Z101 Cell Biology Lecture Notes PDF

History of the Cell Janet Plowe, 1931 Rudolph Virchow, 1855 Theodor Schwann, 1839 Matthias Schleiden, 1838 Anton von Leeuwenhoek, 1674 Robert Hooke, 1665  Cell Theory Matthia...

History of the Cell Janet Plowe, 1931 Rudolph Virchow, 1855 Theodor Schwann, 1839 Matthias Schleiden, 1838 Anton von Leeuwenhoek, 1674 Robert Hooke, 1665  Cell Theory Matthias Schleiden Theodore Schwann Rudolf Virchow cells cells all plants are made all animals are made all cells came from pre- of cells of cells existing ones Cell Theory  Cell Theory Matthias Schleiden Theodore Schwann Rudolf Virchow concluded that all plants concluded that all concluded that all cells are made of cells (1838) animals are made of came from pre-existing cells (1839) cells (1855) Cell Theory all living things are made up of cells cells are the basic units of structure and function in an organism new cells are produced from existing cells  Cellular organization Early studies described the cell as consisting of protoplasm (=primary or essential substance) containing a nucleus and surrounded by a delicate membrane known as cell or plasma membrane. The protoplasm surrounding the nucleus became known as cytoplasm while that of the nucleus is referred to as nucleoplasm. EM revealed two basic plans of cellular organization: 1. Prokaryotes (before nucleus): simpler, with no nuclear envelope or compartmentalization. 2. Eukaryotes (true nucleus): more complex, with nuclear envelope and compartments known as organelles.  Cells: Prokaryote vs. Eukaryote Prokaryotes Eukaryotes Nucleus Endoplasmic reticulum Golgi apparatus Cell membrane Lysosomes Contain DNA Vacuoles Ribosomes Mitochondria Cytoplasm Cytoskeleton  ‫الملساء‬ ‫الريبوسومات‬ ‫جهاز جولجي‬ ‫غشاء الخلية‬ ‫‪Animal Cell‬‬ ‫‪Plant Cell‬‬  Venn Diagrams Compare and Contrast Animal Cells Plant Cells Cell membrane Ribosomes Nucleus Endoplasmic reticulum Golgi apparatus Lysosomes Vacuoles Mitochondria Cell Wall Centrioles Chloroplasts Cytoskeleton Structure of eukaryotic cell  Internal Organization Eukaryotic cells contain ORGANELLES. Cell Components that PERFORMS SPECIFIC FUNCTIONS FOR THE CELL. Compartments of an Animal Cell What Defines an Organelle? Each of these organelles performs a specific function critical to the cell's survival. Nearly all eukaryotic organelles are separated from the rest of the cellular space by a membrane. This partitioning permits different kinds of biochemical reactions to take place in different organelles. Although each organelle performs a specific function in the cell, all of the cell's organelles work together in an integrated fashion to meet the overall needs of the cell. Eukaryotic cells are partitioned into functional compartments There are four life processes in eukaryotic cells that depend upon different organelles –Manufacturing –Breakdown of molecules –Energy processing –Structural support, movement, and communication Eukaryotic cells are partitioned into functional compartments Manufacturing: involves the nucleus, ribosomes, endoplasmic reticulum, and Golgi apparatus. – Manufacture of a protein, perhaps an enzyme, involves all of these. Eukaryotic cells are partitioned into functional compartments Breakdown of molecules: involves lysosomes, vacuoles, and peroxisomes. – Breakdown of an internalized bacterium by a phagocytic cell would involve all of these. Eukaryotic cells are partitioned into functional compartments Energy processing: involves mitochondria in animal cells. – Generation of energy-containing molecules, such as ATP, occurs in mitochondria. Eukaryotic cells are partitioned into functional compartments Structural support, movement, and communication: involve cytoskeleton, plasma membrane. – An example of the importance of these is the response and movement of phagocytic cells to an infected area. Cell (Plasma) membrane Structure of plasma membrane Composition of plasma membrane: The cell’s outer membrane is made up of a mix of proteins and lipids (fats). On the outside of cell membranes, attached to some of the proteins and lipids, are chains of sugar molecules (carbohydrates). Lipids: Phospholipids and cholesterol. Phospholipid bilayer is the main component of plasma membrane (= 2 fatty acids + phosphoric acid + glycerol). Phodpholipid Molecules Hydrophobic interactions is the main force involved in the formation of lipid bilayer as follows:  Proteins: Transmembrane (integral): penetrate the lipid bilayer. Peripheral: at the outer and inner surfaces of the lipid bilayer. Carbohydrates: In the form of oligosaccharides. They may act as receptors or recognition molecules. Carbohydrates are either: Attached to proteins to form glycoproteins or: Attached to lipids to form glycolipids.  Transport across the membrane The cell membrane is able to regulate the exchange of materials between the cell and its surroundings by: 1. Passive transport: a) diffusion: Transport of small molecules as CO2 and H2O. With the concentration gradients (high conc. → low conc.).  b) Facilitated diffusion: Transport of large particles. With concentration gradients (high conc. → low conc.). Transmembrane proteins are involved in this process by: Acting as a carrier. Opening pores inside them. 2. Active transport: Transport of small molecules. Against the concentration gradients (low conc. → high conc.). It needs energy. It needs the help of transmembrane proteins. 3. Bulk transport: Transport of large particles. It needs energy. The modes of transport are: Exocytosis: from inside to outside. Endocytosis: from outside to inside. a- Pinocytosis: transport of fluids. b- Phagocytosis: transport of solids.