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C3 - Biological molecules Flashcards

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1
Q

What elements are living things primarily made of?

A

Carbon
Hydrogen
Oxygen
Nitrogen
(Sulfur and Phosphorus)

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2
Q

What is a covalent bond?

A

Electrostatic force of attraction between shared pair of electrons and the nuclei of the bonded atoms

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3
Q

What are ionic bonds

A

Electrostatic force of attraction between positive and negative ions

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4
Q

What are calcium ions necessary for?

A

Ca2+
Nerve impulse transmission
Muscle contraction

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5
Q

What are sodium ions necessary for?

A

Na+
Nerve impulse transmission
Kidney function

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6
Q

What are potassium ions necessary for?

A

K+
Nerve impulse transmission
Stomatal opening

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7
Q

What are hydrogen ions necessary for?

A

H+
Catalysis of reactions
pH determination

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8
Q

What are ammonium ions necessary for?

A

NH4 +
Production of nitrate ions by bacteria

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9
Q

What are nitrate ions necessary for?

A

NO3 -
Nitrogen supply to plants for amino acid and protein formation

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10
Q

What are hydrogen carbonate ions necessary for?

A

HCO3 -
Maintenance of blood pH

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11
Q

What are chloride ions necessary for?

A

Cl-
Balance positive charge of sodium and potassium ions in cells

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12
Q

What are phosphate ions necessary for?

A

PO4 3-
Cell membrane formation
Nucleic acid and ATP formation

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13
Q

What are hydroxide ions necessary for?

A

OH-
Catalysis of reactions
pH determination

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14
Q

What elements do carbohydrates contain?

A

C, H, O
Cx(H2O)y

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15
Q

What elements do lipids contain?

A

C, H, O

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16
Q

What elements do proteins contain?

A

C, H, O, N, S

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17
Q

What elements do nucleic acids contain?

A

C, H, O, N, P

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18
Q

What are polymers

A

Long chain molecules composed of multiple individual molecules bonded in a repeating pattern

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19
Q

What are monomers

A

Individual molecules that make up a polymer

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20
Q

What is polar?

A

Uneven charge distribution
Electrons closer to one atom
Forming slight positive and negative dipoles

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21
Q

What’s a hydrogen bond?

A

Bond between NOF and hydrogen

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22
Q

What are the unique characteristics of water

A

-High boiling point
-Ice is less dense than water
-Cohesive
-Adhesive
-High surface tension

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23
Q

What is cohesion

A

Molecules attracted to each other

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24
Q

What is adhesion

A

Molecules attracted to other materials

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25
Q

Is water more cohesive or adhesive

A

Cohesive

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26
Q

What are key roles of water?

A

-Solvent: Polar hydrogen bonds, site for chemical reactions
-Transport medium: Cohesion and adhesions:
-Coolant: Large amounts of energy required to overcome H bonds helps maintain constant temp
-Habitat: due to stability

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27
Q

What are carbohydrates?

A

Organic polymers composed of elements C, H, O
Usually in ratio Cx(H2O)y
Saccharides

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28
Q

What is a monosaccharide

A

Single sugar molecule

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29
Q

What’s a polysaccharide

A

Polymer made up of multiple saccharides

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30
Q

Examples of monosaccharides

A

Glucose
Fructose
Ribose

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31
Q

Examples of polysaccharides

A

Glycogen
Cellulose
Starch

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32
Q

What is a hexose monosaccharide

A

Monosaccharide composed of 6 carbons

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33
Q

What’s glucose

A

Hexose monosaccharide with chemical formula C6H12O6
Product of photosynthesis in plants

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34
Q

Structure of alpha glucose

A
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35
Q

Structure beta glucose

A
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36
Q

Are glucose molecules soluble in water?

