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Biology > Molecules and Cells- Chapter 1 > Flashcards

Molecules and Cells- Chapter 1 Flashcards

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1
Q

What 6 elements are present in the largest proportions in living organisms?

A

Carbon, hydrogen, oxygen, nitrogen, phosphorus an sulphur (1st 3 are the most abundant)

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2
Q

How does most oxygen and hydrogen exist in organisms?

A

As Water

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3
Q

What is an ion?

A

An atom or molecule that have an electrical charge due to the number of protons and electrons not balancing.

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4
Q

What are the 7 Biologically important ions?

A
  • Calcium (Ca2+)
  • Iron (Fe2+)
  • Magnesium (Mg2+)
  • Potassium (K+)
  • Nitrate (NO3-)
  • Phosphate (PO43-)
  • Hydrogen Carbonate (HCO3-)
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5
Q

What is the formula of ions: calcium, iron, magnesium, potassium, nitrate, phosphate and hydrogen carbonate

A

Ca2+, Fe2+, Mg2+, K+, NO3-, PO43-, HCO3-

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6
Q

What is the function of Ca2+ ?

A
  • Calcium pectate is an essential component of middle lamella of plant cell walls
  • Component of bones and teeth
  • Essential in blood clotting and muscle contraction.
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7
Q

What is the function of Fe2+ ?

A
  • In Haem group of haemoglobin

- Constituent of election carriers in respiration

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8
Q

What is the function of Mg2+ ?

A
  • Essential in giving chlorophyll its light-absorbing properties
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9
Q

What is the function of K+ ?

A
  • Maintains electrical gradients across neurons
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10
Q

What is the function of NO3- ?

A
  • A component of amino acids, nucleic acids and chlorophyll.
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11
Q

What is the function of PO43- ?

A
  • As phospholipids, it is the main component of cell membranes.
  • Component of other important biological molecules> ATP and Nucleic acids
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12
Q

What is the function of HCO3- ?

A
  • Important as a natural buffer
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13
Q

Why do atoms of the elements found in living organisms combine?

A
  • To form biologically important molecules linked by strong covalent bonds
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14
Q

Explain the hydrogen bonds in water…

A
  • In a H20 molecule, each hydrogen atoms shares a pair of electrons with the oxygen atom, forming a covalent bond.
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15
Q

Why is water molecule described as being polar?

A
  • As the molecule has an uneven distribution of charge..
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16
Q

Why is water an excellent solvent?

A
  • As it can dissolve a wide range of inorganic and organic substances.
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17
Q

What % of cells does water form in living organisms?

A

Between 50% to over 90%

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18
Q

What 3 points values water as a solvent?

A
  • Most of a cell’s reaction takes place in aqueous solution.
  • Transports medium in living organisms
  • The different effects it has on hydrophilic and hydrophobic molecules.
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19
Q

What does hyrdophilic mean?

A

Water loving

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20
Q

What does hydrophobic mean?

A

Water Hating

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21
Q

What are buffers?

A
  • Chemicals or substances that resist changes to pH and ensure that a particular environment maintains a particular pH
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22
Q

Why are atoms of metals positively charged?

A

As they tend to lose electrons

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23
Q

Why are atoms of non-metals negatively charged?

A

As they tend to gain electrons

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24
Q

What are organic molecules? +examples

A
  • Complex carbon-containing molecules

- E.g- Carbohydrates, proteins and lipids

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25
Q

What are many organic molecules formed of?

A
  • Sub-units called monomers
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26
Q

What do monomers join together to form?

A
  • Larger polymers through the process of polymersation
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27
Q

What charge does hydrogen and oxygen hold in a water molecule?

A

Hydrogren- delta positive

Oxygen- delta negative

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28
Q

What are carbohydrates?

A
  • A group of substances used as both energy sources and structural materials in organisms
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29
Q

What 3 elements do carbs contain?

A

Carbon, hydrogen and oxygen ( C6H12O6)

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30
Q

What is the ratio of hydrogen to oxygen atoms in carbs?

A

2:1

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31
Q

What are monosaccharides?

