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Biological Molecules Flashcards

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1
Q

Organic molecules

A

Carbon
Oxygen
Hydrogen

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2
Q

Carbohydrates

A

Respiratory substances which provide energy for cells
Structure in cell membranes (plasma membranes) and cell walls

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3
Q

Lipids

A

Respiratory substances which provide energy for cells
Form a bilayer in cell membranes (plasma membranes)
Make up some hormones

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4
Q

Proteins

A

Main component of many cellular structures
Form enzymes
Chemical messengers
Components of blood

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5
Q

Nucleic acids

A

Carry the genetic code for the production of proteins

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6
Q

Polymers

A

Molecules made form lots of repeating units called monomers that are joined together

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7
Q

Monomers

A

Small units from which larger molecules are made e.g monosaccharides amino acids nucleotides

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8
Q

Condensation reaction

A

Joins two monomers together with the formation of a covalent bond by removing a water molecule

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9
Q

Hydrolysis reaction

A

Breaks the covalent bond between two monomers and involves the addition of water

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10
Q

Monosaccharides and examples

A

The monomers from which larger carbohydrates are made
E.g glucose fructose and galactose

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11
Q

What bond is formed during a condensation reaction between two monosaccharides

A

Glycosidic bond

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12
Q

How is a disaccharide formed

A

Condensation of two monosaccharides

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13
Q

Maltose

A

Disaccharide formed by condensation of two glucose molecules

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14
Q

Sucrose

A

Disaccharide formed by the condensation of a glucose molecule and fructose molecule

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15
Q

Lactose

A

Disaccharide formed by condensation of a glucose molecule and a galactose molecule

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16
Q

Glucose has two isomers
Alpha glucose and bets glucose
What is a isomer

A

Two or more compounds with the same formula but different arrangement of atoms in the molecule

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17
Q

How are polysaccharides formed

A

Condensation of many glucose units

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18
Q

Starch

A

Alpha glucose
Stores energy in plants and is a mixture of two polysaccharides: amylose and amylopectin
Amylose- unbranched chain of glucose molecules joined by 1-4 glycosidic bonds-coiled and compact
Amylopectin- branched made up of 1-6 glycosidic bonds has side branches which can be acted upon simultaneously by enzymes to release its energy
Properties- insoluble will not affect water potential, compact so can be stored in a small place when released alpha glucose can be transported easily

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19
Q

Glycogen

A

Alpha glucose
In animals large number of branches 1-6 glycosidic bonds
Lots of side branches energy can be released quickly
Large but compact maximising amount of energy it can store
Insoluble will not affect water potential

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20
Q

Cellulose

A

Beta glucose
In plants
Long unbranched chains of beta glucose joined by glycosidic bonds
Microfibrils are strong threads which are made of long cellulose chains running parallel to one another and joined by hydrogen bonds forming strong cross links
Important- stops cell wall from bursting, hydrogen bonds make microfibrils strong but flexible, cells become turgid maximising the surface area

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21
Q

Are lipids polymers or not

A

No

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22
Q

Functions of lipids

A

Provide source of energy, help insulate organisms, waterproofing, from membranes and hormones

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23
Q

Two types of lipids

A

Triglycerides
Phospholipids

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24
Q

How are triglycerides formed and structure

A

Formed by the condensation of one molecule of glycerol and three fatty acids
This forms an ester bond between glycerol and fatty acid

