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Yr 12 Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

What type of molecule is glucose?

A

Single sugar= monosaccharide

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2
Q

What is a property of monosaccharides?

A

They’re soluble in water

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3
Q

Why are monosaccharides soluble in water?

A

-because they contain a large amount of OH groups (also known as hydroxyl groups)

  • these hydroxyl groups can form bonds with water molecules making them soluble in water
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4
Q

Because hydroxyl groups are soluble in water what do scientist call them?

A

Hydrophilic, which means water loving & they can dissolve in water

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5
Q

What are sugars which 6 carbon atoms called?

A

Hexose sugars

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6
Q

What are sugars with 5 carbon atoms called?

A

Pentouse

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7
Q

What is a diasaccharide?

A

A large carbohydrate formed from the condensation of 2 monosaccharides

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8
Q

What is a polysaccharide?

A

A large carbohydrate formed from many monosaccharides being bonded together during condensation

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9
Q

What is an isomer?

A

A compounds that contain the wa act same number of atoms

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10
Q

What are the isomers of glucose called?

A

Alpha glucose & beta glucose

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11
Q

What’s the difference between alpha and beta glucose?

A

Alpha glucose- OH group (hydroxyl group) is below the ring

Beta glucose- OH group is above the ring

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12
Q

What is a similarity between alpha and beta glucose?

A

In both isomers of glucose carbon 1 is bonded to the hydroxyl group (OH)

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13
Q

What are the important points about the reaction of 2 monosaccharides forming a disaccharide?

A
  1. When we react two alpha glucose the disaccharide we form is called a maltose
  2. When a disaccharide is formed a water molecule is produced- because a water molecule is formed scientist call this a condensation
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14
Q

How is a water molecule formed?

A

Formed from a hydrogen atom from one monosaccharides and a hydroxyl group from the other

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15
Q

What happens if we add water to a disaccharide?

A

-the glycosidic bond is broken

This converts the disaccharide back into the original monosaccharide- this is called a hydrolysis reaction

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16
Q

In cells what carrys out hydrolysis reaction?

A

Enzymes

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17
Q

What monosaccharides is sucrose formed from?

A

Glucose and fructose

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18
Q

What monosaccharide is lactose formed from?

A

Glucose and galactose.

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19
Q

What is monomer?

A

Monomers are small, basic molecular units that form polymers

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20
Q

What is a polymer?

A

Polymers are large, complex molecules composed of long chains of monomers joined together

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21
Q

When drawing disaccharide how do you draw the glycosidic bond correctly?

A

-You put the OH group from one monosaccharide and the HO group from one monosaccharide side by side

  • Then you take out the H20 and the reaming is the glycosidic bond
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22
Q

What are real life uses of food test?

A
  • test plants for start to see if they’ve carried out photosynthesis
  • test urine for protein to diagnose kidney problems
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23
Q

What safety precautions should be taken out during food test?

A

Wear safety goggles as many chemicals are used

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24
Q

How do we prepare the food samples?

A
  1. Grind the food with a small amount of distilled water in a mortar and pestle, then once it’s a paste we add more distilled water & stir
  2. A problem is that the paste is gonna contain solid food particles and these could make the food tests difficult to see sp we filter the fixture to remove the food particles so we test on the filtrate-solution that passes through the filter
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25
Q

How do we carry out the test for starch?

A
  1. Place 3cm^3 of our food test into a test tube.
  2. Add 1cm of a solution containing iodine and potassium iodide solution
  3. A positive test would be the sample turning a blue-black colour, a negative test would be the iodide solution turning orange
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26
Q

How do we test for the presence of proteins?

A
  1. Place 3cm of the food test solution into a test tube
  2. Add 3cm^3 of dilute sodium hydroxide solution and mix
  3. Add 10 drops of dilute copper (II) sulfate solution and mix
    • result= purple/ lilac
      • result= remain blue
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27
Q

How do we test for lipids?

A
  1. The food sample can’t be filtered cause it’ll stick to the filter paper- so leave for a while for particles to settle
  2. Then add 3cm^3 of the food sample
  3. Add 3cm^3 of ethanol acid and 3cm^3 of water
  4. Shake solution
  5. +white emulsion
  • is the solution staying clear
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28
Q

What do you have to be careful about when testing for lipids?

A

-don’t do the test near flames ethanol is highly flammable

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29
Q

What is a reducing sugar?

