12. Cell Nucleus Cell nucleus showing the nuclear envelope, nucleolus and chromatin. Chromatin is DNA that is visible, like fine threads.
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14. Ribosomes Chromatin (uncoiled chromosomes) Nuclear envelope Nucleolus Pore Diagram of nucleus and associated organelles.
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18. This is one “model” of DNA. It is supposed to show that it is like a ladder, with rungs, that is twisted. This model is focused on showing some other details that we will learn about later, so it does not show the twisting very well. You will see this model many times, later in this course.
19. DNA molecules are built just like a ladder. To make a better model, like the one in the next slide, we just need to twist the ladder into a spiral.
20. Here is a much better model for understanding that DNA is built just like a ladder that has been twisted .
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22. This is a close up electron micrograph of bacterial DNA in its uncoiled state called chromatin .
33. DNA never leaves the nucleus. DNA is “double stranded. Single copies of it, called RNA, leave thru nuclear pores, and direct protein formation
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35. The RNA at right is a single stranded copy of the DNA. Electron micrograph of Chromatin Model of chromatin Real chromosome Model of part of a chromosome
36. So, which one will it be possible to “read”? This chromatin or This chromosome?
37. An actual electron micrograph of a nuclear membrane, showing pores. Nuclear membrane Nuclear pores
38. Close up of electron micrograph looking at a cross section of the nucleus. NM= nuclear membrane. P= nuclear pore.
42. Here is a model of RNA. Ribonucleic Acid. It is single stranded, as you can see. It is very similar to DNA, and has most of the same molecular structure. RNA is a single stranded copy of the information in DNA and oversees protein production
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46. Movie clip #1- Play the movie- “7.2 Eukaryotic Cells- DNA thru Translation” by double clicking on the blue square. 10 min.
57. A close up of the rough ER. The dark spots indicated by arrows are ribosomes that are on the surface of the membrane of the ER.
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59. Rough ER Is A Major Site Of Protein Synthesis RNA is a single stranded copy of DNA (which is double stranded). RNA copies the information from DNA, in the nucleus. RNA oversees protein production (it has the recipe) RNA moves through nuclear pores, into the cytosol , and eventually to the Endoplasmic Reticulum, where it joins with a ribosome . It is here, on the surface of rough ER, that most proteins are made.
60. DNA never leaves the nucleus. DNA is “double stranded. Single copies of it, called RNA, leave thru nuclear pores, join with ribosomes on the surface of the rough ER, and produce proteins. DNA RNA w/ info to make proteins
61. Here is a model of RNA. Ribonucleic Acid. It is single stranded, as you can see. It is very similar to DNA, and has most of the same molecular structure. RNA is a single stranded copy of the information in DNA and oversees protein production
62. DNA molecules are built just like a ladder. To make a better model, like the one in the next slide, we just need to twist the ladder into a spiral.
63. Here is a much better model for understanding that DNA is built just like a ladder that has been twisted .
64. Model of ER, nucleus, nuclear pores, ribosomes and RNA. The RNA is leaving the nucleus through nuclear pores and traveling to the outer surface of the ER, where it joins with a ribosome . DNA & RNA in nucleus RNA travels thru nuclear pore RNA joins ribosome on outer surface of ER. Inner surface of ER
95. A lysosome is a membrane-enclosed sac which contains very powerful digestive enzymes . It is really just a special kind of vesicle . Together, all the lysosomes in a cell make up its digestive system . Lysosomes break down macromolecules , damaged organelles , or even other cells , like bacteria, which a cell has “eaten”. The cell uses the digested products to make all of its own new products - macromolecules, membranes, organelles and so on. Lysosomes are created by the Golgi apparatus.
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98. Diagram of cell performing endocytosis. This could be a white blood cell, which can move, surround and “eat” bacteria. Bacterium
99. Plasma membrane Digestive enzymes Food vesicle is formed. Digestion 2 ○ lysosome Lysosome Cell pinches in here . Once the “ food ” is within vesicle, it must be digested by lysosomes. The lysosome fuses with the food vesicle and digests the contents. Useful products from this digestion pass into the cytosol, to be re-absorbed by various organelles
100. Lysosome breaking down damaged organelle Lysosome Damaged organelle Digestion Lysosomes digest damaged organelles as well. The lysosome simply surrounds the damaged organelle (or a piece of one) and digests it.
101. Enzymes are protein molecules that either speed up or allow chemical reactions. Lysosomes contain powerful digestive enzymes .
102. Because they are proteins, we know enzymes start out in the rough ER and are sent to the Golgi apparatus. Rough ER Golgi apparatus
103. The Golgi apparatus packages these enzymes into a vesicle , and a lysosome has been created. Lysosome- really just a specialized vesicle.
104. Waste products from digestion by lysosomes are disposed of when the secondary lysosome travels back to the cell membrane and accomplishes exocytosis . Food vesicle, digestion complete. exocytosis
107. If the very powerful digestive enzymes in lysosomes were left to float around the cell, they would actually digest the cell itself . They MUST be contained. This brings up an important and unanswered question: If the enzymes in a lysosome can break down anything in a cell, why don't they break down the lysosome too?
108. Rough ER Contains digestive enzymes Repackages digestive enzymes into a lysosome Food captured Food captured digestion Cell gets rid of unusable digested material by exocytosis Joining of food vesicle and lysosome Food vesicle Food vesicle This slide will be on the test!!!!
120. This is an enlarged photograph of a one celled organism using a flagellum to move. The flagellum moves in a spiral and looks like more than one because this is a time lapse photograph, made with a strobe light.
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123. Cross section of some cilia, showing the microtubules that run the length of this organelle. Cilia and flagella are basically a long extension of the cell membrane wrapped around microtubules with some cytosol present.
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125. Basal body, centriole Basal Bodies and Centrioles are two more structures made of microtubules. Basal bodies anchor cilia and flagella to the cell membrane. Centrioles are basal bodies that have moved inside the cell and have a role in cell division that we will study later.
129. What is going on here? A flagellum is moving a cell forward.
130. Cell membrane nucleus mitochondrion centrioles Smooth ER Golgi apparatus Rough ER nuceleolus Either lysosome or vesicle- hard to tell ribosomes
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134. These are amyloplasts, but they are stained so as to be seen on a slide. They store starch.
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137. Vacuoles merging in a plant cell. Over time, one vacuole fills the plant cell. Vacuoles fill with fluid, retain pressure, helping a plant to be rigid.
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