Molecular Cell Biology EXAM 1Question And Answers 100% Verified Answers Guaranteed Pass.

The cell theory - correct answer -All living organisms are made up of one or more cells. -the cell is the fundamental unit of structure and function in all living organisms. -all cells are essentially the same in chemical composition. The central dogma - correct answer The flow of genetic information in all living cells. -DNA>RNA>PROTEIN -replication>transcription>translation Polytene chromosomes from Drosophila - correct answer The giant salivary gland cells of the Drosophila larva go through multiple rounds of DNA replication with NO cell division, resulting in polytene chromosomes. The Miller-Urey experiments - correct answer 1950's -It recreated the conditions thought to exist in the primitive earth. -seven simple molecules (all gasses): water, nitrogen, ammonia, carbon monoxide, carbon dioxide, methane and hydrogen. NO OXYGEN. -Heat: evaporates water. -Radiation: (electrodes discharged sparks into main chamber, simulating lighting): provides energy to arrange the simple gases into more complex structures. -a cooling system captures molecules into liquid form for examination. What were the results of the Miller-Urey experiment? - correct answer With each round of heating, radiation and cooling, more complex organic molecules were formed: 1. aldehydes 2. simple acids 3. more complex acids (including amino acids), many of them found in living systems today. -these experiments suggested that organic molecules could form under the conditions that existed in the primitive earth. The formation of self- replicating macromolecules - correct answer The advent of self-replicating macromolecules was the next step in the origin of life. -necessary for REPRODUCTION and EVOLUTION. -present day: Nucleic acids. which macromolecule is double stranded and which is single stranded? - correct answer Double: DNA Single: RNA The first genetic system might have been ___ based. - correct answer RNA Some RNA molecules (ribozymes) have what kind of activity? - correct answer enzymatic activity. The ribozyme and the substrate may be two separate RNA molecules, or two domains of the same RNA molecule observed in: - correct answer 1. genome replication in some RNA viruses. 2. intron splicing What are the two evidence of the RNA world? - correct answer 1. some RNA molecules (ribozymes) have enzymatic activity. 2. RNA can catalyze the polymerization of nucleotides, including the synthesis of complimentary RNA, using itself as template. (this is NOT observed in DNA) In the hypothetical RNA world, RNA molecules can catalyze ______? - correct answer can catalyze the replication of themselves and of other nucleic acids. Can RNA direct protein synthesis? - correct answer yes. evolution of new enzymes that create DNA and make RNA copies from it. What was the first cell? - correct answer A self-replicating RNA and other life-promoting molecules inside a phospholipid membrane. RNA was replaced in living cells by the more stable DNA, but retained its properties. Phospholipid molecule - correct answer -the head group: hydroPHILIC. -the tail group: hydroPHOBIC. Why are cells so small? - correct answer 1. Greater surface area to volume ratio. 2. as the radius increases, the increase in volume is faster than the increase in cell surface area. 3. high surface area to volume ratio means more membrane area per unit of volume: this is important for the interactions between the cells and its environment. 4. smaller cells can interact with their surroundings more efficiently. 5. smaller cells (and animals) are also more prone to lose energy as heat to their surroundings. 6. smaller animals need to eat more than larger animals (as a percent of their own mass). Prokaryotes - correct answer (Bacteria and Archaea) lack a nuclear envelope, organelles and a cytoskeleton. Eukaryotes - correct answer have a nuclear envelope (the defining feature), organelles, and a cytoskeleton. Escherichia coli - correct answer -no nucleus -no organelles -single chromosome (in the nucleic area) + plasmids -cell wall -capsule -PROKARYOTIC CELL what cells are the most diverse? - correct answer Prokaryotes What type of bacteria have spherical cells? - correct answer Streptococcus What type of bacteria have rod-shaped cells? - correct answer E. coli, salmonella What type of bacteria have spiral cells? - correct answer Treponema pallidum Photosynthetic bacteria - correct answer obtain energy from sunlight. -these cells have an internal system of membranes where photosynthesis occurs ( in photosynthetic eukaryotes such as plants, this system of membranes is the organelle chloroplast.) Anabaena cylindrica specialized cells: - correct answer -nitrogen fixing (H, incorporate atmospheric N2 into organic compounds) -photosynthetic (V, incorporate atmospheric C02 into organic compounds using sunlight energy) -weather resistant spores (reproductive cells) Intracellular membranes where photosynthesis occurs in __? - correct answer Phormidium laminosum Beggiatoa can do what? - correct answer can also fix CO2 but derives energy from the oxidation of H2S (an inorganic substance from the environment). These cells can fix CO2 in the dark. The tree of life based on molecular evolution - correct answer was constructed by comparing the DNA sequences of the small ribosomal RNA, present in all cells. 7 Kingdoms are? - correct answer 1. Animals 2. Plants 3. fungi 4. protist 5. prokaryotes 6. bacteria 7. archaea Nucleus - correct answer is the defining feature of eukaryotic cells. It contains MOST of the DNA in the cell. Endocytosis - correct answer import mediated by the formation of endocytic vesicles. Exocytosis - correct answer export (secretion)