Cell Biology: The Cell PDF

CELL BIOLOGY: THE CELL I. The Cell Theory a. Cells are the basic unit of life. b. Every organism is made up of cells (Schwann & Schleiden). c. Every cell comes from pre-existing cells (Virchow). II. What are the Basic Features of all Cells?...

CELL BIOLOGY: THE CELL I. The Cell Theory a. Cells are the basic unit of life. b. Every organism is made up of cells (Schwann & Schleiden). c. Every cell comes from pre-existing cells (Virchow). II. What are the Basic Features of all Cells? a. Plasma Membrane b. Cytoplasm c. Genetic Material d. Basic Replicating and Protein-making machineries III. What are the Two Types of Cells? a. Prokaryotic Cells – cells that do not contain a nucleus do not have membrane- bound organelles, small in size. Examples are bacteria and archaea b. Eukaryotic Cells – cells that contain a nucleus, have membrane-bound organelles, mostly larger than prokaryotes. Examples are plants, animals, fungi and protists IV. What do Cells do? a. Cells acquire and synthesize energy-laden molecules b. Cells synthesize proteins c. A cell makes more copies of itself V. The Prokaryotes a. The first cell type in the world that arose 3.5 billion years ago b. Basic Components of a Prokaryotic Cell: 1. Fimbriae – for attachment 2. Pilus – for conjugation (gene transfer between bacteria) 3. Flagella – for movement 4. Glycocalyx i. Capsule – jelly-like outer coating outside the plasma membrane ii. Slime Layer – unorganized slimy and sticky covering 5. Cell Wall – rigid structure made of carbohydrates and lipids 6. Plasma Membrane 7. Cytoplasm 8. Nucleoid – a region in the cytoplasm where bacterial DNA is concentrated 9. DNA & Plasmid – Plasmid is a circular DNA molecule in a prokaryotic cell 10. Endospore – formed when bacteria are exposed to harsh conditions c. There are only two kinds: Bacteria (Kingdom Eubacteria) and Archaebacteria (Kingdom Archaebacteria) VI. Basic Morphology of Bacteria a. Coccus (cocci) – spherical or oval shape b. Bacillus (bacilli) – rod, elongated cylindrical shape c. Spiral – curve, spiral (spirilla), or twisted spring (spirochete) d. Vibrio – comma-shaped e.g. Vibrio cholera e. Pleomorphic – no exact shape at a given time VII. What are the Prefixes Used to Describe the Arrangement of Eubacteria? a. Diplo: two b. Staphylo: cluster c. Strepto: chain d. Tetrad: four  e. Sarcina: 8 to 64 (3-D) VIII. The Origin of the Eukaryotes Endosymbiosis (Endosymbiont Theory) states that eukaryotic cells result from endosymbiosis of a prokaryote and aerobic bacteria (becomes mitochondrion), and later a cyanobacteria-photosynthetic prokaryote (becomes chloroplast). a. Nucleus and the ER: Invagination of the plasma membrane produced the nuclear envelope and the ER b. Mitochondria: Engulfing of an aerobic prokaryote resulted to a symbiotic relationship c. Chloroplasts: Engulfing a photosynthetic prokaryote (cyanobacteria) led to a symbiotic relationship IX. What are the Basic Structures of a Eukaryotic Cell? a. Cell Membrane – controls what gets in and out of the cell b. Cytoplasm – where organelles float & chemical reaction occur c. Nucleus – control center of the cell 1. DNA – deoxyribonucleic acid; the genetic code; packaged into chromosomes i. Chromatin – the tangled spread-out form of DNA ii. Chromosomes – condensed form of chromatin 2. Nucleolus – spherical body inside the nucleus which assembles ribosomes 3. Nuclear envelope – also known as the nuclear membrane; covers the nucleus 4. Nuclear pores – holes on the nuclear envelope that regulate entry of materials d. Other organelles – structures that act like specialized organs X. Organelles that Build Proteins – because proteins carry out so many of the essential functions of living things, a big part of the cell is devoted to their production and distribution a. Ribosomes – the protein factories of the cell 1. Synthesize protein by reading the instructions to build proteins from DNA 2. Some are free in cytoplasm 3. Some are attached to Endoplasmic Reticulum (ER) 4. Structure: composed of large and small subunit b. ER is primarily composed of network of membranes, with parts known as cisternae (tubes) and lumen (inside) i. Works on membrane proteins, makes membranes, passageway for transporting materials through transport vesicles ii. Regions of the ER: - Rough ER – ribosomes are attached to it; primarily works on proteins - Smooth ER – without ribosomes; makes lipids (sterols), makes new membranes, storage of calcium ions c. Golgi bodies – receiving, sorting and shipping of cell materials i. Finishes, sorts, labels and ships proteins like a logistic service ii. Ships proteins in vesicles iii. “logistic trucks” of the cell iv. Structure: Membranous flat sacs - Cis face receives from ER - Trans face ships products XI. Organelles that Store, Clean-up & Support a. Vacuoles – storage tanks of the cell (storage materials like