BIO Chapter 4
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This 8 page Class Notes was uploaded by Natalie Berry on Saturday September 17, 2016. The Class Notes belongs to BIO 101 at Missouri State University taught by Kyoungtae Kim in Fall 2016. Since its upload, it has received 33 views. For similar materials see Biology in Your World in Science at Missouri State University.
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Date Created: 09/17/16
Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Chapter 4: The Cell Cell’s as Life’s Fundamental Unit Every form of life is either a single celled organism or composed of many cells One possible exception to this are viruses, but they also must use the machinery of cells to reproduce Every cell comes from a cell Cells can’t be made in labs Nature fashioned cells from simple molecules only once back when life on Earth got started This means that each cell in our bodies is a link in a cellular chain that stretches back more than 3.5 billion years Prokaryotic and Eukaryotic Cells There is no “typical” cell because of all the varieties that exist There are certain categories of cells that are important: prokaryotic and eukaryotic Every cell that exists is one or the other All prokaryotic cells are either bacteria or another microscopic form of life called archaea All other cells are eukaryotic Eukaryotic cells: cells whose primary complement of DNA is closed within a nucleus Prokaryotic cells: are cells whose DNA is not enclosed within a nucleus Nucleus: a membrane lined compartment that has DNA for a Eukaryotic cell Differences between Eukaryotic and Prokaryotic Cells Eukaryotic cells have a nucleus and prokaryotic cells do not Eukaryotic cells are multicellular and prokaryotic cells are unicellular Eukaryotic cells are more compartmentalized They have organelles; highly organized structures inside a cell that have specialized function Think “tiny organs” Mitochondria transform energy from food Lysosomes recycle new materials from cells In prokaryotic cells, there is a single type of organelle that produces proteins There is more diversity of eukaryotic cells Prokaryotic cells differ from one another in the way they get their food Prokaryotic cells can inhabit their environment in great numbers Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important The Eukaryotic Cells There are five parts of eukaryotic: The cell’s nucleus Organelles outside the nucleus Cytosol: protein rich, jelly-like fluid where the cells organelles are immersed Cytoskeleton: internal structure made of three protein fibers Like tent poles or monorails Plasma membrane: outer lining of the cell Cytoplasm: the region of the cell inside the plasma membrane but outside the nucleus Cytoplasm is different than cytosol If you tripped cytoplasm of organelles and the cytoskeleton, cytosol is left (is mostly water) Cytosol is not an organized structure in the way organelles are The Animal Cell You can look at eukaryotic cells as animal cells and plant cells These cells are very similar but different enough The animal cell is spherical Animal Cell’s Protein Protection Proteins are critical molecules in living things DNA has the info for putting protein together starting with building blocks called amino acids DNA is in a nucleus bound by a membrane Nuclear envelope: the double membrane that lines the nucleus in eukaryotic cells Cells reach a point where they divide Cells have to have function (information) so when cells divide the DNA doubles The nucleus is the side where DNA exists and where it is put together, or synthesized, for doubling Messenger RNA The info in the length of the DNA has to be transported from the nucleus to the cytoplasm How it happens: DNA’s instructions are copied onto a second long chain molecule called NA The RNA transported the DNA info out of the nucleus to the site of protein synthesis RNA comes in several forms but in trans of DNA instruction copying, it’s called messenger RNA (mRNA) Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important mRNA gets from the nucleus to the cytoplasm via nuclear pores Ribosomes The destination for the mRNA are the ribosomes Ribosome: an organelle that serves as the site of protein synthesis in the cell A ribosome is the “machine” that carries out the instructions in the mRNA mRNA chains run through a ribosome sequence in the mRNA and start putting amino acids in the order specified from the mRNA the end result is a chain of amino acids that will eventually fold into a protein The rough endoplasmic reticulum Rough endoplasmic reticulum (rough ER or RER): a network of membranes that aid in the processing of proteins in eukaryotic cells It’s rough because it’s studded with ribosomes It’s endoplasmic because it lies within the cytoplasm It’s reticulum because it’s a network, which is what reticulum means in Latin the ribosomes, with its RNA and amino acids (polypeptide) chain, attaches itself to the outside of the rough ER the polypeptide chain that is released from the ribosome is essentially an unfinished protein that needs to go through more steps before leaving the cell Several Locations for the Ribosomes Only some ribosomes end up going to the rough ER even though all mRNA go to ribosomes Some ribosomes remain “free”, or free standing in the cytosol Free ribosomes produce protein that is used in the cells cytoplasm or nucleus Rough ER ribosomes produce proteins that will stay in the cell membranes or exported from the cell (secretory protein) A pause for the Nucleolus Ribosomes are mostly made of RNA (a mixture of proteins and ribonucleic acid) Because the cell has huge need for ribosomes, there’s a special section in the nucleus for the synthesis of RNA the nucleolus Nucleolus: the area within the nucleus of a cell devoted to the production of ribosomal RNA, RNA that is a part of the ribosomes Ribosomes start in the nucleus, leave unfinished through the pores, and are finished in the cytoplasm and start receiving RNA Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Ribosomes are the one variety of cellular organelle not lined by a membrane They are the one variety of cellular organelle not lined by a membrane They are also the one variety of organelle that prokaryotic cells have Traffic in ribosomes is fast, lots of them wear out all the time A thousand need to be replaced every minute Transport Vesicles Proteins processed in the rough ER need to leave it and go to a different destination before being exported Proteins are transported through the