FAVE JUD NAKONG BIOLOGY ahahhahaahah (PAKYU CHEM).docx

Cell Membrane Characteristics \- semi-permeable \- fluid \- structurally and functionally a mosaic of lipids, proteins and carbohydrates Structures Phospholipids molecules Nature and structure of phospholipids: amphipathic molecule The Fluid Mosaic Model A model that shows the structure and...

Cell Membrane Characteristics \- semi-permeable \- fluid \- structurally and functionally a mosaic of lipids, proteins and carbohydrates Structures Phospholipids molecules Nature and structure of phospholipids: amphipathic molecule The Fluid Mosaic Model A model that shows the structure and arrangement of the cell membrane. Proteins Peripheral proteins - not embedded in the lipid bilayer at all. They are appendages loosely bound to the surface of the membrane. Attached in the surface of cell membrane. Glycoproteins Carbohydrates + protein Cell-to-cell communication Glycolipids Carbohydrates + phospholipids Cell-to-cell recognition Cholesterol Helps maintain fluidity of the cell membrane. Organelles Peroxisome Peroxisomes are small, membrane-enclosed organelles that contain enzymes involved in a variety of metabolic reactions including Structure \- A specialized metabolic compartment bounded by a single membrane with crystalline core. \- A dense collection of enzymes. Functions \- Oxidation of various substances with enzyme oxidase, producing hydrogen peroxide. \- Breaking down hydrogen peroxide into water. \- Detoxification of alcohol in liver. \- Oxidizing agent of the cell. \- Organelles that detoxify and houses enzymes. \- Contains enzymes that transfer hydrogen atoms from producing hydrogen peroxide (h2o2) as a byproduct \- h202 is converted into water by another enzyme Plastids Specialized pigment-containing organelles Chromoplast \- Red plastids \- Stores carotenoids Leucoplast (Colorless plastids) EX. Amyloplasts -- starch containing plastids Proteinoplasts -- protein containing plastids Elaloplasts -- lipids containing plastids Mitochondria These are organelles that produce energy for the cell through a process called cellular respiration. They are often referred to as the "powerhouses" of the cell. Makes ATP (adenosine triphosphate) energy by cellular respiration in order to fuel the work of life. Structure Cristae -- infoldings of the inner membrane Matrix -- inner space Intermembrane space -- space between the inner and outer membrane Chloroplasts Chloroplasts are plant cell organelles that convert light energy into relatively stable chemical energy via the photosynthesis process. Structure The Chloroplasts is a double membrane Thylakoid -- coin-like structure Grana -- stack of thylakoid Stroma Cytoskeletal Elements Microtubules Derived from microtubules are the following: \- Centrosome and Centrioles \- Organizers of cell division \- Help coordinate cell division \- Common in animal cells \- Centrosome is the region that contains the centrioles \- Centrioles are made up of 9 sets of triplet microtubules arranged in a ring. (9+0) \- Tubulin are hollow rods constructed from globular protein called tubulin \- Cilia are a group of hair-like extensions used to move substances outside human cells \- In human cells, cilia can be found in the lining of trachea and the oviduct. (9+2) \- Flagella is a whip-like extension \- Flagellum is found among sperm cells Difference between Cilia and Flagella Cilia -- are slender protuberances that project from the much larger cell body Flagella -- is a lash-like appendage that protrudes from the cell body Intermediate filaments \- Keratin \- Only found in cells of some animals, including vertebrates \- Support cell shape, fix organelles in place. Microfilaments \- They have a vital role in cells movements, cell division, and cell contraction \- They are also called actin or myosin filaments because they are built from molecules of actin \- The amoebic cell crawls along a surface by extending cellular extensions called pseudopodia by contraction of actin \- Cytoplasmic Streaming is a circular flow of cytoplasm within the plant cells, is accomplished through contractions of actin Other Organelles Endoplasmic Reticulum Smooth ER \- Without ribosomes \- Makes lipids \- Make new membranes \- Detoxification of drugs and poison Golgi apparatus \- Finishes \- Sorts \- Ships protein like a logistic service Vacuole A vacuole is a membrane-bound cell organelle. In animal cells, vacuoles are generally small and help sequester