Biology Study Session Work in groups if you wish to answer the following questions. 1. Compare and contrast the structure and function of cilia and flagella (in eukaryotes). Cilia and flagella have identical structures (both made up of microtubules oriented in the same way), but flagella are longer. Flagella are used in cell motility, whereas cilia are used to pass liquids over the surface of the cell (as seen in respiratory cells moving mucus containing debris). 2. What are some possible functions of microfilaments? Will you find microfilaments in plant cells? Microfilaments are structural proteins, and also function in the formation of the cleavage furrow, as well as used in cell motility (filopodia and lamellopodia). 3. What’s the difference between a somatic cell and a gamete cell (in humans)? Somatic cells are diploid. Gamete cells are haploid (and become diploid when fertilized). 4. Describe the structure of a chloroplast (draw it if you feel that is helpful). From outside to inside -> outer membrane, intermembrane space, inner membrane, stroma (the fluid in the center space of the chloroplast), and stacks of thylakoids (the stacks are called granum). Inside the thylakoids is a space called the lumen. 5. Why are the cristae important on the inner mitochondrial membrane? The ATP-producing reactions happen on the inner mitochondrial membrane. By having a folded inner membrane, it allows the mitochondria to produce copious amounts of ATP without occupying a very large amount of volume. 6. What is a kinetochore and where is it located? A kinetochore is a protein that is the attachment point of the spindle microtubules onto the chromosomes. It is located at the centromeric region of a chromosome. 7. Put the 5 stages of the mitosis in order. Prophase, prometaphase, metaphase, anaphase, telophase. 8. Suppose you have an experimental drug that inhibits lipid synthesis in a cell. What are some possible consequences of this drug as it relates to mitosis? The cell will not grow larger (for the cell to get larger, more lipids will have to be inserted into the membrane so it doesn’t burst apart). There MAY be problems in the formation of the nuclear envelope (as when the lipids get moved from the Rough ER to the nuclear envelope, there won’t be replenishment of the lipids that the RER lost, which could be detrimental to the function of the Rough ER). This is a hypothetical scenario and there really is not a right answer, but I hope it got you thinking! 9. What are the three stages of interphase, and what occurs during each one? G1 – The cell grows and carries out its normal functions S- DNA Replication G2 – The cell continues growing, but with twice as much DNA as it had before (the total amount of DNA has increased, however it is still just 23 chromosomes, although they are replicated chromosomes). 10. What is the significance of the G0 phase, and does it normally occur in every cell? The cell is arrested in its growth; does not normally occur in every cell. 11. List two of the molecules that can be found in the extracellular matrix. The three major ones: Collagen Fibronectin Proteoglycan 12. List everywhere in a eukaryotic animal cell where you can find ribosomes. For each one, what likely happens to the proteins that are produced on it? Nuclear Envelope outer membrane – perinuclear space Rough Endoplasmic Reticulum – into a membrane or secreted from the cell Cytoplasm – to the RER or elsewhere in the cell Mitochondrial Matrix – probably stays in the mitochondria Stroma – probably stays in the chloroplast 13. What is the end product after the last stage of mitosis is complete? Two genetically identical daughter cells (after cytokinesis occurs, otherwise you just have a single cell with two nuclei). 14. During what stage of the cell cycle do the chromosomes replicate? (Be as specific as possible) ‘S’ phase of interphase. 15. What happens during anaphase? The kinetochore microtubules depolymerize, and the nonkinetochore microtubules push each other apart to sever the chromatids and segregate the chromosomes to opposite sides of the cell. 16. How does the function of the cell wall in a plant relate to the structure/function of the large central vacuole? The cell wall resists the turgor pressure created by the storage of various molecules inside the large central vacuole (which pushes against the cell wall). 17. Draw a plant cell going through the entire cell cycle, starting from G1 and ending with cytokinesis. This plant cell is diploid and has three chromosomes. It would be an absolute chore for me to do this in Microsoft Word, so if you would like me to look this one over, I would be more than happy to at the next study session!