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Biological Molecules Flashcards

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1
Q

What is an electrolyte?

A

An ion in solution

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2
Q

What are 2 things calcium ions are necessary for?

A

Nerve impulse transmission

Muscle Contraction

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3
Q

What are the 2 things sodium ions are necessary for?

A

Nerve impulse transmission

Kidney Function

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4
Q

What are the 2 things potassium ions are necessary for?

A

Nerve impulse transmission

Stomatal opening

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5
Q

What are the 2 things hydrogen ions are necessary for?

A

Catalysis of reactions

pH determination

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6
Q

What is the key thing ammonium ions are necessary for?

A

Production of nitrate ions by bacteria

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7
Q

What is the key thing nitrate ions are needed for?

A

Nitrogen supply to plants for amino acid and protein formation

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8
Q

What is the key thing hydrogen carbonate ions are needed for?

A

Blood pH regulation

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9
Q

What is the key thing chloride ions are needed for?

A

Balance positive charge of sodium and potassium ions within cells

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10
Q

What are the 3 things phosphate ions are needed for?

A

Cell membrane formation
Nucleic acid and ATP formation
Bone formation

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11
Q

What 2 things are hydroxyl ions needed for?

A

Catalysis of reactions

pH determination

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12
Q

What elements are present in carbohydrates?

A

Carbon, Hydrogen, Oxygen

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13
Q

What elements are present in lipids?

A

Carbon, Hydrogen, Oxygen

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14
Q

What elements are present in proteins?

A

Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur

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15
Q

What elements are present in nucleic acids?

A

Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus

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16
Q

What are polymers?

A

Long repeating chains made up of monomers

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17
Q

What does polar mean?

A

Regions of positivity and regions of negativity

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18
Q

What are 3 unusual properties of water?

A

High boiling point
Cohesive
Solid less dense than liquid

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19
Q

What is capillary action?

A

The process of water rising up tubes against the force of gravity

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20
Q

What are the two different types of glucose?

A

Alpha and Beta

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21
Q

What bond is formed when two glucose molecules join together?

A

1,4 Glycosidic Bond

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22
Q

What type of reaction is it when two glucose molecules join together? Why?

A

Condensation reaction, water molecule released

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23
Q

How do you create maltose?

A

Alpha Glucose + Alpha Glucose

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24
Q

How do you create sucrose?

A

Glucose + Fructose

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25
Q

How do you create lactose?

A

Glucose + Galactose

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26
Q

What are pentose monosaccharides?

A

Sugars that contain 5 carbon atoms

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27
Q

What are hexomonosaccharides? Give 3 examples

A

Sugars with 6 carbons, glucose, galactose and fructose

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28
Q

What are hexomonosaccharides? Give 3 examples

A

Sugars with 6 carbons, glucose, galactose and fructose

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29
Q

What bonds are in amylose, what shape does the lead to?

A

1,4 glycosidic

Helix shape

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30
Q

What are the bonds in amylopectin, what shape does this lead to?

A

1,4 and 1,6 glycosidic

Branched monomer

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31
Q

What is the equivalent of starch in animals and fungi?

A

Glycogen

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32
Q

Does amylose or amylopectin release glucose faster, why?

A

Amylopectin, branching leads to more exposed bonds and so is broken down more easily and quickly

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33
Q

Describe solubility of amylopectin and glycogen

A

Insoluble

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34
Q

How is glucose released for respiration?

A

Hydrolysis reactions, breakdown using water into constituent monomers

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35
Q

How does cellulose form?

A

When alternate beta glucose molecules flip 180 so that 1-4 glycosidic bonds can form

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36
Q

What is the shape of cellulose?

A

Straight chain molecule

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37
Q

List process of building up from cellulose to cell walls

A 
Cellulose,
Hydrogen bonds form,
Microfibrils
Macrofibrils
Cell walls
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38
Q

How is cellulose important to humans?

A

Provides roughage as part of diet as it is hard to break down

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39
Q

What is the Benedict’s test for and what is it?

A

Reducing sugars, copper sulfate

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40
Q

Explain in 3 steps the Benedict’s reagent test

A

1) Place sample in boiling tube, if not liquid grind and add water
2) Add equal volume of Benedict’s reagent
3) Heat mixture gently in boiling water Bath for 5 minutes

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41
Q

Explain the chemical reaction occurring in a Benedict’s test

A

Cu 2+ ions react with the reducing sugars, this adds electrons. Cu2+ is reduced to Cu+ forming a red precipitate

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42
Q

What is the positive test for the Benedict’s reagent?

A

Brick-Red precipitate

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43
Q

Why does the colour of the solution vary on volume of Benedict’s solution?

A

The more reducing sugar present, the more precipitate will be formed because less Cu2+ ions are left in solution, so creating a deeper red colour.

