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A Level Biology > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

What is a carbohydrate?

A

A compound with carbon,hydrogen and oxygen

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2
Q

What are monomers and monosaccharides?

A

Monomers are monosaccharides and monosaccarides are simple sugars

These are glucose,fructose,ribose and galactose

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3
Q

What are dissachsrides and how are they formed?

A

Dissacharides are when 2 monosaccharides are joined together

These include: sucrose,maltose and lactose

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4
Q

What are the 2 isomers of glucose and what is an isomer?

A

An isomer is a compound of molecules with same number of atoms in a different shape/structure

These are alpha glucose and beta glucose

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5
Q

Describe a condensation reaction?

A

2 monosaccharides are joined together to form a dissacharide forming a glucosidic bond between carbon and hydrogen
Water is eliminated

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6
Q

What is a hydrolysis reaction?

A

Breaks chemical bond between 2 monomers with the use of water.The opposite of a condensation reaction

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7
Q

Examples of monomers?

A

Monosaccharides,amino acids and nucleotides

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8
Q

What is a glycosidic bond and how is it formed?

A

Type of bond that joins a carbohydrate molecule to another group

Formed by 2 monosaccharides joining together

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9
Q

Maltose is a disaccaride how is it formed?

A

Formed by joining 2 monosaccharides which are 2 alpha glucose molecules,joined by a glycosidic bond

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10
Q

Sucrose is a disaccharide and how is it formed?

A

It is formed from glucose and fructose monosaccarides joined by a glycosidic bond

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11
Q

Lactose is a dissacharide and how is it formed?

A

Formed from galactose and glucose and is joined by a glycosidic bond

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12
Q

How to Test for reducing sugars?

A

First Break Food using pestle and Mortar.Add Benedicts reagent to a sample of sugar and heat TT using water bath at 65
If positive:blue to orange/yellow/red

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13
Q

What is a polysaccharide?

A

When more than 2 monosaccharides are joined together by condensation reactions with glycosidic bonds

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14
Q

What is a nucleotide?

A

Made up of a pentose sugar,nitrogen containing base and a phosphate group

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15
Q

Explain the use of Sodium Ions?

A

Co Transport of glucose/amino acids
Affects water potential
Creates sodium conc gradient during CT

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16
Q

Explain the use of Phosphate Ions?

A

Used to produce ATP
Phosphorylates other compounds
Affects water potential

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17
Q

Explain ALL the properties of water(6)

A

High SHC-to buffer changes in temp
High SLH of vaporisation-Provides cooling effect
Used as a metabolite in hydrolysis,respiration and photosynthesis
Universal Solvent-so metabolic reactions can occur
Metabolic reactions occur quicker in solution
Polar molecule

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18
Q

What are the uses of starch and how is it broken down?

A

Starch stores glucose when cells need it for respiration
Water is used to break glycosidic bonds which requires enzymes and this is a hydrolysis reaction
Starch is insoluble in water and doesn’t affect water potential so water does not enter by osmosis so its good for storage

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19
Q

What is amylose and explain its features and function

A

Amylose is a polysaccharide of many alpha glucose joined by 1-4 glycosidic bonds
Due to hydrogen bonds between glucose they coil into double helix shape
They are compact,unbranched polymers and its function is glucose storage
This is a type of starch

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20
Q

What is amylopectin and its function and features?

A

Amylopectin is a polysaccharide formed by condensation reaction of lots of alpha glucose joined by 1-4 and 1-6 glycosidic bonds
They are highly branched which increases SA so enzymes can break starch rapidly
Amylopectin stores glucose and broken in respiration
Type of starch
Side branches allow for enzymes to break glycosidic bonds easily so released easily

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21
Q

What is cellulose and explain its function and features?

A

Cellulose is a polysaccharide consisting of long chains of beta glucose joined by 1-4 glycosidic bonds
They prevent cell burst and provide stability
They are large so osmotically inactive
Never found in animal cells
Important in maintaining stem and leaves
The hydrogen bonds means that they form strong fibres called microfibrils for structural support

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22
Q

What is glycogen its function,features?

