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Plant and Animal Cells Under the Microscope 1.What indicators were used to help view some organelles under the microscope? 2.What is the structural difference between cheek cells and frog’s blood? How does this affect the function? 3.What structure did plant cells have that animal cells did not? 4.What organelle could be seen in the spinach cells, but not the onion cells? Why?

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

Prokaryote bacteria cells Types of cells Eukaryote animal cells - no organelles - organelles Eukaryote plant cells

Types of cells Prokaryotic cell DNA in nucleoid region, without a membrane separating it from rest of cell Cell wall present in all 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

Prokaryotic Cell Structurally Simpler than Eukaryotic Cells

Eukaryotic Cell: Animal

Eukaryotic: Plant

Cell Membrane (Covered Extensively in Chapter 7)

Nucleus is the cell’s genetic control center

Overview: Many cell organelles are connected through the endomembrane system

Ribosomes make proteins for use in the cell and export Structure: A.Large Subunit B.Small Subunit Function: -Polypeptide (protein) synthesis Location: A.Free: in cytoplasm B.Attached : bound to ER

The endoplasmic reticulum is a biosynthetic factory Structure: Passage ways inside cell Function: A.Rough ER: synthesis of membrane lipids and proteins, secretory proteins, and hydrolytic enzymes; formation of transport vesicles. B.Smooth ER: Lipid synthesis, detoxification in liver cells, calcium ion storage.

Synthesis and packaging of a secretory protein by the rough ER

Golgi apparatus finishes, sorts, and ships cell products

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”

Overview: Many cell organelles are connected through the endomembrane system

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

Lysosomes are digestive compartments

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

Fetal development 15 weeks 6 weeks syndactyly

Review of structures involved in manufacturing and breakdown

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

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

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

Mitochondria harvest chemical energy from food

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

Chloroplasts convert solar energy to chemical energy

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

Endosymbiosis theory Mitochondria & chloroplasts were once free living bacteria – engulfed by ancestral eukaryote Endosymbiont – cell that lives within another cell (host) as a partnership evolutionary advantage for both – one supplies energy – the other supplies raw materials & protection Lynn Margulis U of M, Amherst 1981 | ??

Mitochondria and chloroplasts evolved by endosymbiosis

Food & water storage plant cells central vacuole contractile vacuole food vacuoles animal cells

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

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

Putting it all together, try labeling.. animal cells plant cells

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

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

Cell wall enclose and support plant cells