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Biology A Level AQA > Biological Molecules (from Book) > Flashcards

Biological Molecules (from Book) Flashcards

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1
Q

Carbohydrates are respiratory substrate what else do they do

What role do they play in cell wall

A

They release the energy required to carry out functions

There are structural role in the cell wall they form part of the glycoproteins and glycolipids

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2
Q

Lipids

A

A major component of plasma membranes

Make certain hormones

Act as respiratory substrate

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3
Q

Proteins

A

Diverse – structure/function

Found in plasma membranes

Most important rollers in enzymes

Carry the chemical messages within/between cells

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4
Q

Nucleic acid

A

e.g. DNA

Carries genetic information that determines the structure of proteins
or RNA synthesise proteins

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5
Q

When is glucose produced by plants

A

During photosynthesis it is converted into insoluble starch for storage

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6
Q

During aerobic respiration chemical reactions occur what do they use

A

Glucose +oxygen to release energy

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7
Q

In plants and algae what is used to produce fat for storage + cellulase

A

Glucose is used to produce fat for storage which strengthens the cell wall and produces proteins

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8
Q

Protein molecules are made up of long chains of what

A

Amino acids

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9
Q

What makes Protein molecules shape unique

A

Protein molecules are made up of long chains of amino acids that can fold to produce specific shapes to enable other molecules to fit into the protein

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10
Q

Proteins active structural components of tissues such as

A

Muscles, hormones, antibodies, catalysts

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11
Q

What do catalysts do

A

Increase the rate of chemical reactions

Biological catalysts are proteins called enzymes

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12
Q

The shape of an enzyme is vital for its function what can change the shape of an enzyme

A

High temperatures

PH values

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13
Q

The definition of molecular biology

A

The study of biological molecules which are part of particular groups of chemicals found in living organisms

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14
Q

What is covalent bonding

A

Chemical bonds were two atoms share electrons in the outer shell this creates a more stable compound called a molecule because the outer shell both atoms are filled and therefore more stable

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15
Q

What is ionic bonding

A

Is a weaker bond than covalent bonding

Ions with opposite charges attract one another the ➡️ electrostatic attraction is the ionic bond
E.g. Sodium chloride + chloride ion = sodium chloride

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16
Q

what is hydrogen bonding

A

Hydrogen bond is weaker than covalent or ionic bonding

Result in the electrons in the molecule not evenly distributed
Therefore electron spend more time at one position creating a polarised molecule

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17
Q

What is a polarised molecule

A

When the molecule is either more negative or positive because of its electrons

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18
Q

What is a weak electrostatic bond

A

This occurs when the negative region of a polarised molecule attracts the positive region of another polarised molecule
This bond is very weak individually but the collective force can alter the physical properties of the molecule (especially true for water)

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19
Q

What are some examples of industrially produced polymers and naturally produced polymers

A

Industrially produced = polyester, polythene

Naturally produced = polysaccharides, polypeptides, polynucleotide

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20
Q

What a polymer is from naturally what is formed each time a new sub unit is attached

A

A molecule of water (this is called condensation reaction)

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21
Q

What are polypeptides formed from

A

Amino acids

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22
Q

What are polysaccharides of starch formed from

A

Monosaccharides of glucose

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23
Q

Polymers can be broken down by adding water what is this process called

A

Hydrolysis – water molecules break the bond that link the subunits of the polymer
E.g. polypeptides can be hydrolysis back into amino acids

