Cellular Structures and Functions PDF

Cellular Structures and Functions 1665 - Robert Hooke discovered and described the fundamental unit of all living things (cells) by examining thin slices of cork 1674 - The first man to witness a live cell under a microscope was Anton Van Leeuwenhoek, describing the algae Spirogyra and named the m...

Cellular Structures and Functions 1665 - Robert Hooke discovered and described the fundamental unit of all living things (cells) by examining thin slices of cork 1674 - The first man to witness a live cell under a microscope was Anton Van Leeuwenhoek, describing the algae Spirogyra and named the moving organisms animalcules, meaning "little animals" 1838 – Matthias Schleiden suggested that all plants are made of cells 1839 – Theodor Schwann suggested the same for animals. General cell theory emerged: “the basic unit structure and function of all living organisms is the cell” 1855 – Rudolph Virchow’s theory: “all cells arise from pre-existing cells by cell division” CELL THEORY All living things are made up of cells. Cells are the smallest working unit of all living things. All cells come from pre-existing cells through cell division. Prokaryotic Cells – Cell membrane Allows substances in and out – Cytoplasm Fluid that fills cell – Ribosomes Protein synthesis – Cell wall Holds cell shape – Pili Allows attachment to solid surfaces – Flagella (some cells) movement Eukaryotic Cells Eukaryotic (“true” “nucleus”) cells have a membrane bound nucleus Domain Eukarya contains eukaryotic cells Larger than prokaryotic cells Less surface area to volume Contains organelles (“little organs”) that perform specific functions Cell Structure And Functions Nucleus Notable structure within the cell The genetic control centre of the cell -chromatin(network of dark-staining threads)  Surrounded by nuclear envelope Nucleolus largest structure in the nucleus consists of nucleolar organizers, ribosomal RNA, and proteins Function: primarily serves as the site of ribosome synthesis and assembly. Ribosome Tiny spherical structure Ribosomes are composed of 2 subunits (large and small subunits) Bodies in which the amino acids are bound together FUNCTION: Site of protein synthesis Vesicle A vesicle is a small structure within a cell, consisting of fluid enclosed by a lipid bilayer. FUNCTION: move molecules, secrete substances, digest materials, or regulate the pressure in the cell. Rough Endoplasmic Reticulum network of interconnected flattened sacs- is studded with ribosomes Function: to make protein (secretory protein), to make more membrane channeling products both to the outside of the cell, via the membrane Smooth Endoplasmic Reticulum network of interconnected tubules, lack of ribosomes Function: Synthesizing and secreting of certain steroid hormones, enzymes of carbohydrate metabolism, and enzymes of lipid synthesis. Golgi apparatus (or "Golgi body") A series of from 3 to 20 parallel flattened sacs closely stacked together, cisternae End of the sacs bud off various vesicles Function: receives and modifies and packages the substances manufactured by ER Cytoskeleton ▪ an intracellular matrix that supports cell shape and function ▪ The matrix is a dynamic structure composed of three main proteins ▪ Has three components: microfilaments, microtubules and intermediate filaments Mitochondrion Are spherical to rod- shaped structures from 0.2 to 7µm; a doubled layer membrane cristae( complex folding of inner membrane) Mobile structures, capable of changing their shapes “powerhouse of the cell” Function: produced energy in the form of ATP Vacuole ▪ enclosed compartments which are filled with water containing inorganic and organic molecules including enzymes in solution ▪ Function: Digestion; storage of chemicals, cell enlargement; water balance Cytoplasm is the entire content within the cell membrane. Protoplasm that surrounds the nucleus Cytosol is known as the matrix of the cytoplasm. Lysosome  Produced by the rough ER and the Golgi apparatus. Two Greek words, “breakdown body” Function: acts as waste – disposal units, digesting and removing foreign material “suicidal bag” Centrosome Centriole—pair of small rod –like structure there are attached microtubules in the wall quite near the nucleus inside of it is the centriole Function: active in the process of cell division( mitosis) Cell Membrane The border of the cell, about 8 nm thick A semi-permeable membrane and composed of proteins and lipids Membrane components Membrane LIPIDS 1. phospholipids 2. glycolipids 3. cholesterol The heads (the phospho part) are polar while the tails (the lipid part) are non-polar. The heads, which form the outer and inner linings, are "hydrophilic" (water loving) while the tails that face the interior of the cell membrane are "hydrophobic" (water fearing). Passive Transport Movement of molecules along the concentration gradient Involvement of specialized proteins that change shape to conform to concentration balance Osmosis, simple diffusion, and facilitated diffusion Active Transport energy-driven process where membrane proteins transport molecules across cells The use of ATP to facilitate movement of molecules in a membrane Peroxisomes Diameter- 0.5µm Oxidation reactions and break down metabolic hydrogen peroxide. Cellular Respiration Glycolysis “glyco”= sugar; “lysis”= breakdown Maybe observed in both aerobes and anaerobes. 6-C glucose is converted to 2 molecules of pyruvates (3-C) There are 10 steps, and 10 enzymes that assist and facilitate each step The important compounds produced during Glycolysis are: NET: 2 ATP, 2 Pyruvate and 2 NADH Fermentation (anaerobes) Preparatory Reaction important compounds produced: NADH Acetyl CoA KREB CYCLE important compounds produced: ATP, NADH, FADH2 NADH molecule makes three ATP molecules, whereas each FADH2 molecule produces two. There are 8 steps and 8 enzymes that assist and facilitates in Kreb Cycle Chemiosmosis refers to the movement of hydrogen ions across the membrane via ATP synthase.