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Biology > Chap.1 Chemical elements and biological compounds > Flashcards

Chap.1 Chemical elements and biological compounds Flashcards

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1
Q

Use of Mg2+

A

Constituent of chlorophyll, for photosynthesis

Otherwise chlorosis and stunted growth in plants

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2
Q

Use of Fe2+

A

Constituent of haemoglobin

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3
Q

Use of Ca2+

A

Structural component in bones, teeth

Also in cell walls to give strength

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4
Q

Use of PO4 3-

A

Nucleotide production e.g. ATP

Constituent of phospholipids

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5
Q

Why is water a dipole?

A

A dipole means that the molecule is polar, and it has a positive and negative charge separated by very small distances
No overall charge
H+ ions are slightly electronegative and O2- ions are more electropositive

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6
Q

Type of bonding between H2O molecules

A

Hydrogen bonding

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7
Q

Why is water a good solvent

A

It is polar

so attracted charged particles and other polar molecules

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8
Q

What is good about water being a solvent

A

Act as a transport medium e.g. in xylem and phloem in plants

Chemical reactions taking place in water (aq)

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9
Q

Why water has a high specific heat capacity

A

Hydrogen bonding collectively strong

Requires large amount of energy

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10
Q

Why is water having a high specific heat capacity good

A

No large fluctuations of temp in water
Stable habitat
Enzymes work efficiently
Organisms do not have to adapt to extreme conditions

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11
Q

Why is water having a high latent heat of vaporisation good

A

In temperature control mechanism

Releases energy when sweating, cool down body

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12
Q

What is cohesion in water

A

Attraction between water molecules
Sticking together as a lattice
So columns of water drawn up xylem vessels

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13
Q

How does the high surface tension in water help some organisms

A

Insects able to skate through

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14
Q

What is special about density of liquid water and ice

A

Ice is less dense than water
So float on water if temp drops
as it has to expand when more hydrogen bonds form
Therefore a thermal insulation preventing water beneath to freeze
Organisms at the bottom survive

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15
Q

What is important about water being transparent

A

So light can pass through

Aquatic plants photosynthesise efficiently

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16
Q

General formula of a monosaccharide

A

CH2O

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17
Q

What is the category of monosaccharide glucose is in

A

Pentose sugar (six rings)

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18
Q

Names of isomers of glucose

A

Alpha and Beta glucose

Have same chemical formula but different molecular arrangements

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19
Q

Functions of monosaccharides

A
  1. Energy source from respiration
  2. Building blocks for larger molecules
  3. Intermediates in reactions
  4. Constituents of nucleotides
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20
Q

What is a disaccharide

A

2 units of monosaccharides bonded together

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21
Q

How is a disaccharide formed

A

By condensation reaction
1, 4 Glycosidic bonds in between
Elimination of water

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22
Q

Maltose = ?

A

Alpha glucose + Alpha glucose

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23
Q

Sucrose = ?

A

Alpha glucose + fructose

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24
Q

Lactose = ?

A

Beta glucose + galactose

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25
Q

Test for reducing sugar

A

Add Benedict’s solution and heat

If color changes from blue to brick red, reducing sugar is present

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26
Q

Why sucrose gets a negative result when using Benedict’s solution

A

As it is a non-reducing sugar

27
Q

Test for non reducing sugar using Benedict’s solution

A

Add acid (HCl) and heat
Add alkali e.g. NaOH and Benedict’s solution
as Benedict’s solution works in alkaline conditions
If color changes from blue to brick red, reducing sugar is present

28
Q

How to detect sucrose apart from using HCl

A

Use of sucrase (enzyme)

29
Q

Benefits of starch as storage comparing to glucose

A

Insoluble in water
so no osmotic effects
More compact so can store a lot is a small space
Carries a lot of energy

30
Q

What is the main store of glucose in plants

A

Starch

31
Q

Two types of starch

A

Amylose and amylopectin

32
Q

Describe amylose

A

Bonded by alpha 1,4 glycosidic bonds

Coiled into helices

33
Q

Describe amylopectin

A

Has both alpha 1,4 and 1,6 glycosidic bonds

34
Q

Test for starch

A

Add iodine solution (iodine potassium test)

