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BIOLOGY REVISION > Biological Molecules > Flashcards

Biological Molecules Flashcards

1
Q

What is the general formula of a carbohydrate?

A

CnH2n0n

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2
Q

What are the three types of carbohydrate?

A

Monosaccharides (energy source)

Disaccharides and Polysaccharides (energy stores and structural units)

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3
Q

What are two properties of monosaccharides? Why do they have these?

A

Can release lots of energy- lots of C-H bonds

Soluble in polar solvents

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4
Q

What is the structure of glucose?

A

Glucose = C6 H12 06

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5
Q

Give two types of glucose and how they differ.

A

Alpha glucose- OH are the same way

Beta glucose- OH are facing opposite directions

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6
Q

Give the structures of Ribose and deoxyribose and explain why they differ.

A

Ribose- C5 H10 05 because it has an OH group on carbon 2

Deoxyribose- C5 H10 04 because it has an H group rather than an OH group on carbon 2

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7
Q

How do you make a gycosidic bond?

A

Condensation reaction between two monosaccharides.

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8
Q

What is the byproduct of a condensation reaction?

A

Water is the by product of a condensation reaction

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9
Q

How do you break a glycosidic bond?

A

Hydrolysis reaction breaks a glycosidic bond with the addition of water.

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10
Q

What are the monosaccharides of:

  • Maltose
  • Sucrose
  • Lactose
  • Cellobiose
A 
alpha glucose + alpha glucose = maltose
alpha glucose + fructose = sucrose
alpha glucose + beta galactose = lactose
beta glucose + beta glucose = cellobiose
THESE ARE DISSACHARIDES.
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11
Q

What si the energy store in animals?

A

Glycogen is the energy store in animals

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12
Q

What is the energy store in plants?

A

Starch = amylopectin + amylose

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13
Q

What do glycogen and amylose and amylopectin all have in common?

A

Similarities between energy stores:

  • Spiralling
  • Hydrogen bonding
  • Alpha glucose
  • 1-4 glycosidic bonding
  • hydroxyl groups on inside of spiral
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14
Q

What are the differences between amylose and amylopectin?

A 
Amylose: 
-1-4 glycosidic bonding
- no branching
Amylopectin:
-1-4 AND 1-6 gycosidic bonding
-branching
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15
Q

Discuss the structure of glycogen

A
  • shorter 1-4 glycosidic bonding
  • more 1-6 glycosidic bonding
  • more branching
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16
Q

Why are glycogen and starch suitable as energy stores?

A

Suitability as energy stores:

  • Compact due to spiralling and branching
  • Less soluble in water due to hydroxyl groups being ion the inside of the spiral SO they don’t lower the water potential in cells
  • Easy to snip of molecules in hydrolysis for respiration due to branching (many at a time)
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17
Q

Why is it especially important in animal cells that energy stores aren’t soluble?

A

Animal cells don’t have a cell wall, so if their water potential lowered due to soluble glycogen then water would flood in and the cell would burst (lysis) as it lacks the ability to become turgid.

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18
Q

What is cellulose?

A

A homopolysaccharide of beta glucose. It is a structural polysaccharide

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19
Q

What is a homopolysaccharide?

A

Homopolysaccharide = a polysaccharide of the same monosaccharide

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20
Q

Discuss the structure of cellulose

A

Cellulose

  • homopolysaccharide of beta glucose
  • 1-4 glycosidic bonding
  • one beta glucose is inverted when bonding
  • Straight chains
  • Hydrogen bonds between and in the chains
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21
Q

What are marcofibrils made up of and where are they found?

A

Macrofibrils are embedded in pectins

Macrofibrils = lots of microfibrils = lots of cellulose chains

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22
Q

Why is cellulose suitable for plant cell walls?

A

Suitbaility for cell walls:
-Macrofibrils have high tensile strength
-Criss crossing of macrofibrils give extra strength
- difficult to digest
These together give the plant cell SUPPORT.

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23
Q

Why do plant cells need extra support?

A

They have no skeleton and when cells become turgid they ned to not burst which the cell wall prevents.

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24
Q

Why does the plant cell wall need to be permeable?

A

The plant cell wall need to be permeable so it does not interfere with the role of the plant cell membrane which is partially permeable.

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25
Q

What are bacteria cell walla made of?

A

Bacteria cell walls = peptidoglycan, a polysaccharide of amino acids

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26
Q

Where else are polysaccharides found for structure?

A

Chitin in exoskeletons

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27
Q

What are 4 types of lipid?

