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3- Biological Molecules Flashcards

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1
Q

How many bonds can carbon atoms form?

A

4

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2
Q

How many bonds can nitrogen atoms form?

A

3

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3
Q

How many bonds can oxygen atoms form?

A

2

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4
Q

how many bonds can hydrogen atoms form?

A

1

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5
Q

What is the chemical formula of methane?

A

CH4

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6
Q

What is the chemical formula of ammonia?

A

NH3

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7
Q

what 4 key elements are all living things primarily made from?

A

Oxygen
Hydrogen
Carbon
Nitrogen

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8
Q

what are the two elements also have important roles in the biochemistry of cells?

A

phosphorus
sulphur

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9
Q

What happens in ionic bonds?

A

One atom in the pair donates an electron and the other receives it. This forms positive and negative ions that are held together by the attraction of opposite charges

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10
Q

what are ions in solution called?

A

Electrolytes

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11
Q

what are the five cations (+ve ions) that play important roles in organisms

A

Calcium ions - nerve impulse transmission and muscle contraction
Sodium ions -nerve impulse transmission and kidney function
Potassium, ions – nerve impulse, transmission and stomatal opening
Hydrogen ions – catalystis of reactions and pH determination
Ammonium ions (NH4+) - production of nitrate ions

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12
Q

what are the five anions (-ve ions) that play important roles in organisms?

A

Nitrate ions (NO3-) - nitrogen supply the plants for amino acid and protein formation
Hydrogen carbonate ions (HC03-) -maintenance of blood pH
chloride ions (Cl-) - balance positive charge of sodium and potassium ions in cells
Phosphate ions (PO4 3-) - cell membrane formation, nucleic, acid and ATP formation, bone formation
Hydroxide ions (OH-) - catalysis of reactions, pH determination

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13
Q

what is a molecule the gains electrons called

A

negative charge = anion

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14
Q

what is a molecule that loses electrons called

A

positive charge = cation

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15
Q

what elements are present in carbohydrates?

A

Carbon
Hydrogen
Oxygen

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16
Q

What elements are present in lipids?

A

carbon
Hydrogen
Oxygen

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17
Q

what elements are present in proteins?

A

Carbon
Hydrogen
Oxygen
Nitrogen
Sulfur

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18
Q

what elements are present in nucleic acids

A

carbon
Hydrogen
Oxygen
Nitrogen
Phosphorus

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19
Q

What are polymers?

A

long-chain molecules made up by the linking of multiple individual molecules called monomers in a repeating pattern

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20
Q

what is meant by the term polar in relation to molecules?

A

-Molecules that have regions of negativity and regions of positivity
-This is due to the way in which electrons are distributed between elements joined by a covalent bond
-The electrons spend more time closer to one of the atoms then another

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21
Q

How do polar molecules like water interact with eachother?

A

-the positive and negative regions attract each other to form bonds called hydrogen bonds
-these bonds, give water its cohesive properties - it moves as one body because the molecules are attracted to each other
-these bonds also give water its adhesive properties - it’s molecules are attracted to other surfaces

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22
Q

How does hydrogen bonding occur between water molecules?

A

-water = H20
-covalent bond between oxygen and hydrogen atoms
-unequal sharing of electrons
-oxygen has a greater share of electrons in O-H bond
-oxygen is slightly negative, hydrogen is slightly positive

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23
Q

Hydrogen bonds are….

A

-Relatively weak interactions which break and reform between constantly moving water molecules
-Occur in high numbers which give water its unique characteristic that are essential for life on Earth

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24
Q

What are the unique characteristics of water that are essential for life on Earth?

A

-unusually high specific heat capacity (boiling point)
-becomes less dense when it freezes
-cohesive properties
-adhesive properties
-‘skin’ of surface tension
-capillary action

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25
Q

What makes it more difficult for water to become a gas?

A

hydrogen bonding between molecules

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26
Q

Water has a low viscosity. What does this mean?