A
  • These are simple sugars with general formula = ( CH2O)n n=3-7
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32
Q

What are 3 examples of monosaccharides?

A
  • glucose, fructose and galactose.
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33
Q

What are disaccharides?

A
  • These are double sugars formed from 2 monosaccharide monomers
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34
Q

What are 2 examples of disaccharides?

A

-Maltose and sucrose

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35
Q

What are polysaccharides?

A
  • These are large molecules formed from many monosaccharides

- Complex carbohydrates which often form very long chains

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36
Q

What are 3 examples of polysaccharides?

A

-Cellulose, starch and glycogen

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37
Q

What is a hexose monosaccharide?

A

Glucose - C6H12O6

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38
Q

Why are some substances like monosaccharide known as being isomers of eachother?

A
  • As the have the same molecular formula but different structural formula
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39
Q

How are disaccharides formed?

A

-When 2 monosaccharides( hexoses) react together in a chemical reaction known as a condensation reaction

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40
Q

what type of reaction is a condensation reaction and why?

A
  • A reversible Reaction

- As a disaccharide molecule can be broken down into its constituent monosaccharide monomers in a hydrolysis reaction

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41
Q

What happens to the water during condensation?

A
  • 1 molecule of water is lost
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42
Q

What happens to the water during hydrolysis?

A
  • 1 molecule of water is gained
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43
Q

What is a glycosidic bond?

A

-The bond that is formed between 2 hexose sugars in the formation of a disaccharide

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44
Q

What general formula do all disaccharides have?

A
  • C12 H22 O11
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45
Q

How is maltose formed?

A
  • when 2 a-glucose molecules are linked through a condensation reaction.
  • Formed when starch is digested
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46
Q

How is sucrose formed?

A
  • When an a-glucose molecule condenses with fructose molecule.
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47
Q

what does maltose require further digestion to form?

A
  • The monomer glucose
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48
Q

what is sucrose?

A
  • The form in which carbohydrate is transported through phloem in plants
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49
Q

What reaction forms polysaccharides?

A

Condensation reactions joining large number or monomers together to make complex polymers

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50
Q

What is the general formula of polysaccharides?

A

(C6 H10 O5)n

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51
Q

What is starch?

A

a polymer of a-glucose. starch consists of a mixture of 2 types of chains

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52
Q

How are the a-glucose molecules linked in Amylose?

A

by 1,4 glycosidic bonds

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53
Q

What type of bonds does amylose form?

A

As only 1,4 bonds are involved, amylose forms long unbranched chains. Chains are coiled to form a spiral

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54
Q

how much starch is formed form amylose?

A

20%

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55
Q

How does amylopectin link it’s a-glucose monomers together?

A

by a-1,4 glycosidic bonds, + a-1,6 glycosidic bonds form side branches to produce a branched molecule

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56
Q

How much starch is in amylopectin form?

A

80%

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57
Q

what is the benedict’s test used to detect?

A

Reducing sugars

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58
Q

How do you test for reducing sugars?

A

-Add an equal volume if benedict’s reagent to the test solution and heat to atleast 80degrees in water bath

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59
Q

Describe the positive colour change in Benedict’s test..

A

blue-green-yellow-orange-brick red precipitate

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60
Q

Why would the benedict’s test stop at the green or yellow stage?

A

If there’s only a small amount of sugar present

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61
Q

Why is the benedict’s test Semi-quantitative?

A

As it can only approximate quantities

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62
Q

How can a non-reducing sugar be identified by the benedict’s test?

A
  • Test for reducing sugar (negative)
  • The hydrolyse the rest of the sample by heating with dilute hydrochloric acid in water bath
  • Once cooled, neutralise with sodium hydrogencarbonate
  • Test with benedict’s solution(positive)
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63
Q

Why is starch such a good storage molecule?

A
  • Molecules of amylose and amylopectin are very compact (Rich store of glucose in small space)
  • Insoluble
  • Large molecule
  • The branching nature of amylopectin
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64
Q

Why does insoluble make starch a good storage molecule?