A

A reducing sugar can donate an electron to another molecule

(All monosaccharides are reducing sugars)

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30
Q

How do you test for a reducing sugar?

A
  1. We add 3cm^3 of our food sample into a boiling tube
  2. Then add 3cm^3 of Benedict’s solution to the test tube and place it in a beaker of boiling water and leave for 5 minutes
  3. Negative result= blue

4.bendices solution constrains copper 2+ ions (what makes it blue) so if the test if a reducing sugar is present an electron is added to the ion (forming a copper + ion) forming a red precipitate.

  1. Small amount of reducing sugar= green solution, large levels= brick red
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31
Q

Why is the Benedict’s test semi quantitative?

A

Because the colour change gives an aproximate estimation of the amount of reducing sugars present

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32
Q

What’s the key thing we have to do when testing for non reducing sugars?

A

-we have to break the glycolic bond, releasing the monosaccharides because all monosaccharides are reducing sugars, so we can test them for them first using Benedict solution

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33
Q

How do we test for non reducing sugars?

A
  1. Test for reducing sugars first normally and If the solution stays blue it’s negative and the reducing sugar is not present.
  2. Then get a new sample and add 1cm^3 of Hydrochloric acid. Then heat in a boiling water bath for 5 minutes
  3. Then we have to neutralise the mixture using sodium carbonate solution.
  4. Then add Benedict’s solution, if it stays blue no reducing or non reducing sugars are present but if it turns brick red a non reducing sugar is present .
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34
Q

What are the functions of lipids?

A
  1. Major energy source
  2. Stores energy
  3. They are used for water proofing

4.major part of the structure membranes

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35
Q

What are the two groups of lipids?

A

Triglycerides & phospholipids

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36
Q

What do triglycerides consist of?

A

Consists of a glycerol molecule bonded to 3 fatty acid molecules

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37
Q

What do we call the tail of fatty acids?

A

A hydrocarbon tail because it’s made up of only carbon and hydrogen bonded to a carboxylic group

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38
Q

What is the function of starch?

A

It’s a storage polymer of glucose in plants,

  • when plants need glucose they break down starch to release it
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39
Q

What is starch made up of?

A

It’s made up of 2 polysaccharides:

-Amylose

  • Amylopectin
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40
Q

Describe the structure of amylose?

A
  • Amylose is long, unbranched chain of alpha glucose- which are formed from condensation

-It has a shape of a compact cylinder due to the angles of the glycosidic bonds and it had hydrogen bonds forming between glucose molecules to help hold its structure.

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41
Q

How does amylose having a compact cylinder shape relate to its function?

A
  • the cylinder shape makes it compact so it’s really good for storage as you can fit more into a small space
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42
Q

Describe the structure of amylopectin?

A
  • it’s a long, branched chain of alpha glucose

~The side branches are connected to the main chain by a glycosidic bind

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43
Q

How does the structure of amylopectin relate to its function?

A

The side branches allow the enzymes that break down starch to get at the glycosidic bond easily, this means the glucose can be released quickly

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44
Q

How does the structure of starch relate to its function?

A

-Starch is insoluble in water and doesn’t effect the water potential, this means starch doesn’t cause water to enter the cell by osmosis- so they don’t swell

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45
Q

What is the function of glycogen?

A

Glycogen is the storage molecule of glucose made up of alpha glucose- it’s stores excess glucose as glycogen

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46
Q

Describe the structure of glycogen?

A

It’s a polymer of alpha glucose and also has branches (more branches than amylopectin)

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47
Q

How does glycogens structure relate to its function?

A

Because glycogen has a lot of branches it has a lot of free ends, this means that enzymes can convert glycogen back to glucose very rapidly- this is important because the energy needs of animals can change very quickly

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48
Q

What makes glycogen an ideal glucose storage molecule in animals?

A

-glycogen is Insoluble in water, this means glycogen does not draw water into cells by osmosis

-cannot diffuse out of a cell

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49
Q

What is key about cellulose structure?

A

Every second beta glucose molecule is flipped

50
Q

Describe the structure of cellulose?

A

Cellulose is made of long, unbranched chains of BETA glucose.

When the beta molecules bond they form straight cellulose chains that are linked together by hydrogen bonds- creates strong fibres called microfibrils

51
Q

How does celluloses structure relate to its function?

