Cell Structure and Viruses Class 8 PDF

Welcome to BIOL 1107 Principles of Biology I Dr. John T. Duncan Jr Assistant Professor of Biological Sciences Office: GE-2045 [email protected]  Agenda Lesson 8 ○ Cell Structure and Function I Cell Theory...

Welcome to BIOL 1107 Principles of Biology I Dr. John T. Duncan Jr Assistant Professor of Biological Sciences Office: GE-2045 [email protected]  Agenda Lesson 8 ○ Cell Structure and Function I Cell Theory Organelles ○ Cell Structure and Function II Moving in the cell Endomembrane system Microfilaments ○ Viruses How do they interact with cells How do they “Live” 2 3 Cell Structure and Function I LO1: Tenets of the cell theory and LO2: Biological basis for small cell size LO3: Organelles and structures of the cell and components of all cell types their functions -Nucleus- contains DNA, site of transcription -Cell membrane- enclose the cell, separate from outside environment -Ribosome- produce proteins -Cell wall- protects the cell -Mitochondria- produce energy for the cell All cells have a: -Golgi apparatus- package cargo (proteins and lipids) in -cell membrane vesicles -Chloroplasts- site of photosynthesis -cytoplasm -Smooth ER- produces lipids -DNA -Rough ER- process and modify proteins -Vacuoles- maintains water balance, degrades biomolecules -ribosomes -Lysosomes- breakdown large biomolecules and old organelles LO4: Prokaryotic vs. eukaryotic cells, plant vs animal cells Plants have -Chloroplasts -Vacuoles -Cell wall Animals have -Lysosomes ** Although they are not labeled here, plants have microtubules and secretory vesicles.  Cell Theory Cell Theory states that… ○ All living organisms are made of cells ○ Cells come from pre-existing cells ○ The cell is the structural and functional unit of life 5  Cell Theory Cell size and the square cube law As cells get bigger, the volume increases faster than the surface area Larger volume means less efficient transport of nutrients in/waste out of the cell 6  Cell Parts All cells have 4 common parts A plasma membrane to separate cell from not cell (the environment) Cytoplasm, made of cytosol (the chemical component filling the cell) DNA, the genetic material Ribosomes that synthesize proteins 7  Prokaryotes No organelles Oldest for of cells Archaea and bacteria Smaller than eukaryotic cells 8  Prokaryotes Chromosome localized in the nucleoid Ribosomes in the cytoplasm Cell membrane is surrounded by a cell wall made of peptidoglycans Some other structures in some species or groups 9  Eukaryotes Have organelles Ribosomes in cytoplasm and in some internal membranes Larger than prokaryotes 10 Plasma Membrane 11  Nucleus Normally the largest organelle Larger than most prokaryotic cells Contains DNA Site of transcription 12  Nuclear Envelope A double membrane that separates DNA from the cytoplasm and transcription from translation Nuclear pores cross he membrane to control the flow of molecules between the nucleus and cytoplasm 13  Ribosomes Two different- sized subunits Made of special RNA (rRNA) and proteins During protein synthesis (Translation), ribosomes assemble amino acids into proteins 14  Mitochondria Site for conversion of stored energy into ATP Has its own DNA and ribosomes Has outer and inner membrane Inner membrane is folded ○ Folds are called cristae ○ Area enclosed is the mitochondrial matrix 15  Endoplasmic Reticulum (ER) Interconnected membranous sacs and tubules Rough ER modifies proteins Smooth ER makes lipids Hollow portion is the lumen or cisternal space The membrane of the ER is continuous with the nuclear envelope 16  Endoplasmic Reticulum (ER) Smooth ER Continuous with rough ER No ribosomes Synthesizes carbs, lipids, and steroid hormones Stores Ca2+ Detoxifies chemicals 17  Golgi Apparatus Packages lipids and proteins produced by the ER Made of a series of flattened membranes 18  Lysosomes Only in animal cells ○ (similar can be found in some plats and fungi, but very specific differences) Contain digestive enzymes ○ Break down large biomolecules and worn-out organelles 19 The Typical Animal Cell 20 The Typical Plant Cell 21  Chloroplasts Double-membrane organelles Have their own DNA and ribosomes Site of conversion of light energy in to chemical energy (photosynthesis) 22  Central Vacuole Found in plant cells Helps regulate water concentration under changing environmental conditions Also functions as the plant’s lysosome 23 25 Cell Structure and Function II LO1: The endomembrane system: modification, packaging, and LO2: Microtubules, intermediate filaments, and microfilaments transport Endomembrane system: a group of membranes and organelles within eukaryotic cells that work together to modify, package, and transport lipids and proteins. The system includes: Nuclear envelope Endoplasmic reticulum Microfilaments: Intermediate filaments: Microtubules: Golgi apparatus Made up of strands of the Made up of fibrous Long, hollow cylinders made up of Lysosomes protein actin; often proteins organized into many molecules of the protein interact with strands of tough, ropelike tubulin. Tubulin consists of two Vacuoles assemblies. The subunits, a-tubulin and b-tubulin. other proteins. Function Plasma membrane to help with cell shape function to stabilize a Function as a cytoskeleton of the and movement. cell’s structure and help cell and aid in movement of cargo maintain shape. within the cell LO3: Predict the function of a cell from its structure and the structure of LO4: Predict the effects of organelle and structural alterations a cell from its function To predict the effect of altering a specific organelle/structure: To predict the function of a cell: 1. Identify the organelle or structure: Identify the organelle or structure that is being altered and the manner in Skeletal muscle cell. which it is being altered. This could be through genetic manipulation, chemical treatment, physical damage, 1. Identify the specific organelles and structures present The nucleus is bottom within the cell. or other means. right. An abundance 2. Analyze the function of each organelle and structure. of mitochondria (dark 3. Infer the overall function of the cell based on the 2. Understand the function: Understand the function of the organelle or structure in the normal functioning of purple) produce the the cell. What processes does it contribute to? How does it interact with other components of the cell? presence large amount of and relative abundance of the organelles and structures. energy needed by the 3. Predict the impact: Based on your understanding of the function of the organelle or structure, predict the cell. impact of the alteration on the cell's overall functioning. Will the cell be able to compensate for the loss or Example: large number of mitochondria indicate the cell has a large energy demand. alteration of the organelle/structure, or will it cause significant disruptions to cellular processes? Plasma cell. These 4. Consider secondary effects: Consider any secondary effects that the alteration may have on the cell. For To predict the structure of a cell: cells produce and example, altering the mitochondria may impact the energy production of the cell, which could affect a wide secrete enormous range of cellular processes. 