Biology Exam Ch. 4 & 5 - Review (PDF)

1\. The Cell is the smallest unit of living matter. a\. Cell theory has three basic premises based on early discoveries about cells. There are more modern lists of cell theory principles that have added more information as we learn more about what cell are (but you are responsible for these three t...

1\. The Cell is the smallest unit of living matter. a\. Cell theory has three basic premises based on early discoveries about cells. There are more modern lists of cell theory principles that have added more information as we learn more about what cell are (but you are responsible for these three tenants) i\. All organisms are composed of cells ii\. Cells are the basic unit of structure and function in organisms iii\. Cells only come from pre-existing cells b\. Cells range in size, some can even be seen without a microscope, but most are very small. As a cell grows it increased its volume faster than it increases its surface area. The surface of a cell is important for exchanging nutrients (bringing in nutrients and sending out waste), if the surface area is not large enough for the volume the cell will have trouble maintaining itself i\. Therefore a large surface-area-to-volume ratio is required by cells and this is obtained by cells being very small which gives a larger ratio 2\. Microscopes (also discussed in your lab) a\. Dissecting or stereoscopes -- often have one large objective and a large base. These microscopes can magnify objects 0-4X from the objective and 10X from the eyepiece for total magnification of 10-40X. These are often used with whole specimens (not slides) b\. Light or compound microscopes -- often have multiple objectives (scanning 4X, low power 10X, high power 40X, and oil immersion 60X-100X) that can be rotated on the nosepiece. This, with the 10X eyepiece, gives a total magnification of 40X-1000X, and should be used with slides. As the objective gets higher powered, the working distance decreases. i\. The magnification of a microscope refers to how "zoomed in" it is -- the actual size as compared to the image size ii\. The resolution is how far apart two objects need to be before they can be seen as two objects instead of one. You can think about it the same way as you would on the computer or pictures -- a low resolution picture would look very pixilated and be hard to see clearly, while a high resolution of the same image would be very clear and crisp. iii\. The contrast refers to the difference in the object as compared to the background. You can use stains, or different types/directions of light to get better contrast on your image 1\. Now, we can also use fluorescent images so that the background is black and the object is fluorescent 2\. We can also use confocal microscopes which make it so that you can focus on one layer of a slide at a time without having the rest of the sample that is not quite in focus get in your way c\. Transmission and scanning electron microscopes -- use electrons to scan through (transmission) or over the surface (scanning) of an object. These have excellent resolution and can have higher magnifications, but can also work within the same range of magnification as the light or dissecting scopes (Scanning -- 20X -- 30,000X, transmission -- up to 10,000,000X). 3\. Prokaryotic Cells have no membrane bound nucleus or organelles and have a number of structural and biochemical differences from eukaryotic cells a\. Shape of prokaryotic cells i\. Bacillus -- rod ii\. Spirilla -- spirals (could also be spirochetes) iii\. Coccus -- spherical b\. The cell envelope includes the plasma membrane (cell membrane, or the phospholipid bilayer), the cell wall which provides stability to the cell, especially in harsher environments, or environments that change, and the glycocalyx a layer of polysaccharides that is outside the cell wall, this could be a well-organized capsule, or a disorganized slime layer, either way, this helps the cell adhere to different surfaces and keeps it from drying out. c\. DNA storage (and how they compare to Eukaryotic cells) i\. Plasmids, nucleoid, etc. d\. Components and functions of the external structures (and how they compare to Eukaryotic cells) i\. Flagella, fimbriae, conjugation pili 4\. Eukaryotic cells -- contain a membrane bound nucleus and other membrane bound organelles a\. Explain how organelles allow the cell to be more efficient b\. Endosymbiotic theory -- explain the theory and give multiple lines of evidence for the theory c\. Know general features of an animal and plant cell ( the similarities and the differences) 5\. Cell structures and functions (be able to identify each, know the function of each, any special organization or sub-structures, etc.) a\. The nucleus -- contains chromatin, surrounded by nuclear envelope with nuclear pores in it b\. Endoplasmic reticulum -- smooth and rough (know the differences in appearance and function) c\. Golgi Apparatus d\. Lysosomes e\. Vacuoles f\. Chloroplasts and mitochondria g\. Cytoskeleton 1\. Membrane structure a\. The membrane is a "fluid-mosaic" it is flexible and can proteins can move around within the membrane i\. We see this with the bubble demo -- the colors swirl over the surface and it "bounces" ii\. This also allows the cell to repair small breaks in the cell membrane b\. Composed of phospholipids, proteins (integral, peripheral), cholesterol (a lipid), and modified lipids and proteins (such as glycolipids and glycoproteins which have sugars attached to them and can be recognized as "tags" for the cell) c\. There can be structure on either side of the cell membrane with the cell cytoskeleton on the inside of the cell and an extracellular matrix on the outside of the cell giving structure to tissues. Both are made of proteins. d\. Protein functions: i\. Channel proteins allow molecules or ions to cross the membrane freely ii\. Carrier proteins also allow molecules or ions to cross the membrane but are specific for a molecule or ion iii\. Cell recognition proteins so that cells can identify "self" from "non-self" iv\. Receptor proteins fit with a signal protein like a lock and key, once the signal is received the cell can change its response to the environment v\. Enzymatic proteins catalyze specific chemical reactions vi\. Junction proteins cerate unity in a tissue by joining cells together -- this could just be holding them together tightly or allow for free communication between them e\. The membrane is selectively permeable only some things can go through, others are screened by the cell membrane first, and others are not let through at all 2\. Passive transport - movement through the membrane does not require energy a\. Some molecules are small and non-polar such as CO2 & O2 letting them move through the membrane by diffusion along their concentration gradient (high to low concentration) b\. Some molecules are polar or too large for simple diffusion through the membrane, but if they are moving along their concentration gradient they require a channel or carrier protein to cross but no energy is required c\. Osmosis -- water also has a concentration gradient -- if the solutes cannot cross the membrane to create an isotonic environment on either side, water tries to "even it out" i\. Hypotonic environment -- more solute in the cell than in the environment causes water to move into the cell, this could cause the cell to swell and burst, however in plant cells with a cell wall to help control the internal pressure of the cell, a hypotonic environment helps them to maintain turgor pressure and draw water up their stem. (firm potato strips in lab) ii\. Hypertonic environment -- more solute in the environment than in the cell causes water to move out of the cell and the cell to shrivel or in a plant to have the cell membrane pull away from the cell wall (limp potato strips in lab, and salt on the Elodea leaf) 3\. Active transport -- movement through the membrane that does require energy a\. Often active transport is moving molecules against their concentration gradients (from low to high concentration) b\. For energy the cell can use ATP (mostly made in the mitochondria) or use molecules moving down their concentration gradient as energy c\. Bulk transport moves large molecules into and out of the cell by endocytosis (into the cell) and exocytosis (out of the cell) i\. Here, vesicles are created or released to move molecules