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IB Biology > 2: Molecular Biology > Flashcards

2: Molecular Biology Flashcards

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1
Q

What is an organic compound

A

a compound that contains a C atom and is found in living organisms

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2
Q

Why is carbon considered as the basis of organic life

A

its ability to form large and complex molecules via covalent bonding because it can form 4 covalent bonds this allows carbon to form a wide variety of organic compounds that are chemically stable

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3
Q

What compounds are exceptions to the organic compound rule

A

carbides (e.g. CaC2), carbonates (CO32–), oxides of carbon (CO, CO2) and cyanides (CN–)

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4
Q

What are the four principal groups of organic compounds

A

carbohydrates, proteins, nucleic acids, lipids

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5
Q

Define metabolism

A

all enzyme-catalysed reactions in a cell or organism

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6
Q

State the number and type of bond carbon can form with other atoms

A

4 & covalent bond

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7
Q

Draw the molecular structure of urea

A

H2NCONH2

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8
Q

Describe how urea can be synthesized by living and artificial mechanisms

A

Frederick Wöhler heated ammonium cyanate and produced urea and helped falsify vitalism

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9
Q

What is vitalism

A

It was a theory that stated that organic molecules could only be synthesised by living organisms/things

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10
Q

Define catabolism

A

it is the breakdown of larger molecules (polymers) into smaller ones (monomers)

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11
Q

Define anabolism

A

it is the build-up of larger molecules (polymers) from smaller ones (monomers)

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12
Q

Give an example of anabolic and catabolic reaction

A

anabolic: photosynthesis
catabolic: respiration

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13
Q

What types of reaction are condensation and anabolic reactions

A

anabolic: condensation (releases H2O)
catabolic: hydrolysis (uses H2O)

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14
Q

Where can Sulphur be found

A

Found in certain amino acids

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15
Q

Where can calcium be found

A

Found in bones and teeth, also involved in neurotransmitter release in synapses

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16
Q

Where can phosphorus be found

A

Component of nucleic acids and cell membranes

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17
Q

Where can iron be found

A

Found in haemoglobin (animals), allowing for oxygen transport

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18
Q

Where can sodium be found

A

Involved in the generation of nerve impulses in neurons

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19
Q

Draw the molecular diagram of ribose

A
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20
Q

Draw the molecular diagram of a saturated fatty acid

A
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21
Q

Draw the molecular diagram of glucose

A
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22
Q

Draw the molecular diagram of amino acids

A
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23
Q

Draw the molecular diagram of deoxyribose

A
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24
Q

Contrast adhesion with cohesion

A

cohesion: the attraction between water molecules
adhesion: the attraction between water molecules and other polar molecules

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25
Q

Outline an example of the cohesive property of water being of benefit to life

A

the surface tension between cohering water molecules allows for certain animals to walk over the surface of ponds even though they are denser than water

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26
Q

Describe the main features of water

A
  • it is polar (O is more electronegative than H, which results in an unequal sharing of electrons)
  • Hydrogen bonds
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27
Q

What are the properties of water

A
  • Excellent solvent
  • high specific heat capacity
  • high latent vaporisation
  • cohesion and adhesion
  • great coolant
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28
Q

Outline an example of the adhesive property of water being of benefit to life

A

Water adheres to the xylem walls and it enables water to move up the xylem during transpiration

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29
Q

Outline a benefit to life of water’s high specific heat capacity

A

Provides suitable, stable habitats
- it is able to maintain a constant temperature as water is able to absorb a lot of heat without wide temperature fluctuations

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30
Q

Explain three thermal properties of water that are useful to living organisms

A
  • high specific heat capacity
  • high latent vaporisation
    this is due to the many hydrogen bonds present in water and a lot of energy is needed to break these bonds
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31
Q

Explain why water is such a good solvent

A
  • due to its polarity, it forms H bonds with polar molecules and dissolves them
  • allows chemical reactions to take place and be a great transport medium
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32
Q

List the types of molecules that water will dissolve

A

polar and soluble molecules: proteins, glucose, or ions, such as sodium or calcium

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33
Q

Explain sweating as a mechanism to cool the body

A
  • sweat evaporates, carrying the excess heat away into the air and reducing the temperature of the organism
  • Water’s high latent heat of vaporisation allows only small volumes of water to be needed to carry away a lot of heat
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34
Q