waste products. In plant cells, vacuoles help maintain water balance. Lysosome These are organelles that contain digestive enzymes that break down and recycle old damaged cellular components. Carries out intercellular phagocytosis Autophagy \- Breaking down of damaged organelles \- Is the natural, conservative degradation of the cell that removes unnecessary or dysfunctional components through a lysosome-dependent Structure \- Membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest (hydrolyze) macromolecules (foreign materials) Centriole These are paired barrel-shaped organelles located in the cytoplasm of animal cells near the nuclear envelope. Centrioles play a role in organizing microtubules that serve as the cell's skeletal system. They help determine the locations of the nucleus and other organelles within the cell. Cell Wall \- Cell Walls differ in composition in every Kingdom: \- In plants: It is made up of cellulose, pectin, and some lignin. \- In fungi: It is made up of chitin and glucans. \- In protists: It is made up of cellulose, pectin, mannans, and minerals such as silicon dioxide and calcium carbonate. \- Cell wall structure: \- The cell wall surrounds the plasma membrane of plant cells and provides tensile strength and protection against mechanical and osmotic stress. \- It allows cells to develop turgor pressure, which is the pressure of the cell contents against the cell wall. \- Middle lamella is the thin layer rich in the sticky polysaccharides called pectin found between adjacent cell walls of plants. Cell Membrane \- Roles of proteins: \- Transport \- Enzymatic activity \- Signal transduction \- Cell-to-cell recognition \- Intercellular joining \- Attachment to the cytoskeleton and the extracellular matrix (ECM) \- The signal transduction pathway: \- Reception: The process by which a cell detects a signal in the environment. \- Transduction: The process of activating a series of proteins inside the cell from the cell membrane. \- Response: The change in behavior that occurs in the cell as a result of the signal. Cell Junctions \- Structure that connects cells: \- In plants: Plasmodesmata \- Channels in cell walls that connect plant cells. \- Tight Junctions \- Cells are very tightly pressed against each other, bound together by specific proteins. \- Example: Tight junctions between skin cells make us watertight. \- 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. \- Gap Junctions \- Analogous to Plasmodesmata in plants. \- Allow nutrients and certain materials to pass between the interconnected cells. Organelles that Detoxify and House Enzymes \- Glyoxysomes \- Specialized peroxisomes found in plants (particularly in the fat storage tissues of germinating seeds) and also in filamentous fungi. \- Distinct plant microbodies related to peroxisomes and involved in particular plant aerobic pathways, namely the glyoxylate cycle and fatty acid oxidation. \- Function: \- Fat metabolism: Glyoxysomes contain enzymes for the glyoxylate cycle through which fats are converted into carbohydrates (gluconeogenesis). \- Protein synthesis: Ribosomes are the organelle involved in the synthesis of protein and also involved in the metabolism of protein. \- Intracellular, microbody-like organelles found in all members of the protist order Kinetoplastida examined. \- Nine enzymes involved in glucose and glycerol metabolism are associated with these organelles. These enzymes are involved in pathways which, in other organisms, are usually located in the cytosol. \- Peroxisomes \- Specialized for carrying out oxidative reactions using molecular oxygen. \- They generate hydrogen peroxide, which they use for oxidative purposes- destroying the excess by means of the catalase they contain. \- Function: \- Lipid metabolism and the processing of reactive oxygen species. \- Other peroxisome functions include: Taking part in various oxidative processes, lipid metabolism, and catabolism of D- amino acids, polyamines, and bile acids. \- Peroxisomes vs Lysosomes \- Lysosomes, the cell\'s recycling centers, use acid hydrolases to break down waste into reusable parts through autophagy and crinophagy. \- Peroxisomes protect cells by isolating and breaking down harmful hydrogen peroxide into water and oxygen. \- These organelles ensure efficient and safe cellular function. Specific Components \- (protein) Chitin - cell wall of fungi \- (carbohydrates) Peptidoglycan - bacteria cell wall \[ 08-07-24 \]