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AQA A-LEVEL BIOLOGY > Biological Molecules > Flashcards

Biological Molecules Flashcards

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1
Q

Define biological molecules

A

Biologica molecules are particular groups of chemicals that are found in living organisms

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2
Q

Define covalent bonding

A

Atoms share a pair of their electrons in their outer shells . As a result, the outer shell of both atoms is filled and a more stable compound called a molecule is formed

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3
Q

Define ionic bonding

A

Ions with opposite charges attract one another. The electrostatic attraction is known as an ionic bond. Sonic bonds are weaker than covalent bonds.

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4
Q

Define Hydrogen bonding

A

The electrons within a molecule are not evenly distributed but tend to spend more time at one position
This region is more negatively charged than the rest of the molecule
A molecule with an uneven distribution of charge is said to be polarised in other words it is a polar molecule
The negative region of one polarised molecule and positively charged region of another attract each other
A weak electrostatic bond is formed between the two
Although each bond is individually weak they can collectively form important forces that alter the physical properties of molecules - especially true for water

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5
Q

What are polymers?

A

molecule made up of many identical / similar molecules / monomers

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6
Q

What are the monomers of polymers usually based on?

A

Carbon

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7
Q

What are the monomers of polymers usually based on?

A

Carbon

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8
Q

What are examples of monomers that are industrially produced?

A

Polyethene and polyesters

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9
Q

What are examples of monomers that are naturally by using organisms ?

A

Polysaccharides, polypeptides and polynucleotides

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10
Q

What is the basic sub-unit of a polysaccharide ?

A

Monosaccharide or single sugar for example glucose

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11
Q

What are polynucleotides formed from?

A

Mononucleatide sub units

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12
Q

How are polypeptides formed?

A

Polypeptides are formed by linking together peptides that have amino acids as their basic sub unit

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13
Q

Define condensation reactions

A

● 2 molecules join together
● Forming a chemical bond
● Releasing a water molecule

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14
Q

Define hydrolysis

A

● 2 molecules separated
● Breaking a chemical bond
● Using a water molecule

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15
Q

What are examples of monomers ?

A

Monosaccharides amino acids and nucleotides

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16
Q

What are monomers?

A

smaller / repeating molecules from which larger molecules / polymers are made

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17
Q

What is the formula for alpha glucose?

A

C6H12O6

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18
Q

Define monosaccharides

A

Monosaccharides are the monomers from which larger carbohydrates are made

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19
Q

What are common monosaccharides?

A

Glucose galactose and fructose are common monosaccharides

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20
Q

How does a glycosidic bond form?

A

A condensation reaction between two monosaccharides forms a glycosidic bond

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21
Q

Describe disaccharides

A

Made of two monosaccharides joined together by a glycosidic bond and formed by a condensation reaction

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22
Q

What does glucose and glucose ,make?

A

Glucose +glucose—->maltose + water

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23
Q

What are glucose and galactose make ?

A

Glucose + galactose —> lactose +water

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24
Q

What does glucose and fructose make?

A

Glucose +fructose —-> sucrose and water

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25
Q

What are the two isomers of glucose?

A

Two isomers of glucose are alpha and beta glucose

OH group is below carbon 1 in α-glucose
but above carbon 1 in β-glucose

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26
Q

How are polysaccharides formed?

A

Many monosaccharides joined together with glycosidic bonds
● Formed by many condensation reactions, releasing water molecules

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27
Q

How are glycogen and starch formed ?

A

Glycogen and starch are formed by the condensation of alpha glucose

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28
Q

How is cellulose formed ?

A

Cellulose is formed by the condensation of both beta glucose

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29
Q

What monomers makes starch?

A

Alpha glucose

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30
Q

What are the bonds between the monomers of starch?

A

1-4 glycosidic bonds in amylose formed by condensation reactions
1-4 1-6 in amylopectin

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31
Q

What is the function of starch?

A

Energy store in plant cells

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32
Q

Where is starch found?

A

Plant cell eg chloroplast

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33
Q

What is the structure of starch ?

A

Polysaccharide of alpha glucose
Amylose-an unbrancged helix
Amylopectin - a branched molecule
Large

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34
Q

How does the structure of starch relate to the function ?