Compare and contrast the physical properties of methane and water

A

water has a greater molecular weight, polarity, melting&boiling point, specific heat capacity and latent heat vaporisation than methane

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35
Q

Explain why water and methane have different thermal properties based on their molecular structures

A
  • methane doesn’t form any hydrogen bonds whereas water does
  • less energy is needed to overcome methane bonds
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36
Q

Draw a water molecule and its H bonds

A

the H bonds must be small dashed lines that are between the O atom and the H atom of 2 different water molecules

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37
Q

Define hydrophilic and hydrophobic

A

hydrophobic: not attracted to water and non-polar
hydrophilic: attracted to water and polar

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38
Q

What may affect the solubility of a molecule

A

it’s polarity
- hydrophobic or hydrophilic

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39
Q

What is the mode of transport of glucose

A

polar and soluble hence carried through blood plasma

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40
Q

What is the mode of transport of oxygen

A
  • Haemoglobin can bind oxygen to allow sufficient oxygen to be transported to all body cells
  • Oxygen is less soluble at body temperature (37ºC) than at 20ºC
  • non-polar but small enough to dissolve in water in very small amounts that are not enough to satisfy aerobic respiration
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41
Q

What is the mode of transport of lipids

A
  • they are non-polar and insoluble and travel inside lipoprotein (also lacteals)
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42
Q

What is the mode of transport of amino acids

A

Polar and soluble enough to be dissolved in blood plasma

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43
Q

What is the mode of transport of sodium chloride

A

ions which dissolve and travel through the blood

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44
Q

Define monosaccharide

A

a carbohydrate monomer

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45
Q

Define disaccharide

A

when two monosaccharides bond together via glycosidic bonds through a condensation reaction

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46
Q

Define polysaccharide

A

when more than two monosaccharides bond together via glycosidic bonds through a condensation reaction

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47
Q

List three examples of monosaccharides

A

glucose, galactose and fructose

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48
Q

List three examples of disaccharides

A

sucrose, maltose and lactose

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49
Q

List three examples of polysaccharides

A

cellulose, starch and glycogen

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50
Q

Use molecular diagrams to draw the formation of maltose from two glucose monomers

A
  • a water molecule released must be seen
  • 1,4 glycosidic bond (O)
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51
Q

Which monosaccharides join together to form 3 named examples of disaccharides

A

glucose + glucose: maltose
glucose + fructose: sucrose
glucose + galactose: lactose

52
Q

What are the functions of starch, glycogen and cellulose

A

starch: energy storage in plants
glycogen: energy storage in animals
cellulose: structural components in plant’s cell walls

53
Q

Describe the features of cellulose

A
  • beta glucose
  • 1,4 glycosidic bond
  • found in plants
  • not branched
54
Q

Describe the features of glycogen

A
  • alpha glucose
  • 1,4 & 1,6 glycosidic bond
  • found in animals
  • highly branched
55
Q

Describe the features of amylose

A
  • alpha glucose
  • 1,4 glycosidic bond
  • found in plants
  • not branched
56
Q

Describe the features of amylopectin

A
  • alpha glucose
  • 1,4 & 1,6 glycosidic bond
  • found in plants
  • branched
57
Q

Describe the differences between saturated and unsaturated (mono- or poly-) fatty acids

A

saturated: the carbon atoms in the hydrocarbon are all single bonds
unsaturated: There is at least one carbon-carbon double bond

58
Q

List the different types of lipids and their chemical composition

A
  • triglycerides (3 fatty acids + 1 glycerol)
  • phospholipids (1 glycerol + 2 fatty acids + 1 phosphate group)
  • steroids (4 carbon rings)
59
Q

Describe the differences between cis- and trans- fatty acids

A

cis: hydrogens are on the same side of the carbon double bond
trans: hydrogens are on opposite sides of the carbon double bond

60
Q

what is the BMI formula

A

mass (kg) divided by height (m2)

61
Q

What are the functions of lipids

A
  • long-term energy storage
  • thermal & electrical insulation
  • buoyancy
  • cell-to-cell recognition (glycoproteins)
62
Q

What is the name of the bond which joins the fatty acids and glycerol together

A

ester bond/linkage

63
Q

Discuss the relationship between lipids and health

A

Saturated fats and trans fats raise blood cholesterol levels, while (cis) unsaturated fats lower blood cholesterol levels
- trans fats are worse than saturated fats