A

Yes, due to H bonds

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37
Q

What is a condensation reaction

A

Reaction between two molecules resulting in formation of a larger molecule and release of water molecule

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38
Q

What do two alpha glucose molecules form

A

Maltose
Condensation reaction - removing water molecule
Form 1,4 glycosidic C-O-C bond where to OH groups were

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39
Q

What is lactose made up of

A

Glucose
Galactose

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40
Q

What is sucrose made up of

A

Fructose and glucose

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41
Q

What is maltose made up of

A

Two alpha glucose

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42
Q

What is a pentose monosaccharide

A

Monosaccharide composed of 5 carbons

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43
Q

Examples of pentose monosaccharides

A

Ribose in RNA
Deoxyribose in DNA

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44
Q

Structure of ribose

A
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45
Q

What is starch?

A

Polysaccharide formed from alpha glucose molecules, joined to form amylose or amylopectin

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46
Q

What is the structure of amylose

A

Alpha glucose joined by 1,4 glycosidic bonds
Glucose twists to form helix, further stabilised by H bonding
Makes it more compact, less soluble (glucose)

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47
Q

What is the structure of amylopectin

A

Alpha glucose joined by 1,4 and 1,6 glycosidic bonds
Branched structure
Highly soluble

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48
Q

Glycogen compared to amylopectin

A

Forms more branches
More compact
Less space needed to store it
(glycogen has a similar structure to amylopectin)

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49
Q

What features does coiling/branching give polysaccharides

A

Compact - good for storage
Many free ends where glucose can be added or removed speeding up rate of reaction

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50
Q

What is a hydrolysis reaction

A

Breakdown of a molecule into two smaller molecules requiring the addition of water molecule

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51
Q

How does beta glucose join

A

Alternate beta glucose molecules are rotated 180 degrees
Forming cellulose

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52
Q

What are features of cellulose

A

Form H bonds with each other, forming microfibrils, which join to make macrofibrils, which join to make fibres
Fibres are strong and insoluble and used for cell wall

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53
Q

What does a Benedict’s test identify

A

Reducing sugars

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54
Q

What is a reducing sugar?

A

Saccharides that donate electrons resulting in the reduction of another molecule

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55
Q

How is a Benedict’s test carried out?

A

Alkaline solution of copper(II) sulfate
1) Place sample into boiling tube
2) Add equal volume of Alkaline solution of copper(II) sulfate
3) Heat gently in water bath for 5 mins

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56
Q

What are the results of a Benedict’s test

A

Reducing sugars react with Cu2+ ions in reagent
Blue Cu2+ reduced turning them brick red
The more reducing sugar present, the more red precipitate formed

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57
Q

How do you use a Benedict’s test to test for non reducing sugars

A

Non reducing sugars do not react with Benedict’s solution
1) Boiled with HCl first so sucrose is hydrolysed into glucose and fructose
2) Then carry out normal Benedict’s test

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58
Q

What is the most common non-reducing sugar

A

Sucrose

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59
Q

What does an iodine test for

A

Starch

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60
Q

How do you carry out an iodine test?

A

Add few drops of iodine dissolved in potassium iodide solution

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61
Q

What is a positive test result for iodine?

A

Colour change from yellow/brown to blue/black

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62
Q

How else can reducing sugars be tested

A

Reagent strip with colour coded chart signifying concentration

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63
Q

What is a lipid?

A

Non polar macromolecule containing C H O known as fats and oils

64
Q

Are lipids polar

A

No

65
Q

What is a triglyceride

A

Lipid composed of one glycerol molecule and 3 fatty acids

66
Q

Structure of a triglyceride

A
67
Q

What functional group does glycerol belong to

A

Alcohol
-OH

68
Q

What functional group do fatty acids belong to

A

Carboxylic acids
-COOH

69
Q

What bonds form between glycerol and fatty acid

A

Ester bonds
C(=O)-O-
(Condensation reaction)

70
Q

How many water molecules are required for reverse reaction

A

3

71
Q

What is a saturated fatty acid

A

Fatty acids that have no double bonds between carbon atoms

72
Q

What is an unsaturated fatty acids

A

Fatty acids with C=C double bonds

73
Q

What is a monounsaturated fatty acid and a polyunsaturated fatty acid?