A

Starch (amylose)
Helical → compact for storage in cell

Large, insoluble polysaccharide molecule → can’t leave cell / cross cell membrane
Insoluble in water → water potential of cell not affected (no osmotic effect)

Amylopectin
Branched → compact / fit more molecules in small area
Branched → more ends for faster hydrolysis → release glucose for respiration to make ATP for energy release
Large, insoluble polysaccharide molecule → can’t leave cell / cross cell membrane
Insoluble in water → water potential of cell not affected (no osmotic effect) And

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35
Q

What monomer is glycogen made from?

A

Alpha glucose

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36
Q

What monomer is glycogen made from?

A

Alpha glucose

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37
Q

What monomer is glycogen made from?

A

Alpha glucose

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38
Q

What are the bonds between the monomers of glycogen ?

A

1-4 and 1-6 glycosidic bonds

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39
Q

Function of glycogen

A

Energy store in animal cells

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40
Q

Where is glycogen found ?

A

Animals (mainly in muscle and liver cells) and bacteria

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41
Q

Structure of glycogen

A

Shorter chains than starch
Highly branched molecule

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42
Q

How does the structure of glycogen link to its function?

A

-branched structure -increase surface area for rapid hydrolysis back to glucose
-insoluble so doesn’t affect water potential and doesn’t diffuse out of cells
-its compact so a lot can be stored in a small space

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43
Q

What monomer is cellulose made from?

A

Beta glucose

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44
Q

What are the bonds between the monomers of cellulose?

A

1-4 glycosidic bonds

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45
Q

What is the function of cellulose ?

A

Structure strength for cell wall

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46
Q

Where is cellulose located?

A

Plant cell wall

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47
Q

Structure of cellulose

A

Polymer forms long straight chains
Chains are held in parallel by many hydrogen bonds to form fibrils

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48
Q

Structure of cellulose

A

Polymer forms long straight chains
Chains are held in parallel by many hydrogen bonds to form fibrils

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49
Q

How does the structure of cellulose link to the function ?

A

Many hydrogen bonds provide collective strength
Insoluble won’t affect water potential
Forms long straight unbranched links

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50
Q

What are nucleic acids?

A

Nucleic acids are a group of the most important molecules of which the best known as ribonucleic and deoxyribonucleic acid

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51
Q

What are nucleic acids?

A

Nucleic acids are a group of the most important molecules of which the best known as ribonucleic and deoxyribonucleic acid

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52
Q

What type of molecules are dna and rna?

A

DNA and rna are important information carrying molecules

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53
Q

Function of dna

A

Holds genetic information
Codes for the sequence of amino acids in the primary structure of protein which in turn determines the final 3-D structure and function of a protein

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54
Q

Function of rna

A

RNA transfers genetic information from dna to ribosomes (ribosomes are formed from rna and proteins)

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55
Q

What are dna and rna polymers of?

A

Both dna and RNA are polymers of nucleotides -each nucleotide is formed from a pentose a nitrogen containing organic base and a phosphate group

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56
Q

What are components of a dna nucleotide ?

A

Deoxyribose
Phosphate group
One of the organic bases (adenine cytosine guanine thymine)

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57
Q

Components of rna

A

Ribose
Phosphate group
One of the organic bases(adenine guanine cytosine ueacil )

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58
Q

Structure of a dna molecule

A

A dna molecule is a double helix with two polynucleotide chains held together by hydrogen bonds between specific complimentary base pairs

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59
Q

Structure of rna

A

An rna molecule is a relatively short polynucleotide chqin

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60
Q

What happens when nucleotides join together by condensation reactions?

A

Nucleotides can join together by condensation reactions to form a poly nucleotide strand with a sugar phosphate backbone

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61
Q

What is a nucleotide made of ?

A

A nucleotide is made of pentose sugar( deoxyribose in dna)

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62
Q

Describe DNA

A

codes for the manufacture of particular proteins
can be copied exactly to make new cells
thermostable (doesn’t denature at high temps)

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63
Q

How does the long molecule /coiling of dna link to its function

A

Codes for a lot of things making it more compact and carries a lot of molecules

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64
Q

How does the sugar phosphate backbone link to the function of dna?

A

Bound by relatively strong phosphodiester bonds nit denatured till 86 degrees

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65
Q

How do the bases in the sequences relate to the function ?