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44
Q

What are 3 main colours seen during the Benedict’s test? What do they indicate?

A

Green- low concentration of reducing sugar
Yellow- medium concentration of reducing sugar
Red- high concentration of reducing sugar

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45
Q

Is the Benedict’s test qualitative or quantitative?

A

Qualitative

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46
Q

What is the extra step required in the Benedict’s test for non-reducing sugars?

A

The non-reducing sugar is boiled in hydrochloride acid to hydrolyse into two constituent monomers which are reducing sugars

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47
Q

What is the colour change(from and to) in the iodine test?

A

Yellow/Brown to purple/black

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48
Q

What does the iodine test test for?

A

Starch

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49
Q

Explain the method for the iodine test for starch

A 
Iodine solution(potassium iodide) added to sample 
Wait for colour change
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50
Q

What are reagent strips used to test for? Why is it beneficial?

A

Reducing sugars, use of a colour coded chart the concentration of sugar can be determined

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51
Q

What is a colorimeter?

A

A piece of equipment used to quantitatively measure absorbance, transmission or light by a coloured solution

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52
Q

Discuss the polarity of lipids, explain why it is this way

A

Non-polar molecules
Elections in outer orbitals distributed more evenly
No positive or negative areas so non- polar

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53
Q

What type of molecule is a lipid? Explain what this term means

A

Macromolecules

Large complex molecule built from monomers

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54
Q

What is a triglyceride made of?

A

One glycerol molecule, 3 fatty acids

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55
Q

What group of molecules do fatty acids belong to? Why?

A

Carboxylic acids. Have a -COOH group with a hydrocarbon chain

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56
Q

What is an esterification reaction?

A

Hydroxyl groups on glycerol and fatty acids interact.
3 water molecules are produced
Ester bonds for between glycerol and fatty acid

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57
Q

How do you break a triglyceride down?

A

Hydrolysis reaction using 3 water molecules

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58
Q

What is a saturated fatty acid?

A

Fatty acid chains which contain no double bonds present between carbon atoms, all carbons are taken up with max number of hydrogens

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59
Q

What is an unsaturated fatty acid?

A

A fatty acid with double bonds between some of the carbon atoms

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60
Q

What is the result of an unsaturated fatty acid?

A

Causes kinks in the molecule
Cannot pack so closely
Liquid at room temp rather than solid

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61
Q

What lipid do plants contain?

A

Unsaturated triglycerides

62
Q

What is a phospholipid made from?

A

2 fatty acids, glycerol and a phosphate group

63
Q

Explain the hydrophilic/hydrophobic nature of a phospholipid bilayer

A

Due to its length the phospholipid bilayer has a hydrophobic tail and a hydrophilic head

64
Q

Why is a phospholipid called a surfactant?

A

Forms a layer on the surface of the water with phosphate heads in the water and fatty acid tails sticking out of the water

65
Q

What is the structure of a sterol?

A

4 ring carbons structure with a hydroxyl group on the end

66
Q

How do sterols have a dual hydrophobic/ hydrophilic nature?

A

Hydroxyl group is polar so hydrophilic, rest of molecule is hydrophobic

67
Q

What type of molecule is cholesterol? What is its function?

A

Sterol. Adds stability to membranes and regulates their fluidity

68
Q

What are the 4 biological roles of lipids?

A

Membrane formation and creation of hydrophobic barriers
Hormone production
Electrical insulation necessary for impulse transmission
Waterproofing

69
Q

Where are lipids stored within the body?

A

Under the skin and around vital organs

70
Q

What function do lipids provide in the skin and vital organs?

A

Thermal insulation
Cushioning to protect organs
Buoyancy

71
Q

Explain the method for the emulsion test

A

Sample mixed with ethanol
Water added and shaken
White emulsion forms a layer on top- lipid present

72
Q

What is a peptide?

A

A polymer made up from amino acid molecules

73
Q

How many amino acids are found in cells?

A

20 different amino acids

74
Q

How do two proteins synthesise to form a dipeptide?

A

Amine and carboxylic acid groups connected to the central carbon atoms react. The hydroxyl in the carboxylic acid group reacts with hydrogen in amine group to form a peptide bond

75
Q

What catalyses the reaction of a polypeptide being formed?

A

Peptidyl transferase

76
Q

What is the primary structure of the protein?

A

Sequence in which the amino acids are joined. Only involves peptide bonds.

77
Q

What is secondary structure of the amino acid?

A

Hydrogen bonds forming within the amino acid chain, pulling into a specific shape.

78
Q

What are the two shapes that can form during secondary proteins? What does this mean?

A

Alpha helix- hydrogen bonds pull into a coil shape

Beta pleated sheet- polypeptide chains lying parallel to each other with hydrogen bonds between them

79
Q

What is the tertiary structure of a protein?

