CH/BI 227 SI February 7, 2023 Left WhiteBoard Agenda 1. 2. 3. 4. Do now -> add your email to shared folder on my computer Planning our lesson Before SI (*learning goals) During SI After SI QUestion? Write students’ names Right WhiteBoard Today I want to learn more/talk about… Format options Multiple-choice questions Problem-based (know your vocabs/math) Essay-style questions (know your reasoning/evidence) Discussion-based questions (know your applications) What is the most important thing you learned this week? Section I: Vocabulary Micrometer Micrometer (um) That’s about 25 times smaller than the width of a human hair. DNA DNA made from the same set of four monomers, called nucleotides, strung together in different sequences like the letters of an alphabet RNA RNA The information encoded in these DNA molecules is read out, or transcribed, into a related set of polynucleotides Proteins Proteins Most RNAs are translated into a different type of polymer. What is the central dogma? Evolution Evolution the process by which living species become gradually modified and adapted to their environment in more and more sophisticated ways Genome Genome the entire sequence of nucleotides in an organism’s DNA—provides a genetic program that instructs a cell how to behave Microscope Microscope Eg. 1. Light microscopes, 2. Electron microscopes, 3. Fluorescent microscopes. How do they work? What are their uses? Microscope 1. Micrometer scale (a cell has ~20 um of diameter). Use visible light to illuminate specimens, and they allowed biologists to see for the first time the intricate structure that underpins all living things. 2. A few nanometers. Use beams of electrons instead of beams of light as the source of illumination; because electrons have a much shorter wavelength, these instruments greatly extend our ability to see the fine details of cells and even render some of the larger molecules visible individually. 3. Highest is 20 nanometers. use sophisticated methods of illumination and electronic image processing to see fluorescently labeled cell components in much finer detail Microscope Plasma membrane & Cytoplasm Plasma membrane & Cytoplasm “an enclosing membrane” & “a transparent substance crammed with what seems at first to be a jumble of miscellaneous objects.” Ribosomes Ribosomes a large macromolecular complex in which RNAs are translated into proteins Organelles Organelles separate, recognizable substructures with specialized functions that are often only hazily defined with a conventional light microscope 1. Eukaryotes vs. 2. Prokaryotes 1. Eukaryotes vs. 2. Prokaryotes 1. Have a nucleus. Greek words eu, meaning “well” or “truly,” and karyon, a “kernel” or “nucleus” 2. Do not have a nucleus. From pro, meaning “before” 1. Eukaryotes vs. 2. Prokaryotes Section II: Questions Why are Prokaryotes the Most Diverse and Numerous Cells on Earth? Why are Prokaryotes the Most Diverse and Numerous Cells on Earth? Single-celled Diverse range of habitats Aerobic, anaerobic Eg. bacteria can How are Prokaryotes Divided into Two Domains: Bacteria and Archaea? How are Prokaryotes Divided into Two Domains: Bacteria and Archaea? Why Is the Nucleus the Information Store of the Cell (eukaryotes)? Why Is the Nucleus the Information Store of the Cell (eukaryotes)? It is enclosed within two concentric membranes that form the nuclear envelope, and it contains molecules of DNA—extremely long polymers that encode the genetic information of the organism. How do Mitochondria Generate Usable Energy from Food Molecules? How do Mitochondria Generate Usable Energy from Food Molecules? What are chloroplasts? How do they Capture Energy from Sunlight? What are chloroplasts? How do they Capture Energy from Sunlight? More complex than mitochondria with internal stacks of membranes containing the green pigment chlorophyll They carry out photosynthesis—trapping the energy of sunlight in their chlorophyll molecules and using this energy to drive the manufacture of energy-rich sugar molecules. Note: Like mitochondria, chloroplasts contain their own DNA, reproduce by dividing in two. How Do Internal Membranes Create Intracellular Compartments with Different Functions? How Do Internal Membranes Create Intracellular Compartments with Different Functions? The endoplasmic reticulum (ER) is an irregular maze of interconnected spaces enclosed by a membrane: where most cell-membrane components, as well as materials destined for export from the cell, are made. The Golgi apparatus are stacks of flattened, membrane-enclosed sacs:modifies and packages molecules made in the ER that are destined to be either secreted from the cell or transported to another cell compartment How Is the Cytoskeleton Responsible For Directed Cell Movements How Is the Cytoskeleton Responsible For Directed Cell Movements Cytoskeleton is composed of three major filament types: 1. Actin filament (for muscle contraction) 2. Microtubules (pull apart chromosomes in dividing cells) 3. Intermediate filaments (strengthen animal cells) “They form a system of girders, ropes, and motors that gives the cell its mechanical strength, controls its shape, and drives and guides its movements.” Why Is The Cytosol Is Far from Static? Why Is The Cytosol Is Far from Static? - Think about cytoskeleton and motor proteins. - The large and small molecules in the cell are knocked to and fro by random thermal motion, constantly colliding with one another and with other structures in the crowded cytosol. Section III: Discussions Eukaryotic Cells May Have Originated as Predators? Some general tips: 1. Work through problems (end-of-chapter problems & questions in the chapters). 2. Look at end-of-chapter summary for big picture ideas (try to summarize in your own words as well). 3. Try to understand the vocabularies and concepts in context of the whole system.