A

Codes for protein base sequence is the genetic code .The sequence of bases determines the primary structure of a protein

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66
Q

How does rather complementary base pairing link to the function of dna?

A

Holds polynucleotide strands together when not being transcribed or replicated
Allows information to be replicated /transferred as new dna is or rna nucleotides can join to the exposed bases

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67
Q

How does the hydrogen bonds allowing chains to split easily link to the function of dna?

A

For replication/transcription

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68
Q

How does the helical structure link to the function of dna ?

A

Protects weak hydrogen bonds and to make the molecules protected from being corrupted by outside chemicals and physical forces

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69
Q

Describe the sense strand

A

It’s important that the strands can easily separate and rejoin without damaging the molecule

One strand of the dna molecule at any particular point in the double stranded molecule the anti sense strand is used to make proteins other side is there for support

THE ANITSemse strand for different genes may be found on different sides of the molecule

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70
Q

What happens in step one of dna replication?

A

A representative portion of DNA which is about to undergo replication

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71
Q

What happens in step two in dna replication?

A

An enzyme DNA helicase causes the two strands of the DNA to separate by breaking the hydrogen bonds that join the complementary bases together ?

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72
Q

What happens in step three of dna replication ?

A

DNA helicase completes the splitting of the strand meanwhile three nucleotides that have been activated bind specifically to their complementary bases

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73
Q

What happens in step four of DNA replication?

A

Once the activated nuclear tides are bound, they are joined together by DNA polymerase which makes phosphodiester bonds. The remaining unpaired bases continue to attract their complimentary nucleotides.

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74
Q

What in step five of DNA replication?

A

Finally all the nuclear tides are joined to form a complete polynucleotide chain using DNA polymerase in this way. Two identical strands of DNA are formed as each strand retains half of the original DNA material. This method of replication is called the semiconservative method.

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75
Q

What are the three facts meselson and stahls experiment is based on?

A

All bases in DNA contain nitrogen
Nitrogen has two forms nitrogen 14, which is lighter and nitrogen 15, which is heavier
Bacteria will incorporate nitrogen from their grow medium into any new DNA they make

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76
Q

What does a semiconservative replication of DNA ensure ?

A

The semi conservative replication of DNA insures genetic continuity

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77
Q

What did James Watson and Francis Crick out in 1953?

A

In 1953 James Watson and Francis Crick works out the structure of DNA following pioneering work by Rosalind Franklin on the x-ray diffraction parent patterns of DNA opening the door of many of the major developments in biology over the next half century

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78
Q

What does a relative simplicity of DNA lead to?

A

The relative simplicity of DNA led to many scientists doubting it carried the genetic code

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79
Q

Define metabolism

A

All the reactions that take place in living organisms involve energy for example respiration, protein synthesis and photosynthesis. This is called metabolism.

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80
Q

Active transport

A

Example uptake of mineral ions by root hair cells against conc gradient

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81
Q

What is a single molecule of ATP?

A

A single molecule of adenosine triphosphate is a nucleotide derivative and is formed from a molecule of ribose a molecule of adenine and three phosphate groups

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82
Q

What are the bonds like between the phosphate group in ATP?

A

Unstable bond has low activation energy which means they’re easily broken

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83
Q

Describe ATP

A

-made in the membrane
-lots of mitochondria =lots of ATP
-chloroplasts=small amounts of ATP

84
Q

How is the hydrolysis of ATP catalysed?

A

Hydrolysis to atp to adenosine diphosphate ADP and an inorganic phosphate group is catalysed by the enzyme ATP hydrolase

85
Q

How can the hydrolysis of ATP be coupled?

A

The hydrolysis of ATP can be coupled to energy requiring reactions within cells

86
Q

What can the inorganic phosphate release during the hydrolysis of ATP be used to phosphorylate?

A

Inorganic phosphate release during the hydrolysis of ATP can be used to phosphor relate other compounds often making the more reactive

87
Q

How is ATP resynthesised?

A

ATP is re synthesised by the condensation of ADP and an inorganic phosphate group. This reaction is catalyse by the enzyme ATP synthesis during photosynthesis or during respiration

88
Q

Word equation for formation of ADP

A

ATP + h20->adp+inorganic phosphate +energy

89
Q

What does it mean when there is high energy ?