A

It flows easily

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27
Q

Why is it good that water has a high specific heat capacity?

A

-keeps habitats stable for living things add a lot of energy is required to change it by 1°C

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28
Q

explain how the ‘skin’ of surface tension of water enables a pond skater to inhibit the surface?

A

The skin is because water molecule are more strongly cohesive to each other than air, the skin supports the pond skater

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29
Q

due to water being a liquid at room temperature what four things does this allow it to do?

A

-provide a habitat for living things
-form major component of tissues in living organisms
-provide a reaction medium for chemical reactions
-provide efficient, transport medium

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30
Q

Why is it good that ice is less dense than water?

A

-aquatic animals have a stable environment in which to live throughout winter
-ponds and other bodies of water are insulated against extreme cold

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31
Q

because water is a good solvent what two things?

A

-Acts as a medium for chemical reactions
-Help transport dissolved compounds in and out of a cell

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32
Q

how does water dissolve solutes?

A

-The negative part of water molecules attach to the positive parts of the solutes
-The positive part of water molecules attach to the negative parts of solutes
-this keeps them away from each other eventually dissolving the solute in a solution

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33
Q

why when water freezes does it turn into ice?

A

-it becomes less dense than ice due to hydrogen bonds being formed
-Water is cooled at 4°C because the hydrogen bonds fix the positions of the polar molecules slightly apart from the average distance in liquid state
-This produces a giant, rigid but open structure, with each oxygen atom, at the centre of a tetrahedral arrangement of hydrogen atoms
-Resulting in a solid that is less dense than liquid
-Due to this, ice floats

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34
Q

how is water an efficient transport medium?

A

-cohesive properties between water molecules, when water transported through body, molecules will stick together
-adhesive properties between other molecules (polar)
-effects of adhesion and cohesion result in water exhibiting capillary action
-This is a process by which water can rise up a narrow tube against gravity

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35
Q

why is water being a coolant efficient for life?

A

-Helps to buffer temperature changes during chemical reactions in prokaryotic and eukaryotic cells due to it, taking a large amount of energy to overcome hydrogen bonding
-Important in cellular environments, as enzymes are often only active in narrow temperature ranges

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36
Q

what does a condensation reaction?

A

-Joins two monomers together
-Formation of a covalent bond
-Involves elimination of a water molecule

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37
Q

What is a hydrolysis reaction?

A

-Opposite of a condensation reaction
-Breaks the covalent bond between two monomers
-Water is added to break the chemical bond, involves use of a water molecule 

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38
Q

what covalent bond is created by the joining of carbohydrates, proteins and nucleic acids?

A

Carbohydrates- glycosidic
Proteins- peptide
Nucleic acids- phosphodiester

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39
Q

which enzymes need chlorine and zinc to function correctly?

A

chlorine- amylase
zinc- carbonic anhydrase

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40
Q

what is a single sugar known as?

A

Monosaccharide

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41
Q

what are the monosaccharides of carbohydrates?

A

Glucose
Fructose
Galactose

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42
Q

what are monosaccharides?

A

-Individual sugar molecules that make up disaccharides and polysaccharides
-Glucose, fructose and galactose

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43
Q

What are the two types of sugar molecules?

A

hexose sugars - 6 carbon atoms
Pentose sugars - 5 carbon atoms

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44
Q

What is the structure of glucose?

A

-hexose sugar
-Can form isomers: a-glucose (alpha) and b-glucose (beta)
-C6H12O6
-Carbon ring structure

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45
Q

What is a disaccharide?

A

-formed through condensation reaction
-Two monosaccharides joined together
-Form a glycosidic bond between the two OH groups

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46
Q

what are three examples of disaccharides? What monosaccharides are used to form then?

A

Maltose - glucose + glucose (reducing)
Lactose - glucose + galactose (reducing)
Sucrose - glucose + fructose (non-reducing)

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47
Q

what is a polysaccharide?