A

Lipids:

  • triglycerides
  • phospholipid
  • cholesterol
  • gylcolipid
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28
Q

Why are lipids not polymer? What are they instead?

A

Lipids are MACROMOLECULES

because they are not repeating units they are made up of different molecules

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29
Q

What are lipids soluble in?

A

Lipids are soluble in ALCOHOL

Lipids are insoluble in water (polar solvents)

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30
Q

What is a triglyercide?

A 
Trigylceride = glycerol + fatty acid
glycerol ( 3 carbon 5 hydrogen 3 OH)
fatty acid (carboxyl group and hydrocarbon chain)
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31
Q

Discuss unsaturated fatty acids and the effects of c=c bonds

A

Unsaturated fatty acids:

  • c=c bonds
  • 1 c=c bonds is a monounsaturated fatty acid
  • more than one c=c bond is a polyunsaturated fatty acid
  • c=c bonds create kinks which means weaker intermolecular forces making the fatty acid more fluid and have a lower melting point
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32
Q

How do c=c bonds affect fluidity?

A

C=C bonds increase fluidity due to the kinks in the structures giving weaker intermolecular forces

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33
Q

How are triglycerides formed

A

Triglyercies are formed in ESTERIFICATION a form of condensation reaction that creates an ester bond between OH groups on glycerol and carboxyl group on fatty acid (3 fatty acids in a triglyceride)

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34
Q

What is saturated?

A

Saturated= no C=C bonds

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35
Q

what are the functions of triglycerides

A

Functions of triglycerides:

  • Energy source (hydrolyse ester bonds)
  • energy store (insoluble in cells)
  • insulation
  • protection of organs as a shock absorber
  • waterproofing (hydrophobic)
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36
Q

How is fat stored in animals

A

In animals fat is stored as adipose cells under the skin

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37
Q

What are phospholipids?

A

Phospholipid = glycerol + phosphate group + 2 fatty acids

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38
Q

What are the fatty acids in phospholipids like?

A

Fatty acids in phospholipids:

  • one saturated
  • one unsaturated
  • even numbers of Cs on them
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39
Q

Why are phospholipids amphipathic?

A

they are amphipathic because the phosphate heads are hydrophilic (polar) and the rest of the molecule is hydrophobic (non polar)

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40
Q

What is a micelle?

A

Phospholipids can form micelles- a small ball where all hydrophilic heads face out in a spherical shape and hydrophobic tails stay within the sphere

41
Q

How do phospholipids move in the bilayer?

A

Phospholipids in the bilayer move LATERALLY (sideways) but so that the hydrophobic tails always face in, this combo gives the membrane stability

42
Q

What is cholesterol? where is it made?

A

Cholesterol is a steroid alcohol.
It is 4 isoprene units (carbon rings) witj some hydrocarbon chains
It is small and hydrophobic
made in the liver

43
Q

What is the plant version of cholesterol?

A

Plants have Stimasterol instead of cholesterol

44
Q

What properties of cholesterol make it suitable for regulating the fluidity of the cell surface membrane?

A

It is small and hydrophobic so it can embed itself into the phospholipid bilayer.

45
Q

What is the general structure of an amino acid?

A

Amino group NH2
R-C-H (R = functional group)
Carboxyl group O=C-OH

46
Q

Why can we call proteins polymers of amino acids when they weren’t all the same?

A

They are polypeptides because they all have the same general structure

47
Q

How do amino acids bond? What is the bond?

A

Amino acids bond by CONDENSATION and form a PEPTIDE BOND (O=C-N-H). This is the OH from the carboxyl of one amino acid bonded to the H from the amino group on another

48
Q

What is primary structure?

A

Sequence of amino acids

49
Q

What is secondary structure? (types +susceptibility)

A

Scondary structure = coiling or folding of the amino acid chain
alpha helix OR beta pleated sheet OR unstructured region
Has H bonding so is susceptible to pH and temperature

50
Q

What is Tertiary structure? (bond tyoes)

A

Tertiary Strcutrue= folding of the alpha helix, beta plkeated sheet and the unstructured regions

  • ionic bonding (opposite charges)
  • hydrogen bonding (O/N-H—O/N)
  • disulphide bridge
  • hydrophobic interaction (inside)
  • hydrophilic interaction (outside)
51
Q

What is quaternary structure?