A

-the strong microfibrils gives it strength which allows it to provide structural support for cells

52
Q

How does cellulose provides support for plant cells

A

When water moves in by osmosis the plant cell contents push outwards against the cell wall

-but the strength of the cellulose cell wall means that it can resist the outwards pressure due to the cell contents- preventing the cell from bursting

53
Q

What is a saturated fatty acid?

A

They are fatty acids that only contain one single bond between the carbon atoms

54
Q

What is an unsaturated fatty acid?

A

It’s when there is a double covalent carbon to carbon bond in the hydrocarbon tail

55
Q

What are proteins made from?

A

Proteins are made up of monomers of amino acids

56
Q

What are amino acid?

A

Amino acids are monomers which join together to form proteins.

57
Q

What are the key structures which every amino acid contains?

A
  • a carboxylic group (-COOH)
  • an amine group (-NH2)
  • a carbon containing “r” group what is attached to a carbon atom (they are different for every protein)
58
Q

What is a peptide bond?

A

It’s the bond formed between 2 amino acids

59
Q

How is a peptide formed?

A
  • it’s when the OH group from amino acid 1 & H from amino acid 2 are bonded together and a molecule of water is released
  • a peptide bond is formed
60
Q

What is a polypeptide?

A

It’s when three or more amino acids are bonded together

61
Q

How do you break a peptide bond?

A

We add water which breaks the bond- this is called hydrolysis

62
Q

What is a dipeptide?

A

It’s when 2 amino acids bond together

63
Q

What is the primary structure?

A

This is the specific order of amino acids in a polypeptide.

64
Q

Why is the primary structure important for the proteins function?

A

-the primary structure helps determine the final three demencial shape of the protein molecules

-and the shape of a protein is critical for its function.

65
Q

What is the primary structure of a polypeptide determined by?

A

The primary structure of a polypeptide is determined by the DNA structure of the gene which encodes that polypeptide

66
Q

What is the secondary structure?

A

It’s the folding of the polypeptide chain into either alpha helix or beta pleated sheets due to hydrogen bonds forming between the amino acids in the chain

67
Q

What’s an example of a protein with a secondary structure?

A

Keratin- found in the hair and nails- it’s made up of fibres wrapped round each other, providing it with strength so it’s can’t break easily e.g: the nails

68
Q

What is the tertiary structure?

A

It’s the final 3 dimensional shape of a protein with one polypeptide chain.

(They determine the function of proteins)

69
Q

How is the tertiary structure formed?

A

It’s formed form the secondary structure being folded further and further, then more bonds such (as ionic and hydrogen) are created between positive and negative attractions on different parts of the molecule.

Sometimes form disulfide bridges when cysteine and two molecules of amino acids come close together

70
Q

What is the quaternary structure?

A

The quarternary structure is the final 3 dimensional shape for proteins with more than one polypeptide chain

71
Q

Where do the bonds form in proteins?

A

Between the “R” groups of the amino acid on a polypeptide chain.

72
Q

What are the main bonds that form in the tertiary structure of a protein?

A

Hydrogen bonds, ionic bonds and disulfide bonds

73
Q

What type of “r” groups do hydrogen form between?

A

Forms between “R” groups that contain hydroxyl groups

74
Q

What is a property of hydrogen bonds?

A

-They are weak

-easily broken by high temperatures and changes in pH

75
Q

How are hydrogen bonds important to proteins?

A

They contribute to the 3D shape of the protein

76
Q

Where are ionic bonds in the tertiary structure of proteins found?

A

Found between amino acids with opposite charged “R” groups

77
Q

What is the function of the ionic bond found in the tertiary structure of proteins?

A

Holds different polypeptides together and contributes to the final 3D shape

78
Q

What are disulfide bonds formed from between in the tertiary structure of a protein?

A

Formed from two amino acids called cystine which contain sulfur atoms which then form covalent bonds= disulfide bonds

79
Q

What is a property of disulfide bonds?

A

They are strong and not broken by high temperatures or pH changes

80
Q

Describe the structure and function of globular proteins?

A

-spherical and compact

  • have a hydrophilic r group on the amino acids on the surface- attracted to water= globular proteins are soluble

-involved in metabolic reactions e.g: enzymes & haemoglobin

81
Q

Describe the structure and function of fibrous proteins?

A

-can form long chains or fibres

  • insoluble in water
  • useful for structure and support
    E.g: collagen in the skin
82
Q

What are enzymes?

