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Biology > Chemical and Cellular Basis of Life > Flashcards

Chemical and Cellular Basis of Life Flashcards

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1
Q

How many elements are recognized in nature?

A

92

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2
Q

What percentage of those elements are essential to continue healthy life and reproduction?

A

20 - 25%

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3
Q

How many elements are essential for,
a) Humans
b) Plants

A

a) 25
b) 17

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4
Q

Elements that make up 96% of living matter?

A

C, H, O, N

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5
Q

Elements that make up most of the remaining 4%?

A

Ca, P, K, S

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6
Q

Elements found in minute amounts in living matter?

A

Na, Cl, Mg, B, Co, Cu, Cr, F, I, Fe

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7
Q

Two reasons why water is important?

A
  1. Vital chemical constituent of living cell
  2. Provides a biological medium for all organisms
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8
Q

Describe the chemical structure of water?

A

Small, polar, angular molecules.

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9
Q

Describe the polarity of water?

A
  • Oxygen atom is slightly negative and hydrogen atom is slightly positive.
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10
Q

Define hydrogen bonds in water?

A

Weak attractions between the slightly polar hydrogen atom of one water molecule and an oxygen atom of an adjacent water molecule.

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11
Q

Nature of hydrogen bonds of water when it’s a liquid?

A
  • Very fragile
  • Form and break with great frequency.
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12
Q

Four major properties of water to maintain life on earth?

A
  1. Cohesive behaviour
  2. Ability to moderate temperature
  3. Expansion upon freezing
  4. Versatality as a solvent
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13
Q

Define,
1. Cohesion
2. Adhesion

A
  1. Attractions between water moelcules due to hydrogen bonding
  2. Attraction between water molecules and other substances.
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14
Q

Properties of water that allow it to act as a transport medium?

A

Cohesion, Adhesion

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15
Q

Use of cohesion in plants?

A

Water and dissolved substances such as minerals are transported as a continuous column through xylem against gravity.

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16
Q

Use of adhesion in plants?

A

Adhesion between water molecules and cell walls helps in conduction of water and dissolved subtances.

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17
Q

Why does water has high surface tension?

A

Due to cohesion between water molecules, the uppoer surface water molecules are attracted by lower surface molecules and it forms a water film.

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18
Q

Explain water’s ability to moderate temperature

A

Water can absorb/ release a relatively high amount of heat energy by a slight change in its own temperature.

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19
Q

Advantage of high specific heat of water?

A

Acts as a thermal buffer in living system and aquatic bodies during temperature fluctuations on earth.

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20
Q

Advantage of high heat of vaporization?

A

An organism can release much heat energy with minimum loss of water. This helps organisms to cool their body surfaces.
1. Evaporation of water from human skin helps to maintain the body temperature at consant level.
2. Transpiration in plants help to cool the plant body surface and prevent from becoming too warm in the sunlight.

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21
Q

Explain the expansion upon freezing in water.

A

When the temperature of water falls below 4 ˚C, it begins to freeze and forms a crystalline lattice called ice cubes. Therefore water has the maximum density at 4˚C. Hence, ice floats on the surface of water bodies

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22
Q

What trait gives water its versatality as a solvent?

A

Polarity

23
Q

Explain water’s versatality as a solvent.

A

The following substances can dissolve in water,
* Polar - Glucose
* Ionic compunds - NaCl
* Polar and ionic - Lysozymes

24
Q

What does the solubility of a solute depends on?

A

Polarity

25
Q

Features of carbohydrates?

A
  • Most abundant group of organic compounds
  • Major elemental composition
  • H:O = 2:1
  • General formula - Cx(H2O)y
  • Has three major groups
26
Q

Features of monosaccharides?

A
  • Simplest form of carbohydrates
  • General molecular formula - (CH2O)n
  • No. of C atoms varies from 3-7
  • Reducing sugar
  • Water soluble
  • Crystalline form

Refer to table

27
Q

Types of carbs according to type of carbonyl group with e.g.?

A
  1. Aldoses - Glucose, Galactose
  2. Ketoses - Fructose
28
Q

What are disaccharides?

