BIOL108 Lecture Notes - Lecture 1: Antonie Van Leeuwenhoek, Matthias Jakob Schleiden, Rudolf Virchow
22 Oct 2018
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HUMAN BIOLOGY
The Cell Theory
1. Organisms are composed of one or more cells
2. All cells arise from pre-existing cells
3. The cells is the smallest unit of life
Discovery of Cells
Robert Hooke (1635- 1703)
•Examined a thin slice of cork under a light microscope
•Observed that the cork was composed of ‘pores’
•Coined the term ‘cells’
Antony Van Leeuwenhoek (1632- 1723)
•First to describe bacteria, spermatozoa and other single cell organisms
Matthias Schleiden (1804-1887)
•Described plant cells
•All organisms are made of cells
Theodor Schwann (1810- 1882)
•All organisms are made of cells
•Animals and plants consist of cells that exhibit a degree of independence
Rudolf Virchow (1810- 1882)
•Cells arise from pre-existing cells
The Components of Cells
Plant Cells Animal Cells
Cell Membrane
•Selective barrier, controls
movement between the
intracellular and
extracellular space
•Separates cells from their
external surroundings
•Composed of a
phospholipid bilayer and
embedded proteins
Centrioles
•Spindles production in
cell division
•Near nucleus of animal
cells, small
•Pairs of centrioles make
centrosomes, lying at
right angles to each other
•Site of microtubule
organisation in the cell
•Give rise to basal bodies
that organise
microtubules into cilia
and flagella
Cell Wall
•Structural support
•Composed primarily of
cellulose
•Plant Cells only
Chloroplasts
•Site of photosynthesis
•Contains Chlorophyll and
enzymes
•Green pigmented.
•Thylakoids are organised
into grana stacks in the
stroma fluid
•Plant Cells only
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Actin Filaments
•The length of filaments increases and decreases by assembly or disassembly of subunits
•This mechanism allows cell structures to move or for cells themselves to move
•Organelles move around the cell using actin interactions
•Myosin molecules attached to organelle membranes can bind to filaments, bend at the head, detach and
reattach further down the filament, creating movement
Intermediate Filaments
•Intermediate in size between microfilaments and microtubules
•They are a rope like assembly of polypeptide chains that impart mechanical strength
Microtubules
•Hollow cylinders composed of repeating subunits of tubulin
Cytoskeleton
•Cell shape and movement
of organelles
•Protein filaments,
crisscrossed network of
fibres, actin filaments,
intermediate filaments
and microtubules
•Composed of actin,
tubulin and other fibrous
proteins
Endoplasmic Reticulum
•Rough Endoplasmic
reticulum is a network of
folded membranes
studded with ribosomes
•Involved in protein
synthesis
•Products are enclosed in
vesicles for transport
Golgi apparatus
•Package and distribute
proteins and lipids for
distribution
•Fuses with the vesicles in
the Endoplasmic
Reticulum and modifies
the vesicles contents,
using enzymes to add a
sugar group to proteins
and lipids, glycoproteins
and glycolipids
•Vesicles exocytose
through the plasma
membrane
Lysosomes
•Vesicle containing
enzymes involved in
intracellular digestion
Mitochondria
•Responsible for aerobic
respiration in the cell
Nucleolus
•Inside the nucleus of the
cell
•Site of ribosomal subunit
synthesis
Nucleus
Membrane bound body
containing DNA, site of
RNA transcription
Vacuoles and Vesicles
•Membranous sacks for
storage of substances
•Plant Cells only, vacuoles
!2
•Maintain cell shape
•With assist from motor molecules kinesin and dynein, they move organelles around the cell
Motor Molecules
•Kinesin and dynein move organelles across microtubule tracks
•Motor Molecules are attached to the cytoskeleton
•Cilia and flagella are responsible for movement in cells
Procaryotes
•DNA not enclosed in a membrane bound nucleus
•No membrane bound organelles
•Have a cell wall, plasma membrane, ribosomes and flagella
The Cell’s Plasma Membrane
•Plasma membranes are phospholipid bilayers
•Contains many embedded proteins and lipids, carbohydrate chains protrude from the cell
•Cytoskeleton filaments are attached to the inside of the membrane
•The membrane is fluid, imparting to flexibility of cells
Permeability
•Neutral, small molecules freely pass through the membrane
•Charged molecules cannot pass the hydrophobic phase of the bilayer
•Large molecules, macromolecules cannot move across the membrane
Diffusion
•Diffusion is the process in which an area with a large concentration of molecules dissipates until even
distribution
•Passive transport
Facilitated Diffusion
•A carrier protein embedded in the plasma membrane binds to a specific molecule and transports it to inside
the cell
•Passive Transport
Osmosis
•The movement of water from an area of dilute solution to concentrated until even distribution
•Passive Transport
Active Transport
•Energy input is required to accumulate substances in a specific area
Endocytosis
•A pit forms in the plasma membrane that encloses a substance in a small vesicle
•Receptor- mediated endocytosis is substrate specific
Exocytosis
•Endocytosis in reverse
Phagocytosis
•Large particles are engulfed and a vacuole forms
•Contents is digested when the vacuole fuses with a lysosome
Joining Cells
•Cells join at cell junctions
•Junctions can be held together loosely or tightly
•often connected to the fibres that comprise the cytoskeleton
•Specialised junctions speed up the transfer of materials between cells
Tight Junctions
•Seal two cells together so that no liquid can move between spaces
Desmosomes
•Join cells together but allow for flexibility
•Loosely held joint
•Composed of intermediate proteins that attach to intermediate filaments that traverse the cell
Gap Junctions
•Create a channel so that molecules can quickly pass from one cell to another
•Channel is created between adjacent cells
Tissues
•There are 4 major tissue groups in the human body
Epithelial Tissues
•Surface is exposed to internal fluids or the environment
•Cover the body surfaces and line body cavities
•Single cell layers or multicellular
!3
Document Summary
Organisms are composed of one or more cells. 1: all cells arise from pre-existing cells, the cells is the smallest unit of life. Robert hooke (1635- 1703: examined a thin slice of cork under a light microscope, observed that the cork was composed of pores", coined the term cells". Antony van leeuwenhoek (1632- 1723: first to describe bacteria, spermatozoa and other single cell organisms. Matthias schleiden (1804-1887: described plant cells, all organisms are made of cells. Theodor schwann (1810- 1882: all organisms are made of cells, animals and plants consist of cells that exhibit a degree of independence. Rudolf virchow (1810- 1882: cells arise from pre-existing cells. Cytoskeleton: cell shape and movement of organelles, protein filaments, crisscrossed network of fibres, actin filaments, intermediate filaments and microtubules, composed of actin, tubulin and other fibrous proteins. Vacuoles and vesicles cell: site of ribosomal subunit synthesis. Rna transcription: membranous sacks for storage of substances, plant cells only, vacuoles.