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24
Q

Amino acids can become

A

Polypeptides

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25
Nucleotides can become
Polynucleotide
26
monosaccharides can become
Polysaccharides
27
Fatty acids and glycerol can become
Lipids
28
What is metabolism
All the chemical processes that take place in a living organism
29
A mole is the S1 unit of measuring the amount of substance. One mole = the same number of particles as there are in?
1 mole = The same number of particles as there are in 12 g of carbon 12 atoms
30
What is the avogado number/avogado constant
6.022 X10 to the power of 23
31
What is an atom
The smallest unit of chemical element that can exist independently Nucleus = protons + neutrons Electrons surround the outside
32
Neutrons Protons Electrons Hydrogen
Neutrons = no electrical charge, say mass of protons, occur in nucleus Protons = have a positive electrical charge Electrons = orbit the shell of the nucleus, very small mass, negatively charged, their number determines the chemical properties of the atom Hydrogen = only atom with no neutrons
33
What is the atomic number
The number of protons in an atom
34
What is the mass number
The total number of protons and neutrons in an atom
35
How do you determine what the overall charge is of an atom
The number of protons + electrons = 0
36
What is an isotope
The number of protons in an element always stays the same – number of neutrons can vary Same chemical properties but different masses - useful for tracing biological processes e.g. fossil dating
37
What is an ion
Ion = if an atom loses or receives an electron If it loses an electron = positively charged ion If it receives an electron = negatively charged ion More than one electron can be received or lost
38
What size can Carbohydrates be
Small or large carbon molecules
39
Carbon atoms very readily form bonds with other
Carbon atoms This forms a “backbone “which are the atoms can be attached – a large number of different types/size molecules to form all based on carbon (Life on Earth thanks to this)
40
What can carbon containing molecules also be called
Organic molecules
41
Long chains of monomers = polymers – these are made up of just four elements what are they
Carbon, hydrogen, oxygen, nitrogen
42
A pair of monosaccharides can combine to form award + examples
Polysaccharides e.g. glucose, galactose , fructose
43
To all monosaccharides + some disaccharides
Reducing sugars
44
Reduction = chemical reaction involving?
The gain of electrons or hydrogen
45
What is a Reducing sugar
A sugar that can donate electrons to another chemical
46
What test do you use to test for a reducing sugar
Benedicts test Benedicts reagent = an alkaline solution of copper (II) sulphate If a reducing sugar is present the Benedicks reagent forms an insoluble red precipitate of copper (I) oxide
47
In a disaccharide glucose + glucose = Glucose + fructose = Glucose + galactose =
Glucose +glucose = maltose Glucose + fructose = sucrose Glucose + galactose = lactose
48
When is the glycosidic bond formed
When are monosaccharide join, a molecule of water is removed ➡️ a condensation reaction occurs ➡️ the bond that is formed is called a glycosidic bond
49
When water is added to a disaccharide are usually breaks what type of bond. And what is this reaction called
``` It breaks the glycosidic bond Called hydrolysis (adding water that causes the breakdown) ```
50
How do you test for non-reducing sugars, (Some disaccharides don’t change colour with the normal Benedicts test)
First you must hydrolysis it into its monosaccharide component
51
Polysaccharide polymers formed by many monosaccharide molecules joined together by what bond
Glucose bonds Perfect for storage because they are the storage of monosaccharides and disaccharides
52
How do you test for starch
Starch is easily detected because it changes the colour of iodine when in a solution of potassium iodine (goes from yellow to black)
53
Starch is a polysaccharide found in many parts of what
Of the plant in the form of small grains Large amounts found in seeds and storage plants e.g. potato tubers (the major energy source in most diets)
54
Starch is made up of chains of what type of glucose
Alpha glucose Monosaccharides linked by glycosidic bonds formed by condensation reaction chains can be branched or unbranched If the chain is wound into a tight coil to make the molecules very compact
55
What is starches main role
An energy source
56
Why is starch well suited to be an energy source
1) It is insoluble and therefore doesn’t affect water potential (water is not drawn into the cell by osmosis) 2) because it is large it does not diffuse out of cells 3) it is compact so a lot can be stored in a small space 4) when hydrolysed it forms alpha glucose which is both easily transported and regularly used in respiration 5) because the branches have many ends each and can be acted on by enzymes simultaneously meaning glucose monomers are released very rapidly
57
Starch is never found an animal cells what is found instead
Glycogen serves the same role
58
Glycogen (animal starch) is found in animals and bacteria but never in what
Plant cells
59
Why is glycogen suited for energy storage in animals
1) insoluble so it doesn’t defuse out of cell 2) insoluble so it doesn’t tend to draw water into cell by osmosis 3) compact so a lot can be stored 4) more highly branched so more ends can be acted upon by enzymes for a faster breakdown of glucose monomers (very important because of high metabolic rate)
60
What is the main difference between Celulose and starch
Celulose is made of monomers of B– glucose Starch is made of monomers of alpha-glucose