A

Folding of a protein into its final shape, secondary structure pulls R groups close enough that they can interact.

80
Q

What are hydrophobic hydrophilic interactions?

A

Weak interactions between polar and non-polar R groups

81
Q

What are ionic bonds?

A

Bonds formed between oppositely charged R groups

82
Q

What are disulfide bridges?

A

Covalent bonds that form between R groups that contain sulfur atoms

83
Q

How many amino acids are common in the human body?

A

20

84
Q

How do two peptides join together?

A

Amine and carboxylic acid group connected to central atoms react. Hydroxyl groups of one amino acid reacts with a hydrogen in the amine group.

85
Q

Why type of reaction is it when two peptides react?

A

Condensation

86
Q

What enzyme catalyses reaction of formation of polypeptide chains?

A

Peptidyl transferase

87
Q

What is primary protein structure?

A

The sequence in which the amino acids are joined

88
Q

What bonds are present in the protein structure?

A

Peptide bonds

89
Q

What is the secondary protein structure?

A

The basing repeating structure of amino acids interact and hydrogen bonds are formed within the amino acid chain

90
Q

What two shapes are formed from secondary protein structure? Explain the shapes.

A

Alpha Helix- coil shape of amino acids with hydrogen bonds between the helix
Beta Pleated Sheet- Polypeptide chains lying parallel to each other with hydrogen bonds between

91
Q

What is the tertiary structure?

A

The folding of protein into its final shape. Coiling and folding in secondary brings R groups close enough to interact, holding sections together.

92
Q

What are hydrophobic and hydrophilic interactions?

A

Weak interactions between polar and non-polar R groups

93
Q

What are ionic bonds?

A

Bonds between oppositely charged R groups

94
Q

What are disulfide bridges?

A

Covalent bonds between R groups that contain sulfur atoms

95
Q

What is the quaternary structure?

A

Interaction between 1 or more polypeptide chains

96
Q

How are peptides broken down?

A

Protease enzyme breaks down the peptide into its constituent amino acids

97
Q

Give 3 features of a globular protein

A

Compact
Water Soluble
Spherical

98
Q

When do globular proteins form?

A

Hydrophobic R groups are moved into the middle to be kept around the aqueous environment. So hydrophilic R groups on the outside

99
Q

Why does insulin have to be globular?

A

Hormone involved with the regulation of blood glucose concentration.
Hormones transported in blood stream so needs to be soluble
Hormones have to fit specific receptors on cell surface membranes so need to have precise shape

100
Q

What are conjugated proteins?

A

Globular proteins with a prosthetic group

101
Q

What is a prosthetic group?

A

A non-protein part of a protein

102
Q

Give 4 examples of molecules that make up prosthetic groups

A

Lipids
Carbohydrates
Metal ions
Vitamins

103
Q

Explain the structure of haemoglobin

A

Quaternary protein made up of 4 polypeptide chains, two alpha and two beta subunits, 4 haem groups

104
Q

What does haem contain, and what is its role?

A

Fe II, allows it to combine reversibly with an oxygen molecule

105
Q

What prosthetic group does catalase contain? What does this allow for?

A

Fe II ions, allow catalase to interact with hydrogen peroxide and speed up its breakdown.

106
Q

What are fibrous proteins made from?

A

Long insoluble molecules

107
Q

Give 3 examples of fibrous proteins

A

Keratin, Elastin and Collagen

108
Q

Why do fibrous proteins form?

A

High proportion of amino acids with hydrophobic R groups, and a limited range of amino acids with small R groups

109
Q

What is the structure of a fibrous protein?

A

Strong, long molecules which do not fold into 3D molcules

110
Q

Where is keratin found?

A

Hair, skin and nails

111
Q

What characteristics does keratin have? Why?

A

Strong, Inflexible and Insoluble

Due to high proportion of disulfide bridges which decrease flexibility

112
Q

What is elastin made from?

A

A quaternary protein made of tropoelastin

113
Q

Where are elastic fibres found? Why?

A

Walls of blood vessels and alveoli

Give structures flexibility

114
Q

What is collagen and where is it found?

A

Fibrous protein that is a connective tissue found in skin, tendons, ligaments and the nervous system.

115
Q

Describe the structure of collagen

A

3 polypeptide chains wound in a long strong rope-like structure

116
Q

What are the 2 roles of nucleic acids?

A

Storage and transfer of genetic material

Synthesis of polypeptides

117
Q

What 3 components make up a nucleotide?

A

A pentose monosaccharide
A phosphate group
A nitrogenous base

118
Q

Explain how two nucleotides join together

A

Condensation reaction
Phosphate group on 5th carbon forms a covalent bond (phosphodiester) with hydroxyl group on 3rd carbon of the pentose sugar on adjacent nucleotide

119
Q

What type of bond is formed when two nucleotides join together?