A

Sugars fromed by joining two monosaccharidess by a glycosidic bond.

29
Q

Define glycosdic bond.

A

Covalent bonds formed by removal of a water molecule from two adjacent monosaccharides by a condensation reaction.

30
Q

Reducing and non reducing disaccharides?

A
  1. Reducing - Maltose, Lactose
  2. Non-reducing - Sucrose
31
Q

Features of polysaccharides?

A
  • Macromolecules and biopolymers
  • Made of monosaccharide sub units.
  • Non crystalline
  • Water insoluble
  • Not considered as sugars
32
Q

Two functions of polysaccharide?

A
  • Act as storage components
  • Contribute to living structure of organisms
33
Q

Two classification criteria for polysaccharides?

A
  1. Function
  2. Architecture
34
Q

Types of polysaccharides according to function with e.g.?

A

1.Storage - Starch, Glycogen
2. Structural - Cellulose, Hemicellulose, Pectin

35
Q

Types of polysaccharide according to architecture with e.g.?

A
  1. Linear - Amylose, Cellulose
  2. Branched - Amylopectin, Hemicellulose, Glycogen
36
Q

Functions of disaccharides?

A
  • Energy source
  • Building blocks of disaccharides and polysaccharides
  • Components of nucleotides
37
Q

Functions of disaccharides?

A
  • Storage sugar in milk - Lactose
  • Translocation in phloem - Sucrose
  • Storage sugar in sugarcane - Sucrose
38
Q

Functions of polysaccharides?

A

Table

39
Q

Characteristics of lipids?

A
  • Diverse group of hydrophobic molecules
  • Large biological molecules but not considered as polymers or macromolecules
  • H:O ratio isn’t 2:1
  • Three types of biological importance
40
Q

What are fatty acids made of?

A

Glycerol + Fatty acids

41
Q

Characteristics of proteins?

A
  1. Made up of amino acids
  2. Twenty different amino acids are involved in protein formation
  3. Elemental composition - C,H,O,N,S
42
Q

Draw the structure of an amino acid.

A

In notes

43
Q

Why are amino acids amphoteric molecules?

A

Because amino acids may have one or more carboxyl and amino groups. Amino groups are alkaline and carboxyl groups are acidic. Since both these features are found in one molecule, it is amphoteric.

44
Q

How are peptide bonds formed?
Words and picture

A

Two amino acids undergo a condensation reaction by removing a water molecule.

45
Q

What are proteins composed of?

A

One/ more polypeptide chains which are composed of amino acids.

46
Q

What are the levels of protein stucture?

A
  1. Primary
  2. Secondary
  3. Teritary
  4. Quaternary
47
Q

Define primary structure of proteins?

A

Unique sequence of linearly arranged amino acids linked by peptide bonds.

48
Q

Define secondary structure of proteins?

A

The primary structure of a single polypeptide chain coils and folds as a result of intra molecular hydrogen bonds between oxygen atoms of carboxyl groups and Hydrogen atoms of amino groups of the same polypeptide chain backbone, to form the secondary structure/

49
Q

What are the two types of secondary structures? Give examples.

A
  • Alpha helix - Keratin
  • Beta pleated sheet - Spider’s silk fiber
50
Q

What is the tertiary structure of proteins?

A

Usually, the secondary polypeptide chain bends and folds extensively forming a precise, compact, unique, functional and three dimensional shape resulting from interactions between the side chain.

51
Q

Give such interactions? e.g.

A
  1. H bonds
  2. Disulphide bonds
  3. Ionic bonds
  4. Hydrophobic and Van der Waals interactions
    e.g. Most enzymes, myoglobin, albumin
52
Q

Define quaternary structure of proteins?

A

Aggregation of two/more polypeptide chains involve in the formation of one functional protein.
e.g. Haemoglobin, collagen

53
Q

What is denaturation of proteins?

A

Loss of specific three dimensional shaped due to alteration of weak chemical bonds and interactions.

54
Q

What are the agents affecting denaturation?

A
  1. High temperature and high energy radiation
  2. Strong acids, alkaline and high concentration of salts.
  3. Heavy metals
  4. Organic solvents and detergents.

Biology (3 decks)

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