A

-Formed when more than two monosaccharides are joined together by condensation reaction
-Can be broken down by hydrolysis into their monomers
-Glycosidic bonds formed
-examples: startch (amylose and amylopectin) , glycogen, cellulose

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48
Q

What are the properties and structure of startch?

A

-made from monosaccharide a-glucose
-Mixture of two polysaccharides: amylose and amylopectin

AMYLOSE
-unbranded chain
-joined by 1,4 gylcosidic bonds
- meaning it is coiled
-coiled = compact, more stored in smaller space, lots of energy stored

AMYLOPECTIN
-long branched chain
-1,6 and 1,4 glycosidic bonds
-branches increase surface area for enzymes to hydrolyse glycosidic bonds allowing glucose to be released quickly
-insoluble

-Strach is insoluble - does not affect cells water potential
-Compact so lots of energy is stored in one place
-Can be hydrolysed to release glucose for respiration
-Easily digestible

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49
Q

how does a-glucose differ from b-glucose?

A

-The hydroxyl groups (OH) on carbon one are in opposite positions (flipped)
-This effects the structure and properties of the polysaccharides when it bonds

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50
Q

Which two pentose sugars are important components of biological molecules?

A

Ribose (in RNA)
Deoxyribose (in DNA)

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51
Q

What are the properties and structure of glycogen?

A

-long branches chains of a-glucose
-lots of side branches
-Joined by 1-4 glycosidic bonds (chains) and 1-6 glycosidic bonds (branches)
-Lots of branches increase surface area for enzymes to hydrolyse bonds and release glucose quickly (during respiration)
-compact and insoluble so good for storage

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52
Q

What are the properties and structure of cellulose?

A

-made of beta glucose
-long unbranded straight chains
-contains 1-4 glycosidic bonds
-Beta glucose molecules bond forming straight cellulose chains
-Every other glucose molecule is orientated 180°
-Chains are linked by hydrogen bonds forming strong fibres called microfibrils (compact)
-Microfibrils are very strong but still flexible allowing them to provide support

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53
Q

What is the function of glycogen?

A

-main energy store in animals
-stores soluble glucose that affects water potential as insoluble polysaccharide until needed

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54
Q

What is the function of cellulose?

A

-Cellulose is an important part of our diet as it is very hard to break down so if the fibre necessary for a healthy digestive system
-Cellulose provides structural support for cells

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55
Q

How is a disaccharide broken down?

A

-hydrolysis reaction
-addition of water to hydrolyse the disaccharide into monomers
-reactions are catalysed by enzymes

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56
Q

How can you tell if a molecule is a reducing sugar?

A

-free OH group at the anomeric carbon

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57
Q

What is the anomeric carbon?

A

Find a carbon which is bonded directly to 2 different oxygen atoms

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58
Q

What is a reducing sugar?

A

-can donate electrons
-reduce another molecule or chemical

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59
Q

Which of the disaccharides are reducing and non-reducing sugars?

A

Maltose - reducing
Lactose - reducing
Sucrose - non-reducing

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60
Q

What is the test for identification of reducing sugars?

A

-Benedict’s test

  1. add 2cm^3 of the same into a boiling tube. (if non liquid, grind it up or blend it in water)
  2. add 2cm^ of Benedict’s reagent
  3. heat the mixture gently in a boiling water bath for five minutes
  4. Record observations

positive result = brick red

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61
Q

What is the test for non-reducing sugars?

A
  1. Add 2cm^3 of the same into a boiling tube
  2. Add 2cm^3 of dilute hydrochloride acid
  3. Place the boiling tube in a water bath for 5 minutes. (the dilute HCl will hydroluse the sample into their constituent monosaccharides)
  4. Neutralise the acid by adding sodium hydrocarbonate until no effervescence is observed (could also use pH paper)
  5. Now add 2cm^3 of benedict’s reagent to the sample
  6. Place in a water bath for 5 minutes
  7. Record your observations

positive result = change from blue to brick red

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62
Q

What is the test for starch?

