I. The Fundamental Units of LifeII. Biologists use microscopes and the tools of biochemistry to study cellsIII. Eukaryotic cells have internal membranes that compartmentalize their functionsIV. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomesV. The endomembrane system regulates protein traffic and performs metabolic functions in the cellVI. Mitochondria and Chloroplasts Change Energy from one form to anotherChapter 6 (part 1) – A Tour of the Cell – Lecture 5 I. The Fundamental Units of Life 1. All organisms are made of cells 2. Cell is the simplest collection of matter that can be alive 3. Plants and animals are multicellular 4. Cell is the basic unit of structure and function 5. Although cells can differ substantially from one another, they share common features. II. Biologists use microscopes and the tools of biochemistry to study cells 1. Organelles – the membrane-enclosed structures within eukaryotic cells. III. Eukaryotic cells have internal membranes that compartmentalize their functions 1. Cells- the basic structural and functional units of every organism are of two distinct types: prokaryotic and eukaryotic. 2. Organisms of the domains Bacteria and Archaea consist of Prokaryotic cells 3. Protists, fungi, animals, and plants all consist of eukaryotic cells. 4. * The prokaryotes include all bacteria. The defining feature of a prokaryotic cell is the lack of internal membranes * CLICKER QUESTION 5. All cells share certain basic features: - All bounded by a selective barrier called the plasma membrane. - Inside all cells is a semifluid, jellylike substance called cytosol, in which subcellular components are suspended. - All cells contain chromosomes, which carry genes in the form of DNA. - All cells have ribosomes, tiny complexes that make protein according to instructions from the genes. 6. Eukaryotic cell, most of the DNA is in an organelle called the nucleus, which is bounded by a double membrane. 7. Prokaryotic cell, the DNA is concentrated in a region that is not membrane-enclosed, called the nucleoid8. Cytoplasm- interior of either type of cell - In eukaryotic refers only to the region between the nucleus and the plasma membrane - Membrane-bounded structures are absent in prokaryotic cells 9. Presence or absence of a true nucleus is just one aspect of the disparity in structural complexity between the two types of cells. 10. Eukaryotic cells are generally much larger than prokaryotic cells size is a general feature of cell structure that relates to function. 11. At the boundary of every cell, the plasma membrane functions as a selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the entire cell.12. Larger organisms do not generally have larger cells than smaller organisms they just have more cells. A panoramic view of the eukaryotic cell 1. Plasma membrane and organelle membranes also participate directly in the cell’s metabolism, because many enzymes are built right into the membranes 2. Basic fabric of most biological membranes is a double layer of phospholipids and other lipids. Embedded in this lipid bilayer or attached to its surfaces are diverse proteins ( each type of membrane has a unique composition of lipids and proteins suited to that membrane’s specific function). IV. The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes 1. Two cellular components involved in the genetic control of the cell: the nucleus, which houses most of the cell’s DNA, and the ribosomes, which use information from the DNA to make proteins. 2. Nucleus contains more of the genes in the eukaryotic cell (some genes are located in the mitochondria and chloroplasts) 3. Nuclear envelope encloses the nucleus, separating its contents from the cytoplasm. 4. Pore complex – an intricate protein structure that lines each pore and plays an important role in the cell by regulating the entry and exit of proteins and RNAs, as well as large macromolecules. 5. Nuclear lamina- at the pores, the nuclear side of the envelope by this which is a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope6. Nuclear matrix- a framework of protein fibers extending throughout the nuclear interior - Both lamina and matrix may help organize the genetic material so it functions efficiently 7. Within the nucleus the DNA is organized into discrete units called chromosomes, structures that carry the genetic information. 8. The complex of DNA and proteins making up chromosomes is called chromatin. Ribosomes: Protein Factories 1. Ribosomes- complexes made of ribosomal RNA and protein, are the cellular components that carry out protein synthesis. 2. Free ribosomes – suspended in the cytosol most proteins made function within the cytosol3. Bound ribosomes – attached to the outside of the endoplasmic reticulum or nuclear envelope generally make proteins that are destined for insertion into membranes, for packaging within certain organelles such as lysosomes. - Both are structurally identical and can alternate between the 2 roles.V. The endomembrane system regulates protein traffic and performs metabolic functions in the cell1. *** Endomembrane system- what many of the different membranes of the eukaryotic cell are part of, which includes the nuclear envelope, the endoplasmic reticulum the Golgi apparatus, lysosomes, various kinds of vesicles and vacuoles, and the plasma membrane carries out a variety of tasks in the cell, including synthesis of proteins, transport of proteins into membranes and organelles or out of the cell, metabolism and movement of lipids, and detoxification of poisons. The Endoplasmic Reticulum: Biosynthetic Factory 2. Endoplasmic reticulum (ER) – an extensive network of membranes that accounts for more than half the total membrane in may eukaryotic cells. 3. Two distinct, though connected, regions of the ER that differ in structure and function: Smooth ER is so named because its outer surface lacks ribosomes &Rough ER which is studded with ribosomes on the outer surface of the membrane 4. Smooth ER functions in diverse metabolic processes including synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions. 5. Rough ER makes secretory proteins (most are glycoproteins, proteins that have
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