Cytology · MU Pleven

Topic 5. The cell – chemical composition. Hyaloplasm (Cytosol)

Covers the chemical make-up of the cell, split into organic compounds (carbohydrates, lipids, proteins and nucleic acids) and inorganic compounds (water and mineral salts), before turning to the hyaloplasm. The proteins section gives four structural levels and classifies proteins both by structure and by function, and the water section lists its roles. The hyaloplasm part describes the cytoskeleton's three filament types and two cytoplasmic processes, glycolysis and translation.

Inside: 4 sections · 28 flashcards · 7 min

Topic 5 of 59 in the MU Pleven syllabus for Cytology (Medicine, Year 1). The free AceMed note covers it in 4 sections, about 988 words (7 min of reading), with 28 flashcards.

In this note

  1. TOPIC 5. The cell – chemical composition. Hyaloplasm (Cytosol)
  2. Organic compounds:
  3. Inorganic compounds:
  4. Hyaloplasm (cytosol)

TOPIC 5. The cell – chemical composition. Hyaloplasm (Cytosol)

In the cells we can find:

  • Organic compounds (complex molecules carbon-containing)
  • Inorganic compounds (water and minerals are among the most important)

Organic compounds:

  1. 1) Carbohydrates

The 3 basics elements of this molecule are carbon, hydrogen and oxygen.

  • They can be found as monosaccharides (glucose), disaccharides (sucrose) or polysaccharides(starch, glycogen and cellulose)
  • The monosaccharides and disaccharides carbohydrates are found in cell in the chloroplast, mitochondrion or cytoplasm
  • The polysaccharides are found in plastid, cytoplasm or cell wall
  • The carbohydrates have the functions of energy source and storage, strengthen plant cell walls and providing tough exterior covering
  • Polysaccharides can be demonstrated in a cell using the PAS reaction (periodic acid Schiff)
  1. 2) Lipids
  • The 4 basics elements of this molecules are carbon, hydrogen, oxygen and phosphorus (in phospholipids)
  • Composed by hydrocarbon rings and a long hydrocarbon side chain
  • They are relatively insoluble in water and are hydrophobic substances. They’re soluble in non-polar (organic) solvents like chloroform, methanol and ethanol
  • They have high energy content and are metabolised to release calories
  • Lipids are electrical insulators, insulating axons
  • The fats and oils are found in the cytoplasm, the phospholipids and steroids are found in the cell membrane and the waxes in the cell surface. The fats are hydrolysed by lipase enzymes, to produce fatty acids and glycerol. Fats are bad conductors of heat
  • Examples of lipids are – fats (esters of fatty acids and glycerol) and oils, phospholipids, steroids (cholesterol, testosterone), waxes (esters of long chain fatty acids and long chains alcohol)
  • The lipids have the functions of energy storage, cell membrane components, chemical messengers and protection
  • Phospholipids – components of cell membranes
  • Glycolipids - unlike phospholipids, they have no phosphate group. But they do have hydrophobic region containing two hydrocarbon tails
  1. 3) Proteins
  • The 4 basics elements of these molecules are carbon, hydrogen, oxygen, nitrogen and sometimes sulphur and phosphorus.
  • They are very large molecules of linked monomers called amino acids
  • There are 20 types of aa, they can be classified as essential and non-essential
  • The aa are the smallest unit of the proteins, and their major function is the building of blocks of proteins, but also are the precursors for the biosynthesis of some biological molecules, part of coenzymes, metabolic intermediates and neurotransmitters (excitatory, inhibitory).
  • The proteins are organized in four levels:
  1. A) Primary structure: the amino acid sequence
  2. B) Secondary structure: regularly repeating local structures stabilized by hydrogen bonds

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