A

High energy means bonds broken and energy released

90
Q

What reaction converts atp to ADP?

A

Hydrolysis as it involves water

91
Q

What enzyme breaks the bond concerning atp?

A

Atpase
ATP hydrolase

92
Q

What enzyme makes the bond concerning atp?

A

ATP synthase

93
Q

What enzyme makes the bond concerning atp?

A

ATP synthase

94
Q

What are the three ways to make ATP?

A

1.AP is formed by production of the reaction (substrate level phosphorylation)
2.respiration-mitochondria (oxidative phosphorylation)(phosphorylation means add a phosphate group)
3.photosynthesis-chloroplast(photophosphorylation

95
Q

Define basal metabolic rate

A

Measurement of energy required to keep the body functioning at rest measured in calories

96
Q

What are the two groups of lipid?

A

Triglycerides and phospholipids are two groups of lipid

97
Q

Describe triglycerides

A

Formed by the condensation of one molecule of glycerol and three molecules of fatty acid

98
Q

Describe phospholipids

A

One of the fatty acids of a triglyceride is substituted by a phosphate containing group

99
Q

What does the hydrolysis of a triglyceride produce?

A

Hydrolysis of a triglyceride produces glycerol and three fatty acids

100
Q

How are ester bonds formed?

A

A condensation between glycerol and a fatty acid (RCOOH) forms an ester bond

101
Q

What may a r group of a fatty acid be?

A

R group of a fatty acid may be saturated or unsaturated

102
Q

Describe lipids

A

-contains carbon hydrogen and oxygen
-insoluble in water
-proportions of oxygen to carbon and hydrogen is smaller than in carbs
-they are soluble in organic solvents such as alcohols and acetone
-poor conductors
-exists as fats( solid at room temp 10-20 degrees)/oils/waxes
-good energy source

103
Q

What are the functions of lipids?

A

Source of energy
Waterproofing
Insulation
Protection

104
Q

How is a source of energy a function of lipids?

A

When oxidised lipids provide more energy as the same mass of carbs and releases water

105
Q

How is waterproofing a function of lipids?

A

Lipids are insoluble in water so useful as waterproofing eg plants =waxy lipid cuticle to conserve water
Mammals=produce oily secretion from sebaceous glands in the skin

106
Q

How is insulation a function of lipids?

A

Fats are slow conductors of heat and when stored beneath the body surface help to retain body heat they also act as electrical insulators in the myelin sheath around nerve cells

107
Q

How is protection a function of lipids?

A

That is often stored around delicate organs such as the kidney

108
Q

How do you test for lipids?

A

Take test tube add 2 cm³ of sample add 5 cm³ of ethanol check the tube thoroughly to dissolve any lipid in the sample add 5 cm of water shake gently a cloudy white emulsion should form if lipids are present.

109
Q

Define saturated fats

A

If the chain has no carbon carbon double bond the fatty acid is then described as saturated due to all the carbon atoms linked to maximum possible hydrogen atoms

110
Q

Define unsaturated fats

A

If there is a single double bond, it’s mono on saturated if more than bond is present it’s polyunsaturated

111
Q

How are the structure triglycerides related to function?

A

High ratio of energy storing carbon hydrogen bonds to carbon atoms and other therefore an excellent source of energy

Low mass energy ratio making them good storage molecules because much energy can be stored in a small volume. This is especially beneficial to animals as it reduces the mass they have to carry as they move around.

Insoluble in water, large nonpolar molecules the storage doesn’t affect osmosis and cells of the water potential of them

As they have a high ratio of hydrogen oxygen atoms triglycerides release water when oxidised and therefore provide an important source of water, especially for organisms living in dry deserts

112
Q

Describe phospholipids

A

The similar to lipids except one of the fatty acid molecules is replaced by phosphate whereas fatty acid molecules repel water (hydrophobic) phosphate molecules attract water (hydrophilic)

113
Q

How does the structure of phospholipids relate to their properties?

A

-pull up molecules in aqueous environments phospholipid molecules from a bilayer within cell membranes as a result a hydrophobic barrier its forms between the inside and outside of a cell-

hydrophilic phosphate heads of phospholipid molecules help to hold at the surface of the cell membrane

-structure allows them to form glycol lipids by combining with carbohydrates within the cell surface membrane. These glycol lipids are important in cell recognition.