A

-Enzymes speed up chemical reactions by acting as a biological catalyst.

-they catalyse metabolic reactions at cellular level (e.g: respiration) and for organisms as a whole (e.g: digestion in mammals)

-enzymes are proteins. They have an active site which has a specific specific shape

-the active site is the part of an enzyme which the substrate molecule binds to.

83
Q

What is an enzyme- substrate complex?

A

It’s a molecule formed when the substrate fits into the enzymes active site

84
Q

Explain the lock and key theory?

A

-The substrate and enzyme have a complimentary shape

  • a enzyme substrate complex was formed

-products were released

  • the enzyme was unchanged
85
Q

Explain the induced fit model?

A

-shape of the active site isn’t directly complementary to the substrate

  • the shape of active site changes this then enables the enzyme- substrate complex to form

-this puts a strain on the substrate bonds, lowering the activation energy

86
Q

How have the models of enzyme action changed?

A

-originally scientist thought the substrate only had to have a complimentary shape to the active site

  • induced fit model- enzyme also has to make the active site change shape in the right way as well and the substrate complex changes shape slightly to complete the fit
87
Q

Name 5 factors that affects the rate of enzyme controlled reactions?

A

-enzyme concentration

  • substrate concentration
  • concentration of inhibitors

-pH

  • temperature
88
Q

How does substrate concentration affect the rate of reaction?

A

-Higher the substrate concentration the faster the reaction= more substrate molecules means a collision between substrate and enzyme is more likely so more active sites will be occupied

  • this is true until a saturation point= so many substrate molecules that the enzyme can occupy so adding more makes no difference
89
Q

How does enzyme concentration affect the rate of reaction?

A

-The more enzyme molecules there the more likely a substrate molecule is to collide with one and form a enzyme-substrate complex= increases rate of reaction

  • but if the amount of substrate is limited there comes a point where there enough enzyme molecules to deal with all the available substrate so adding more will have no effect
90
Q

How does temperature have an affect of the reaction?

A

Rate increases as the temperature does because the kinetic energy of the substrate molecules increase, increasing the collisions, so this makes them more likely to collide and bind to an active site

  • but if the temperature gets to high the reaction stops as the increasing temp makes the enzymes vibrate, above a certain point these vibrations begin to break the bonds holding the enzyme in shape. At this point the enzyme is denatured and it no longer functions as a catalyst
91
Q

How does pH affect the rate of reaction in enzyme controlled reactions?

A

All enzymes have an optimum pH value. Above and below the optimum pH the H+ ions and the OH- ions found in acids and alkalis can disrupt the ionic bonds that hold the enzymes tertiary structure in place- the enzyme becomes denatured and the active site changes shape.

92
Q

What is the affect of the concentration of a competitive inhibitor on an enzyme controlled reaction?

A

The rate of reaction decreases because the inhibitor takes up all the active site and hardly any of the substrate will bind to the active site. But if there is a higher concern trato on of substrate then the substrates chances of getting to active site before the inhibitor increase= increase rate of reaction to a certain point

93
Q

What is effect of the concentration of non-competitive inhibitors on an enzyme controlled reaction?

A

Has little effect because they don’t compete with the substrate but they bind to the enzyme away form the active site (so increasing substrate concentration has little effect)- this causes the enzyme to change shape so the substrate molecules no longer fits inhibiting enzyme activity.

94
Q

What are the main parts of DNA

A

-phosphate group

  • pentose sugar
  • nitrogen containing base
95
Q

Name the pentose sugars in DNA and RNA?

A

DNA- deoxyribose

RNA- ribose

96
Q

State the role of DNA in living organisms?

A

Used to store genetic information which determines inherited characteristics= influences the function and structure of organisms

97
Q

State the role of RNA in living cells?

A

It’s main role is to transfer gentecilla information from the the DNA to the ribosomes. Here the ribosomes read the RNA to make polypeptides (proteins)

98
Q

How do polynucleotides form?

A

Condensation reaction takes place between nucleotides to form strong phosphodiester bonds (consisting of a phosphate group and sugars) = sugar-phosphate backbone

99
Q

Describe the structure of DNA?

A

-Double helix of 2 polynucleotide strands

-hydrogen bonds formed between complimentary purine and pyrimidine base pairs on opposite strands:

A-T
G-C

100
Q

What bases are purine and which are pyrimdine?

