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Lecture

LECTURE 1- INTRO TO CELL BIOLOGY.docx

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Department
Biology
Course Code
BIO1140
Professor
Kathleen Gilmour

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LECTURE 1 - TOPIC 1 (INTRO TO CELL BIOLOGY) Slide 2-What is a cell collective definition: -all living things are made of cells -regulates internal environment -reproduces to produce other cells -responds to external environment surrounding it -cytoplasm enclosed by lipid and protein membrane -contains genetic information -most have metabolic processes cell theory: 1. all organisms consist of one or more cells 2. the cell is the basic unit of structure fro all organisms (theodore schwann 1839 & Matthias Schleiden 1838) 3. All cells arise only from pre existing cells (i.e the cell is the basic unit of reproduction. (rudolf Virchow 1855) Slide 3-Can one speak of THE cell? They vary, and are very diverse Slide 4-Can one speak of THE cell? Enormous diversity, shapes can be very diverse, and also interns of size. Most cells are very small (smalls 2nm) they can be as big as 13cm in diameter (eggs are an example) Nerve cells that extend from the spinal cord to the foot of a giraffe are approximately a meter in size cells vary also in function; some cells are really good at everything, but in multicellular organisms you can get cells that highly specialized in terms of what they do. although cells are immensely diverse, they have very important similarities. looking at the proteins, you'll find similar amino acids, DNA aswell for genetic information, looking at metabolism they use ATP for cellular energy. Slide 5-Size of Cells avg prokaryotic cell 1-5 microns avg eukaryotic 10-30 microns ribosome diameter-30nm nucleus diameter-0.006mm (6 microns) mitochondrion length-3x10^-6 (3 microns) giraffe axon length-1x10^6 Microfilament diameter-0.007microns (7nm) Slide 6- Why cells are small relates to surface area to volume ration if the surface are to volume aren't well matched the cell either starves of nutrients.Volume of the cell tells you how much it needs in terms of nutrients moving in, and wage moving out. SUrface area is the area in which that exchange can take place. (you need enough SA to match cells volume) surface area is falling as cell becomes larger (6:1 --> 3:1) think of an entire class trying to leave marion through only 4 small doors How do we get large organisms? We make the cells smaller. the blue and the green organism are both the same size, but the green one is made up of many small units, as to not jeopardize the SA:V, this allows exchange area to keep up with the cells nutrients and waste requirements. Limitation #2 is diffusion. It is good as long assistances are small. cells cannot afford to be large because the rate of diffusion cannot keep up. diffusion is relatively slow, this is what keeps cells small. 78d to move O2 molecule across a cell that is 1m. this provides a major constraint on cell size.(diffusion is slow over long distances) limitation #3, are the cell size increases, the number of molecules (substrates) that need to be synthesized for reactions to occur increases. At a certain size, the synthetic machinery just simply cannot produce enough molecules, to produce a great enough concentration for reactions to proceed. Slide 7-Prokaryotic and Eukaryotic cells differ in their solutions to size problem Prokaryotic cells: -lack a true nucleus (very simple cells) -a cell membrane bounded by cell wall -inside is (semi liquid fluid) cytoplasm -Cytoplasm includes ribosomes for protein synthesis -Genetic material of the cell is in the form of a single circular chromosome without structural proteins. -All folded on itself and forms nucleiod (NO NUCLEUS) Slide 8- (slide 7 cont'd) Small simple cells is their solution to the constraints on cell size; They just stay small (despite the fact that they are small, they are incredibly diverse. fall into group arches and eukarya) Archea = extreme-o-philes Slide 9 Eukaryo
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