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BIOLOGY 1A03 (168)
Chapter 7

BIO 1A03-Chapter 7Notes.docx

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McMaster University
Lovaye Kajiura

CHAPTER 7: INSIDE THE CELL KEY CONCEPTS Structure of a cell is closely related to its function Inside cells, materials are transported to their destinations with the help of the molecular “postal codes” Cells are dynamic, thousands of chemical reactions occur each second within the cells; molecules are constantly being moved across the membrane, cell products are shipped along protein fibres, elements of the cells internal skeleton grow and shrink WHATS INSIDE A CELL Eukaryotes have a membrane bound compartment, nucleus Prokaryote does not have a nucleus According to phylogeny there are three groups: Bacteria, Archaea, Eukarya PROKARYOTIC CELLS Plasma membrane encloses a single compartment; cell has few or no substructures separated from the rest of the cell by internal membrane Bacterial and Archael cell walls are a tough, fibrous layer surrounding the plasma membrane Most of them have a single, circular chromosome that consists of a large DNA molecule associated with small proteins and genes In the nucleoid, the cells centre, you find the chromosomes Plasmids: Circular, supercoiled DNA molecules containing genes but are physically independent of the main, cellular chromosome Ribosomes are also found in these cells and manufacture proteins Flagella rotate to power swimming in aquatic species Photosynthetic membranes contain enzymes for photosunthesis Contain long, thin fibres that serve a structural role in the cell Cytoskeleton is formed by filaments shaping the cell Bacteria and Archaea EUKARYOTIC CELLS Nucleus: Has a double membrane (envelope) with openings called nuclear pores o Contain chromosomes, nucleolus and nuclear lamina o Main purpose is for structural support, assembly of ribosome subunits and genetic info Ribosomes: Have large/small subunits-complex of RNA and proteins and is in charge of protein synthesis Rough ER:Network of branching sacs with ribosomes associated o In charge of protein synthesis and processing o Has receptors for selected entry Golgi: Contains receptors for rough ER products o Stack of flattened cisternae and processes protein Smooth ER: Contains enzymes for synthesizing phospholipids and it synthesizes lipids o Has a network of branching sacs Peroxisomes: Contains transporters for selected macromolecules o Processes fatty acids and contains enzymes that catalyze oxidation reactions Lysosomes: Contain protein pumps, catalyzes hydrolysis reactions o In charge of digestion/recycling Vacuoles: Contain transporters for selected molecules o Various different components including pigments, oils, carbs, water, or toxins o Many different functions including colouration, storing oils, carbs or toxins Mitochondria: Has a double membrane o Outer membrane used for enzymes processing pyruvate o Inside membrane used for enzymes for ATP production o Main function is ATP production and has components that are enzymes that catalyze ATP synthesis/ oxidation and reduction reactions Chloroplasts: Have a double membrane with interior sacs o Found in plants and produces ATP and sugars via photosynthesis Cytoskeleton: Does not have a membrane o Function is structural support, movement of material in species and movement in cell o Has microtubules, intermediate filaments and actin filaments Plasma Membrane: Has a single membrane containing transport/receptor proteins on the phospholipid bilayer o Has selective permeability and maintains the cells intracellular environment Cell Wall: Does not have a membrane o Meant for protection and structural support with carb fibres running through carbs or proteins HOW DOES CELL STRUCTURE CORRELATE WITH FUNCTION Example: Muscle Cells o They are extremely long with a tube shaped structure o Filled with protein fibres that slide to allow you to flex o Also packed with mitochondria Example: Leaf o Containing hundreds of chloroplasts The type of organelles in each cell and their size/ number correlates with the cells specialized function Differential Centrifugation A technique that makes it possible to isolate particular cell components and analyze their chemical composition Based on breaking cells apart and creating a complex mixture then separating components in a centrifuge Then a transmission electron microscope takes a snapshot of the cell that needs to be observed Nuclear Envelope: Transporting In/Out of Nucleus Overall shape is defined by the lamina which also helps anchor each chromosome Remainder of the
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