2: Molecules to Metabolism

Question 1

Are living and non-living things made out of different materials? What is the accepted belief now?

Answer 1

• no

- living organisms are governed by the same chemical and physical forces as non-living organisms

Question 2

What was the ‘theory of vitalism’? How was it falsified?

Answer 2

• that l.o were composed of organic chemicals
• that could only be produced in l.o because a ‘vital force’ was needed

-synthesizing urea artificially (among other discoveries)

Question 3

What does the science of molecular biology aim to explain?

Answer 3

living processes in terms of the chemical substances involved

Question 4

A ‘vital force’ does not explain the difference between living organisms and non-living matter. What idea better demonstrates the differences between living and non-living?

Answer 4

natural selection

Question 5

What was discovered about human urine in the 18th Century?

Answer 5

human urine contained urea

Question 6

What sort of compound is urea?

Answer 6

an organic compound

Question 7

Draw the structure of urea. (p17)

Answer 7

-

Question 8

Why was it believed that urea could only be made in living organisms?

Answer 8

because urea is an organic compound so it was believed that a vital force was needed (theory of vitalism)

Question 9

Who and when synthesized urea artificially? How did they do it?

Why was this significant?

Answer 9

• German chemist Friedrich Wohler
• 1828
• silver isocyanate and ammonium chloride
• was the first time an organic compound was synthesized artificially which helped falsify the theory of vitalism. Scientific theories are rarely abandoned until several pieces of evidence show them to be false.

Question 10

What is an atom?

Answer 10

a single particle of an element, consisting of a positively charged nucleus surrounded by a cloud of negatively charged electrons

Question 11

What is a molecule?

Answer 11

a group of two or more atoms held together by covalent bonds (single, double, or even triple bonds)

Question 12

Draw the chemical structure of ethanol.

Answer 12

-

Question 13

Draw the chemical structure of carbon dioxide.

Answer 13

-

Question 14

Draw the chemical structure of nitrogen. What sort of molecule of this?

Answer 14

-

- nitrogen is an element

Question 15

Draw the chemical structure of hydrogen cyanide. What sort of molecule of this?

Answer 15

-

- compound because 2+ separate elements bonded together

Question 16

What are the molecules used by living organisms based on?

Answer 16

carbon

Question 17

How many and of what sort of bonds can one carbon atom form? What is the significance of this?

Answer 17

• 4 covalent bonds

- allowing great diversity of compounds to exist

Question 18

What are the chemical symbols for nitrogen, hydrogen, carbon, and oxygen? How many covalent bonds can each element form?

Answer 18

1. N, H, C, O

bonds = 3, 1, 4, 2

Question 19

Covalent bonds are relatively strong. What can be said about molecules that are formed by covalent bonds? Give an example of a much weaker bond.

Answer 19

• molecules have stable structures

- intermolecular forces

Question 20

State the main types of molecule used by living organisms?

Answer 20

carbohydrates, lipids, proteins, and nucleic acids

Question 21

Define ‘metabolism’.

Answer 21

the web of all the enzyme-catalysed reactions in a cell or organism

Question 22

What do most metabolic pathways consist of?

Answer 22

chains of reactions but there are also some cycles of reactions

Question 23

Define ‘anabolism’.

Answer 23

the synthesis of complex molecules from simpler molecules

Question 24

What are macromolecules? What are macromolecules made up of?

Answer 24

• very large molecules produced by living organisms

- made up of smaller sub-unit structures called monomers

Question 25

What type of reactions are anabolic reactions? Why?

Answer 25

• condensation reactions

- because water is produced

Question 26

Define ‘catabolism’.

Answer 26

the breakdown of complex molecules into simpler molecules including the hydrolysis of macromolecules into monomers

Question 27

What happens in hydrolysis reactions?

Answer 27

molecules are split

Question 28

What sort of reactions are catabolic reactions? Why?

Answer 28

• hydrolysis reactions

- because water is used to split the molecules