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25
What are triglycerides used for
As an energy store as a lot of energy is released when fatty acids are broken down
26
Structure of phospholipids
A glycerol molecule, phosphate group and 2 fatty acid chains Forms an ester bond
27
Are fatty acids hydrophobic or hydrophilic
Hydrophobic meaning they repel water
28
Is phosphate group hydrophobic or hydrophilic
Hydrophilic meaning it attracts water
29
Saturated
Do not have any double carbon bonds
30
Unsaturated
Have double carbon bonds This causes chain to bend/kink
31
Phospholipid bilayer
Heads are hydrophilic Tails are hydrophobic So when in water they form a double layer with heads facing outwards and tails inwards Centre of bilayer is hydrophobic and this creates a barrier so different conditions can be created either side of the membrane
32
Are proteins polymers or not
They are polymers made up of monomers called amino acids
33
What are the monomers of protein called
Amino acids There are 20
34
General structure of amino acids
Carboxyl group Amine group Variable group (this is the only difference between the 20 amino acids) Contain nitrogen as well as hydrogen carbon and oxygen
35
What bond forms between two amino acids during what reaction
Condensation reaction forming a peptide bond
36
Dipeptides
Condensation of two amino acids
37
Polypeptides
Condensation of many amino acids
38
Primary structure of proteins
Sequence of amino acids in polypeptide chain
39
Secondary structure of a protein
Hydrogen bonds form between amino acids in the chain This causes it to coil into an alpha helix or fold into a beta pleated sheet
40
Tertiary structure of proteins
3D shape of polypeptide chain, hydrogen bonds, ionic bonds and disulphide bridges from between R groups
41
Quaternary structure of proteins
More than one polypeptide chain e.g haemoglobin
42
Globular proteins
Soluble Generally spherical shape Compact
43
Fibrous proteins
Insoluble Used to form fibres E.g keratin and collagen
44
Disulphide bridges
Strong and not easily broken
45
Ionic bonds
Form between carboxylate group and amine groups Easily broken by pH Weaker than disulphide bridges
46
Hydrogen bonds
Easily broken
47
What are enzymes
Biological catalysts that increase the rate of reaction without being used up and lowering the activation energy
48
Structure of enzymes
Proteins with a 3D structure (tertiary structure of a protein) They have an active site which has a specific shape and only binds to a complementary substrate
49
What happens when the enzymes binds to substrate
An enzyme substrate complex is formed
50
Lock and key model
Active site is exactly complementary to the specific substrate molecule
51
Induced fit model
Active site is not exactly complementary to the substrate The active site changes shape slightly to fit the substrate
52
How does temperature affect the rate of an enzyme reaction
Temp increases kinetic energy increases so molecules are moving faster so rate increases as more ES are formed Once optimum temp is reached increasing temp further decreases rate because above optimum the enzymes active site changes shape and the bonds in the tertiary structure are broken so the enzyme becomes denatured
53
How does pH affect the rate of an enzyme controlled reaction
Affects enzymes shape as it can disrupt the bonds in the tertiary structure therefore enzyme is denatured
54
How does enzyme concentration affect the rate of an enzyme controlled reaction
Rate increases as enzyme conc increases as there are more active sites from the substrates to bind to However increasing the enzyme conc beyond a certain point has no effect on rate as there are now more active sites than substrates so substrate conc becomes the limiting factor
55
How does substrate concentration affect the rate of an enzyme controlled reaction
Increasing conc of substrate the rate increases as more enzyme substrate complexes are formed However beyond a certain point the rate no longer increases and the enzyme conc becomes the limiting factor
56
What is a competitive inhibitor
Similar shape to substrate and competes with substrate to bind to active site They block the active site so substrate cannot bind so no ES complexes are formed
57
Non competitive inhibitor
Do not bind to active site as they are a different shape to substrate Binds to allosteric site Causes enzyme to change shape
58
How does competitive inhibitors affect rate of enzyme reaction
Increasing conc of competitive inhibitors decreases rate as active sites are blocked
59
How does non competitive inhibitors affect rate of an enzyme controlled reaction
Increasing conc of non competitive inhibitors rate decreases as enzyme changes shape due to inhibitors binding to allosteric site
60
What does DNA hold
Genetic information
61
What does RNA do
Transfers genetic information from DNA to the ribosomes
62
Are DNA and RNA both polymers
Yes they have nucleotides
63
What is contained in each nucleotide of DNA and RNA
Pentose sugar, a nitrogen containing base and a phosphate group
64
Components of a DNA nucleotide
Deoxyribose sugar, a phosphate group, and one of the organic bases: adenine cytosine guanine and thymine
65
What are the complementary base pairings
Adenine and thymine Guanine and cytosine
66
Components of RNA
Ribose sugar, a phosphate group and one of the organic bases adenine, guanine, cytosine and uracil
67
What Bond is formed between two nucleotides and during what reaction
Condensation reaction and a phosphodiester bond
68
Structure of DNA
Double helix with two polynucleotide chain held together by hydrogen bonds between the complementary base pairs
69
Scientists who discovered DNA
Rosalind Franklin James Watson Francis Crick
70
Why is DNA stable
The phosphodiester backbone protects the more reactive bases Hydrogen bond bridges form 3 hydrogen bonds between G+C and 2 between A+T So higher proportion of G+C makes DNA more stable
71
Structure of RNA
Short polynucleotide chain Single strand No thymine has uracil instead
72
What is the method called for DNA replication
Semi conservative replication Watson-crick model
73
What does the semi conservative replication of DNA ensure
Genetic continuity between generations of cells
74
Process of semi conservative replication
- the unwinding of the double helix- enzyme DNA helicase causes the two strands of DNA to separate breaking the hydrogen bonds between the complementary base pairings - one of the strands is used as a template and the free nucleotides are attracted to the exposed complementary base pairs - nucleotides are bound and the enzyme DNA polymerase joins them together by forming phosphodiester bonds via a condensation reaction
75
What is the result of semi conservative replication
Two identical strands of DNA are formed contains half of original strand and half of new strand
76
What is ATP made of
Molecule of ribose Molecule of adenine Three phosphate groups
77
What happens when ATP is hydrolysed
Forms ADP and a phosphate molecule and this is catalysed by ATP hydrolyse Energy is released
78
What happens during condensation of ADP and phosphate
ATP is produced catalysed by ATP synthase
79
Properties of ATP
Immediate source of energy Easily broken as bonds are unstable between the phosphate groups Can easily be reformed from ADP Breaking is quick due to low activation energy Releases manageable amount of energy
80
What can the inorganic phosphate from ATP be used for
To phosphorylate other compounds making them more reactive
81
Why is water an important molecule
- its polar due to uneven distribution of charge - its a metabolite in reactions such as condensation and hydrolysis - its a solvent allowing gases to readily diffuse - has a high specific heat capacity which helps to minimise temperature fluctuations acts as a buffer - large latent heat of vaporisation proving a cooling effect with little water loss - has strong cohesion between water molecules which supports columns of water to enable effective transport
82
Where do inorganic ions occur in the body
In solution in the cytoplasm and body fluid of organism
83
Role of hydrogen ions
Determine pH of substances such as blood Higher concentration of hydrogen ions lower the pH
84
Role of iron ions
They are a component of haemoglobin
85
Role of sodium ions
Involved in co transport of glucose and amino acids
86
Role of phosphate ions
They are a component of DNA and ATP
87
Test for protein
Add buiret solution to sample If protein is present solution will turn from blue to purple
88
Test for starch
Add iodine to sample If starch if present solution will turn from orange to to blue black
89
Test for lipids
Add lipid to sample and shake Pour solution into water Is lipid is present there will be milky emulsion
90
Test for reducing sugars E.g maltose
Add Benedict’s reagent to sample Heat in a water bath If a reducing sugar is present solution will turn from blue to brick red
91
Test for non reducing sugars E.g sucrose
Add HCl to sample and heat using a Bunsen burner Neutralise solution with an alkali Add Benedict’s Place in water bath If turns brick red a non reducing sugar is presents

Biology (4 decks)

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