Biology Lecture 11 B - Exam 3
Biology Lecture 11 B - Exam 3 BIO 121 A
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This 3 page Class Notes was uploaded by Devin Mart on Friday March 25, 2016. The Class Notes belongs to BIO 121 A at Missouri State University taught by Dr. Durham in Spring 2016. Since its upload, it has received 10 views. For similar materials see General Biology in Biology at Missouri State University.
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Mart 1 Lecture 11B: The Endomembrane System ● The endoplasmic reticulumis a network of membranes tubules within the cytoplasm of a eukaryotic cell, continuous with the nuclear membrane. ○ The smooth ER lacks ribosomes and primarily deals with the synthesis of lipids and the mobilization of glucose from stored glycogen. ○ The rough ER is the site of protein synthesis (the binding of ribosomes) ■ These are abundant in cells that secrete proteins. ■ Glycoproteins are any of a class of proteins that have carbohydrate groups attached to the polypeptide chain. ■ Transport vesicles can move molecules between locations in the cell (i.e. proteins from the rough ER to the golgi apparatus). ● The golgi apparatusis a complex of vesicles and folded membranes within the cytoplasm of most eukaryotic cells, involved in secretion and intracellular transport. ○ This is the center of manufacturing, warehousing, sorting, and shipping in the cells (finishes, sorts, and ships cell products). ○ The cis side receives material, the trans side buds off vesicles. ● Lysosomes are organelles in the cytoplasm of eukaryotic cells containing degradative enzymes enclosed in a membrane. ○ These cells are membranebounded sacs of hydrolytic enzymes that digest macromolecules, a leakage from lysosomes can destroy a cell by autodigestion. ○ The lysosome creates a space where the cell can digest macromolecules safely. ○ Phagocytosis is the digestion of foreign material. ○ Autophagy i s the recycling of organelles. ● Vacuoles are a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid. ○ Food vacuoles are vacuoles with a digestive function in the protoplasm of a protozoan. ○ Contractile vacuoles are vacuoles in some protozoans that expel excess liquid on contraction. ○ Central vacuoles are found in many mature plant cells. ○ Tonoplast is a membrane that binds the chief vacuole of a plant cell. ● Mitochondria are an organelle found in large numbers in most cells, in which the biochemical processes of respiration and energy production occur. ○ The number of mitochondria correlates with the aerobic metabolic activity an individual has. ○ Cristae (membranes) are each of the partial partitions in a mitochondria formed by the infolding of the inner membrane, the site of ATP synthesis. Mart 2 ○ Mitochondrial matrix is the substance occupying the space enclosed by the inner membrane of a mitochondria. ● A plastiis any of a class of small organelles, such as chloroplasts, in the cytoplasm of plant cells, containing pigment or food. ○ Chloroplasts are a plastid that contains chlorophyll and in which photosynthesis takes place (found in green plant cells). ○ Amyloplasts store starch in roots and tubers, think potatoes. ○ Chromoplasts store pigments for fruits and flowers. ○ Stroma contains DNA, ribosomes, and enzymes for part of photosynthesis. ○ Thylakoids, flattened sacs inside a chloroplast, bound by pigmented membranes on which the light reactions of photosynthesis take place, and arranged in stacks or grana. ● Peroxisomes , small organelle that is present in the cytoplasm of many cells and that contain the reducing enzyme catalase and usually some oxidases, generates and degrades H₂ O₂ . ○ The product of this process, hydrogen peroxide (HO₂ ), is a poison but has another enzyme that converts H₂O₂ to water. ○ Glyoxysomes are used to convert the fatty acids in seeds to sugars. ● The cytoskeletois a microscopic network of protein filaments and tubules in the cytoplasm of many living cells, giving them shape and coherence. ○ The cytoskeleton provides mechanical support, anchorage for many organelles and cytosolic enzymes. ○ Motor molecules carry vesicles or organelles to various destinations along “monorails” provided by the cytoskeleton. ■ Dynein is a motor protein in cells which converts the chemical energy contained in ATP into the mechanical energy of movement. ○ Three main types of fibers in the cytoskeleton: microtubules, microfilaments, and intermediate filaments. ■ Microtubules are microscopic tubular structures present in numbers in the cytoplasm of cells, sometimes aggregating to form more complex structures. ■ Microfilaments are small rodlike structures, present in numbers in the cytoplasm of many eukaryotic cells. ● Pseudopodia are cellular extensions, reversible assembly and disassembly of actin subunits into microfilaments. ● Cytoplasmic streaming is the circular flow of cytoplasm, this speeds the distribution of material within the cell. ■ Intermediate filaments are cytoskeletal components found in the cells of many animal species. Mart 3 ● The cell wall is a rigid layer of polysaccharides lying outside the plasma membrane of the cells of plants, fungi, and bacteria. ○ The cell wall protects the cell, maintains its shape, and prevents excessive uptake of water. ○ The majority of the cell wall is made up of cellulose, along with some proteins and other polysaccharides. ● The extracellular matrix functions in support, adhesion, movement, and regulation. ● Intracellular junctions are structures that provide adhesion and communication between cells. ○ The plasmodesmata is a narrow thread of cytoplasm that passes through the cell walls of adjacent plant cells and allows communication between them. ○ In animal cells there are three main intercellular links: tight junctions, desmosomes, and gap junctions. ● A cell in a living unit greater than the sum of its parts. ○ While the cell has many structures that have specific functions, they must work together.