A

-It won’t affect the water relations of the cell. If carb were stored as glucose a lot of water would enter by osmosis

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65
Q

How does being a large make starch a good storage molecule?

A

-Can be retained in cell and won’t easily pass through cell membrane

66
Q

How does branching make starch a good storage molecule?

A
  • It creates many terminal ends that are easily hydrolyse
67
Q

Where is glycogen found?

A

The storage carbohydrate found in animal and fungal cells

68
Q

In what form is glycogen stored?

A

Small granules

69
Q

Describe the glycogen structure?

A
  • Similar to amylopectin
  • Formed of chains of a-glucose monomers
  • Has 1,4 and 1,6 glycosidic bonds but chains more branches and shorter
70
Q

Where is glycogen stored?

A

-In liver and muscle cells in mammals

71
Q

What are 3 properties of glycogen?

A
  • compact
  • insoluble
  • proportionally more terminal ends, enabling faster hydrolysis
72
Q

what is the role of cellulose?

A

-Not a storage polysaccharide, it’s rôle is structural

73
Q

What monomers is cellulose made of?

A

B-glucose

74
Q

What occurs when two B-glucose molecules join together?

A

-Form B-1,4 glycosidic bonds, alternate molecules are rotated through 180degrees

75
Q

What 2 effects does the flipping of adjacent glucose monomers have?

A
  • The unbranched chains are straighter

- Hydrogen bonds can form cross-linkages between adjacent chains

76
Q

What are cellulose chains grouped together in?

A

microfibrils

77
Q

What is formed with cellulose microfibrils?

A
  • Plant cell walls.

- Put into many planes in lattice structure to increase its tensile strength

78
Q

Are lipids soluble?

A
  • Not soluble in water (hydrophobic)

- Soluble in organic solvents, ether and ethanol

79
Q

What is a fatty acid made up of?

A

Long hydrocarbon tails linked to a carboxyl group

80
Q

What is the formation of a triglyceride?

A

One glycerol molecules is joined with 3 fatty acid molecules

81
Q

Explain what occurs during the reverse reaction of a triglyceride…

A

Hydrolysis of triglyceride happens during lipid digestion. Uses 3 molecules of water and produces 3 fatty acids and one molecules of glycerol

82
Q

How are the carbon atoms linked in saturated fatty acids?

A

By C-C single bonds

83
Q

How are carbon atoms linked in unsaturated fatty acids?

A

By atleast one C=C double bond

84
Q

What type of fatty acid is it if there’s one double bond?

A

Monounsaturated

85
Q

What type of fatty acid is it when there’s more than one double bond?

A

Polyunsaturated

86
Q

Give two examples of unsaturated fatty acids…

A
  • Oleic acid and linoleic acid
87
Q

Give one example of a saturated fatty acid…

A

Stearic acid

88
Q

What type of fatty acid is fat?

A

Saturated fatty acids

89
Q

What type of fatty acid is oil?

A

Unsaturated hydrocarbon chains

90
Q

Why are triglycerides excellent energy stores?

A

As they release more energy per unit mass than carbohydrate

91
Q

What are the functions of fat?

A

Important for insulation, store in a layer below the body surface in many animals.
- Body organs are protected by a layer of fat

92
Q

What do lipids form?

A

Large molecules (macromolecules) - insoluble

93
Q

What are the 4 main types of lipids?

A
  • Triglycerides, phospholipids, waxes and steroids
94
Q

How are triglycerides formed?

A

Through combination of glycerol and fatty acid molecules

95
Q

Describe the structure of a triglyceride…

A

One glycerol molecule is joined with 3 fatty acids by 3 condensation reactions

96
Q

When does hydrolysis of triglyceride occur?

A

Reverse reaction- During lipid digestion

97
Q

What is used and made during hydrolysis of triglyceride?

A

3 H2O molecules- produces 3 fatty acids and 1 glycerol molecule

98
Q

What 5 elements do proteins contain?

A

Carbon, hydrogen, oxygen, nitrogen and sulfur

99
Q

What are proteins?