A

A&G= 2 ring purine bases

T & C & U= 1 ring pyrimdine bases

101
Q

Name the complimentary base pairs for DNA

A

2- hydrogen bonds

Adenine + thymine

3-hydrogen bonds

Guanine + cystosine

102
Q

Name the complimentary base pairs for RNA?

A

2 hydrogen bonds between

Adenine + uracil

3 hydrogen bonds between

Guanine + cysostine

103
Q

Relate the function of DNA to its structure?

A

Sugar phosphate backbone gives it a stable structure= rarely mutates which allows the DNA to pass information form one generation to another with little change

Two separate strands bonded by hydrogen bonds= allows strands to separate during DNA replication & protein synthesis

Large molecule = carry a lot of information

Base paring= allows DNA to replicate and transfer information to the RNA

104
Q

Describe the structure of RNA?

A

Long ribose polynucleotide (shorter than DNA)

Single stranded and linear (no base pairing)

Contains uracil instead of thymine

105
Q

Why is DNA replication described as semiconservative?

A
  • because half of the strands in each new DNA molecule are from the original DNA molecule

DNA= 1 old strand & 1 new strand

106
Q

Describe semi conservative DNA replication?

A
  1. DNA helicase breaks H bonds between base pairs- causing helix to unwind and form two single strands
  2. Each strand acts as a template for a new strand
  3. Free nucleotides from nuclear sap are attracted to their complementary exposed base
  4. DNA polymerase catalyses reaction a condensation reaction and joins the two strand of nucleotides together by forming hydrogen bonds between them.
107
Q

Describe l the meleson- stahl experiment?

A

-bacteria were grown in a medium containing isotope 15N for many generations

  • some bacteria were moved to a medium containing light isotope 14N. Samples were extracted after 1 & 2 cycles of DNA replication
  • centrifugation formed a pellet - heavier DNA (bases made from 15N) settled closer to the bottom of the tube whilst 14 N was above it
108
Q

Describe the structure of ATP?

A

It’s made from the nucleotide base adenine, combined with a Ribose sugar and three phosphate groups

109
Q

Give a property of ATP?

A

-It takes a small amount of energy to break the covalent bond holding the last phosphate group in place, but when it is broken a large amount of energy is released, but water is required= hydrolysis

110
Q

What is the equation for ATP being used/ condensation?

A

ATP+water-> ADP + Pi + energy

-The products are adenosine diphosphate and a phosphate group

  • the reaction is catalysed by ATP synthesis
111
Q

What does it mean if ATP is an immediate energy source?

A

It’s transfers energy from sites of respiration to the parts of the cells that require energy

112
Q

Show how energy is released?

A

ADP + Pi -> ATP + water

-The phosphate group released from condensation is recycled back to form ATP= phosphorylation

-Catalysed by ATP hydrolase

-water is released= condensation

113
Q

How are triglycerides formed?

A

Condensation reaction between 1 molecule of glycerol & 3 fatty acids forming ester bonds

114
Q

Which part of phospholipid is hydrophobic?

A

Phospholipid= hydrophilic head and hydrophobic tail

115
Q

What part of triglycerides are hydrophobic?

A

The whole molecule

116
Q

Why is a water molecule polar?

A

Because the shared negative electrons are pulled towards the oxygen atom, the other side of each hydrogen atom is left with a slight positive charge. The unshared negative electrons on the oxygen atom has a slight partial negative charge- making it polar.

117
Q

Give a function of the ion Fe+?

A

It’s in haemoglobin what transports oxygen around the body

Fe+ binds to oxygen and temporary turns into Fe+3 until oxygen is released

118
Q

Give a function of hydrogen ions?

A

Hydrogen ions are used to calculate pH

The more hydrogen ions= lower pH

119
Q

Give a function of Na+ ions?

A

-Na+ ions help a molecule of glucose or amino acid be transported into a cell across a membrane with a Na+ ion

120
Q

Give a function of a phosphate ions?

A

A phosphate group in DNA and RNA allow nucleotides to join up and form polynucleotides

121
Q

Why are nucleotides added in a 5’ to 3’ direction?

A

Because DNA polymerase attaches to the OH group on one strand of the nucleotide and moves from 3’ to 5’ but it synthesises it from 5’ to 3’ because the active site of DNA polymerase is complementary to the OH group on the pentose sugar at the end of 5’

Yr 12 Biology (8 decks)

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