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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
Test for reducing sugar
Add Benedict's solution and heat | If color changes from blue to brick red, reducing sugar is present
26
Why sucrose gets a negative result when using Benedict's solution
As it is a non-reducing sugar
27
Test for non reducing sugar using Benedict's solution
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
How to detect sucrose apart from using HCl
Use of sucrase (enzyme)
29
Benefits of starch as storage comparing to glucose
Insoluble in water so no osmotic effects More compact so can store a lot is a small space Carries a lot of energy
30
What is the main store of glucose in plants
Starch
31
Two types of starch
Amylose and amylopectin
32
Describe amylose
Bonded by alpha 1,4 glycosidic bonds | Coiled into helices
33
Describe amylopectin
Has both alpha 1,4 and 1,6 glycosidic bonds
34
Test for starch
Add iodine solution (iodine potassium test) | Color changes from brown to dark blue
35
Main energy storage in animals
Glycogen
36
Describe glycogen
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
What is cellulose consisted of
beta glucose units
38
Structure of cellulose
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
Usage of cellulose
Found in plant cell walls Provides strength to withstand pressure (from osmosis) Structural stability
40
Where is chitin found
1. Exoskeleton of insects | 2. Fungi cell walls
41
Structure of chitin
Similar to cellulose Beta 1,4 glycosidic bonds Plus an amino group Rotating 180 degrees, alternating adjacent monomers Crosslinks and microfibrils (hydrogen bonding)
42
What is consisted of a triglyceride
1 glycerol and 3 fatty acids
43
How is a triglyceride made
Each glycerol joined by 3 fatty acid tails by condensation reaction Forms ester bonds for each tail Elimination of water
44
Property of lipid
Insoluble in water, but soluble in organic solvents e.g. ethanol
45
What does a phospholipid contain
1 phosphate group, 2 fatty acid chains, 1 glycerol
46
Properties of a phospholipid
Phosphate head is hydrophilic, attracted to water | Fatty acid tails are hydrophobic, non polar, repel away from water
47
Difference between a saturated and an unsaturated fatty acid chain
Saturated: Contains the max number of carbon atoms Unsaturated: bend in directions, monomers do not align uniformly
48
Properties of a lipid with mostly unsaturated fatty acids
Oil at room temp, as lipid doesn't solidify readily
49
Roles of phospholipids
1. Cell membranes | 2. Electrical insulation
50
Uses of triglycerides
1. Energy storage 2. Thermal insulation 3. Physical protection 4. Produces metabolic water from condensation
51
Test for lipid
Mix solution with ethanol *Shaken with equal volume of water White emulsion formed
52
Consequences of diet high in saturated fats
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
Why is HDL good
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
What element is only contained in proteins, not in lipids or polysaccharides
Nitrogen
55
What is a polypeptide made of
amino acid chain
56
Formation of a dipeptide
Elimination of water, OH from carboxyl group of one amino acid, H from amine group of another Peptide bond by condensation reaction
57
Primary structure of protein
Unique sequence of amino acids held by peptide bonds Sequence determined by DNA
58
Secondary structure of protein
either alpha helices or beta pleated sheets hydrogen bonding Initial 3D shape
59
Tertiary structure of protein
``` 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
Quaternary structure of protein
More than 1 polypeptide chain or bonded with non-protein groups e.g. haem Fe2+ to be functional
61
Properties of fibrous proteins
Insoluble in water Many cross links and long fibres Strong and tough, provides strength E.g. collagen, keratin
62
Properties of globular proteins =
Soluble in water Spherical in shapes E.g. enzymes
63
Test for proteins
Add Biuret solution | Color changes from blue to purple
64
Diagrams check!
1. Amino acid -> dipeptide 2. Triglyceride 3. Alpha/Beta glucose

Biology (4 decks)

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