water, salts, proteins and carbohydrates) i. Central vacuole – large vacuole found in plants  ii. Food vacuole – small vacuole found in animals iii. Contractile vacuole – found in protest for maintaining a suitable concentration of ions and molecules inside the cell b. Vesicles – smaller than a vacuole, carries and transports substances - Buds off from the ER, the Golgi bodies, or from the cell membrane c. Lysosomes – suicidal bags/ recycle bins of the cell 1. Carries out intracellular digestion: phagocytosis 2. Breaks down damaged organelles: autophagy 3. Structure: membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules d. Cytoskeleton – the skeletal system of the cell 1. Functions: mechanical support, anchor organelles, help move substance and the cell 2. Made of filaments and fibers: i. Microfilaments (actin) – also called actin filaments because they are built from molecules of actin - The amoebic cell crawls along a surface by extending cellular extensions called pseudopodia by contractions of actins - Cytoplasmic streaming, a circular flow of cytoplasm within plant cells, is accomplished through contractions of actin. ii. Intermediate filaments (keratin) – only found in the cells of some animals, including vertebrates iii. Microtubules (tubulin) – hollow rods constructed from a globular protein called tubulin structures derived from microtubules are the following: - Centrosome and Centrioles: Organizers of Cell Division Help coordinate cell division, common in animal cells Structure: ✓ Centrosome is a region that contains the centrioles ✓ Centrioles are made of nine sets of triplet microtubules arranged in a ring - Cilia – group of short hair-like extensions used to move substances outside human cells; in humans, cilia can be found in the lining of trachea and the oviduct - Flagella – whip-like extensions; in humans, flagellum is found among sperm cells XII. Organelles That Capture & Release Energy a. Mitochondria – powerhouse of the cell; “power plant” 1. make ATP energy by cellular respiration; fuels the work of life 2. Structure: Double membrane i. Cristae – infoldings of the inner membrane ii. Matrix – inner space iii. Intermembrane space – space between the inner and outer membrane b. Plastids – specialized pigment-containing organelles 1. Chromoplast – red, orange, and yellow-colored plastids that contain pigments called carotenoids. 2. Leucoplast – colorless plastids c. Chloroplasts – convert solar energy into chemical energy; found only in autotrophs; “solar plant” 1. derived from photosynthetic bacteria; solar energy-capturing organelle 2. Structure: Double membrane i. Thylakoid – coin-like structure  ii. Grana – stacks of thylakoid iii. Stroma – spaces between grana XIII. Cellular Boundaries a. Cell Membrane (Plasma Membrane) – regulates the entrance and exit of substances 1. Structure primarily made of: i. Phospholipid molecules Nature and Structure of Phospholipids - A phospholipid is an amphipathic molecule that has a polar phosphate head that can interact with water molecules nonpolar two fatty acid tails that cannot interact with water ii. Proteins - Integral proteins – penetrate the hydrophobic interior of the lipid bilayer - Peripheral proteins – not embedded in the lipid bilayer at all; they are appendages loosely bound to the surface of the membrane iii. Glycoproteins – carbohydrates + protein iv. Glycolipids – carbohydrates + phospholipids v. Cholesterol 2. What is The Fluid Mosaic Model? – a model that shows the structure and arrangement of the plasma membrane 3. What is the characteristic of the plasma membrane? i. The membrane is semi-permeable. ii. The membrane is fluid. iii. The membrane is structurally and functionally a mosaic of lipids, proteins and carbohydrates. b. Cell Wall – shapes, supports and protects the cell against force and pressure; provides much of the strength needed for plants to stand against the force of gravity Cell Walls differ in composition in every kingdom: i. In plants it is made of cellulose, pectin, and some with lignin. ii. In fungi it is made of chitin and glucans. iii. In bacterial it is made of peptidoglycan. XIV. Cell Junctions – structures that connect cells; neighboring cells often adhere, interact, and communicate via sites of direct physical contact a. Plasmodesmata – channels in cell walls that connect plant cells b. Cell junctions in animal cells: 1. Tight junctions – cells are very tightly pressed against each other, bound together by specific proteins e.g. tight junctions between skin cells make us watertight. 2. Desmosomes – made of intermediate filaments made of sturdy keratin proteins anchor desmosomes in the cytoplasm; Desmosomes attach muscle cells to each other in a muscle 3. Gap junctions – similar to Plasmodesmata in plants; they are channels between neighboring cells that allow for the transport of ions, water, and other substances