A

Large polymers formed from amino acid sub-units

100
Q

How many types of amino acids are there? What does this mean for protein?

A
  • 20

- Infinite number of arrangements in a protein

101
Q

What is the shape of a protein determined by?

A
  • by the sequence of the amino acids in the protein
102
Q

What bonds are amino acids linked by?

A

Peptide bonds

103
Q

What do 2 amino acids joined together form?

A

A dipeptide

104
Q

What is formed when many amino acids join together?

A
  • Polypeptide
105
Q

What 3 elements do lipids contain?

A

-Carbon, hydrogen and oxygen

106
Q

What is the ratio of hydrogen and oxygen in lipids?

A

2:1

107
Q

What is the general formula of glycerol?

A

C3H8O3

108
Q

How is the formation of a triglyceride formed?

A

By 3 condensation reactions

109
Q

what is the state of fats at room temp.?

A

-Solid

110
Q

What is the state of liquids at room temp.?

A
  • Liquid
111
Q

What bond is formed with each condensation reaction in a triglyceride?

A

Ester bond

112
Q

What is the primary structure of a protein?

A
  • The sequence of the amino acids in the polypeptide chain

- usually formed by hundreds of amino acids linked by peptide bonds

113
Q

What 2 groups do the amino acids in a polypeptide contain?

A

-NH and -C=O

114
Q

How is the formation of hydrogen bonds in secondary structure enabled?

A

By the O of the -C=O >négative and H of -NH >positive

115
Q

What are the two most common types if secondary structures?

A
  • a-helix

- B-pleated sheets

116
Q

Where are hydrogen bonds formed in a-helix?

A

-Between amino acids occurring at regular intervals in the sequence.

117
Q

What does the tertiary structure involve?

A
  • The further folding of the secondary structure.

- This gives each protein its unique 3D shape

118
Q

What 4 roles does proteins have

A
  • Structural- Main component of body tissues, muscle, skin, ligaments and hair
  • Catalytic- all enzymes are proteins, catalysing
  • Signalling- Many hormones and receptors are proteins
  • Immunological-all antibodies are proteins
119
Q

What are the four levels of a protein structure…

A
  • Primary
  • Secondary
  • Tertiary
  • Quaternary
120
Q

What 4 types of bonds will hold the tertiary structure in place?

A
  • Ionic bonds
  • Hydrogen Bonds
  • Disulfide bonds (bridges)
  • Hydrophobic interactions
121
Q

Where are hydrophobic interactions found?

A

-Between non-polar sections of a protein

122
Q

Where does a disulfide bond occur?

A
  • Between 2 cysteine amino acids

- One of the strongest and most important bonds

123
Q

What are 3 fibrous proteins?

A
  • Collagen
  • Keratin
  • Silk
124
Q

What is collagen?

A
  • Consists of 3 identical polypeptides.

- The main component of connective tissue like ligaments, tendons and cartilage.

125
Q

Describe the structure of Globular proteins..

A

-A spherical shape caused by tightly folded polypeptide chains

126
Q

Why are the chains folded in Globular proteins?

A
  • So hydrophobic groups are on the inside and hydrophilic groups are on the outside> makes them soluble in water
127
Q

What are 3 examples of globular proteins?

A
  • Transport proteins(haemoglobin)
  • Enzymes( lipase and DNA polymerase)
  • Hormones (Oestrogen and insulin)
128
Q

What does the additional folding of tertiary structure do?

A

Give each protein it’s unique 3D shape and is a consequence of the range of bonds formed between R-Groups of amino acids

129
Q

Describe hydrogen bonds…

A

-Are numerous but weak and easily broken

130
Q

Describe Ionic bonds…

A

-Formed between amino and carboxyl groups in some amino acid R groups ( stronger then H bonds but damaged by change in pH)

131
Q

Describe disulfide bonds…

A
  • Covalent bonds formed between R-groups of sulfur containing amino acids (cysteine)
  • Strong bonds and give strength to structural fibrous proteins like collagen
132
Q

Describe the secondary structure of protein a-helix…

A
  • H2 bonds formed between amino acids.
  • Bonds twist the chain into helical shape.
  • Held by H2 bonds
133
Q

Describe the secondary structure of protein B-pleated sheets…

A
  • More rigid and less flexible
  • Formed by sections of polypeptide chain
  • Orientated in opposite directions lying adjacent to each other
  • Hydrogen bonds form C=O and NH groups
134
Q

What term is used to describe the structure of unsaturated fatty acids?

