sugar and boil it
Cool the solution and then acid to neutralise it
Add benedicts solution and heat in a water bath
If there is a colour chnage from blue to green/yellow/brick red, —– conc of non reducing sugars are present

87
Q

When testing for non reducing sugars, why do you add acid and then why do you neutralise it with alkali

A

Acid hydrolysis - Hydrolysis of the glycosidic bonds in sucrose releasing glucose and fructose
Benedicts test doesn’t work in acidic conditions

88
Q

What is the explanation for how reducing sugars make a colour change observable

A

When a reducing sugar is tested, the reducing sugar is oxidised and the benedicts solution is reduced as the reducing sugar loses an electron so Cu²+ can form Cu+ which forms a red precipitate

89
Q

Why do non reducing sugars not show a colour change

A

In non reducing sugars, the reducing group is involved in the glycosidic bonds in sucrose so sucrose can’t lose an electron so Cu²+ does not form Cu+ ions

90
Q

What is a carbohydrate

A

A molecule formed from one or more monosaccharides

91
Q

What is a disaccharide

A

A molecule formed by the condensation of two monosaccharides

92
Q

What is Maltose, sucrose and lactose

A

A disaccharide formed by the condensation of a glucose molecule and a …. molecule

93
Q

What is a polysaccharide

A

A molecule formed by the condensation of many monosaccharide units

Biology Paper 1/2 (3 decks)

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