A

1 c=c
Or multiple c=c

74
Q

What does the C=C bond do in a fatty acid

A

Causes chain to kink/bend
Not closely packed together
Liquid at room temperature
Oils not fats

75
Q

What are healthier unsaturated or saturated triglycerides

A

Unsaturated

76
Q

What is a phospholipid

A

Modified triglycerides where fatty acid has been replaced with a phosphate group

77
Q

Inorganic phosphate ion formula

A

PO4 3-

78
Q

How many of the fatty acids in triglyceride are replaced with a phosphate group

A

1

79
Q

What is the structure of a phosphlipid

A

Non polar tail - fatty acid chains
-hydrophobic
Polar head - phosphate group
-hydrophilic

80
Q

How do phospholipids interact with water

A

Form layer with hydrophilic phosphate heads in water and hydrophobic fatty acid tails facing inwards/away
Surfactants - surface active agents

Form bilayer

81
Q

What is a sterol

A

Steroid alcohols - complex molecules based on a four carbon ring structure with polar hydrophilic OH group on the end

82
Q

Name an example of a sterol

A

Cholesterol

83
Q

Role of cholesterol in phospholipid bilayer

A

Positioned between phospholipids adding to stability of membrane and regulates fluidity

84
Q

What are roles of lipids

A

-Membrane formation
-Hydrophobic barriers
-Hormone production
-Electrical insulation
-Waterproofing
-Thermal insulation
-Cushioning
-Buoyancy

85
Q

How can you test for lipids

A

Emulsion test
1) sample mixed with ethanol
2) water added and then shaken
If white emulsion forms as a layer on top, lipid is present

86
Q

What is an amino acid?

A

Monomer used to build polypeptides, therefore, proteins

87
Q

What are proteins?

A

One or more polypeptides arranged as a complex macromolecule

88
Q

What causes each amino acid to be different?

A

Different R-groups

89
Q

What is a polypeptide?

A

Chains of three or more amino acids

90
Q

What is the reaction between two amino acids?

A

Condensation reaction
Forming peptide bond
Removes water molecule

91
Q

What enzyme catalyses the condensation reaction between amino acids?

A

Peptidyl transferase

92
Q

What is the primary structure of proteins?

A

-Sequence which the amino acids join
-Peptide bonds

93
Q

What is the secondary structure of proteins

A

O, H and N atoms interact
H bonds form
(can form alpha helix or beta pleated sheet)

94
Q

What is the tertiary structure of proteins?

A

R-groups interact
Hydrophobic/hydrophilic interactions, hydrogen bonds, ionic bonds, disulfide bridges (strongest but only between R-groups containing sulfur)

(protein formed)

95
Q

What is the quaternary structure of proteins?

A

Association of two or more proteins
Hydrophobic/hydrophilic interactions, hydrogen bonds, ionic bonds, disulfide bridges

96
Q

What catalyses the hydrolysis reaction of polypeptides?

A

Protease

97
Q

What are globular proteins?

A

Spherical, water-soluble, compact proteins

98
Q

What makes globular proteins soluble in water?

A

Protein foods into tertiary structure so hydrophobic R groups are kept away from aqueous environment and hydrophilic R groups are on the outside of the protein

99
Q

Give an example and the function of a globular protein

A

Insulin
Hormone involved in regulation of blood glucose conc
Transported in bloodstream so solubility necessary

100
Q

What is a conjugated protein?

A

Globular proteins containing a prosthetic group
3D

101
Q

What is a prosthetic group

A

Non-protein component of a conjugated protein

102
Q

Give an example of a conjugated protein and it’s function

A

Haemoglobin
Red, oxygen-carrying pigment found in rbc
Quaternary protein made from 4 polypeptides (2 alpha, 2 beta subunits)
Each subunit contains 1 harem group
Haem group contains iron II which combine reversibly with oxygen

Catalase
Enzyme that catalyses the breakdown of hydrogen peroxide
Quaternary protein containing 4 haem prosthetic groups

103
Q

What is a fibrous protein?