A

Animals store excess glucose as glycogen which is a polysaccharide of alpha glucose
Similar to amylopectin but has loads more side branches so glucose can be released quickly as side branches increase SA
Compact and good for storage
Broken down by enzymatic hydrolysis

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23
Q

What are the roles of a Lipid?

A

Forms cell membranes in Phospholipid bilayer
Source of energy
Waterproofing
Insulation

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24
Q

What is a triglyceride?

A

Type of lipid where
A molecule where glycerol(organic alcohol with 3 OH) is bonded to 3 fatty acids
The bonds are ester bonds(bond between glycerol and fatty acid)

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25
How is a triglyceride formed?
Formed by a condensation reaction of one molecule of glycerol with 3 fatty acids and it becomes bonded with an ester
26
What are lipids and describe some features?
Molecule with glycerol ester bonded to 3 fatty acids They are large complex and non polar They are mostly carbon hydrogen and oxygen They have a hydrocarbon tail represented by the letter R
27
How will triglyceride be broken down?
It can be broken down into glycerol and 3 fatty acids by a hydrolysis reaction
28
What are fatty acids?
Organic acids with a carboxyl(COOH) joined by a hydrocarbon
29
What is a Phospholipid?
A molecule with glycerol bonded to 2 fatty acids and a phosphate group(Phosphate group replaces 1 fatty acid)
30
How does a Phospholipid form?
It forms by a condensation reaction between a triglyceride and phosphoric acid forming a Phospholipid and water
31
Describe a Phospholipid?
Contains a phosphate group and is bonded to the glycerol by an ester bond the ester bond is bonded to the repeating chain of fatty acids Glycerol and phosphate part of Phospholipid is hydrophilic Fatty acid tail is hydrophobic Polar-forms bilayer And is for cell surface integrity Insoluble in water
32
What is the difference between saturated and unsaturated fats?
Saturated=No double carbon bonds whereas unsaturated has a double bond
33
What are proteins?
Proteins are polymers made up of repeating monomer chains called amino acids
34
Describe the structure and explain what are amino acids?(bonding,elements,groups)
Amino acids are monomers of proteins They have a carboxyl group(COOH) An Amine group(NH2) And an R group(different for different amino acids)joined by a carbon and hydrogen They contain hydrogen,nitrogen,oxygen,carbon and sometimes sulfur
35
What is a dipeptide and a polypeptide?
When 2 or more amino acids are joined together in a condensation reaction to form a dipeptide held by a peptide bond Same thing except with more than 2 amino acids joined together
36
How do we break a peptide bond?
By using water in a hydrolysis reaction which is catalysed by the enzyme protease to break the bond and form 2 amino acids
37
What is the primary structure and significance?
It is the specific order of amino acids in a polypeptide,determined by the DNA sequence of a gene that encodes for amino acid chain Significance:Amino acids determine the type of folding of protein
38
What are the tertiary structures of proteins?
The tertiary structure is the overall 3D shape of a polypeptide chain where folding occurs It has many bonds which could be intermolecular forces,Ionic bonds,disulphide bonds and covalent bonds They are a 3D shape and determine the protein function
39
Explain hydrogen bonding in Proteins?
Hydrogen bonds are formed between the R groups of 2 amino acids as there is attraction between slight positive hydrogen and slight negative oxygen However they are weak bonds broken by high temperature chain
40
Explain Ionic Bonding in Proteins?
They are present between amino acids with charged R groups The Ionic bond is caused by an attraction between positive charged amino acid and a negative charged amino acid,it holds different parts of the polypeptide together But they are broken by changes in pH
41
What are Disulfide proteins found in Proteins?
Covalent bond formed between 2 cysteine amino acids The R group of cysteine contains a sulfur atom They are relatively strong bonds
42
Explain hydrophobic and hydrophilic interactions?
Weak interactions between polar and non polar R groups Hydrophobic R groups are on the inside
43
What is the test for reducing sugars?