A

Iodine test

  1. Add a few drops of iodine

positive result = from yellow/brown to purple/back

63
Q

What is benedict’s reagent?

A

An alkaline solution of Copper (II) Sulfate

64
Q

What colour would blue Benedict’s Reagant change is reducing sugars are present?

A

Brick Red

65
Q

Why does Benedict’s Reagant turn red when reducing sugars are present?

A

Because the blue Cu2+ ions have an electron is added to form brick red Cu+ ions

66
Q

What percentage of starch is amylopectin and what percentage is amylose?

A

70-80% amylopectin
20-30% amylose

67
Q

How can you make the Benedict’s test quantative?

A

Use a colorimeter to test the transmission of red light in the soloutions
more reducing sugars = more red light

68
Q

What are 2 examples of biosensors?

A

Pregnancy test, blood sugar monitor

69
Q

What is an analyte in a biosensor?

A

the sample containing the molecule you are testing for

70
Q

What is the receptor in a biosensor?

A

The part which interacts with the molecule you are testing for

71
Q

What is the transducer in a biosensor?

A

Detects the change in the receptor and provides a response

72
Q

What does the display do in a biosensor?

A

Gives a visual representation of the change in the receptor

73
Q

What are biosensors?

A

use biological components to determine the presents and concentration of molecules (such as glucose)

74
Q

What are the two types of lipids?

A

Phospholipids
Triglycerides

75
Q

Are phospholipids polar?

A

Partially
-they have a polar head (phosphate group)
-non-polar tail (fatty acids)

76
Q

What is the difference between fats and oils?

A

-oils are liquids at room temperature, fats are solid

77
Q

What is the structure of a triglyceride?

A

-a glycerol molecule and 3 fatty acids (hydrocarbon chains with a carboxyl group)
-joined by ester bonds (between 3 OH groups and glycerol)

78
Q

Where are triglycerides found in the body?

A

-bloodstream
-adipose tissue

79
Q

Why are triglycerides insoluble in water?

A

Because of their non polar tails

80
Q

What is the structure of a phospholipid?

A

-a glycerol molecule, a phosphate group and 2 carry acid chains
-ester bond between 2 OH groups on the glycerol and OH groups of each fatty acid chain
-bilayer arrangement

81
Q

What is the main use of triglycerides and why?

A

Energy storage because their hydrocarbon tails contain lots of energy released when the fatty acid chains are broken down

82
Q

What is the tests for lipids in food?

A

Emulsion test

83
Q

What result indicates the presence of lipids when using the emulsion test?

A

A milky emulsion forming

84
Q

How would you conduct a test for lipids?

A
  1. Add 2cm^3 of ethanol to the sample
  2. Add 2cm^3 of water and shake gently
  3. observe the appearance of the test tube contents
85
Q

What are the hazards associated with the emulsion test?

A

-ethanol is flammable - do not conduct near naked flame

86
Q

Why can ethanol form emulsions

A

it is not polar

87
Q

Why do unsaturated fats tend to be liquid rather then solid at room temperature?

A

Because the double bonds cause a kick in the hydrocarbon chain so the molecules can’t pack closely together

88
Q

What type of alcohol is cholesterol?

A

A sterol alcohol

89
Q

Where is cholesterol made?

A

Mostly livers and intestine

90
Q

What are saturated fatty acids?

A

-don’t have double bonds between carbon atoms
-has all of its hydrogens

91
Q

What are unsaturated fatty acids?

A

-double bonds between carbon atoms
-fewer hydrogens
-causes a kink/bend
- can contain one (mono) or many (poly) carbon double bonds

92
Q

What is the bilayer arrangement like in phospholipids?

A

-phospholipid heads = hydrophilic
-tails = hydrophobic
-when placed in water form a double layer with heads facing outwards towards the water and tails facing inwards
-centre of bilayer is hydrophobic, water soluble substances cannot easily pass through, creates a barrier + allows separation of solutions and create different conditions either side of membrane

93
Q

What is meant by hydrophobic?

