PCCH104 - BIOCHEMISTRY
2nd Year 1st SEM | LABORATORY
Cell
โCells are the structural and functional units of all
living organisms.
โAlso called the โbuilding blocks of life.โ
โAll cells are made from the same major classes of
organic molecules: nucleic acids, proteins,
carbohydrates, and lipids.
History of the Cell
โIn 1665, Robert Hooke made an improved microscope
and discovered cells in cork.
Types of Cell
Prokaryotic Cell
โUnicellular organisms that do not develop or
di๎erentiate into multicellular forms.
โIdentical and capable of independent existence.
โNo continuity or communication between the cells.
โCapable of inhabiting almost every place on the
earth.
โInclude all bacteria and archaea (archaebacteria).
โLack a nucleus and membranous organelles.
โMost of the functions of organelles , such as
mitochondria, chloroplasts, and the Golgi apparatus,
are taken over by the prokaryotic plasma membrane.
Architectural Regions of a Prokaryotic Cell
1. Appendages include ๏ฌagella and pili (proteins
attached to the cell surface).
2. Cell envelope consisting of a capsule, a cell wall, and
a plasma membrane
3. Cytoplasmic region - contains the cell genome
(DNA) and ribosomes and various sorts of inclusions.
Eukaryotic Cell
โInclude fungi, animals, and plants as well as some
unicellular organisms.
โAbout 10x the size of a prokaryote and can be as
much as 1000x greater in volume.
โContain membrane-bound compartments in which
speci๏ฌc metabolic activities take place.
โContains a nucleus.
โHas other specialized structures, called organelles
Major Parts of the Cell
1. Cell membrane
2. Cytoplasm
3. Nucleus
Cell Membrane
โAlso called plasma membrane or plasmalemma
โSemi-permeable membrane
โAll membranes are phospholipid bilayers with
embedded proteins.
Functions of the Cell Membrane
1. Delimits the cell from its surroundings.
2. Controls what gets in and out of the cell.
3. Provides attachment for the skeleton of the cell.
4. Receives and sends out stimuli.
5. Provides binding sites and receptors for enzymes and
other substances.
6. Allows cell-to-cell recognition.
7. Forms specialized junctions with cell membrane of
adjacent cells
Cytoplasm
โJelly-like matrix that surrounds the nucleus and is
bound by the cell membrane.
โContains dissolved nutrients, helps break down
waste products, and moves material around the cell.
โThe living substance of the cell
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