A
  • A kink
135
Q

Where are lipids stored in?

A
  • Adipose tissue
136
Q

What does the polar nature of the phosphate group in phospholipids mean?

A
  • the ‘head’ end of the phospholipid is attracted to water (hydrophilic)
137
Q

What does the non-polar nature of the fatty acids in a phospholipid mean?

A

-The ‘tail’ end of the phospholipid is repelled by water (hydrophobic)

138
Q

What is the nature of phospholipids?

A
  • Amphipathic, as molecule has both hydrophobic and hydrophilic sections
139
Q

What test tests for lipids?

A
  • Emulsion test
140
Q

Describe the emulsion test:

A
  • Ethanol added to sample
  • Test tube shaken
  • Lipids dissolve in ethanol as non-polar
  • Added to pure water once dissolved >insoluble
  • white cloudy emulsion formed
141
Q

What 3 groups make up an amino acid?

A
  • Amino group
  • Carboxyl group
  • R Group> defines amino acid
142
Q

What is a quaternary structure?

A
  • proteins that have more than one polypeptide chain
143
Q

What is the non-amino acids part called in conjugated proteins?

A

-prosthetic group

144
Q

What are fibrous proteins formed from?

A
  • Parallel polypeptide chains held together by cross-links
145
Q

What are fibrous proteins (3 points)?

A
  • long rope-like fibres
  • Insoluble in water
  • high tensile strength
146
Q

When does a protein become denatured?

A

-If the bonds that maintain the proteins shape are broken the protein will stop working properly

147
Q

What 3 points can denature a protein?

A
  • Changes in temp.
  • pH
  • Salt concentration
148
Q

How do fibrous proteins change when they become denatured?

A

-Lose their structural strength

149
Q

How do globular proteins change when they become denatured?

A

-Insoluble and inactive

150
Q

What test is used to detect proteins (peptide bonds)?

A
  • Biuret Test
151
Q

Describe the stages of the Biuret test…

A
  • A few drops of Biuret reagent, blue copper(II) sulfate (cu2+ ions) and sodium hydroxide are added
  • Shake
  • Solution will change colour in presence of peptide bonds
152
Q

What is the positive colour change in Biuret test?

A

-Blue to Mauve/lilac

153
Q

Why does it turn mauve/lilac when positive?

A
  • Due to the Cu2+ ions bonding to adjacent pairs of -CO-NH- groups in peptide bonds
154
Q

What are prions?

A

A particular type of protein found in mammals and some other animal groups

155
Q

Where are prions found in mammals?

A

Nervous system involved in synaptic transmission

156
Q

What occurs if a disease causing prion is present in an individual?

A

-Acts as a template causing other normal prions to convert. Leads to a chain reaction and disease causing prions increase

157
Q

What is the symbol for normal and disease-causing prions?

A 
Disease= PrPsc
Normal= PrP/ PrPc
158
Q

Describe the structure of disease causing form…

A

Higher proportion of beta pleated sheets

159
Q

What are two key features of disease causing prions?

A

-Replicate and infectious

160
Q

How long is the incubation period for prions?

A

5 to 20 years

161
Q

In what three ways can the disease causing prion increase?

A
  • Normal prion can spontaneously adopt PrPsc form
  • Mutations in DNA codes for prion, disease causing can be passed to offspring
  • Eating contaminated food that contains disease causing form
162
Q

What are the 3 prion diseases?

A
  • Scrapie in sheep
  • Bovine Spongiform encephalopathy (BSE) in cattle
  • Variant Creutzfeldt-Jakob disease- human version by eating contaminated food

Biology (6 decks)

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