2.1 Molecules to Metabolism

Question 1

Organic Compounds

Answer 1

A compound that contains carbon and is found in living things.

Question 2

Carbon

Answer 2

Carbon forms the basis of organic life due to its ability to form large and complex molecules via covalent bonding.
Carbon atoms can form four covalent bonds (with bonds between carbon atoms being particularly stable (catenation)).
These properties allows carbon to form a wide variety of organic compounds that are chemically stable: rings, chains & chains of rings
All life is based of carbon compounds such as proteins, carbohydrates, lipids and nucleic acids

Question 3

Carbohydrates

Answer 3

Most abundant compound found in nature, composed primarily of C,H, and O atoms in a common ratio- (CH2O)n

Question 4

Lipids

Answer 4

Non polar, hydrophilic molecules which may come in a variety of forms (simple, complex, derived).
Lipids serve as a major component of cell membranes.
They may be utilized as long term energy storage (fats and oils)
Also may function as signaling molecules (steroids)

Question 5

Nucleic Acids

Answer 5

Genetic material of all cells and determines the inherited features of an organism.
Dna functions as a master code for protein assembly, while RNA plays an active role in the manufacturing of proteins.

Question 6

Proteins

Answer 6

Make over 50% of the dry weight of cells.
They are composed of of C,H,O and N atoms (some may include S).
Major regulatory molecules involved in catalysis (all enzymes are proteins).
May also function as structural molecules or play a role in cellular signalling (transduction pathways)

Question 7

Main Classes of Organic Compounds in Cells

Answer 7

Carbohydrates, Proteins, Lipids, and Nucleic Acids

Question 8

Ribose

Answer 8

carbon
hydrogen
oxygen

Question 9

Glucose

Answer 9

carbon
hydrogen
oxygen

Question 10

Fatty Acid

Answer 10

carbon
hyrdrogen
oxygen

Question 11

Monosaccharides

Answer 11

Carbohydrates are composed of monomers called monosaccharides (‘single sugar unit’)
Monosaccharides are the building blocks of disaccharides (two sugar units) and polysaccharides (many sugar units)
Most monosaccharides form ring structures and can exist in different 3D configurations (stereoisomers)
Glucose, Galactose, Fructose

Question 12

examples of mono saccharides

Answer 12

ribose
glubose
galactose
fructose

Question 13

3 TYPES OF LIPIDS

Answer 13

1. Triglyceride
   glycerol + 3 fatty acids
2. Phospholipid
   phosphate + glycerol + 2 fatty acids
3. Steroid
   4 fused hydroarbon rings

Question 14

Falsifying Vitalism

Answer 14

Vitalism was a doctrine that dictated that organic molecules could only be synthesised by living systems

It was believed that living things possessed a certain “vital force” needed to make organic molecules
Hence organic compounds were thought to possess a non-physical element lacking from inorganic molecules

Vitalism as a theory has since been disproven with the discovery that organic molecules can be artificially synthesised

In 1828, Frederick Woehler heated an inorganic salt (ammonium cyanate) and produced urea
Urea is a waste product of nitrogen metabolism and is eliminated by the kidneys in mammals
The artificial synthesis of urea demonstrates that organic molecules are not fundamentally different to inorganic molecules

Question 15

Phosphorus

Answer 15

Building block of nucleotides

Phospholipids essential
component of cell membranes

Question 16

Iron

Answer 16

Important role in mitochondrial
cellular respiration

Cofactor for enzymes
important in processes such
as cell protection and cell
division

Question 17

Sodium

Answer 17

In animal cells
-Essential role in active
transport across membranes
- Conducting nerve impulses
and muscle contractions

In Plants
- is not essential, but may substitute for potassium in maintaining water homeostatis

Question 18

Sulphur

Answer 18

essential to make two of the twenty amino acids protein contain

Question 19

Metabolism

Answer 19

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

Most of these reactions occur in the cytoplasm of
the cell but some can occur outside of the cell for
example digestion.

*Therefore metabolism is the sum of all the
chemical reactions that occur in an organism

Metabolism consists of pathways whereby one
molecule is transformed into another

These pathways are mostly chains or reactions but
can be cycles as well.

Question 20

Metabolic reactions serve two key functions:

Answer 20

They provide a source of energy for cellular processes (growth, reproduction, etc.)

They enable the synthesis and assimilation of new materials for use within the cell

Question 21

Anabolism

Answer 21

Anabolism is the synthesis of complex molecules
from simpler molecules including the condensation
of macromolecules from monomers by condensation
reactions

Examples of anabolism include-

Protein synthesis (using ribosomes)

DNA synthesis during replication

Photosynthesis - production of glucose from carbon
dioxide and water

Synthesis of complex carbohydrates such as starch,
cellulose and glycogen

Purpose: synthesizing complex molecules from simpler ones

Energetics: uses energy to construct new bonds (endergonic)

Mechanism: Typically involves reduction reactions

Examples: glucogenesis

Question 22

Condensation Reaction

Answer 22

Monosaccharides are joined via glycosidic linkages to form disaccharides and polysaccharides

Amino acids are joined via peptide bonds to make polypeptide chains

Glycerol and fatty acids are joined via an ester linkage to create triglycerides

Nucleotides are joined by phosphodiester bonds to form polynucleotide chains

Joining of molecules releases water molecule

Question 23

Catabolism

Answer 23

Catabolism is the breakdown of complex
molecules into simpler molecules including
the hydrolysis of macromolecules into
monomers.

Examples include-
Digestion of food
Cell respiration
Decomposition of organic material

Purpose:
Breaking down complex molecules into simpler ones

Energetics:
Releases energy when bonds are broken (exergonic)

Mechanism:
Typically involves oxidation reactions

Examples;
glycolysis