2.1 Metabolic molecules

Question 1

What is molecular biology?

Answer 1

Field of study that focuses on investigating biological activity at a molecular level.

1. Elucidating the structure and function of chemical substances.
2. Determining their interactions as parts of living processes.

Question 2

How are biological processes regulated?

Answer 2

Biological processes are tightly regulated by enzymes, whose expression is controlled by gene activation (DNA).

Changes in activity are typically determined by signaling molecules (either endogenous or exogenous in origin).

Question 3

What are organic compounds? example + exceptions

Answer 3

Organic compounds contain carbon and are found in living organisms.

EXAMPLE: carbohydrates, fats (lipids), proteins, and nucleic acids.

EXCEPTIONS: carbides (CaC2), carbonates, oxides of carbon (CO, CO2) and cyanides (CN-).

Question 4

What are the classes of carbon compounds?

Answer 4

Carbohydrates
Lipids
Nucleic Acids
Proteins

Question 5

What are carbohydrates?

composition + function + example

Answer 5

Composed primarily of C, H, O atoms - common ratio = (CH2O)n

Principally function as energy source & short-term storage, recognition molecule + structural component.

E.G. Monosaccharide (sub-unit), Starch (polymer), granules in chloroplast (cellular structure).

Question 6

What are lipids?

composition + function + example

Answer 6

Non-polar, hydrophobic molecules - simple, complex, derived

Major component of cell membranes, long term energy storage & signaling molecule

E.G. Fatty acid (subunit), triglyceride (polymer), adipose cells (cellular structure).

Question 7

What are nucleic acids?

composition + function + example

Answer 7

Genetic material that determines inherited features of an organism.

DNA functions as a master code for protein assembly. RNA active role in manufacturing proteins

E.G. Nucleotide (subunit), DNA (polymer), chromosome (cellular structure).

Question 8

What are proteins?

composition + function + example

Answer 8

C, H, O, N (sometimes S) atoms

A regulatory molecule in catalysis (enzymes = proteins), structural molecule & role in cellular signaling (transduction pathways).

E.G. Amino acid (subunit), polypeptide (polymer), intermediate filaments (cellular structure).

Question 9

macromolecules

Answer 9

Commonly composed of monomers (recurring subunits).

carbohydrates, nucleic acids & proteins = joined monomeric subunits, larger polymer.

lipids ≠ recurring monomers, however certain types are composed of distinct subunits. e.g. triglycerides.

Question 10

Carbohydrates

Answer 10

Composed of monosaccharides (‘single sugar unit’) monomers. AKA, composition of monomeric subunits to form a complex carbohydrate structure.

Builds disaccharides (2) & polysaccharides (many).

forms ring structures and exists in different 3D configurations (stereoisomers).

Question 11

Glucose monomers combine to form various polymers:

Answer 11

glycogen
cellulose
starch

Question 12

Composition of nucleic monomers:

Answer 12

join to form polynucleotide chains.

Composition of bases and sugar type differs between RNA and DNA.

Question 13

Describe DNA composition

Answer 13

Nucleotide bonds form polynucleotide chains.

In DNA, 2 complimentary chains pair by H-bonds between nitrogenous bases, to form a double-stranded molecule to form a double-helical arrangement

Question 14

Describe a nucleic acid

Answer 14

Phosphate group + pentose sugar + nitrogenous base

Question 15

Describe a protein

Answer 15

Composed of amino acid monomers joining to form polypeptide chains.

amine group (2H + N) + H + C + (R) variable group + carboxyl group (O ++ C + OH)

The variable group determines properties of the amino acid

Question 16

Dipeptide + H20 results from

Answer 16

fusion of 2 amino acids

Question 17

Polypeptide chain results from

Answer 17

fusion of 2+ amino acids

Question 18

Different classes of lipids

Answer 18

1. simple (neutral) lipids
2. compound lipids
3. derived lipids

Question 19

simple (neutral) lipids

Answer 19

esters of fatty acids and alcohol

triglycerides, waxes

Question 20

compound lipids

Answer 20

esters of fatty acids + alcohol + additional groups

phospholipids, glycolipids

Question 21

derived lipids

Answer 21

derived from simple/compound lipids

steroids, carotenoids

Question 22

What is vitalism?

Answer 22

dictates that organic molecules could only be synthesised by living organisms. It was believed that organisms possessed a certain “vital force” / non-physical element lacking from inorganic molecules.

Question 23

Disproving vitalism

Answer 23

Disproven with the discovery of artificially synthesizing organic molecules (1828, Frederick Woehler) - heated inorganic salt (ammonium cyanate), producing urea.

Question 24

What is urea? (and why is it so important?)

Answer 24

waste of nitrogen metabolism, eliminated by kidneys in mammals.

artificial synthesis of urea – demonstrates that organic molecules are not fundamentally different to inorganic molecules.

Question 25

define metabolism

Answer 25

Total chemical processes (web of all enzymes-catalysed reaction) that occur within a living organism in order to maintain life.

E.g. The Urea cycle, citric acid cycle, beta-oxidation, and the electron transport chain.

Question 26

Why is metabolism important?

Answer 26

1. provides a source of energy for all cellular processes

2. enables the synthesis and assimilation of new materials for use

Question 27

Define anabolism

Answer 27

Synthesises complex molecules from simpler ones, occurs via condensation reactions (monomers are covalently joined + H2O by-product).

Uses energy to construct new bonds (endergonic) < typically involves reduction reactions.

Question 28

example of an anabolic reaction

Answer 28

Gluconeogenesis.

The process of making glucose from the breakdown products of lipids or proteins. Gluconeogenesis occurs mainly in cells of the liver or kidney

Question 29

Define catabolism

Answer 29

Breaks down complex molecules into simpler ones via hydrolysis reaction (consumption of H2O to break bonds).

Releases energy when bonds are broken (exergonic) < typically involves oxidation reactions.

Question 30

example of a catabolic reaction

Answer 30

Glycolysis.

The process in which glucose is broken down to produce energy. It produces two molecules of pyruvate, ATP, NADH and water. The process takes place in the cytosol of the cell cytoplasm, in the presence or absence of oxygen. Glycolysis is the primary step of cellular respiration.