A

Phosphodiester

120
Q

What structure is a polynucleotide said to have?

A

A long strong sugar phosphate backbone with a base attached to each sugar

121
Q

What are pyrimidines? Give 2 examples

A

Small bases which contain one single carbon ring

Thymine and Cytosine

122
Q

What are purines? Give 2 examples

A

Large bases which contain a double carbon ring structure

Adenine and Guanine

123
Q

What does it mean for DNA to be ‘anti parallel’?

A

Each strand has a phosphate group at one end and hydroxyl group at the other. The two strands run in opposite direction.

124
Q

In complementary base pairing, describe which pairs join and how many hydrogen bonds they form

A

Adenine and Thymine- 2 hydrogen bonds

Cytosine and Guanine 3 hydrogen bonds

125
Q

How do the two strands of DNA remain parallel?

A

As a purine always binds to a pyrimidine, so there is a constant distance

126
Q

What are 2 structural differences of RNA to DNA?

A

Ribose rather than deoxyribose

Uracil rather than thymine

127
Q

Explain the 4 steps in semi conservative replication

A

1) DNA helicase causes two strands of DNA to separate
2) Free nucleotides activated are attracted to complementary bases
3) Hydrogen bonds formed between nucleotides and complementary bases
4) DNA polymerase catalyses formation of phosphodiester bonds between adjacent nucleotides.

128
Q

What is semi conservative replication?

A

Two new molecules of DNA produced from one strand. Each one consists of one old strand of DNA and one new strand.

129
Q

What is the role of DNA helicase?

A

Enzyme that travels along DNA backbone, breaking hydrogen bonds between complementary base pairs. ‘Unzipping’ them

130
Q

What is the role of DNA polymerase?

A

Catalyses the formation of phosphodiester bonds between nucleotides

131
Q

What is the genetic code?

A

The sequences of bases in DNA are the ‘instructions’ for the sequences of amino acids in the production of proteins.

132
Q

What is a codon?

A

A sequence of 3 bases coding for 1 amino acid

133
Q

What is a gene?

A

A section of DNA that contains the complete sequence of bases to code or an entire protein

134
Q

What is the most common start protein?

A

Methionine

135
Q

Why is genetic code said to be ‘degenerate’?

A

Many amino acids can be coded for by more than one codon

136
Q

Where does protein synthesis occur?

A

Ribosomes in the cytoplasm

137
Q

What is the process of ‘transcription’?

A

The base sequence of genes being copied and transported on to smaller molecules of RNA so they can move out of the nucelus.

138
Q

What is the sense strand?

A

Strand of DNA that contains the code for the protein to be synthesised
Runs from 5’ to 3’

139
Q

What is the anti-sense strand?

A

Complementary copy to the sense strand

Acts as a template strand so complementary RNA strand formed has the same sequence as the sense strand

140
Q

Explain the process of transcription

A

1) Section of DNA unzips via DNA helicase
2) Free RNA nucleotides pair with complementary bases on anti-sense strand
3) Phosphodiester bonds are formed by RNA polymerase
4) Stops at the end of the gene and mRNA is formed
5) mRNA detaches from DNA template and leaves via nuclear pore

141
Q

What are the two roles of rRNA?

A

Maintaining structural stability

Biochemical role in catalysing reaction

142
Q

What is the process of translation?

A

mRNA binding to a specific site on a small subunit of ribosome
Ribosome holds mRNA in position whilst it is decoded into sequence of amino acids

143
Q

What is an anti codon?

A

A sequences of 3 bases on the tRNA that is complementary to specific codon on mRNA

144
Q

Where is energy supplied from for translation?

A

Hydrolysis of ATP

145
Q

Describe 5 step process of translation

A

1) mRNA binds to ribosome
2) tRNA with specific anticodon and amino acid binds to mRNA
3) another tRNA molecule binds to next complementary codon
4) 1st amino acid binds to 2nd amino acid via peptide bond and peptidyl transferase
5) tRNA leaves mRNA moves along

146
Q

What are the 3 main types of cell activity that require energy?

A

Synthesis
Transport
Movement

147
Q

What is ATP made up of?

A

Adenine, Ribose, 3 phosphate groups

148
Q

What is the process of phosphorylation?

A

Reattaching a phosphate group to a molecule of ADP

149
Q

Explain 5 key properties of ATP

A 
Small
Water Soluble
Contains bonds with phosphates with intermediate energy
Releases energy in small quantities
Easily regenerated
150
Q

How is energy released by cells?

A

ATP converted to ADP, the phosphate ion releases energy

Biology OCR A A level (17 decks)

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