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MHS1101 > Chemistry & Biochemistry > Flashcards

Chemistry & Biochemistry Flashcards

1
Q

What are the 6 main chemical elements in the human body? (And the percentages)

A 
Oxygen (O) - 65%
Carbon (C) - 18.6%
Hydrogen (H) - 9.7%
Nitrogen (N) - 3.2%
Calcium (Ca) - 1.5%
Phosphorus (P) - 1%
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2
Q

What are trace elements?

A

Trace elements exist in minute quantities compared to the main elements and no one accounts for more than 0.02% of body weight.

Despite this they play important physiological roles in the body.

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3
Q

What are minerals and which minerals are most abundant in the human body?

A

Inorganic elements extracted from the soil by plants and passed up the food chain to humans and other organisms.

The most abundant minerals are calcium and phosphorus.

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4
Q

What are isotopes?

Explain radioisotopes.

A

Isotopes are varieties of an element. They differ in their number of neutrons only, but chemically behave the same.

Radioisotopes are unstable isotopes that decay by emitting radiation.

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5
Q

What is ionising radiation?

How is it dangerous?

A

High energy electrons ejected from radioisotopes covert other atoms to ions.

This destroys molecules and creates free radicals that can trigger a chain reaction of destruction of other molecules.

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6
Q

What are antioxidants?

Where do we get them from?

A

Antioxidants are chemicals that neutralise free radicals.

Some are produced by the body and some must be obtained from the diet.

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7
Q

What are the four types of chemical bonds?

List them in order of strength.

A
  1. Covalent
  2. Ionic
  3. Hydrogen
  4. Van der Waal’s forces
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8
Q

Explain ionisation.

A

Atoms with incomplete valence shells transfer electrons from one to the other to result in a complete valence shell.

This results in one atom becoming positively charged (loses electrons) - Cation

And one atom becoming negatively charged (gains electrons) - Anion

The action and anion are then electrically attracted to one another.

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9
Q

What are covalent bonds? Explain the different types.

A

Covalent bonds are formed by the sharing of electrons between atoms to complete their valence shells.

Single covalent - share one pair of electrons
Double covalent - share two pairs of electrons

Non polar - electrons spend equal tome around each nucleus
Polar - electrons spend more time around one nucleus

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10
Q

What are hydrogen bonds?

A

Weak attraction between a slightly positive hydrogen atom in one molecule and a slightly negative oxygen or nitrogen atom in another molecule (or within a molecule)

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11
Q

What are Van der Waal’s forces?

A

Weak, brief attractions between neutral atoms caused by the random movement of electrons around the nuclei of the atoms. Brief crowding of electrons to one side of an atom create momentary polarity.

The forces are weak alone but, in a large molecule with many atoms, can be quite strong.

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12
Q

Describe the properties of solutions.

A

Particles are <1nm

Solute and solvent cannot be visibly distinguished

Transparent as particles do not noticeably scatter light

Solute will pass through most selectively permeable membranes

Solute does not separate from solvent when allowed to stand

Eg. Calcium in blood

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13
Q

Describe the properties of colloids.

A

Particles are 1-100nm

Cloudy as the particles do scatter light

Particles too large to pass through most selectively permeable membranes

Particles do not separate from solvent when left to stand

Eg. Proteins in blood

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14
Q

Describe the properties of suspensions.

A

Particles are >100nm

Cloudy or opaque

Particles too large to penetrate selectively permeable membranes

Particles are too heavy to remain permanently suspended and so separate on standing

Eg. Blood cells

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15
Q

What is an emulsion?

A

An emulsion is a suspension of one liquid in another.

Eg. Fat in breast milk

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16
Q

What are the properties of water?

A

Solvency

Cohesion

Adhesion

Chemical reactivity

Thermal stability

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17
Q

What is the difference between an acid and a base?

A

Acids are proton donors

Bases are proton acceptors (or donors of OH-)

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18
Q

What are buffers?

A

Buffers are solutions that resist changes in pH.

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19
Q

What is the rough pH range of the blood?

A

7.35 to 7.45

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20
Q

What are the four main types of energy?

A

Potential energy - energy stored but not currently doing work

Kinetic energy - energy of motion

Chemical energy - potential energy stored in bonds of molecules

Activation energy - energy required to start a chemical reaction

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21
Q

What is the difference between exergonic and endergonic reactions?

A

Exergonic reactions release energy and endergonic reactions conserve energy.

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22
Q

Name and describe the three classes of chemical reactions. What are their basic equations?

A

Decomposition - breaks down a large molecule into two or more smaller molecules
AB -> A + B

Synthesis - combines two or more smaller molecules to form a larger molecule
A + B -> AB

Exchange - two molecules exchange atoms or groups of atoms
AB + CD -> AC + BD

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23
Q

What are reversible reactions? What law do they follow?

A

Reversible reactions go in either direction under different circumstances. Direction is determined by relative abundance of products and reactants on either side.

This follows the law of mass action: proceeding from reactants in greater quantity to products in lesser quantity.

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24
Q

What factors affect reaction rates?

A

Concentration of reactants

Temperature

Presence of catalysts

25
Q

What is metabolism and what are it’s two main divisions?

A

Metabolism is all chemical reactions that occur in the body

Catabolism (exergonic) - decomposition

Anabolism (endergonic) - synthesis

26
Q

What is oxidation and reduction?

What is the anagram?

A

Oxidation is a reaction in which a molecules gives up electrons and releases energy

Reduction is a reaction in which a molecule gains electrons and gains energy

OIL RIG

27
Q

What are the four categories of carbon compounds?

A

Carbohydrates
Lipids
Proteins
Nucleus Acids

28
Q

What is the ratio of hydrogen to carbon in carbohydrates?