A

Long, insoluble, structural protein
Not 3D

104
Q

Why are fibrous proteins insoluble

A

High proportion of hydrophobic R-groups
Repetitive amino acid sequence in primary structure

105
Q

Give 3 examples of fibrous proteins

A

Keratin
Elastin
Collagen

106
Q

Describe the function of keratin

A

Group of fibrous proteins
Present in hair, skin, nails
Large proportion of sulfur containing amino acids, leads to many strong disulphide bridges
Results in strong, inflexible, soluble materials

107
Q

Describe the function of elastin

A

Fibrous protein
Found in elastic fibres
Present in wall of blood vessels and alveoli of lungs
Provides structure and flexibility
Quaternary protein

108
Q

Describe the function of collagen

A

Fibrous protein
Connective tissue
Found in skin, tendons, ligaments, nervous system
Consists of 3 polypeptides wound together
Strong, flexible

109
Q

Diagram of haemoglobin

A
110
Q

How can quantitative methods be used when carrying out Benedict’s test

A

Colour produced in Benedict’s test depends on concentration of reducing sugar in sample

1) Filter placed in colorimeter
2) Colorimeter calibrated using distilled water
3) Benedict’s test carried out on known concentrations of glucose
4) Solutions filtered to remove precipitate
5) % transmission of each solution measured
6) Calibration curve plotted
7) Carry out Benedict’s test on unknown solution, filter it and find its % transmission
8) Use calibration curve to find its concentration

111
Q

How do you carry out TLC to separate amino acids?

A

1) Draw a pencil line 2cm from the bottom of the chromatography plate
2) Sample placed in centre of pencil line
4) Plate placed into dish with solvent no more than 1cm deep
5) Plate left in solvent until it’s reached 2cm from top
6) Plate sprayed with ninhydrin which reacts with amino acids to form a purple brown colour

112
Q

Formula for Rf value

A

Distance travelled by component / distance travelled by solvent

113
Q

What is a nucleic acid

A

Large polymer formed from nucleotides
Contain C H O N S

114
Q

What is a nucleotide

A

Monomer used to form nucleic acid
Consists of pentose monosaccharide, phosphate group, nitrogenous base

115
Q

What is a nucleotide made up of?

A

Pentose monosaccharide (sugar)
Inorganic phosphate group (acidic, negatively charged)
Nitrogenous base

116
Q

How do nucleotides bond

A

Phosphodiester bond between phosphate group on carbon 5’ and OH group on carbon 3’

117
Q

What is the sugar-phosphate backbone?

A

Structural component of DNA consisting of alternating deoxyribose sugars and phosphate groups involved in carrying the genetic code.

118
Q

What is DNA

A

Deoxyribonucleic acid
Molecule responsible for the storage of genetic information

119
Q

How are phosphodiester bonds broken down?

A

Hydrolysis

120
Q

How do you differentiate between ribose and deoxyribose

A

Deoxyribose had one fewer oxygen atoms

121
Q

How do DNA bases bond

A

Complimentary base pairing
Adenine to thymine
Cytosine to guanine
(pyramid to purine)

122
Q

What is pyrimidine?

A

Smaller bases, contain single carbon ring
CT

123
Q

What is a purine?

A

Larger bases, contain double ring structures
AG

124
Q

How many H bonds form between adenine and thymine

A

2

125
Q

How many H bonds form between cytosine and guanine

A

3

126
Q

What is the structure of DNA

A

-Two strands of polynucleotides coiled into the DNA double helix
-Two strands held together by hydrogen bonds between bases
-Each strand has a phosphate group (5’) and OH group (3’)
-Strands are antiparallel

127
Q

Why is DNA said to be antiparallel

A

Two parallel polynucleotide strands run in opposite directions

128
Q

What is RNA

A

Ribonucleic acid
Polynucleotide molecule involved in the copying and transfer of genetic information from DNA

129
Q

Why is RNA necessary

A

DNA is too large to leave the nucleus
RNA is smaller so can leave the nucleus

130
Q

Difference between DNA and RNA nucleotides

A

Thymine is replaced with uracil
Ribose sugar instead of deoxyribose sugar

131
Q

What is DNA replication

A

Semi-conservative process of the production of identical copies of DNA molecules

132
Q

How does semi-conservative DNA replication work

A

-DNA helix causes the double helix structure to unwind and separates the two stands
-Hydrogen bonds between complementary bases are broken
-Separates two strands
-Free DNA nucleotides pair with exposed complimentary base pairs
-Hydrogen bonds form between them
-New nucleotides bond to adjacent with phosphodiester bond