A

Quaternary= not in all proteins but is how multiple polypeptide chains (e.g. haemoglobin) are arranged to make a protein

52
Q

Compare structures of fibrous and globular proteins

A 
Fibrous
- extended 
-primary structure is regular and repetitive 
-secondary structure is simple
Globular
-compact
-no strict patterns in primary structure
-Secondary structure is complex
53
Q

Compare properties and functions of fibrous and globular

A 
Fibrous 
-structural roles
-insoluble
-less sensitive to changes in pH and temperature
Globular
-metabolic/functional roles
-soluble
-sensitive to changes in pH and temperature
54
Q

Give examples of fibrous and globular proteins

A 
Fibrous = collagen, keratin, elastin
Globular = Haemoglobin, insulin, pepsin
55
Q

Discuss haemoglobin structure

A

Haemoglobin is GLOBULAR it has FOUR POLYPEPTIDE CHAINS and it is called a CONJUGATED protein because each polypeptide chain is associated with a IRON HAEM GROUP (prosthetic group)

56
Q

How can you tell whether the haemoglobin is associated with oxygen or not?

A

Associated with O2 = blood is bright red

Without O2 = blood is dark purple

57
Q

Briefly describe two types of computer modelling of proteins and the purpose of computer modelling

A

Computer modelling allows prediction of secondary structures so we find new uses for proteins

  • Ab initio uses amino acid sequence and looks at the properties of atoms. Gives a lot of solutions
  • Comparative- use protein threading to scan and compare a protein to an existing data base of proteins
58
Q

Describe the test for starch

A

STARCH
Grind sample + add iodine
positive = yellow brown to blue black
BECAUSE Iodine forms triiodide ( I2—-I3’ )

59
Q

What is a reducing sugar?

A

Reducing sugar = sugar that donates an electron. All monosaccharides are reducing sugars and some disaccharides are

60
Q

Describe the test for reducing sugars

A

REDUCING SUGAR
1 . add benedicts solution (alkaline copper ii sulphate)
2.heat in water bath at 80 degrees for 3 minutes
3. use test strips
Positive = blue — green —- orange —-red
BECAUSE Cu2+ + electron —— Cu+ (been reduced)

61
Q

Describe test for non reducing sugars

A

NON REDUCING SUGARS

  1. test for reducing sugars
  2. boil sample in HCL
  3. cool and neutralise with sodium hydrogen carbonate
  4. test for reducing sugars again
62
Q

What is the test for lipids?

A 
LIPIDS 
Emulsion test 
1.Mix sample with ethanol 
2.Filter
3.pour into water
Positive = cloudy white emulsion
63
Q

What is the test for proteins

A 
PROTEINS
Biuret test
1. add biuret 1 of sodium hydroxide 
2. add biuret 2 of calcium sulphate
Positive = light blue ---- lilac
64
Q

What are cations and anions?

A

Cations are positively charged ions

Anions are negatively charged ions

65
Q

What are the functions of calcium ions?

A

CALCIUM IONS Ca2+

  • rigidity of structures
  • Muscle contraction + release of vesicles
  • blood clotting
  • permeability of cell membranes
66
Q

Functions of sodium ions?

A

SODIUM IONS Na+

  • nervous transmission and ,muscle contraction
  • osmotic pressure
  • absorption of water in the kidney (loop of Henle)
67
Q

Functions of Potassium ions?

A

POTASSIUM IONS K+

  • nervous transmission (pumps)
  • water levels in the body
  • synthesis of glycogen and breakdown of glucose
  • healthy leaves and flowers
68
Q

What two ions have lots of overlapping functions

A

Functions of sodium and potassium ions tend to overlap

69
Q

Functions of hydrogen ions?

A

HYDROGEN IONS H+

  • pH maintenance
  • photosynthesis and respiration (proton gradient)
  • CO2 and O2 transport
70
Q

Functions of ammonium?

A

AMMONIUM IONS NH4+

  • building blocks for amino acids (amino group) and proteins
  • nitrogen cycle
  • hormones and nucleic acids
71
Q

What are the roles of Nitrate ions?

A

NITRATE IONS NO3-

  • nucleic acids
  • nitrogen cycle
  • vitamins
72
Q

Functions of Hydrogen carbonate ?

A

HYDROGEN CARBONATE HCO3-

  • Blood pH (dissociation into H+)
  • CO2 transport
73
Q

Functions of chloride ions?

A

CHLORIDE IONS Cl-

  • blood ph
  • regulate haemoglobins affinity for oxygen
  • production of urine
74
Q

Functions of phosphate ions?

A

PHOSPHATE IONS PO4 3-

  • rigidity of structures
  • phospholipids (phosphate head)
  • nucleic acids
  • helps root growth
75
Q

Functions of hydroxide ions?

A

HYDROXIDE IONS OH-

-blood pH

76
Q

What can happen if you consume inadequate amounts of these ions?

