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Transcript
CHAPTER 6 A Tour of the Cell You Must Know • • • • • 3 diff. prokaryotic and eukaryotic cells. Common organelles (Plant/Animal) Unique organelles (Plant/Animal) Organelles > Cell Function Size and Shape affect rate of nutrient/waste Tuesday December 1st Agenda: Checklist for Chapter 6 Due Thursday Videos: 1. Introduction to Cells Wednesday December 2, 2015 Agenda: 1. Surface area to volume demonstration 2. Checklist for Chapter 6 Due Tmrw Videos: 1. Cell Size What factors constrain cell size? Surface Area to Volume Ratios • Need a large surface area to accommodate for growing demands of cell – energy, nutrients, wastes, gasses • More cells vs. Larger cells • Cells must be small to maintain a large surface area to volume ratio • Large S.A. allows rates of chemical exchange between cell and environment Practice Problem Simple cuboidal epithethial cells line the ducts of certain human exocrine glands. Various materials are transported into and out of the cell by diffusion. What would be the volume of the larger cell in um3? SA Formula: 6 x S2 Volume: S3 S = length of side 10 um 20 um Surface Area Example (Animal): Small Intestine: highly folded surface to increase absorption of nutrients – Villi: finger-like projections on SI wall – Microvilli: projections on each cell Diverticulitis of the colon Surface Area Example (Plant): Root hairs: extensions of root epidermal cells; increase surface area for absorbing water and minerals Thursday – December 3rd Agenda: Ch 6 Check for Understanding Microscope Lab Chapter 6 Check for Understanding 1. What are the 2 main types of cells? Which Domains do they consist of? 2. List 3 ways that eukaryotes differ from prokaryotes. Special Note: Archaea and bacteria generally lack internal membranes and organelles and have a cell wall. 2 Types of Cells: 1. Prokaryotes: Domain Bacteria & Archaea 2. Eukaryotes (Domain Eukarya): Protists, Fungi, Plants, Animals A Prokaryotic Cell (bacteria) Commonalities Prokaryote and Eukaryote • Plasma Membrane • Ribosomes (Not membrane bound in P) • DNA: – Prokaryote: Region, Circular Chromosome – Eukaryote: Nucleus, Linear Chromosome Summary Prokaryote Vs. Eukaryote • “before” “kernel” • No nucleus, DNA in a nucleoid • Cytosol • No organelles other than ribosomes • Small size • Primitive • i.e. Bacteria & Archaea • 1-10 um • “true” “kernel” • Has nucleus and nuclear envelope • Cytosol • Membrane-bound organelles with specialized structure/function • Much larger in size • More complex • i.e. plant/animal cell • 1-100 um Chapter 6 Check for Understanding Compare and contrast Animal vs. Plant Cells Animal Cell Plant Cell Parts of plant & animal cell p 108-109 Endosymbiont theory • Mitochondria & chloroplasts share similar origin • These prokaryotic cells engulfed by ancestral eukaryotic cells • Evidence: – Double-membrane structure – Have own ribosomes & DNA – Reproduce independently within cell For the AP Exam Know the function of the cytoskeleton. Not needed. Specifics on structure & function of: 1. Microtubules 2. Microfilaments 3. Intermediate filaments For the AP Exam NOT NEEDED FOR THE EXAM…. 1. Plasmodesmata 2. Gap junctions 3. Tight junctions 4. Desmosomes Friday December 4th Agenda: Organelles Review Chapter 7 Checklist – Due Monday Warmup Worksheet Chapter 6 Part 1 Organelles What is the function of an organelle? Why does the cell compartmentalize? What are some commonalities between the nucleus, mitochondria and chloroplast? Structure Function Mitochondria • Function: site of cellular respiration • Double membrane: outer and inner membrane • Cristae: folds of inner membrane; contains enzymes for ATP production; increased surface area to ATP made • Matrix: fluid-filled inner compartment Chloroplasts • Function: site of photosynthesis • Double membrane • Thylakoid disks in stacks (grana); stroma (fluid) • Contains chlorophylls (pigments) for capturing sunlight energy Other types of plastids • Amyloplastids: colorless plastids that store starch in roots and tubers • Chromoplasts: Store colored pigments for fruits and flowers Tubers are various types of modified plant structures that are enlarged to store nutrients. Used to survive the winter or dry months, to provide energy and nutrients, and a means of asexual reproduction. What is the relationship between the nucleus and the endomembrane system? Nucleus • Function: control center of cell • Contains DNA (code for making proteins) • Surrounded by double membrane (nuclear envelope) – Continuous with the rough ER – Supported by protein filament network called nuclear lamina • Nuclear pores: control what enters/leaves nucleus Inside of the nucleus – • Nuclear matrix – internal support , protein framework • Chromatin: complex of DNA + proteins; makes up chromosomes • Nucleolus: region where ribosomal subunits are formed • Prokaryote: Nucleoid Region- dense region Nucleus • Contains DNA • Function: control center of cell • Surrounded by double membrane (nuclear envelope) – Continuous with the rough ER • Nuclear pores: control what enters/leaves nucleus • Chromatin: complex of DNA + proteins; makes up chromosomes • Nucleolus: region where ribosomal subunits are formed DNA to Chromatin to Chromosome Do all eukaryotic cells have a single nucleus? Ribosomes • • • • Function: protein synthesis Composed of rRNA + protein Large subunit + small subunit Types: 1. 2. Free ribosomes: float in cytosol, produce proteins used within cell Bound ribosomes: attached to ER, make proteins for export from cell Nuclear Envelope ER Golgi Lysosomes Vesicles Vacuoles Plasma Membrane ENDOMEMBRANE SYSTEM: Regulates protein traffic & performs metabolic functions in the cell Endoplasmic Reticulum (ER) “Within the cytoplasm” - “Little net” 1. Rough ER: ribosomes on surface Function: package proteins for secretion, send transport vesicles to Golgi, make replacement membrane 2. Smooth ER: no ribosomes on surface Function: synthesize lipids, metabolize carbs, detox drugs & poisons, store Ca2+ What types of lipids are synthesized in the smooth ER? Where (in the human body) would we find a lot of SER for this purpose? What type of body cells would have a high number of Smooth ER for detoxification? Barbiturates – CNS Depressants Anxiety, Seizures and Sleep Disorders Example: Alcohol • Induce the proliferation (growth of production) of smooth ER and it’s detoxification enzymes (increase the rate) • In turn, this increases your tolerance • Can also decrease effectiveness to drugs you need – like antibiotics Golgi Apparatus Function: synthesis & packaging of materials (small molecules) for transport (in vesicles); produce lysosomes Series of flattened membrane sacs (cisternae) Cis face: receives vesicles Trans face: ships vesicles Lysosomes • Function: intracellular digestion; recycle cell’s materials; digestion in prokaryotes • Contains hydrolytic enzymes What happens if a lysosome accidentally ruptures in the cell? What is the name of the lysosomal disorder where individuals lack the enzyme needed to breakdown lipids? Peroxisomes • Functions: break down fatty acids for the mitochondria; detox alcohol • Contain catalase, Involves production of hydrogen peroxide (H2O2) Vacuoles • Function: storage of materials (food, water, minerals, pigments, poisons) • Eg. food vacuoles, contractile vacuoles (pump) • Plants: large central vacuole -- stores water, ions Why would the construction of a protein take place through a long system? Why not just one organelle? Cilia & Flagella Flagella: long and few; 10-200 microns, propel through water Cilia: short and numerous; 2-20 microns, locomotion or move fluids Let’s begin Chapter 7!