Color changes from brown to dark blue

35
Q

Main energy storage in animals

A

Glycogen

36
Q

Describe glycogen

A

Similar to amylopectin
Has both alpha 1,4 and 1,6 glycosidic bonds
But more branches/break ends
So more energy could be stored
More suitable for high metabolic needs in animals

37
Q

What is cellulose consisted of

A

beta glucose units

38
Q

Structure of cellulose

A

Beta glucose monomers joined by 1,4 glycosidic bonds
But alternating unit every adjacent molecule
of 180 degrees
Parallel hydrogen bonding between chains
so form microfibrils

39
Q

Usage of cellulose

A

Found in plant cell walls
Provides strength to withstand pressure (from osmosis)
Structural stability

40
Q

Where is chitin found

A
  1. Exoskeleton of insects

2. Fungi cell walls

41
Q

Structure of chitin

A

Similar to cellulose
Beta 1,4 glycosidic bonds
Plus an amino group
Rotating 180 degrees, alternating adjacent monomers
Crosslinks and microfibrils (hydrogen bonding)

42
Q

What is consisted of a triglyceride

A

1 glycerol and 3 fatty acids

43
Q

How is a triglyceride made

A

Each glycerol joined by 3 fatty acid tails
by condensation reaction
Forms ester bonds for each tail
Elimination of water

44
Q

Property of lipid

A

Insoluble in water, but soluble in organic solvents e.g. ethanol

45
Q

What does a phospholipid contain

A

1 phosphate group, 2 fatty acid chains, 1 glycerol

46
Q

Properties of a phospholipid

A

Phosphate head is hydrophilic, attracted to water

Fatty acid tails are hydrophobic, non polar, repel away from water

47
Q

Difference between a saturated and an unsaturated fatty acid chain

A

Saturated: Contains the max number of carbon atoms
Unsaturated: bend in directions, monomers do not align uniformly

48
Q

Properties of a lipid with mostly unsaturated fatty acids

A

Oil at room temp, as lipid doesn’t solidify readily

49
Q

Roles of phospholipids

A
  1. Cell membranes

2. Electrical insulation

50
Q

Uses of triglycerides

A
  1. Energy storage
  2. Thermal insulation
  3. Physical protection
  4. Produces metabolic water from condensation
51
Q

Test for lipid

A

Mix solution with ethanol
*Shaken with equal volume of water
White emulsion formed

52
Q

Consequences of diet high in saturated fats

A

Build up of low density lipoproteins
Carries fats to arteries for deposit
Fatty materials can build up to block blood flow
May lead to heart attack, angina

53
Q

Why is HDL good

A

Made when diet has a higher proportion of unsaturated fats (plant oils)
Transports harmful fats to liver for disposal
Lower risks of cardiovascular diseases

54
Q

What element is only contained in proteins, not in lipids or polysaccharides

A

Nitrogen

55
Q

What is a polypeptide made of

A

amino acid chain

56
Q

Formation of a dipeptide

A

Elimination of water, OH from carboxyl group of one amino acid, H from amine group of another
Peptide bond
by condensation reaction

57
Q

Primary structure of protein

A

Unique sequence of amino acids
held by peptide bonds
Sequence determined by DNA

58
Q

Secondary structure of protein

A

either alpha helices or beta pleated sheets
hydrogen bonding
Initial 3D shape

59
Q

Tertiary structure of protein

A 
Mixture of alpha helices and beta pleated sheets
Gives complex 3D structure of a protein
Bonding: 
1. disulphide bridges
2. hydrogen bonding
3. ionic bonding
4. hydrophobic interactions
60
Q

Quaternary structure of protein

A

More than 1 polypeptide chain
or bonded with non-protein groups
e.g. haem Fe2+
to be functional

61
Q

Properties of fibrous proteins

A

Insoluble in water
Many cross links and long fibres
Strong and tough, provides strength
E.g. collagen, keratin

62
Q

Properties of globular proteins =

A

Soluble in water
Spherical in shapes
E.g. enzymes

63
Q

Test for proteins

A

Add Biuret solution

Color changes from blue to purple

64
Q

Diagrams check!

A
  1. Amino acid -> dipeptide
  2. Triglyceride
  3. Alpha/Beta glucose

Biology (4 decks)

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