64
Q

What are the possible effects of fats on health

A
  • increases risks of CHD
  • build up of fats in the blood vessels can constrict them and limit the flow of blood
65
Q

What is the effect of trans fats on the various types of cholesterol

A
  • they increase LDL (increases risks of CHD)
  • they decrease HDL
66
Q

Compare lipids to carbohydrates

A

lipids have greater energy storage (long-term)
- harder to transport and digest
- insoluble
- twice as much energy per grm

67
Q

State the number of amino acids used by living organisms to make polypeptides

A

20

68
Q

Outline the formation of a dipeptide

A

when two amino acids join together through a condensation reaction and are bonded by a peptide bond

69
Q

Draw peptide bond formation in a condensation reaction

A

water molecule released must be present
- peptide bond (CONH)

70
Q

Define denaturation

A

the irreversible change of protein conformation (change in tertiary structure)

71
Q

List the causes of denaturation

A

ph and temperature

72
Q

Outline the relationship between genes and polypeptides

A
  • Three consecutive DNA bases (triplets) are required to code for each amino acid in a polypeptide
  • genes code for polypetides
73
Q

List functions of proteins with named examples for each (S.H.I.T.S.M.E)

A
  • structural (collagen, spider silk)
  • hormone (insulin)
  • immunity (antibody)
  • sensation (rhodopsin)
  • movement (actin/myosin)
  • enzymes (rubisco)
74
Q

What is great about the 20 amino acids

A

20 amino acids can give an almost infinite number of polypeptides (large range of polypeptides)

75
Q

Define genome

A

the set of genetic material in a cell or organism

76
Q

Define proteome

A

all of the proteins expressed in a cell or organism and it is unique for each individual

77
Q

Why is the genetic code considered universal

A

All known organisms have the same four nucleotide bases + most organisms use the same 20 amino acids

78
Q

Outline the primary structure

A

sequence of amino acids linked by peptide bonds

79
Q

Outline the secondary structure

A

folding of beta-pleated and alpha-helices held through hydrogen bonding

80
Q

Outline the tertiary structure

A

it determines the 3D conformation of the polypeptide held with ionic, hydrogen bonds and disulphide bonds

81
Q

Outline the quaternary structure

A

linking multiple polypeptides together
- ex: hemoglobin

82
Q

Explain the effect of temperature on proteins

A

High temperatures disrupt the hydrogen bonds that hold the protein together
- it will lose its tertiary structure and become denatured

83
Q

Explain the effect of pH on proteins

A

Changing the pH will alter the charge of the protein, which in turn will alter protein solubility and overall shape
- lose its tertiary structure and become denature

84
Q

State the effect of denaturation on enzyme structure and function

A

it alters the shape of the active site and the substrate can no longer bind to it
- stops the enzyme from functioning

85
Q

Explain how temperature affects the rate of enzyme activity

A
  • Increasing the temperature will increase the speed and motion of both enzyme and substrate, resulting in higher enzyme activity
  • will result in more frequent collisions between the enzymes and substrates
  • beyond the optimum, higher temperatures will alter the active shape and stop enzyme activity
86
Q

Draw a graph depicting the effect of temperature on the rate of enzyme activity

A

label the axis (x: temperature, y: enzyme activity)
label optimum point

87
Q

Draw a graph depicting the effect of pH on the rate of enzyme activity

A
  • label the axis (x: PH, y: enzyme activity)
  • label optimum point
88
Q

Draw a graph depicting the effect of substrate concentration on the rate of enzyme activity

A
  • label the axis (x: substrate concentration, y: enzyme activity)
  • label the plateau point
89
Q

Explain how substrate concentration affects the rate of enzyme activity

A
  • Increasing substrate concentration will increase enzyme activity
  • will result in more frequent collision between enzyme and substrate
  • at a certain concentration, the rate will plateau because all the enzymes have been saturated
90
Q

Explain how pH affects the rate of enzyme activity

A
  • Enzymes have an optimal pH and moving outside this range reduces enzyme activity (less collisions btw substrate and enzymes)
  • too high or too low of a pH will alter the shape of the enzyme and eventually denature it and stop enzyme activity
91
Q

Outline the three stages of enzyme activity

A
  • substrate complementary to the active site of the enzyme binds to the enzyme
  • it forms a substrate-enzyme complex
  • products form and detach themselves from the enzyme
92
Q

Define enzyme

A

globular protein which acts as a biological catalyst that speed up the rate of a reaction and are specific to a substrate