114
Q

What are water molecules made up of?

A

Water molecules are made up of two atoms of hydrogen and one of oxygen -one atom of oxygen combines with two atoms of hydrogen by sharing electrons (covalent bonding)

115
Q

What type of molecule is water?

A

Although the molecule has no overall charge oxygen atom has a slightly negative charge while hydrogen has slightly positive charge water molecule has positive and negative polls thus its dipolar molecule

116
Q

Why is water important to cells?

A

Water is the median in which or metabolic reactions take place in cells

117
Q

What percentage of a cell mass is water?

A

70% of 95% mass of a cell is water

118
Q

What percentage of the Earth surface is water?

A

71% of the Earth surface is water – major habitat for organisms

119
Q

Describe the nuclear charge within a water molecule

A

Auction automatic Trax electrons more strongly than the hydrogen atoms resulted in a weak negatively charged region on the auction atom and a weekly positive charged region on the hydrogen atoms resultant in a symmetrical shape

120
Q

What ones are between water molecules?

A

Hydrogen bonds form between water molecules
As a result of the polarity of water hydrogen bonds forms between the positive and negatively charge regions of the adjacent water molecules

121
Q

Hydrogen bonds, weak or strong?

A

Hodgen bonds a week when there are a few so they are constantly breaking and reforming however when the large numbers present they form a structure

122
Q

Why are hydrogen bonds in important?

A

Hydrogen bonds contribute to the many properties water molecules have that make them so important to living organisms such as:
-actsas a reagent
-excellent solvent -many substances dissolve in water
-relatively high specific heat capacity
-relatively high latent heat of vaporisation
-water is less dense when a solid
-water has a high surface tension and cohesion

123
Q

What some of the properties of water ?

A

-polarity of water molecules
-Present number of hydrogen bonds between water molecules

124
Q

Describe water as a solvent

A

Water is a polar molecule so many ions and covalently bonded polar substances (e.g. glucose) will dissolve in it.

This allows chemical reactions to occur within cells (as a dissolves are more chemically reactive when they are free to move about)

Metabolites can be transported efficiently (except nonpolar molecules which are hydrophobic)

125
Q

Define specific heat capacity

A

Specific heat capacities amount of thermal energy required to raise the temperature of 1 kg of a substance by 1°

126
Q

What is water specific heat capacity?

A

Water specific heat capacity is for 4200 j/kg degrees

127
Q

Describe whywater has a high specific heat capacity

A

Due to many hydrogen bonds present in water, it takes a lot of of them more energy to break these bonds and a lot of energy energy to build them. Does the temperature of the water doesn’t fluctuate greatly

128
Q

What are the advantages of living organisms for what having a high specific heat capacity?

A

Provide suitable habitats

Is able to maintain a constant temperature of as water is able to absorb a lot of heat without big temperature fluctuations which is vital when maintaining temperatures that are optimal for enzyme activity

129
Q

Why is water in the blood plasma vital?

A

Water in the blood Plasma is also vital in transferring heat around the body helping maintain valley constant temperatures. Blood passes through more active (warmer) regions of the body. Heat is absorbed by the temperature remains fairly constant water in tissue fluid also plays an important regulatory role in maintaining a constant body temperature.

130
Q

Describe how water has latent heat of vaporisation

A

In order to change stay (liquid to gas) a large amount of thermal energy must be absorbed by water to break the hydrogen bonds and evaporate

Advantage for living organisms as only a little water is required to evaporate for the organisms to lose a great amount of heat providing a cooling affect for living organisms e.g. the transpiration from leaves to or evaporation of water in sweat on skin

131
Q

What are the monomers from which proteins are made?

A

Amino acids to the monomers from which proteins are made

132
Q

What is the twenty amino acids that are common in all organisms differ in ?

A

Side – the 20 amino acids that are common in all organisms differ only in their side group

133
Q

What are proteins made up of?

A

Carbon hydrogen oxygen nitrogen and sometimes sulphur

134
Q

What do proteins contain?

A

The side chain amine group and a carboxyl group

135
Q

How can amino acids be joined?

A

Amino acids can be joined in any order/length

136
Q

How is a peptide bond formed?

A

Condensation reaction between two amino acids forms of peptide bond

137
Q

How are peptide bonds broken?