A

Section of molecule which is repulsed by water

94
Q

What is meant by hydrophilic?

A

Section of molecule which is attracted to water

95
Q

What are sterols?

A

-type of lipid found in cells
-complex alcohol molecules based on a four carbon ring structure with a hydroxyl (OH) group at one end
-dual hydrophilic/hydrophobic characteristics like phospholipids

eg. cholesterol

96
Q

What is cholesterol and its function in the body?

A

-primarily manufactures in liver + intestines
-important role in formation of cell membranes, adds stability to cell
-regulates cell fluidity by keeping low temperatures and stopping them becoming too fluid at high temps
-hormones (eg. testosterone, oestrogen, vitamin D) made from cholesterol. Because they are small and hydrophobic they can pass through hydrophobic part of cell membrane

97
Q

What are the roles of lipids?

A

-membrane formation and the farted on of hydrophobic barrie’s
-hormone production
-electrical insulation necessary for impulse transmission
-waterproofing
-energy storage

98
Q

what are the chemical properties of water?

A

-hydrogen bonding, polar molecule
-good solvent

99
Q

What are the monomeric units (monomers) of proteins?

A

Amino Acids

100
Q

How many common amino acids are there?

A

20

101
Q

Give 4 functions of proteins?

A

-enzymes
-hormones
-antibodies
-structural proteins

102
Q

What do the interactions of differing R-groups determine?

A

The types of bond, leading to the folding of the protein

103
Q

What type of reaction occurs when 2 amino acids join?

A

-condensation reaction
-peptide bond forms (between amine group of one and hydroxyl group of another)
-water molecule released and a dipeptide formed

104
Q

What is the general formula of an amino acid?

A

-R group (at top)
-Carbon in the middle
-Hydrogen at the bottom
-Amine group (H2N) on left
-Carboxyl group (COOH) on right

105
Q

What is a chain of amino acids called?

A

A polypeptide

106
Q

What is the end of a polypeptide with an amino group called?

A

The N-terminus

107
Q

What is the end of a polypeptide with an carboxyl group called

A

The C-terminus

108
Q

What is the definition of primary structure of a protein?

A

-the sequence of amino acids in the polypeptide chain
-this contains the initial sequence of amino acids which will influence how the polypeptide folds to give its final shape. This is turn determines its function

109
Q

What type of bonding holds the primary structure of a protein together?

A

Peptide

110
Q

What shape is the primary structure of a protein?

A

Linear

111
Q

What forms the secondary structure of a protein?

A

-the folding of the primary structure

112
Q

What type of bonds hold together the secondary structure of a protein?

A

Hydrogen

113
Q

In the secondary structure what do hydrogen bonds form between?

A

Partially positive H and partially negative O

114
Q

What are the two possible shapes of the secondary structure?

A

-alpha helix
-beta pleated sheets
(caused by the hydrogen bonds pulling it into a shape)

115
Q

What is the tertiary structure of a protein?

A

-interactions of R groups (which are closer together due to folding in the secondary structure) causing further folding

116
Q

What are the 4 types of bond formed at the tertiary structure level?

A

-ionic bonds
-hydrogen bonds
-disulfide bonds
-hydrophobic and hydrophilic reactions

117
Q

What do ionic bonds form between in the tertiary structure of a protein?

A

positively and negatively charged ions (oppositely charged R groups)

118
Q

What do hydrogen bonds form between in the tertiary structure of a protein?

A

Partially positive H and partially negative O (weakest bond)

119
Q

What do disulfide bridges form between in the tertiary structure of a protein?

A

Sulfur atoms contained within some R-groups

120
Q

Which amino acid contain sulfur?

A

Cysteine

121
Q

What do hydrophobic and hydrophilic interactions form between in the tertiary structure of a protein?

A

polar and non-polar R groups

122
Q

What kind of shape does the tertiary structure have?

A

3D

123
Q

What forms the quaternary structure?

