CELLS AND MULTICELLULAR ORGANISMS
,TOPIC 1: Cells as the Basis of Life
Prokaryotic and Eukaryotic Cells
1.1.2 a-f
Recognise the requirements of all cells for survival, including
• energy sources (light or chemical)
• matter (gases such as carbon dioxide and oxygen)
• simple nutrients in the form of monosaccharides, disaccharides, polysaccharides
• amino acids, fatty acids, glycerol, nucleic acids, ions and water
• removal of wastes (carbon dioxide, oxygen, urea, ammonia, uric acid, water, ions, metabolic
heat).
Recognise that prokaryotic and eukaryotic cells have many features in common, which is a
reflection of their common evolutionary past.
Recall that prokaryotic cells lack internal membrane bound organelles, do not have a
nucleus, are significantly smaller than eukaryotes, usually have a single circular chromosome and
exist as single cells.
Understand that eukaryotic cells have specialised organelles to facilitate biochemical
processes.
Photosynthesis (chloroplasts)
Cellular respiration (mitochondria)
Synthesis of complex molecules including proteins (rough endoplasmic reticulum),
carbohydrates, lipids and steroids (smooth endoplasmic reticulum), pigments, tannins and
polyphenols (plastids)
The removal of cellular products and wastes (lysosomes)
Identify the following structures from an electron micrograph: chloroplast, mitochondria,
rough endoplasmic reticulum and lysosome.
Compare the structure of prokaryotes and eukaryotes.
Requirements for Cell Survival
All cells require basic needs to survive.
i. Energy sources:
• Can be light or chemical.
i.e ATP via glucose
ii. Matter:
• Includes 𝐻2 𝑂, 𝐶𝑂2 , 𝑂2 , nitrates, phosphates, and inorganic compounds.
• Organic molecules.
iii. Simple nutrients:
• Monosaccharides: carbohydrate monomers i.e simple sugars.
, • Disaccharides: formed from 2 monosaccharides; forms glycosidic bond e.g sucrose.
• Polysaccharides: formed by the addition of monosaccharides by condensation reactions e.g
starch, glycogen.
iv. Lipids:
• Ester of fatty acids and glycerol.
v. Proteins:
• Macromolecule consisting of 1 or more polypeptide chains.
• Formed by the condensation of amino acids.
vi. Nucleic acids:
• Macromolecules that make up genetic material (rNA and DNA)
• Built up by nucleotides, each consists of
- A pentose sugar (5C) arranged in a ring.
- Organic nitrogen base.
- A phosphate group.
vii. Waste removal:
• Via lysosomes
• Wastes include:
- Urea
- Ammonia
- Uric acid
- 𝐻2 𝑂
- 𝐶𝑂2
- 𝑂2
Eukaryotic Cells
Eukaryotic cells have specialised cells to facilitate biochemical processes.
i. Chloroplast
• Site of photosynthesis.
• Absorb sunlight and uses 𝐻2 𝑂 and 𝐶𝑂2 to produce glucose, oxygen and water.