A

Hydrolysis reactions breaks a peptide bond by adding a molecule of water

138
Q

How are dipeptides formed?

A

Dipeptides are formed by the condensation of two amino acids

139
Q

What is the functional protein contain?

A

Function of protein contains (maybe) one or more polypeptides

140
Q

How are polypeptides formed?

A

Peptides are formed by the condensation of many amino acids

141
Q

Describe the primary structure of proteins

A

Order of amino acids in the polypeptide chain joined with peptide bonds
Primary structure determines its ultimate shape and hence its function
A change in just a single amino acid in the primary sequence can lead to changing shape and may not carry out functions

142
Q

Describe the secondary structure of proteins

A

hydrogen bonds form between N – H and C =O parts of different amino acids in the polypeptide

Alpha helix (coiled structure)

143
Q

Describe the tertiary structure of proteins

A

Further folding
Hydrogen bonds, ionic bonds, sulphide bridges form between our groups of amino acids in the polypeptide
Final structure for proteins made from polypeptide

144
Q

Describe disulfide bonds

A

Fairly strong and therefore not easily broken

145
Q

Describe ionic bonds in proteins

A

Bonds between any carboxyl and amino groups that are not involved in informing peptide bonds they are weaker than I sulphide bonds – easily broken by changes in pH

146
Q

Describe hydrogen bonds in proteins

A

Numerous but easily broken

147
Q

Describe the quaternary structure in proteins

A

Some proteins have more than one polypeptide chain polypeptide held together with hydrogen bonds, ionic bonds and sulphide bonds, e.g. haemoglobin for polypeptide

148
Q

How do you test for proteins?

A

Place a sample of the solution to be tested in a test tube and equal volumes of sodium hydroxide

Add a few drops to dilute (0.05%) copper I I sulphate solution and mixed gently

Purple collation indicates the presence of peptide bonds and hence a protein if no protein is present it remains blue

149
Q

What are enzymes?

A

Enzymes are globular large proteins and actors catalyst they have a tertiary structure

150
Q

What enzymes do?

A

Each enzyme low activation energy of the reaction of catalyses -they speed up the rate of chemical reaction (which would occur) without being used themselves

151
Q

How do enzymes increase activation energy?

A

Increase the number of successful collisions that take place

Ensure that energy of the product is less than the energy of a substrate

The strain distort particular bonds in the substrate

Lowers is the activation energy

152
Q

How is an enzyme substrate complex formed?

A

When the substrate fits into the active site of an enzyme it forms an enzyme – substrate complex

153
Q

How does forming an enzyme substrate complex lower the activation energy?

A

This low activation energy because holding two molecules together reduces any repulsion between them so they bond more easily

Fitting into the active site of an enzyme put strain on the bonds in the substrate so it breaks up more easily

154
Q

What factor determines the shape of the active site?

A

The sequence of amino acids determines the shape of the active site

155
Q

What factor determines the shape of the active site?

A

The sequence of amino acids determines the shape of the active site

156
Q

What can enzymes only attach to?

A

Enzymes are specific enzymes so they can only attach to substrate that are complementary in shape

157
Q

Describe the active site

A

A Specific region of the enzyme is functional (active site) active site is made up of a relatively small number of amino acids. Active site forms small depression with the much larger enzyme molecule

158
Q

Describe the substrate

A

The molecule on which the enzyme ax is called a substrate which fits neatly into the depression and forms an enzyme substrate complex. The substate molecule is held within the active site by bonds that temporarily form between certain amino acids of the active side and group on substrate molecule.

159
Q

Describe the induced fit model

A

The enzyme and the active site can change shapes slightly as a substrate molecule enters the enzyme

These changes in shape are known as conformational changes

This insures an ideal binding arrangement between the enzyme and substrate is achieved

This maximises the ability of the enzymes catalyse the reaction

160
Q

Describe denaturation

A

Breaking bonds down-pH and temperature affects the bonds in the structure of the enzymes

Hydrogen/ionic bonds are broken
Tertiary Structure loss
Shapes of enzyme active site change
Substrate no longer complimentary
No enzyme substrate complex formed

161
Q

Define inorganic ions

A

Inorganic ions or ones that do not contain carbon (there are exceptions) these are inorganic ions in solution, in the cytoplasm of cells and in the body fluids of organisms. each ion has a specific role depending on properties.