A

Formed by the interaction of more than one tertiary protein and/or with prosthetic groups

124
Q

What type of bonds holds a quaternary structure together?

A

-ionic
-hydrogen bonds
-disulfide bridges
-hydrophobic and hydrophilic interactions

125
Q

What is a prosthetic group?

A

A non-protein component of a conjugated protein

126
Q

What is an example of a quaternary protein?

A

-haemoglobin
-Antibodies

127
Q

define simple proteins

A

Proteins without a prosthetic group

128
Q

What are three characteristics of globular proteins?

A

-Compact
-Water soluble
-Roughly spherical shape

129
Q

why are globin proteins water soluble?

A

-tertiary structures are folded so that the hydrophobic R-groups are kept away from aqueous environment
-hydrophilic R-groups are on the outside

130
Q

What are globular proteins used for?

A

-regulating many processes

131
Q

What is an example of a globular protein?

A

Insulin

132
Q

what is insulin? why is it beneficial for insulin to be water soluble?

A

-globular protein
-hormone involved in the regulation of blood glucose concentration
-hormones are transported in the blood stream so must be water soluble

133
Q

what is the structure of insulin?

A

-2 polypeptide chains held together by hydrogen bonds and disulphide bridges
-no beta pleated sheets
-compact
-tertiary structure held together by 3 S-S bonds
-hydrophobic core, hydrophilic exterior

134
Q

Are conjugated proteins a type of globular protein?

A

Yes

135
Q

What are conjugated proteins?

A

globular proteins that contains a non-protein component called a prosthetic group

136
Q

Give an example of 2 conjugated proteins?

A

-haemoglobin
-catalase

137
Q

What is the function of haemoglobin?

A

carries oxygen in the blood in erythrocytes

138
Q

What is the structure of haemoglobin?

A

-made of 4 polypeptide chains (2 alpha-helixes and 2 beta-pleated sheets)
-4 subunits which each contain a prosthetic haem group
-each haem group contains Fe 2+ ion
-iron ions in haem groups can reversibly combine with a molecule of oxygen

139
Q

What is catalase? Its structure and function?

A

-an enyme
-quaternary protein containing 4 haem prosthetic groups
-Fe2+ ions are present which allow catalase to interact with hydrogen peroxide (by product of metabolism which is damaging to cell components if allowed to accumulate) and speed up its breakdown

140
Q

What are fibrous proteins?

A

-long, insoluble, structural proteins
-due to the presence of a high proportion of amino acids with hydrophobic R-groups in their primary structure
-amino acids sequence in primary structure is usually quite repetitive leading to an organised structure, makes strong molecules that do not fold in complex 3D shapes

141
Q

What type of protein is catalase?

A

conjugated (globular)

142
Q

What are examples of fibrous proteins?

A

-collagen
-elastin
-keratin

143
Q

Where is keratin found?

A

in hair, skin, nails

144
Q

what amino acid does keratin contain in a high proportion?

A

cysteine - which contains sulfur

145
Q

What type of bonding occurs a lot in keratin?

A

disulfide bonds/bridges

146
Q

How does the high proportion of disulfide affect the properties of keratin?

A

it makes it inflexible and strong

147
Q

How does the degree of disulfide change in different places where keratin is found?

A

hair = fewer bonds making it less flexible then nails which contain more bonds

148
Q

Where is elastin found?

A

in the walls of blood vessels and alveoli in the lungs

149
Q

What do elastin tissue do?

A

allow structures the flexibility to expand and return to size when needed

150
Q

What makes up elastin?

A

aggregates of tropoelastin (stretchy molecules)

151
Q

Where is collagen found?

A

in the skin, tendons, ligaments and nervous system

152
Q

What is the basic structure of collagen like?

A

-3 polypeptides wound together in a long and strong rope-like structure
-has flexibility
-glycine for every 3rd amino acid as it is the smallest amino acid so allows collagen to pack together more tightly

153
Q

What property does collagen have?

A

flexibility

Biology (11 decks)

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