133
Q

Why is it called semi conservative replication

A

Each new DNA molecule consists of one old strand and one new strand

134
Q

What is the sense strand

A

Strand of DNA that runs 5’ to 3’ and contains genetic code for a protein

135
Q

What is the anti-sense strand

A

Strand of DNA that runs 3’ to 5’ and is complementary to sense strand
Acts as a template strand during transcription

136
Q

What enzymes are present in DNA replication

A

-DNA helicase: Enzyme that catalyses the unwinding and separating of strands
-DNA polymerase: Enzyme that catalyses the formation of phosphodiester bonds between adjacent nucleotide

137
Q

What is a mutation

A

Change in genetic material that may affect the phenotype of an organism

138
Q

What is a genetic code

A

Sequences of bases in DNA are the instructions for the sequences in amino acids in the production of proteins

139
Q

What is DNA described as

A

-Triplet code: each codon (series of 3 bases) codes for an amino acid
-Degenerate: different codons can code for the same amino acid
-Universal

140
Q

What are the two key stages of protein synthesis?

A

Transcription: Process of copying sections of DNA base sequence to produce mRNA
Translation: Process by which mRNA is decoded by tRNA into sequence of amino acids

141
Q

Describe transcription

A

Sense strand (5’ to 3’) codes for protein
Antisense strand (3’ to 5’) acts as template
Section of DNA coding for gene unzipped by DNA helicase
Complimentary RNA lines up against DNA
Phosphodiester bond form by RNA polymerase forming mRNA
mRNA leaves through nuclear pore
DNA double helix reforms

142
Q

Describe translation

A

mRNA binds to specific site on small subunit of ribosome at its start codon
tRNA with complimentary anticodon binds to mRNA start codon
tRNA carries complimentary amino acid
Repeats
Maximum of 2 tRNA can be bound at a time
First amino is transferred to second tRNA by formation of peptide bond catalysed by peptidyl transferase (rRNA)
Ribosome moves along mRNA releasing first tRNA, second becomes first
Repeated until stop codon reached, polypeptide released
Amino acid sequence forms primary structure

143
Q

What enzyme catalyst is important in translation

A

Peptidyl transferase

144
Q

What is ATP

A

Adenosine triphosphate is a nucleotide composed of a nitrogenous base (adenine), a pentose sugar and three phosphate groups
Universal energy currency for cells

145
Q

What activities do cells require energy for?

A

Synthesis
Transport
Movement

146
Q

Structure of ATP

A
147
Q

How does ATP release energy

A

Small amount of energy needed to break bond between last phosphate group
Large amount if energy released when liberated phosphate undergoes other reactions
Net energy release

148
Q

What type of reaction occurs when phosphate group is removed

A

Hydrolysis

149
Q

Hydrolysis of ATP

A
150
Q

Why is ATP not a good long term energy store?

A

Instability of phosphate bonds in ATP
Rapidly broken down and reformed

151
Q

Hydrolysis of ATP diagram

A
152
Q

What is ADP

A

Adenosine diphosphate is a nucleotide composed of a nitrogenous base (adenine), a pentose sugar and two phosphate groups

153
Q

Properties of ATP

A

Small: moves into and out of cells easily
Water-soluble: energy-req process happen in aqueous environments
Contains bonds between phosphate with immediate energy: large enough for cellular reactions, not too large creating waste
Releases energy in small quantities: suitable to cellular needs, reduces waste
Easily regenerated: can be recharged with energy

153
Q

What is the reverse reaction of hydrolysis of ATP

A

Phosphorylation, condensation reaction

154
Q

What ion is required for hydrolysis of starch by enzyme

A

Cl

155
Q

Most to least soluble out of ribose, amylopectin, amylose, glucose

A

Glucose
Ribose
Amylose
Amylopectin

biology (15 decks)

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