162
Q

What is the function of iron?

A

Haemoglobin – contains iron – carries oxygen in blood

163
Q

What is the function of iron?

A

Haemoglobin – contains iron – carries oxygen in blood

164
Q

What is the function of hydrogen?

A

Determines the pH of solutions so effects enzyme

165
Q

What is the function of sodium?

A

Transport glucose in amino acids across cell membranes – conduction of nerve impulses

166
Q

What is the function of phosphate?

A

ATP (energy store) nucleotides – structural role in DNA

167
Q

What is the function of nitrates?

A

Synthesis of protein in plants

168
Q

What is the function of potassium?

A

Conduction of nerve impulses

169
Q

What factors affect the enzyme activity ?

A

pH
Temperature
Substrate concentration
Enzyme concentration

170
Q

What factors affect the enzyme activity ?

A

pH
Temperature
Substrate concentration
Enzyme concentration

171
Q

How does temperature affect enzyme activity?

A

Increased temperature increases kinetic energy of molecules (enzyme and substrate )
More successful collisions between enzyme and substrate which leads to the formation of enzyme substrate complexes

172
Q

How does temperature affect enzyme activity after the enzyme is denatured?

A

Rate of reaction decreases and increased temperature
Increased kinetic energy of molecules (enzymes and substrates )
Hydrogen bonds in tertiary structure break
Alters shape of active site
Substrate no longer complementary no e-s complexes formed

173
Q

How does temperature affect enzyme activity after the enzyme is denatured?

A

Rate of reaction decreases and increased temperature
Increased kinetic energy of molecules (enzymes and substrates )
Hydrogen bonds in tertiary structure break
Alters shape of active site
Substrate no longer complementary no e-s complexes formed

174
Q

What is the optimum ph for intercellular ?

A

7.3-7.45 mammalian optimum ph is almost neutral

175
Q

What is the optimum ph for intercellular ?

A

7.3-7.45 mammalian optimum ph is almost neutral

176
Q

How does ph affect enzyme activity ?

A

Increase enzyme activity as pH increases
Until extremes or ph the disruption of ionic bonds at active site and changes shape/ shape is lost
If active site is disrupted it’s no longer Complementary to substrates therefore substrates can no longer bind.

177
Q

Examples of some enzymes with extreme optimums

A

Proteases in stomach with ph 1

178
Q

What enzyme catalyses the breakdown of hydrogen peroxide into water and oxygen ?

A

Catalase

179
Q

What enzyme catalyses the breakdown of hydrogen peroxide into water and oxygen ?

A

Catalase

180
Q

How is hydrogen peroxide formed !

A

Hydrogen peroxide is formed continually as a byproduct of various chemicals reactions in living cells it’s toxic and if we’re not immediately broken down by cells it would kill them. Hence the importance of the enzyme

181
Q

How is hydrogen peroxide formed !

A

Hydrogen peroxide is formed continually as a byproduct of various chemicals reactions in living cells it’s toxic and if we’re not immediately broken down by cells it would kill them. Hence the importance of the enzyme

182
Q

What is the method for investigating the effect of substrate concentration on the rate of reaction?

A
  1. Ensure the gas syringe is on zero and that it’s connected to the delivery tube and the rubber bung
    2.pour 20cm3 of the 100% h2O2 into the conical flask
  2. Add 2cm3 of the yeast solution(catalase ) insert the bung that connects the deliver tube to the gas syringe and start rhe stop clock
    4.swirl the conical flask gently 5 times ensuring that you do not dislodge the bung or connecting tube
  3. Record the volume of gas produced after 1 minute
    6.reoeat the experiment directly the other concentrations of h2O2 you’ve prepared
183
Q

What is the method for investigating the effect of substrate concentration on the rate of reaction?

