BIOS 2110 - My Summary of Chapter 4 PDF

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Download BIOS 2110 - My Summary of Chapter 4 PDF

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Chapter 4 Notes Organisms are either single-celled (prokaryotes, protists) or multi celled (plants, animals, some fungi) Everything you do- every action and every thought- reflects processes that occur at the cellular level Two important factors: Magnification an increase in the object’s image size compared with its actual size Resolving Power the ability of an optical instrument to show two objects as separate clarity of the magnified image every item has a limit to its resolving power Types of Micrographs: Light Microscope (LM) Visible light is projected through the specimen (Ex. protist) Glass lenses enlarge the image and project it into a human eye or camera Electron Microscope (EM) Uses a beam of electrons to resolve objects gives 100-fold better resolution than light microscope Scanning Electron Microscope (SEM) used to study the detailed architecture of the cell surface Transmission Electron Microscope (TEM) used to study the internal structure of a cell Cells first described in 1665 Cell Theory states that all living things are composed of cells and that all cells come from other cells The size Range of Cells Unaided Eye Human height, length of some nerve and muscle cells, chicken eggs, frog eggs Light Microscope Plant and animal cells, Nuclei, Most Bacteria, Mitochondria Electron Microscope Smallest bacteria, viruses, ribosomes, proteins, lipids, small molecules, atoms Two Basic Categories of Cells: Prokaryotic Cells found in organisms of the domains Bacteria and Archaea, known as prokaryotes Eukaryotic Cells organisms of the domain Eukarya- protists, plants, fungi, animals, called eukaryotes

All cells have several features in common: Plasma Membrane bounded by a barrier regulates the traffic of molecules between the cell and its surroundings Cytosol thick, jelly like fluid cellular components are suspended it Chromosomes all cells have one or more carry genes made of DNA Ribosomes build proteins according to instructions from the genes Prokaryotic and Eukaryotic Cells differ in several important ways: Prokaryotes came first Prokaryotic cells are usually much smaller (about one-tenth) and simpler in structure Only eukaryotic cells have organelles organelles = membrane-enclosed structures that perform specific Most important is the nucleus houses most of a eukaryotic cell’s DNA and is surrounded by a double membrane Not in prokaryotic cells, lack a nucleus DNA coiled into a ‘nucleus-like’ region, which is not partitioned from the rest of the cell by membranes Eukaryotic Cells all fundamentally similar to one another Cytoplasm entire region of the cell between the nucleus and plasma membrane consists of various organelles suspended in the liquid cytosol. Most organelles are found in both animal and plant cells, but some important differences Plant cells only have chloroplasts where photosynthesis occurs Only animal cells have lysosomes bubbles of digestive enzymes surrounded by membranes Not in animal cells: central vacuole, cell wall, chloroplast Not in most plant cells: centriole, lysosome Plasma Membrane: A Fluid Mosaic of Lipids and Proteins edge of life, the boundary that separates the living cell from its nonliving surroundings remarkable thin film can regulate the traffic of chemicals into and out of the cell Phospholipids most of the lipids belong to a special category have only two fatty acid tails (hydrophobic- water-fearing)

in place of the third fatty acid, a phospholipid has a phosphate group a combination of phosphorus and oxygen electrically charged, making it hydrophilic (water-loving) chemical ambivalence in their interaction with water forms a Phospholipid Bilayer a two-layered membrane hydrophobic fatty acid tails of the molecules stay in the membrane interior away from the water, while the hydrophilic phospholipid heads remain surrounded by water on the inside or outside of the cell not static sheets locked rigidly in place, free to drift about in the plane of the membrane Fluid Mosaic fluid because the molecules can move freely past one another and a mosaic because of the diversity of proteins that float like irebers in the phospholipid sea Plant cells have a cell wall made from cellulose fibers embedded in other molecules protect the cells, maintain cell shape, keep cells from absorbing so much water that they burst connected via channels that pass through the cell walls, joining the cytoplasm of each cell allow water and other small molecules to move between the cells, integrating the activities of a tissue Extracellular Matrix although animal cells lack a cell wall, most of them secrete a sticky coat holds cells together in tissues can also have protective and supportive functions Cell Junctions surfaces of most animal cells structures that connect cells together into tissues, allowing them to function in a coordinated way Nuclear Envelope nucleus is separated from the cytoplasm by a double membrane each membrane of the nuclear envelope is similar in structure to the plasma membrane Chromatin long DNA molecules and associated proteins from fibers within the nucleus Nucleolus prominent structure within the nucleus the site where the components of ribosomes are made