61
Rather than a coiled chain like starch what does Celulose have
Straight unbranched chains that run parallel to each other allowing for hydrogen bonds to form cross linkages between adjacent chains Each individual hydrogen bond is weak but the overall number of them makes a strong +a valuable structural material
62
Cellulose molecules group together to form what
Microfibrils which are arranged in parallel group is called fibres
63
Cellulase Is a major component of the plant cell wall, why
Provides rigidity And prevents the cell wall from bursting as water enters it by osmosis
64
Cellulose is very important In the maintenance of stems and leaves to keep them turgid so they can provide a maximum service area for what
Photosynthesis
65
Lipids are very group of substances that share 4 characteristics
1) they contain carbon, hydrogen and oxygen 2) The proportion of oxygen to carbon and hydrogen is smaller than carbohydrates 3) they are insoluble in water 4) They are soluble in organic solvents e.g. alcohol + (the main group of lipids = triglycerides(fats + oils) +Phospholipids
66
What 4 things are lipids useful for
1) Source of energy➡️When oxidise they produce more than twice the energy as the same mass of carbohydrates + release valuable water 2) waterproofing➡️ insoluble in water➡️ insects have waxy lipid cuticles that conserve water, mammals produce an oily secretion from the sebaceous gland in the skin 3) insolation➡️Fats are slow conductors of heat + act as electrical insulators around the myelin sheath around the nerve cells 4) protection➡️ Factor often stored around delicate organs e.g. kidneys
67
Triglycerides have 3 what combined with what?
Three fatty acids combined with glycerol (glycerine)
68
What type of bond is there between each fatty acid and glycerol In a triglyceride What type of reaction is it
Ester Bond Condensation reaction Therefore hydrolysis of the triglycerides produces glycerol + 3 fatty acids
69
Glycerol molecules In all triglyceries are the same, so what is the difference in properties of fats and oils
The variation and fatty acids | They’re over 70 different fatty acids (they all have carboxyl (-COOH) Group with a hydrocarbon chain attached
70
When is a fatty acid described as saturated | When is a fatty acid described as unsaturated
When the chain has no carbon-carbon double bond The carbon atoms are linked to the maximum number of hydrogen atoms therefore they are saturated with maximum number of hydrogen atoms Unsaturated = one double bond = mono unsaturated = more than one double bond = polyunsaturated
71
What 4 things make triglycerides useful
1) High ratio of energy store and carbon hydrogen bonds = excellent source of energy 2) lots of energy can be stored in small volume (reduces the mass animals have to carry) 3) large nonpolar molecules = insoluble in water therefore doesn’t affect osmosis 4) releases water when oxidised therefore an important source of water
72
Phospholipids are similar to lipids except for one molecule what is it
One of the fatty acid molecules is replaced by a phosphate molecule
73
Fatty acid molecules repel water what is this known as Phosphate molecules attract water what is this known as
Hydrophobic Hydrophilic
74
A phospholipid is made up of two parts what are they
1) hydrophilic head | 2) hydrophobic tail
75
Polar molecules
Molecules that have two ends that behave differently such as phospholipids which have a hydrophobic tail and a hydrophilic head
76
The phospholipid structure allows for the formation of glycolipids by combining carbohydrates in the cell surface membrane why is this useful
Important in cell recognition in the cell surface membrane
77
What is the test for lipids called
Emotion test
78
Amino acid is a basic monomer is that make up polymers called what
Polypeptides - these can combine to form proteins
79
Every amino acid has a central carbon atom attached to 4 different chemical groups what are they
1) amino group = basic group 2) carboxyl group = acidic group 3) hydrogen atom 4) R (side) group = a variety of different chemical groups (20 naturally occurring amino acids differ only in their R (side) group
80
Formation of a peptide bond
Amino acid monomers combined to form dipeptides through condensation reaction
81
What is Polymerisation
Condensation reaction that joins many amino acid monomers - Results in a chain of hundreds of amino acids called polypeptides- The chain forms the structure of any protein The sequence is determined by DNA
82
The primary structure of a protein determines what
The shape and function | A single change in one amino acid can change/stop its function
83
A simple protein can consist of a single chain of what
Polypeptide. What is more commonly made up of a chain of polypeptides
84
The secondary structure of proteins
The linked amino acids that make up a polypeptide possess both -NH and minus C = O groups on either side of every peptide bond - The hydrogen = positive charge - The O = negative charge - hydrogen plus oxygen = 2 weak hydrogen bonds - This causes long polypeptide chains to be twisted and 3-D shape (alpha – helix coil)
85
Tertiary structure of a protein
Maintained by a number of different bonds which are determined by primary structure of the protein These bonds include: 1)Disulfide Bridges = very strong/not easily broken 2) ionic bonds: formed between carboxyl and amino groups – not involved in forming peptide bonds - Weaker than disulfide bonds + easily broken by changing pH 3) hydrogen bonds: numerous + easily broken

Biology A Level AQA (2 decks)

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