A
  1. Ensure the gas syringe is on zero and that it’s connected to the delivery tube and the rubber bung
    2.pour 20cm3 of the 100% h2O2 into the conical flask
  2. Add 2cm3 of the yeast solution(catalase ) insert the bung that connects the deliver tube to the gas syringe and start rhe stop clock
    4.swirl the conical flask gently 5 times ensuring that you do not dislodge the bung or connecting tube
  3. Record the volume of gas produced after 1 minute
    6.reoeat the experiment directly the other concentrations of h2O2 you’ve prepared
184
Q

Describe what happens in low substrate concentration

A

Two few substrates molecules to occupy all active sites the rate of reaction is only half the maximum possible

185
Q

Describe what happens in low substrate concentration

A

Two few substrates molecules to occupy all active sites the rate of reaction is only half the maximum possible

186
Q

Describe what happens in the intermediate substrate concentration

A

Twice the substrate molecules now enough substrates so in a given time all active sites have been occupied by them
The rate of reaction has doubled to its maximum because all the active sites are filled

187
Q

Describe the hugh substrate concentration

A

Addition of further substrate molecules has no effect as all active site are already occupied at one time no increase in rate of reaction

188
Q

What’s the only way to reach rate if reaction when maximum is reached ?

A

To increase the conc if enzymes as more active sites available

189
Q

Define the competitive inhibitor

A

Compete with the substrate for the active site

190
Q

What determines the effect the competitive inhibitor has on enzyme activity?

A

It’s the difference between the concentration of the inhibitor and the conc of the substrate that determines the effect that this has on enzyme activity

191
Q

What determines the effect the competitive inhibitor has on enzyme activity?

A

It’s the difference between the concentration of the inhibitor and the conc of the substrate that determines the effect that this has on enzyme activity

192
Q

Describe competitive inhibitors

A

Molecules that have a similar shape to the usual substrate
If molecules are present in the same solution as the substrate they compete for the active site
Rate of reaction reduces due to the active site being occupied and thus there are few available substrates to bind to

193
Q

How do you overcome the effects of the competitive inhibitor

A

Increase the substrate concentration

194
Q

Define non competitive inhibitor

A

Bind to the enzymes at a site other than the active site

195
Q

Describe how the non competitive inhibitor works

A

Binding of the non competitive inhibitor causes a change in shape of active site of the enzyme therefore preventing the formation of the enzyme substrate complex and could increase / stop rate of reaction

196
Q

Why can the non competitive inhibitor not be overcome by increasing substrate concentration?

A

Active site has change

197
Q

How are metabolic pathways controlled ?

A

By acting as an inhibitor the end product of a series of reactions can prevent its own production-end point inhibition

Example in the body is aerobic respiration

198
Q

Examples of non competitive inhibition in the body

A

NCI can affect many enzymes eg mercury lead arsenic
More specific inhibitors can be used as insecticides or drugs

199
Q

What is the effect of substrate concentration on the rate of enzyme action ?

A

If the concentration of enzyme is fixed and substrate concentration is slowly increased rate of reaction in proportion to the conc of substrate

A low substrate conc the enzyme molecules have only a limited number of substrate molecules to collide with therefore active sites of enzymes aren’t working to full capacity

More substrate added active sites gradually filled working as fast as they can

Rate of reaction is maximum

After that adding more substrate has no fetch on rate of reaction

200
Q

What is the effect of substrate concentration on the rate of enzyme action ?

A

If the concentration of enzyme is fixed and substrate concentration is slowly increased rate of reaction in proportion to the conc of substrate

A low substrate conc the enzyme molecules have only a limited number of substrate molecules to collide with therefore active sites of enzymes aren’t working to full capacity

More substrate added active sites gradually filled working as fast as they can

Rate of reaction is maximum

After that adding more substrate has no fetch on rate of reaction

201
Q

Roles of lipids in the body

A

Regulate hormones
Transmit nerve impulses
Store energy
Protects organs

202
Q

How to test for non reducing sugars

A

You test for the reducing sugars and if the test is not positive set up a new test tube then add 5 mL sample then add five drops of hydrochloric acid and heat for five minutes neutralise the spatula sodium hydrogen carbonate add 5 mL of Benedict solution and heats in boiling water by for five minsprecipitate indicates presence of non-reducing sugar

203
Q

Why is the active site of an enzyme specific and unique in shape ?

A

The active site is specific and unique and shape due to the specific folded and bonded in the tertiary structure of the protein. The location of the bonds is determined by the primary structure.

204
Q

Why is it essential cells contain a copy of a genetic code?

A

And that it can be passed to new cells without being damaged

205
Q

Why is complementary based pairing important?

A

It helps maintain the order of genetic code when DNA replicates

AQA A-LEVEL BIOLOGY (7 decks)

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