A

Deficiencies

77
Q

Why is water a polar molecule?

A

Water is polar because it has a negative dipole (oxygen) and a positive dipole (hydrogen)

78
Q

What are the 6 properties of water?

A

Properties of water:

  • liquid at room temperature
  • ice is less dense than water
  • good solvent due to it being polar
  • cohesion and surface tension
  • high specific heat capacity
  • high latent heat of vaporisation
79
Q

What is waters specific heat capacity?

A

Water has a specific heat capacity of 4.2 kJ. This raises 1KG of water by 1 degree

80
Q

Why is it good that water is a liquid at room temperature?

A

Gives a reaction medium, transport medium and provides a habitat

81
Q

Why is it good that ice is less dense than water?

A

It means ice floats on top of bodies of water giving an insulating layer and meaning the water can remain a habitat

82
Q

Why is it good that water is a good solvent?

A

allows for transport of things and reactions can take place in it

83
Q

Why is it good that water has a high specific heat capacity and high latent heat of vaporisation?

A

As the value is high it means habitats are stable as they have a stable temperature and having a high latent heat of vaporisation means mammals can cool themselves through sweating

84
Q

Why is water having cohesion and surface tension good?

A
  • water can act as a column in xylem vessels

- surface tension allows for life to occur on the surface of water

85
Q

When is water at its most dense?

A

Water is most dense at 4 degrees Celsius

86
Q

What happens when water temperature gets lower than 4 degrees Celsius?

A

Before 4 degrees water increases in density as it lowers but after 4 degrees it starts to get less dense.

87
Q

What is the aim of chromatography?

A

The aim of chromatography is to separate the constituents of a mixture to identify them individually

88
Q

What is the stationary phase of thin layer chromatography?

A

The stationary phase is either
-chromatography paper of cellulose
- thin layer chromatography plate coated with silica gel or aluminium hydroxide
both have free -OH groups pointing outwards in contact sith the mobile phase

89
Q

What is the mobile phase of chromatography?

A

The mobile phase of the solvent for the biological molecules. It flows across the stationary phase carrying the biological molecules with it

  • water for polar moledules
  • ethanol for non polar molecules
90
Q

What does the Rf value shpow you?

A

Different pigments have different Rf values so finding their Rf value helpsmyou identify the pigment/ bioloigcql molecule

91
Q

How do you see colourless amino acids?

A

To see colourless amino acids you can spray the dried plate with ninhydrin making them purple or brown spots

92
Q

How do you use iodiene to see colourless moleucles in TLC?

A

In TLC you can leave the dried plate in a sealed container with iodine crystals. The iodine forms a gas which binds to the molecules

93
Q

How do you use UV light to see colourless molecules in TLC?

A

Thin layter chromatography plates have a chemical which fluoresces under UV light. Everythiung byt the spots of pigment/ molecules will glow. The molecules block the plate from the uv light

94
Q

What does the speed/distance travrlled by molecules in chromatography depend on?

A

The speed at which molecules move along the paper of TLC plate depends on their solubility in the solvent and their polarity.

95
Q

If two molecules move at exactly the same speed what can you do to separate them?

A

To separate two molecules travelling at the same speed you can try using a different solvent or changing the pH

96
Q

Discuss speeds of molecules dependeing in their polarity and how this works.

A
  • Exposed -OH groups on the plate/paper make it very polar allowing it to fomr hydrogen bonds with the moleules and their dipoles
  • Highly polar solute tends to stick to the surface (adsorbed) so moves slowly
  • Less polar solutes will not stick so travel quickly up the plate
97
Q

Describe how you would for thin layer chromatography

A
  1. Prepare a beaker with a small amount of solvent (mobile phase)
  2. Draw a line along the bottom of the chromatography paper piece
    a) Draw in pencil
    b) The line should high enough on the strip to not be submerged in solvent when placed in the beaker
  3. Draw a tiny dot on the line to mark where you will apply your sample
  4. Place the paper in the beaker
  5. Cover the beaker with a glass plate
  6. Leave the apparatus until the solvent has been absorbed by the paper and travelled to the other end of it
  7. Use Rf = x/y where:
    a) x = distance travelled by each solute
    b) y = distance travelled by the solvent
  8. Each biological molecule has its own Rf and is thereby identifiable
98
Q

What does a high Rf value represent?

A

The higher the Rf value, the longer the distance that a specific compound has travelled.

99
Q

Discuss charged particles and electricity in thin layer chromatography

A

Thin layer chromatography does not use electricity and does not deal with charged molecules, just polar ones

BIOLOGY REVISION (21 decks)

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