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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
Q

Nucleotides can become

A

Polynucleotide

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26
Q

monosaccharides can become

A

Polysaccharides

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27
Q

Fatty acids and glycerol can become

A

Lipids

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28
Q

What is metabolism

A

All the chemical processes that take place in a living organism

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29
Q

A mole is the S1 unit of measuring the amount of substance. One mole = the same number of particles as there are in?

A

1 mole = The same number of particles as there are in 12 g of carbon 12 atoms

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30
Q

What is the avogado number/avogado constant

A

6.022 X10 to the power of 23

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31
Q

What is an atom

A

The smallest unit of chemical element that can exist independently

Nucleus = protons + neutrons

Electrons surround the outside

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32
Q

Neutrons

Protons

Electrons

Hydrogen

A

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

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33
Q

What is the atomic number

A

The number of protons in an atom

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34
Q

What is the mass number

A

The total number of protons and neutrons in an atom

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35
Q

How do you determine what the overall charge is of an atom

A

The number of protons + electrons = 0

36
Q

What is an isotope

A

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
Q

What is an ion

A

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
Q

What size can Carbohydrates be

A

Small or large carbon molecules

39
Q

Carbon atoms very readily form bonds with other

A

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
Q

What can carbon containing molecules also be called

A

Organic molecules

41
Q

Long chains of monomers = polymers – these are made up of just four elements what are they

A

Carbon, hydrogen, oxygen, nitrogen

42
Q

A pair of monosaccharides can combine to form award + examples

A

Polysaccharides e.g. glucose, galactose , fructose

43
Q

To all monosaccharides + some disaccharides

A

Reducing sugars

44
Q

Reduction = chemical reaction involving?

A

The gain of electrons or hydrogen

45
Q

What is a Reducing sugar

A

A sugar that can donate electrons to another chemical

46
Q

What test do you use to test for a reducing sugar

A

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
Q

In a disaccharide glucose + glucose =

Glucose + fructose =

Glucose + galactose =

A

Glucose +glucose = maltose

Glucose + fructose = sucrose

Glucose + galactose = lactose

48
Q

When is the glycosidic bond formed

A

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
Q

When water is added to a disaccharide are usually breaks what type of bond. And what is this reaction called

A 
It breaks the glycosidic bond
Called hydrolysis (adding water that causes the breakdown)
50
Q

How do you test for non-reducing sugars, (Some disaccharides don’t change colour with the normal Benedicts test)

A

First you must hydrolysis it into its monosaccharide component

51
Q

Polysaccharide polymers formed by many monosaccharide molecules joined together by what bond

A

Glucose bonds

Perfect for storage because they are the storage of monosaccharides and disaccharides

52
Q

How do you test for starch

A

Starch is easily detected because it changes the colour of iodine when in a solution of potassium iodine (goes from yellow to black)

53
Q

Starch is a polysaccharide found in many parts of what

A

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
Q

Starch is made up of chains of what type of glucose

A

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
Q

What is starches main role

A

An energy source

56
Q

Why is starch well suited to be an energy source

A

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
Q

Starch is never found an animal cells what is found instead

A

Glycogen serves the same role

58
Q

Glycogen (animal starch) is found in animals and bacteria but never in what

A

Plant cells

59
Q

Why is glycogen suited for energy storage in animals

A

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
Q

What is the main difference between Celulose and starch

A

Celulose is made of monomers of B– glucose

Starch is made of monomers of alpha-glucose

61
Q

Rather than a coiled chain like starch what does Celulose have

A

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
Q

Cellulose molecules group together to form what

A

Microfibrils which are arranged in parallel group is called fibres

63
Q

Cellulase Is a major component of the plant cell wall, why

A

Provides rigidity And prevents the cell wall from bursting as water enters it by osmosis

64
Q

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

A

Photosynthesis

65
Q

Lipids are very group of substances that share 4 characteristics

A

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
Q

What 4 things are lipids useful for

A

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
Q

Triglycerides have 3 what combined with what?

A

Three fatty acids combined with glycerol (glycerine)

68
Q

What type of bond is there between each fatty acid and glycerol In a triglyceride
What type of reaction is it

A

Ester Bond

Condensation reaction

Therefore hydrolysis of the triglycerides produces glycerol + 3 fatty acids

69
Q

Glycerol molecules In all triglyceries are the same, so what is the difference in properties of fats and oils

A

The variation and fatty acids

They’re over 70 different fatty acids (they all have carboxyl (-COOH) Group with a hydrocarbon chain attached

70
Q

When is a fatty acid described as saturated

When is a fatty acid described as unsaturated

A

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
Q

What 4 things make triglycerides useful

A

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
Q

Phospholipids are similar to lipids except for one molecule what is it

A

One of the fatty acid molecules is replaced by a phosphate molecule

73
Q

Fatty acid molecules repel water what is this known as

Phosphate molecules attract water what is this known as

A

Hydrophobic

Hydrophilic

74
Q

A phospholipid is made up of two parts what are they

A

1) hydrophilic head

2) hydrophobic tail

75
Q

Polar molecules

A

Molecules that have two ends that behave differently such as phospholipids which have a hydrophobic tail and a hydrophilic head

76
Q

The phospholipid structure allows for the formation of glycolipids by combining carbohydrates in the cell surface membrane why is this useful

A

Important in cell recognition in the cell surface membrane

77
Q

What is the test for lipids called

A

Emotion test

78
Q

Amino acid is a basic monomer is that make up polymers called what

A

Polypeptides - these can combine to form proteins

79
Q

Every amino acid has a central carbon atom attached to 4 different chemical groups what are they

A

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
Q

Formation of a peptide bond

A

Amino acid monomers combined to form dipeptides through condensation reaction

81
Q

What is Polymerisation

A

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
Q

The primary structure of a protein determines what

A

The shape and function

A single change in one amino acid can change/stop its function

83
Q

A simple protein can consist of a single chain of what

A

Polypeptide. What is more commonly made up of a chain of polypeptides

84
Q

The secondary structure of proteins

A

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
Q

Tertiary structure of a protein

A

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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