1. Identify the specific function of the cell. amounts of protein 2. Analyze the specific requirements of the cell's function. antibodies in 3. Predict the structures and organelles that are likely to be response to infection. present within the cell based on these requirements. Note the massive amount of rough ER Example: a cell involved in protein synthesis and secretion that encompasses the would be expected to have rough ER and Golgi bodies. cell’s interior.  The Endomembrane System Internal membranes and organelles in eukaryotic cells that work together to modify, package, and transport lipids and proteins Includes: Nuclear Envelope, Lysosomes and vesicles, ER, Golgi, and plasma membrane 27  The Endomembrane System The receiving side of the Golgi apparatus is called the cis face; the opposite is the trans face. Transport vesicles from the ER fuse with the cis face and empty their contents into the lumen of the Golgi apparatus. Proteins and lipids modified as they move through the Golgi ○ Often involves adding short chains of sugar molecules. Vesicles leave the Golgi and can either leave the cell or move to other organelles 29  The Cytoskeleton Network of protein fibers Helps to maintain the shape of the cell. Holds some organelles in specific positions. Allows movement of cytoplasm and vesicles within the cell. Enables cells within multicellular 30 The Cytoskeleton 31  Microfilaments Involved with movement of the cell or internal parts of the cell Helps shape the cell Made from actin monomers Smallest fibers in the 32  Intermediate Filaments Structural Many types of proteins involved 33  Microtubules Form ridged internal skeleton for some cells Provide framework for motor proteins to move things within 34  Help with moving the cell of the environment Made of microtubules Cilia are shorter but more of them Different movement patterns 35 LO3: Predict: 1. the function of a cell, given a drawing, micrograph, or description of its structure and organelle content, and 2. the structure of a cell, given information on its function. In each case, explain your reasoning. Predict Cell Structure and Function To predict the function of a cell: Skeletal muscle cell. The nucleus is bottom right. An 1. Identify the specific organelles and structures present abundance of mitochondria (dark purple) within the cell. produce the large amount 2. Analyze the function of each organelle and structure. of energy needed by the 3. Infer the overall function of the cell based on the cell. presence and relative abundance of the organelles and structures. Examples: large number of mitochondria indicate cell has a large energy demand. To predict the structure of a cell: Plasma cell. These cells produce and secrete 1. Identify the specific function of the cell. enormous amounts of protein antibodies in 2. Analyze the specific requirements of the cell's function. response to infection. Note 3. Predict the structures and organelles that are likely to the huge amount of rough be present within the cell based on these requirements. ER that encompasses the cell’s interior. Examples: a cell involved in protein synthesis and secretion would be expected to have rough ER and Golgi bodies. 36  LO4: Predict what would happen to a cell if a particular organelle or structure was altered in a specified manner. Predict the Effect of Altering a Specific Organelle or Structure To predict the effect of altering a specific organelle/structure: 1. Identify the organelle or structure: Identify the organelle or structure that is being altered and the manner in which it is being altered. This could be through genetic manipulation, chemical treatment, physical damage, or other means. 2. Understand the function: Understand the function of the organelle or structure in the normal functioning of the cell. What processes does it contribute to? How does it interact with other components of the cell? 3. Predict the impact: Based on your understanding of the function of the organelle or structure, predict the impact of the alteration on the cell's overall functioning. Will the cell be able to compensate for the loss or alteration of the organelle/structure, or will it cause significant disruptions to cellular processes? 4. Consider secondary effects: Consider any secondary effects that the alteration may have on the cell. For example, altering the mitochondria may impact the energy production of the cell, which could affect a wide range of cellular processes. 37 VIRUSES LO1: Viruses are obligate intracellular parasites LO2: Are viruses alive or not alive? LO3: Viral Structure LO4: Viral Life cycle Life cycle 1) attachment to Many different shapes and host sizes to viruses All viruses have: 2) Entry into host Capsid: Protein structure Genetic Material: DNA or 3) Viral component RNA released into host Some viruses have lipid 4) Viral genome is membranes (enveloped used to make new viruses) and some do not viruses (nonenveloped viruses) 5) New viruse are released Virus Obligate intracellular parasites Require living host to replicate Host is species-specific Cannot replicate nucleic acids No mechanism for gene expression MUST invade and take over host cell’s functions and resources LO1: Viruses are obligate intracellular parasites  Properties of life But what Order Response to stimuli about Reproduction Viruses? Growth and development Regulation Homeostasis Energy processing Evolution Characteristics of life – from the Study of Life LO2: Are viruses alive or not alive? Viral Structure ALL VIRUSES Protein Coat  Capsid Genetic Material DNA or RNA SOME VIRUSES Membrane envelope  Enveloped No membrane  Nonenveloped LO3: Viral Structure Viral Life Cycle LO4: Viral Life cycle