Presentation on theme: "AP Biology The Cell. AP Biology Why are cells so small? Why can’t they be as huge as an hippo?"— Presentation transcript:
AP Biology The Cell
AP Biology Why are cells so small? Why can’t they be as huge as an hippo?
AP Biology What limits cell size? Surface to volume ratio as cell gets bigger its volume increases faster than its surface area smaller objects have greater ratio of surface area to volume Why is a huge single-celled creature not possible? What cell organelle governs this? 6:1 1.2:1 6:1 s:v
AP Biology Limits to cell size Metabolic requirements set upper limit in large cell, cannot move material in & out of cell fast enough to support life CHO aa CH CO 2 NH 3 O2O2 aa O2O2 CHO aa CH O2O2 aa CHO CH aa O2O2 CO 2 NH 3 CO 2 NH 3 CH What’s the solution? What process is this? O2O2
AP Biology How to get bigger? Become multi-cellular (cell divides) O2O2 CHO aa CH CO 2 NH 3 aa O2O2 CH But what challenges do you have to solve now? aa CO 2 NH 3 O2O2 aa CH aa CHO O2O2
AP Biology Cell characteristics All cells: surrounded by a plasma membrane have cytosol semi-fluid substance within the membrane cytoplasm = cytosol + organelles contain chromosomes which have genes in the form of DNA have ribosomes tiny “organelles” that make proteins using instructions contained in genes
AP Biology Prokaryote bacteria cells Types of cells Eukaryote animal cells - no organelles - organelles Eukaryote plant cells
AP Biology Types of cells Prokaryotic cell DNA in nucleoid region, without a membrane separating it from rest of cell Cell wall present in all (type differs) Eukaryotic cell chromosomes in nucleus, membrane- enclosed organelle Cell walls present in fungi and plants only More complex Membrane bound organelles present Prokaryotic vs. eukaryotic cells
AP Biology The prokaryotic cell is much simpler in structure, lacking a nucleus and the other membrane-enclosed organelles of the eukaryotic cell.
AP Biology Why organelles? Specialized structures specialized functions cilia or flagella for locomotion Containers partition cell into compartments create different local environments separate pH, or concentration of materials distinct & incompatible functions lysosome & its digestive enzymes Membranes as sites for chemical reactions unique combinations of lipids & proteins embedded enzymes & reaction centers chloroplasts & mitochondria mitochondria chloroplast Golgi ER
AP Biology Cells gotta work to live! What jobs do cells have to do? make proteins proteins control every cell function make energy for daily life for growth make more cells growth repair renewal
AP Biology Building Proteins Organelles involved nucleus ribosomes endoplasmic reticulum (ER) Golgi apparatus vesicles nucleusribosomeER Golgi apparatus vesicles The Protein Assembly Line
AP Biology Synthesizing proteins cytoplasm cisternal space mRNA ribosome membrane of endoplasmic reticulum polypeptide signal sequence ribosome
AP Biology Nucleolus Function ribosome production build ribosome subunits from rRNA & proteins exit through nuclear pores to cytoplasm & combine to form functional ribosomes small subunit large subunit ribosome rRNA & proteins nucleolus
AP Biology membrane proteins Types of Ribosomes Free ribosomes suspended in cytosol synthesize proteins that function in cytosol Bound ribosomes attached to endoplasmic reticulum synthesize proteins for export or for membranes
AP Biology Rough ER function Finalize protein formation and prepare for export out of cell (protein folding) protein secreting cells will have lots packaged into transport vesicles to golgi Which cells have lot of rough ER?
AP Biology Golgi Apparatus Which cells have lots of Golgi? transport vesicles secretory vesicles Function finishes, sorts, tags & ships cell products like “UPS shipping department” ships products in vesicles membrane sacs “UPS trucks”
AP Biology proteins transport vesicle Golgi apparatus vesicle smooth ER rough ER nuclear pore nucleus ribosome cell membrane protein secreted cytoplasm Making proteins Putting it together…
AP Biology Smooth ER function Membrane production Many metabolic processes synthesis synthesize lipids oils, phospholipids, steroids & sex hormones hydrolysis hydrolyze glycogen into glucose in liver detoxify drugs & poisons in liver ex. alcohol & barbiturates
AP Biology Lysosomes Function little “stomach” of the cell digests macromolecules “clean up crew” of the cell cleans up broken down organelles Structure vesicles of digestive enzymes only in animal cells only in animal cells synthesized by rER, transferred to Golgi Where old organelles go to die!
AP Biology Cellular digestion Lysosomes fuse with food vacuoles polymers digested into monomers pass to cytosol to become nutrients of cell vacuole lyso– = breaking things apart –some = body
AP Biology When cells need to die… Lysosomes can be used to kill cells when they are supposed to be destroyed some cells have to die for proper development in an organism apoptosis “auto-destruct” process lysosomes break open & kill cell ex: tadpole tail gets re-absorbed when it turns into a frog ex: loss of webbing between your fingers during fetal development
AP Biology Fetal development 15 weeks 6 weeks syndactyly
AP Biology Making Energy Cells must convert incoming energy to forms that they can use for work mitochondria: from glucose to ATP chloroplasts: from sunlight to ATP & carbohydrates ATP = active energy carbohydrates = stored energy + ATP
AP Biology Mitochondria & Chloroplasts Important to see the similarities transform energy generate ATP double membranes = 2 membranes semi-autonomous organelles move, change shape, divide internal ribosomes, DNA & enzymes
AP Biology Mitochondria Function cellular respiration generate ATP from breakdown of sugars, fats & other fuels in the presence of oxygen break down larger molecules into smaller to generate energy = catabolism generate energy in presence of O 2 = aerobic respiration
AP Biology Mitochondria Almost all eukaryotic cells have mitochondria there may be 1 very large mitochondrion or 100s to 1000s of individual mitochondria number of mitochondria is correlated with aerobic metabolic activity more activity = more energy needed = more mitochondria What cells would have a lot of mitochondria? active cells: muscle cells nerve cells
AP Biology Chloroplasts Chloroplasts are plant organelles class of plant structures = plastids amyloplasts store starch in roots & tubers chromoplasts store pigments for fruits & flowers chloroplasts store chlorophyll & function in photosynthesis in leaves, other green structures of plants & in eukaryotic algae
AP Biology Chloroplasts Function photosynthesis generate ATP & synthesize sugars transform solar energy into chemical energy produce sugars from CO 2 & H 2 O Semi-autonomous moving, changing shape & dividing can reproduce by pinching in two Who else divides like that? bacteria!
AP Biology Mitochondria & chloroplasts are different Organelles not part of endomembrane system Grow & reproduce semi-autonomous organelles Proteins primarily from free ribosomes in cytosol & a few from their own ribosomes Own circular chromosome directs synthesis of proteins produced by own internal ribosomes ribosomes like bacterial ribosomes Who else has a circular chromosome not bound within a nucleus? bacteria
AP Biology Food & water storage plant cells central vacuole contractile vacuole food vacuoles animal cells
AP Biology Vacuoles & vesicles Function little “transfer ships” Food vacuoles phagocytosis, fuse with lysosomes Contractile vacuoles in freshwater protists, pump excess H 2 O out of cell Central vacuoles in many mature plant cells
AP Biology Vacuoles in plants Functions storage stockpiling proteins or inorganic ions depositing metabolic byproducts storing pigments storing defensive compounds against herbivores selective membrane control what comes in or goes out