Ribosomes responsible for protein synthesis In eukaryotic cells, made in the nucleus, transported through the pores of the nucleus into the cytoplasm

in the cytoplasm they begin their work others attached to the outside of the nucleus or organelle called the endoplasmic reticulum makes proteins that are incorporated into the membranes or secreted by the cell Sequence of events during protein production in a eukaryotic cell: 1. DNA programs protein production in the cytoplasm by transferring its coded information to a molecule called messenger mRNA (carries the order form the nucleus to the cytoplasm) 2. The mRNA exits through pores in the nuclear envelope and travels to the cytoplasm, where it then binds to ribosomes 3. The ribosome moves along the mRNA, translating the genetic message into a protein with a specific amino acid sequence Cytoplasm of a eukaryotic cell is partitioned by organelle membranes connected to each other, directly to membranes, transfer of membrane segments between them Endomembrane system nuclear envelope, endoplasmic membrane, Golgi apparatus, lysosomes, vacuoles Endoplasmic Reticulum main manufacturing facilities within a cell produces an enormous variety of molecules connected to the nuclear envelope forms an extensive labyrinth of tubes and sacs running throughout the cytoplasm Rough ER ribosomes that stud the outside of its membrane make more membrane phospholipids made by enzymes as it grows, portions of it are transferred to other parts of the cell ribosomes attached produce proteins that will be inserted into the growing ER membrane, transported to other organelles, eventually exported Transport Vesicles some products manufactured by rough ER are dispatched to other locations in the cell sacs made of membrane that bud off from the rough ER Smooth ER organelle lacks the ribosomes that populate the surface of rough ER diversity of enzymes enables it to perform many functions synthesis of lipids, including steriods growth of smooth ER in response to one drug can also increase tolerance of other drugs

Golgi Apparatus working in close partnership within the ER receives, refines, stores, and distributes chemical products of the cell products made in the ER reach the Golgi apparatus in transport vesicles Consists of a stack fo membrane plates

1. One side of a Golgi stack serves as a receiving dock for vesicles from the ER 2. Proteins within a vesicle are usually modified by enzymes during their transit from the receiving to the shipping side of the Golgi apparatus 3. The shipping side of a Golgi stack is a depot from which finished products can be carried in transport vesicles to other organelles or to the plasma membrane Lysosomes membrane-enclosed sac of digestive enzymes found in animal cells absent from most plant cells develop from vesicles that bud off from the Golgi Apparatus enzymes within break down large molecules provides a compartment where the cell can digest these molecules safely, without unleashing these digestive enzymes on the cell itself several types of digestive functions: engulf nutrients into tiny cytoplasmic sacs called food vacuole fuse with food vacuole leave the lysosome and nourish the cell destroy harmful bacteria break down large molecules of damaged organelles engulf and digest parts of another organelle sculpting functions in embryonic development lysosomal storage diseases importance of lysosomes to cell function and human health is made strikingly clear by hereditary disorders Vacuoles large sacs of membrane that bu from the ER variety of functions Central Vacuoles account for more than half the volume of a mature plant cell versatile compartment stores organic nutrients contributes to plant growth may contain pigments that attract pollinating insects may contain poisons that protect against plant-eating animals

Chloroplasts unique to the photosynthetic cells to plants and algae, are the organelles that perform photosynthesis partitioned into three major components by internal membranes Space between the two membranes that surround the chloroplast Stroma

thick fluid within the chloroplast suspended in that fluid, the interior of a network of membrane-enclosed disks and tubes forms the third component Grana disks occur in interconnected stacks chloroplast’s solar power packs, the structures that trap light energy and convert it to chemical energy Mitochondria organelles of cellular respiration in nearly all cells, harvesting energy from sugars and other food molecules and using it to produce another form of chemical energy called ATP direct energy source for most of their work found in almost all eukaryotic cells, including those of plants and those in your body Matrix envelope of two membranes encloses the mitochondrion, which contains a thick fluid Cristae inner membrane of the envelope has numerous infoldings ability to provide cellular energy, mitochondria and chloroplasts share another feature: contain their own DNA that encodes some of their own proteins evidence that mitochondria and chloroplasts evolved from free-living prokaryotes in the distant past Cytoskeleton cells have an infrastructure both skeleton and “muscles” for the cells, functioning in support and movement Give mechanical support to the cell and maintain its shape especially important for animal cells, which lack rigid cell walls several types of fibers made from different types of proteins Microtubule straight, hollow tubes composed of proteins other kinds of cytoskeletal fibers, called intermediate filaments and microfilaments are thinner and solid provides anchorage and reinforcement for many organelles in a cell move along tracks made from microtubules dynamic quickly dismantle in one part of the cell by removing protein subunits and re-form in a new location by reattaching the subunits provide rigidity in a new location, change the shape of the cell, or even cause the whole cell or some of its parts to move process contributes to the amoeboid movements of the protist Amoeba and some of our white blood cells Cilia and flagella are motile appendages- extensions from a cell that aid in movement Eukaryotic flagella

propel cells through their undulating, whiplike motion often occur singly, but may also appear in groups on the outer surface of protists Cilia generally shorter and more numerous than flagella and promote movement by a coordinated back-and-forth motion Both propel various protists through water Different in length, number per cell, and beating pattern, cilia and flagella have the same basic architecture, with a core of microtubules wrapped in an extension of the plasma membrane Some animal cells have cilia and flagella, many do not, almost never found on plant cells Some extend from nonmoving cells that are part of a tissue layer...