Guided Reading Qs L03 A Tour of the Cell Do these before the Mastering Assignment Reading Modules 4 2 4 16 and additional readings on Sakai about cystic fibrosis Reading Objectives Describe properties of all cells relative to surface area structural components and function Differentiate bacteria plant and animal cell structures Describe the structure and function of eukaryotic cell components Explain how proteins are secreted from a eukaryotic cell Describe the cellular defects associated with cystic fibrosis Module 4 2 1 Why can t cells get very big They must have a large enough surface area to serve the volume of a cell 2 As cell size increases what happens to its surface to volume ratio As cell size increases surface to volume ratio gets smaller 3 What is the structure and function of the plasma membrane It forms a flexible border between the live cell and its environment it is exceedingly thin separating life from nonlife a stack of more than 8 000 plasma membranes would be required to equal the thickness of this page It works as a selective barrier to ion and molecule transit into and out of the cell Modules 4 3 4 4 4 There are two kinds of cells in nature a Prokaryotic cells b Eukaryotic cells Plasma membrane Cytosol semifluid cytoplasmic part Chromosomes Ribosomes Cytoplasm 5 All cells have some features in common list them define any you aren t familiar with 6 Draw figure 4 3 a bacterium for yourself Label and be sure to define each part Take note of what a prokaryotic cell contains so that you can easily see what it is missing compared to a eukaryotic cell 7 Compare and contrast eukaryotic and prokaryotic cells Prokaryotic doesn t have nucleus cell wall surface projections flagella do not have other membrane enclosed organelles ribosomes are smaller and different from eukaryotes Eukaryotic has nucleus 8 What is the advantage for the cell in having compartments within a eukaryotic cell Many chemical activities cellular metabolism occur in compartments increasing process efficiency 9 Compare and contrast a plant cell and an animal cell Examine diagrams of typical organelles of plant and animal cells what differences do you see Plant cells have chloroplasts central vacuole cell wall and plasmodesmata that animal cells don t have Animal cells have lysosomes and centrosomes that plant cells don t have Modules 4 5 4 6 10 Genetic Control of the cell The Nucleus and ribosomes Name and sketch the structure that matches the functional description of each component below a The cell s genetic instructions inside the nucleus nucleus b A barrier separating the cell s genetic information from the cell s cytosol nuclear envelope c How materials enter and exit the nucleus proteins DNA is transcribed into another set of instructions called mRNA that directs protein synthesis A cell with many ribosomes structural characteristic tells you what about this cell s function It tells that the cell makes a lot of proteins What is the difference between proteins that are made on either Free ribosomes in the cytosol proteins that are made on free ribosomes function within the cytosol e g enzymes that catalyze the first steps of sugar breakdown for cellular respiration Ribosomes attached to the endoplasmic reticulum or nuclear envelope they can function anywhere or Modules 4 8 4 12 11 The Endomembrane System The rough ER and Golgi form a functional unit that help to produce what for the cell Describe this process as this will be a major focus of our study of cells Drawing will help you work through biological processes Transport vesicles budded from the ER and containing proteins produced by bound ribosomes are sent to the Golgi The Golgi completes protein processing and sends transport vesicles to the plasma membrane where the proteins are secreted What is the function of lysosomes It digests breaks down damaged organelles and recycles their molecules What is one disease associated with malfunction of the lysosomal enzymes Tay Sachs Modules 4 13 4 15 11 Energy Converting Organelles What is the function of mitochondria Carry out cellular respiration and transforms chemical energy of food to ATP Do prokaryotes have no Animal cells yes Plant cells no What is the function of chloroplasts Responsible for photosynthesis Do prokaryotes have yes Animal cells no Plant cells yes Draw pictures of both a mitochondrion and a chloroplast as these structures of these become very important to our discussion of cellular respiration and photosynthesis What are the names of each compartment spaces Be sure they are labeled on your pictures How many phospholipid bi layer membranes in each All eukaryotes have mitochondria but not all eukaryotes have chloroplasts Can you propose an evolutionary explanation for this observation According to the endosymbiont theory mitochondria and chloroplasts were tiny prokaryotes that entered the bigger cell as undigested prey or parasites Module 4 16 12 What is the function of the cytoskeleton Structural support aids in movement it s a fiber Name three fibers that make up the cytoskeleton Microtubules thickest Microfilaments thinnest Intermediate filaments in between in thickness Why does cell structure and function matter Please read two very short articles about cystic fibrosis posted on Sakai Many diseases are based in defective cellular structures or macromolecular components Let s explore one disease where lung cells and a few other cells of the body malfunction Cystic Fibrosis a How does someone get cystic fibrosis Mutation of the CFTR gene b What is the median age of survival now 37 c Major symptoms associated with the disease are Lung infections wheezing coughing poor growth and weight gain d The first line of drugs that helped improve the quality of life did what Pulmozyme thins the mucus making it simpler to remove Tobramycin it distributes medication directly into the lungs making it a more effective approach to combat infections e What s the link in this article to UNC f What does a CFTR modulator do https www nytimes com topic organization university of north carolina inline nyt org In persons with these mutations ivacaftor aids the faulty CFTR protein s function at the cell s surface Ivacaftor helps salt and fluid go into the airways which helps thin the thick sticky mucus caused by CF that builds up in the lungs and makes it easier to cough up Lumacaftor aids in the movement of the faulty CFTR protein to its appropriate location at the cell surface Ivacaftor boosts the
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