93
Q

Define enzyme

A

globular protein which acts as a biological catalyst that speeds up the rate of a reaction and their active site is specific to a substrate

94
Q

Advantages of immobolised enzymes

A
  • no enzyme in the product
  • reusable
  • cost-effective/cheaper because you can re-use the enzyme
  • greater tolerance to temperature and pH
95
Q

Disadvantages of immobilised enzymes

A
  • they are more costly to buy
  • the rate of reaction is sometimes slower
96
Q

Outline the production of lactose-free milk

A
  • lactose is found in milk
  • can be broken down by the enzyme lactase (glucose + galactose)
97
Q

The advantages of lactose free-milk

A
  • some people are lactose intolerant
  • it is sweeter
  • gives a smoother texture
  • bacteria ferment glucose and galactose quicker
98
Q

State the polymers of nucleotides

A

RNA and DNA

99
Q

Describe the structure of a nucleotide

A
  • pentose sugar
  • nitrogenous base
  • phosphate group
100
Q

State the 4 types of nitrogenous bases

A
  • adenine, cytosine, guanine and thymine
101
Q

Compare the structure of DNA and RNA

A

DNA: double-stranded, thymine, deoxyribose
RNA: single-stranded, uracil, ribose

102
Q

Describe DNA structure

A
  • double helix
  • anti-parallel strands
  • complementary base pairings
103
Q

Draw a simple diagram of the structure of RNA

A
104
Q

Draw a simple diagram of the structure of DNA

A
105
Q

What did Crick and Watson discover

A
  • DNA strands are antiparallel and form a double helix
  • DNA strands pair via complementary base pairing
  • Outer edges of bases remain exposed
106
Q

What does anti-parallel mean

A

Each strand has a chain of nucleotides linked by covalent bonds, two strands are parallel but run in opposite directions so they are antiparallel

107
Q

State the nucleotides that purines and pyrimidines

A

purines: guanine and adenine
pyrimidines: cytosine and thymine

108
Q

State the number of hydrogen bonds between each nucleotide

A

thymine and adenine: 2 H bonds
guanine and cytosine: 3 H bonds

109
Q

What is meant by semi-conservative

A

both made up of the original strand and a newly synthesized strand

110
Q

Outline the function of the PCR

A

It is used to copy and amplify DNA samples

111
Q

Outline the process of PCR

A
  • DNA sample is heated to break the H bonds and separate the DNA in two strands
  • DNA primers attach to the 3’ ends of the target sequence
  • Taq polymerase, a heat-tolerant DNA polymerase binds to the primers and copies the DNA
112
Q

Outline Meselson & Stahl’s Experiments support for the theory of semi-conservative replication of DNA

A
  • semi-conservative: the DNA contained 14N and 15N both at the middle of the tube
  • conservative: the 15N would settle at the bottom of the tube and 14N at the top
113
Q

What demonstrates that the genetic code is universal

A

the transfer of genes across species and bacteria

114
Q

What is a triplet

A

a sequence of three DNA bases that codes for a specific amino acid

115
Q

What is a codon

A

a sequence of three mRNA bases that codes for a specific amino acid

116
Q

What is a special feature of mRNA codons

A
  • Multiple mRNA codons can encode the same amino acid
  • a change in the genetic code doesn’t necessarily result in a change in the amino acid sequence
117
Q

What are the products of anaerobic respiration in humans

A

glucose –> pyruvate-> lactic acid + 2ATP (glycolysis)

118
Q

When does anaerobic respiration occur

A

during vigorous exercise

119
Q

Outline the equation for anaerobic respiration in yeast

A

glucose –> alcohol + carbon dioxide

120
Q

Outline the uses of anaerobic respiration in yeast

A
  • baking
  • ethanol production
121
Q

Outline the use of a respirometer to measure cellular respiration rate

A
  • an increase in CO2 = increase in respiration
  • a decrease in O2 = increase in respiration
122
Q

Chlorophyll and visible light

A
  • red and blue light is absorbed
  • green light is reflected
123
Q

Outline the photolysis of water

A
  • water is broken down by light
  • it produces protons, electrons and light
124
Q

Which were the first organisms to carry out photosynthesis

A
  • prokaryotes would began to release oxygen into the atmosphere
125
Q

What are the 3 limiting factors of photosynthesis

A
  • light intensity
  • temperature
  • carbon dioxide concentration

IB Biology (11 decks)

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