cell by transport vesicles Transport vesicles: membrane lined spheres that move within the endomembrane system carrying proteins and other molecules Endomembrane vesicles: an interactive group of membrane-lined organelles and transport vesicles within eukaryotic cells The Golgi Complex Once a transport vesicle leaves a golgi complex, it goes and fuses with the membrane of the Golgi complex Golgi complex: a network of membrane that processes and distributes proteins that come to it from the rough ER The Golgi complex “sorts and ships” proteins Proteins arrive at the GC and fuse to the side of it that’s closest to the RER Then the proteins leave in the final transport vesicle Secretory proteins (proteins that leave the cell) travel in the vesicle to the cell membrane and the protein is ejected out of the cell Cell structure outside the protein production path Smooth Endoplasmic Reticulum (SMR) Smooth ER is the 2 nd type of reticulum SMR: the part of the endoplasmic reticulum membrane farthest from the nucleus that has no ribosomes Network of membranes that is the site of the synthesis of various lipids and potentially harmful substances are detoxified SMR tasks vary according to cell type lipids are put together and stored in the smooth ER of liver and fat cells steroid lipids (testosterone and estrogen) are put together in the SMR of the ovaries and testes detoxification of harmful substances takes place largely in the SMR of liver cells Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Lysosome and Cellular Recycling Lysosome: an organelle found in animal cells that digest worn-out cellular materials and foreign materials that enter the cell Take in large molecules break them down and then return them to cytosol What they cannot return, the keep inside them or expel them outside the all They don’t only do this to molecule from the outside but from the inside as well (worn out organelle parts) A lysosome may be filled w/ up to 40 different enzymes that can break down larger molecules Molecules that are broken down are released to the cytosol for reuse elsewhere The pace of this recycling depends on an organism’s nutritional state Mitochondria The processes discussed come with price, spending energy The fuel for this energy is in the cells food but the energy needs to be extracted and transferred to a molecule called ATP This takes place in mitochondria Mitochondria: primary energy conversion sites in eukaryotic cells Most of the heat within our bodies is generated in mitochondria Almost all the food we eat is ultimately consumed by them The cytoskeleton Cytoskeleton: a work of protein filaments that functions in cold structure movement and the transport of materials within a cell This network is found in its full form only in eukaryotic cells Some of its fibers are permanent and don’t move and some do, and some assemble and disassemble The cytoskeleton is developed is developed into 3 parts (from smallest to largest): microfilament intermediate filaments microtubules Microfilaments: are made of protein actin and serve as support in almost all eukaryotic cells Help cells move to capture prey by growing rapidly at one end towards the prey and decomposing at the other Intermediate filaments Intermediate in diameter between microfilaments and microtubules Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Most permanent of cytoskeletal elements Stabilize positions of the nucleus and other organelles within the cell Microtubules Largest of the cytoskeletons filaments and take form of tubes formed from protein Important structural role in terms of giving the cell its shape Vesicles move from one organelle to the other via tubules Cilia and Flagella Microtubules form structure for two cell extensions: cilia and flagella Cilia: microtubule extension of cells that take form a large number of atoms, hair like growth Cilia move back and forth rapidly (30 or 40 times/second) to propel a cell or move stuff around the cell Cilia are common among unicellular organisms (sponges, jellyfish) Cilia are in our lungs; they sweep out foreign things that have been inhaled Cilia beat all at once in the same direction Flagella: long tail-like extension of cells that function in cell movement The Plant Cell Plant cells don’t have lysosomes Plant cells have things animal cells don’t: A thick cell wall Chloroplasts A large central vacuole The central vacuole The central vacuole is the big jelly the middle Vacuoles can take up 90% of a plant cell’s volume Animals have vacuoles but plant vacuoles are different Plant vacuoles are mostly composed of water The vacuole contains other substances other than water The larger molecules (solutes) in the central vacuole spurs the movement of water into it called osmosis The CV expands pushing against cytosol giving the plant healthy internal pressure Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important Central vacuole: a large watery plant organelle that maintains cell pressure, stores nutrients and controls retention and degradation of waste The Cell Wall – plant cell’s outer protective lining the cell membrane is thin in comparison almost always present in plant cells exist in protists animal cells never have cell walls cell walls provide structural strength, limit water absorption, protect plants from harmful outside influence cell walls make an organism rigid, inflexible that’s why animal cells don’t have them; they need to move freely cell walls are formed from cellulose provide good metabolic activity Chloroplasts Plants make their own food through photosynthesis, which takes place in chloroplast Chloroplasts: organelle sites of photosynthesis in plant and algae cells No other organisms have chloroplasts They are abundant in the leaves of plants Cell to cell communication Cells are not single entities Most plant and animal cells are linked together making tissues Plant cells communicate through channels in cell wall called plasmodesmata Animal cells communicate through gap junctions Gap junctions: protein structures that shoot through the plasma membrane of a cell from one side to the other Results in a channel for passage of small molecules and electrical signals The difference in plant and animal cell communication: Plasmodesmata are permanent channels Gap junctions only open when necessary Key: Light Blue = main idea Purple = important parts of the main idea Green = examples Orange = key terms Pink = the definition of the key term Red = especially important
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