Benedicts Test Add sample and benedicts reagent to a boiling tube Heat boiling tube at 80C for 5 mins Mix well PR:blue to brick red
44
Explain the reducing sugar reaction in terms of electrons?
Reduction reaction involves the gain of electrons
45
What are non reducing sugars and why can't they donate electrons?
Non reducing sugars are sugars that do not have a functional group to donate electrons They are typically disaccharides,which contain glycosidic bonds which means it is too stable to allow the negative oxygen to donate electrons
46
How to Test for non reducing sugars?(Disaccharides)
Needs to be hydrolysed into monosaccharides by adding boiled HCL and NaHCO3 Let it cool than add alkali to neutralise This will split disaccharide into a monosaccharides Then just use benedicts Test
47
What is Biurets Test?(Protein Test)
Add 2cm³ sample with biuret solution to a Test Tube and mix well Is positive:blue to lilac/purple
48
What is the emulsion Test?
Add ethanol and distilled water to a Test Tube(2cm³) Shake well If positive:milky cloudy colour appears
49
Why does dissacharides have a greater sugar conc than monosaccharides?
Dissacharides have 2 glucose molecules joined together by a glycosidic bond,so when hydrolysis breaks glycosidic bond Dissacharides has 2 moles of glucose instead of 1
50
What is the Test for starch?
Add iodine to solution Positive Test:Orange to Blue/black
51
Name 5 reducing sugars?
Glucose,fructose,galactose,lactose and maltose
52
Name 1 reducing sugars?
Sucrose
53
What are globular proteins and explain some properties?
They are roughly spherical in shape,with hydrophobic R groups on the inside and hydrophilic R groups on the outside They are therefore soluble in water Very specific shape to allow for very specific functions They typically have metabolic roles Examples:Haemoglobin,insulin,pepsin
54
Explain the role of Haemoglobin as a globular proteins?
Globular proteins found in red blood cells It transports oxygen from lungs into body tissues Made of 4 polypeptide chains so has a quaternary structure Has a prosthetic group attached to each polypeptide chain Has one oxygen molecule which binds to a heam group,allowing heamoglobin to transport 4 oxygen molecules
55
What is a prosthetic group?
A non protein component that is necessary for the protein to carry out its function
56
Explain the globular protein insulin and its function,and features to allow for it to function?
Secreted by the pancreas,to maintain blood glucose concentration Composed of 2 polypeptide chains-one with an alpha helix and the other with a beta pleated sheet 2 polypeptide chains joined together by disulphide links Shape of insulin allows for it to specifically bind to receptors on cell membrane to lower blood glucose concentration Hydrophilic R groups making it soluble in water-allows insulin to be dissolved in blood and transported easily
57
Explain the globular protein pepsin?
GP can be enzymes which catalyses the digestion of proteins Found in the stomach with a low pH Primary structure has few basic R groups preventing the tertiary structure and enzyme being affected by low pH Hydrogen bonds and disulphide links in pepsin allow pepsin to be stable
58
Explain what type of testing can be used to identify amino acids in Proteins?
Hydrolyse and break down protein into amino acids Place sample on chromatography paper Place chromatography paper in solvent and dry and repeat
59
What is the secondary structure and significance?
Secondary structure-Polypeptide starts to form a regular shape;held by hydrogen bonds which cause polypeptide to twist and fold Determines the 3D shape and whether it has alpha helix or beta pleated sheet
60
What is the quaternary structure?
Association of 2 or more proteins so they will have more than one polypeptide chain They have hydrogen bonds
61
Explain the protein collagen its structure use and function?
Collagen is the most structural protein that is found in vertebrates and in skin which provides structural support to tissues They have a triplet of amino acids sequence,and contains glycine as the 3rd amino acid They have hydrogen bonds to form a triple helix and covalent bonds which form crosswinds between R groups of amino acid;it also holds collagen molecules to form fibrils Fibrils have staggered ends 3D shape is collagen triple helix Quarternary:3 polypeptide chains,alpha chains are wrapped around each other to form triple helical macromolecule