A

2:1

29
Q

What are the three major monosaccharides?

A

Glucose

Galactose

Fructose

These are all isomers of each other and are all eventually converted to glucose.

30
Q

What are the three main disaccharides and what are their subunits?

A

Sucrose
- glucose + fructose

Lactose
- glucose + galactose

Maltose
- glucose + glucose

31
Q

Give three examples of polysaccharides and describe their function.

A

Glycogen
- energy storage in humans

Starch
- energy storage in plants

Cellulose
- structural molecule in plants, important for dietary fiber

32
Q

Which carbon compound produces the most energy?

A
  1. Lipids - 9kcal/g
  2. Carbohydrates - 4kcal/g
  3. Proteins
33
Q

What are the 5 primary types of lipids?

A 
Fatty acids
Triglycerides
Phospholipids
Eicosanoids
Steroids
34
Q

What is polymerisation?

A

The joining of monomers to form polymers. This is done by dehydration synthesis

35
Q

What is hydrolysis?

A

Hydrolysis is the breakdown of a water molecule into its ions, which are then added to monomers in a polymer that have been broken apart.

36
Q

What are proteoglycans?

A

Macromolecules in which the carbohydrate component is dominant and a peptide or protein forms the smaller component.

37
Q

What is the difference between saturated and unsaturated fatty acids?

A

Saturated - has as much hydrogen as possible

Unsaturated - double bonds between carbons allow for more hydrogens

38
Q

What are essential fatty acids?

A

Fatty acids that cannot be synthesised by the body and must be obtained from the diet. There are about 3.

39
Q

What is the makeup of a triglyceride?

A

Three carbon alcohol (glycerol) linked to three fatty acids.

Triglycerides are called neutral fats because the fatty acids can no longer donate H+

40
Q

Explain the difference between cos and trans fats.

A

Cis fats are triglycerides with double bonds that cause angles in the same direction. They don’t pack as closely together

Trans fats are triglycerides with double bonds that cause angles in opposite directions. They pack closely, bind more strongly and are resistant to enzymatic breakdown.

41
Q

What does amphipathic mean? Give an example of a molecule.

A

Amphipathic means that one end of a molecule is hydrophobia and the other is hydrophilic.

Eg. Phospholipids

42
Q

What is the primary function of eicosanoids?

A

Primarily function as hormonelike chemical signals between cells. Play a variety of signalling roles in inflammation, blood clotting, hormone action etc

43
Q

What is a steroid? And which steroid is the “parent”?

A

A steroid is a lipid with 17 of its carbon atoms arranged in 4 rings.

Cholesterol is the parent steroid from which all other steroids are synthesised.

44
Q

What is the structure of an amino acid?

How many are there?

A

Central carbon with amino (-NH2) and carboxyl (-COOH) groups. Plus a radical group which determines the type of amino acid.

There are 20 different amino acids.

45
Q

How are peptides formed?

A

Peptides are formed by dehydration synthesis between the amino group of one and the carboxyl group of the next.

46
Q

How long must a chain be before it’s considered a polypeptide?

A

Larger than 10-15 amino acids long.

47
Q

Describe the levels of protein structure.

A

Primary - amino acid sequence

Secondary - alpha helix or beta sheet formed by hydrogen bonds

Tertiary - folding and coiling due to interactions between R groups and between R groups and surrounding water (hydrophobic vs hydrophilic)

Quaternary - association of two or more polypeptide chains with each other

48
Q

What is the difference between fibrous and globular proteins?

A

Globular - compact tertiary structure. Ideal for embedding in cell membranes and for proteins that need to move about freely in body fluids (eg. Enzymes)

Fibrous - slender filaments better suited for roles such as muscle contraction and providing strength to skin, hair, tendons, etc.

49
Q

What is protein denaturation?

A

Drastic change in conformational nature due to extreme heat or pH change. This causes the protein to be unable to perform its function. Can be reversible but is usually irreversible.

50
Q

What are the functions of proteins?

A

Structure

Communication

Membrane transport

Catalysis

Recognition and protection

Movement

Cell adhesion

51
Q

What are enzymes and what do they do?

A

Proteins that function as biological catalysts. They enable biochemical reactions to occur rapidly at normal body temperatures.

52
Q

Describe enzyme action.

A

Substrate molecule binds to the active site on the enzyme. Forming enzyme-substrate complex

An enzyme can only bind with particular substrates. Enzyme-substrate specificity

Enzyme breaks the bond in the substrate and releases the products without being consumed in the reaction itself

53
Q

What are cofactors?

A

Cofactors are non-protein molecules that help enzymes to carry out their functions.

They can be organic or inorganic.

54
Q

What are coenzymes?

A

Coenzymes are organic cofactors that transport electrons between enzymes in subsequent metabolic pathways.

55
Q

What are the components of a nucleotide.

A

Nitrogenous base
Monosaccharide
Phosphate group/s

Eg. Adenosine triphosphate

  • Adenine
  • Ribose
  • Triphosphate
56
Q

Name the enzyme that hydrolyses ATP to ADP.

A

Adenosine triphospatase (ATPase)

57
Q

Describe the functions of DNA and RNA.

A

DNA

  • contains the instructions for synthesising all of the body’s proteins
  • transfers hereditary information from cell to cell and from generation to generation

RNA

  • carry out the instructions of DNA
  • synthesise the proteins in the correct amino acid order
58
Q

What is phosphorylation and which enzyme is involved?

A

Phosphorylation is the addition of an inorganic phosphate group to enzymes and other molecules.

It is carried out by kinases.

59
Q

What are the main functional groups and their formulae?

A 
Carboxyl  -COOH
Hydroxyl  -OH
Methyl  -CH3
Amino  -NH2
Phosphate  -H2PO4

MHS1101 (5 decks)

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