62
What is and explain the structure of fibrous proteins?
They are long polypeptide chains They are insoluble They have hydrophilic R groups on the inside so they are unreactive Rich in glycine which is a small amino acid so,which allows close packing of molecules They have hydrophobic R groups on the outside
63
What are conjugated proteins?
Conjugated proteins are proteins which have a prosthetic group(non protein component) They are globular and are held by covalent bonding
64
What are enzymes and describe its functions and are they globular or fibrous?
Enzymes are biological catalysts which increase the rate of reaction without being used up,which lowers activation energy Enzymes are globular as they have a specific shape with an active site
65
What is the function of fibrous proteins?
Used for strength and structure such as collagen
66
What is the function of globular proteins?
Used for transportation,chemical reactions,muscle contraction,metabolism
67
Are enzymes tertiary structure proteins
Yes and they catalyse reactions
68
What is the active site?
The part of the enzymes where the substrate binds to the enzyme to form an enzyme substrate complex The active site is specific and unique due to specific bonding and folding in tertiary structure
69
Explain the lock and key theory?
The lock and key theory states that the enzyme active site is a fixed shape so the substrate will bind perfectly,and due to random collisions enzyme substrate complex are formed This forms enzyme product complex and lowers activation energy
70
What is the induced fit model?
It's when the enzymes active site changes shape to mould around the substrate,this forms an enzyme substrate complex which puts strain on the bonds and thus lowers the activation energy
71
Explain the secondary structure of a protein(4)
Hydrogen bonds between Amine and the carboxyl group Chains will twist and fold and could be alpha helix or beta pleated sheet Determines 3D structure of protein
72
Factors affecting Rate of Enzyme activity?
Change amount of collisions Temp Enzyme/substrate concentration pH Active site shape
73
Explain the enzyme concentration against Rate of reaction graph?
Straight line-Initial rate of reaction increases as enzymes and substrates are moving randomly and are more likely to collide forming enzyme substrate complex However,it platoes as substrate is the limiting factor
74
Explain how changes in pH affects enzyme activity?
Hydrogen bonds and Ionic forces of attraction hold tertiary structure Increase in H+ ions lowers the pH,positive H+ ions are attracted to negative charge and replace hydrogen bonds They cluster around negative R groups and interfere with binding of substrate
75
Whatever competitive inhibitors and impact?
Competitive inhibitors is a substance that reduces the activity of an enzyme by competing with the substrate to go in the active site They can either block the active site or alter the turnover rate of enzymes They are mostly reversible
76
Explain how enzyme inhibition can be overcome?
Could be overcome by increasing the concentration of substrate as it reduces the effect of reversible competitive inhibition
77
Explain what is meant by an inactivator?
An inactivator is an irreversible bonding of an inhibitor
78
Explain competitive inhibitors function(5)
Compete with substrate molecules for a position on AS forming an enzyme inhibitor complex Once of AS,inhibitor does not change shape Presence of inhibitor prevents substrate from binding to enzyme Reduces the number of free enzymes available Binding can be reversible
79
Explain non competitive inhibition?
This is where the inhibitor binds to an area other than the active site called the allestoric site They do not compete for the AS In binding they alter the specific shape of the enzymes tertiary site This disrupts the shape of the active site so the substrate can no longer bind to the enzyme
80
Describe how the max reaction rate could be altered using non competitive inhibitors?
Max rate of enzyme action is reduced by non competitive inhibition Increasing substrate could lower this effect More inhibitors=lower enzyme substrate complex
81
Describe how monomers join to form the primary strucutre of a protein?
Condensation reaction between amino acids Forms peptide bonds Creating sequence of amino acids

A Level Biology (7 decks)

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