BIOL110 Lecture 5: Cell Structure and Function PDF

BIOL 110: Integrated Science- Biology Lecture 5. Cell Structure and Function  Lab report guideline : announced ‘Guideline for BIOL110 Lab Report’. please check your email or Canvas, Announcement for more detail. Title: A concise, informativ...

BIOL 110: Integrated Science- Biology Lecture 5. Cell Structure and Function  Lab report guideline : announced ‘Guideline for BIOL110 Lab Report’. please check your email or Canvas, Announcement for more detail. Title: A concise, informative, and catchy (if possible) title. You can use the same title as the lab manual. Authors: Your name Abstract (more than 5 sentences) A short summary of your major goal (more than 1 sentence), major findings (more than 3 sentences), and the significance of your study (more than 1 sentence).  Lab report guideline : announced ‘Guideline for BIOL110 Lab Report’. please check your email or Canvas, Announcement for more detail. Introduction (more than 200 words) This section will set the framework for your entire report. Outline the overall purpose and the background that leads to your study. An overview of the experimental method(s) and why the particular approach was chosen should also be discussed. Make sure to state the question(s) that will be answered by the experiments you have conducted. The only information that is relevant to your experiment should be included in the introduction. You may include a figure from various references (optional). Materials and Methods (Please simplify this section. This section should not be the major section of your report) Provide an account of the procedure followed to complete the experiments reported. - Please do not include every bit of information, but only include what is necessary for someone recreating the experiment should know. - No bullet points or numbering. Use complete sentences with subsections if possible. - No copy and paste from the lab manual  Lab report guideline : announced ‘Guideline for BIOL110 Lab Report’. please check your email or Canvas, Announcement for more detail. Results (more than 200 words; include result figures here) – main section Report your findings in a clear, interesting, and organized fashion. Your results will contain a “story” you would like to present. You may divide the results into multiple subsections. Think logically about the results and information needs to be included in which order. Please include at least three figures. Using visuals can be very effective in communicating data, but a figure should not standalone and must be explained in the text. A figure may contain multiple panels. All figures must have a descriptive title and a brief paragraph explaining the figure, i.e., figure legend, to guide the reader. The figure legends should not be included in the word count. A table may be used instead of a figure. Discussion (more than 200 words) – main section Please include your hypothesis and a brief explanation of the expected results. Reiterate your results, but rather than simply repeating your findings, discuss the results in the context of the overall goal. Discuss how your actual data related to your hypothesis. Provide explanations for unexpected results and briefly explain potential modifications for the next experiment and/or possible ways to test your ideas for unexpected results. In addition, you can add a statement of future directions based on your results. References (required) Include any (but only) the articles, books, lab manuals, website, etc. that you used when writing your report. Concepts today: Chapter 7. Cell Structure and Function 7.1: Biologists use microscopes and the tools of biochemistry to study cells 7.2: Eukaryotic cells have internal membranes that compartmentalize their functions 7.3: The eukaryotic cell’s genetic instructions are housed in the nucleus 7.4: The endomembrane system regulates protein traffic and performs metabolic functions in the cell 7.5: Mitochondria and chloroplasts change energy from one form to another  Concept 7.1: Biologists use microscopes and the tools of biochemistry to study cells ▪ Cells are usually too small to be seen by the naked eye ▪ Microscopes are used to visualize cells ▪ light microscope (LM) creating a magnified image through the use of a series of glass lenses, which focus a beam of light through an object.  Light Microscope (LM) Electron microscopy Super- Light microscopy resolution microscopy Unaided eye Nucleus Length Most Smallest Small of some Most bacteria bacteria Proteins molecules nerve plant Viruses and and Human muscle Chicken Frog Human animal Mito- Ribo- height cells egg egg egg cells chondrion somes Lipids Atoms 10 m 1m 0.1 m 1 cm 1 mm 100 μm 10 μm 1 μm 100 nm 10 nm 1 nm 0.1 nm © 2018 Pearson Education Ltd.  Electron Microscopes (EMs) ▪ The resolution of standard light microscopy is too low to study organelles, the membrane-enclosed structures in eukaryotic cells ▪ Two basic types of electron microscopes (EMs) are used to study subcellular structures ▪ Scanning electron microscopes (SEMs) ▪ Transmission electron microscopes (TEMs)  Electron Microscopes (EMs) Scanning electron microscopes Transmission electron microscopes (SEMs) (TEMs) - to study the outside of surface - to study the internal structure of cells  How to determine the functions of organelles? : Cell Fractionation ▪ Cell fractionation takes cells apart and separates the major organelles from one another ▪ Centrifuges fractionate cells into their component parts ▪ Cell fractionation enables scientists to determine the functions of organelles Centrifugation by density  Differential centrifugation Homogenization Tissue cells Homogenate Centrifugation 1,000 g Supernatant poured into next tube 10 min 20,000 g 20 min 80,000 g Pellet rich in 60 min nuclei and cellular debris 150,000 g 3 hr Pellet rich in mitochondria (and chloroplasts) Pellet rich in “microsomes” Pellet rich in © 2018 Pearson Education Ltd. ribosomes  Concept 7.2: Eukaryotic cells have internal membranes that compartmentalize their functions ▪ The basic structural and functional unit of every organism is one of two types of cells: prokaryotic or eukaryotic ▪ Only organisms of the domains Bacteria and Archaea consist of prokaryotic cells ▪ Protists, fungi, animals, and plants all consist of eukaryotic cells  A Panoramic View of the Eukaryotic Cell ▪ A eukaryotic cell has internal membranes that divide the cell into compartments—the organelles (subcelluar organelles) ▪ The basic fabric of biological membranes is a double layer of phospholipids and other lipids ▪ Plant and animal cells have most of the same organelles Figure 7.8a ENDOPLASMIC RETICULUM (ER) Animal cell Rough ER Smooth ER Nuclear envelope Nucleolus NUCLEUS Flagellum Chromatin Centrosome Plasma membrane CYTOSKELETON: Microfilaments Intermediate filaments Microtubules Ribosomes Microvilli Golgi apparatus Peroxisome Lysosome Mitochondrion © 2018 Pearson Education Ltd. Figure 7.8b Nuclear NUCLEUS envelope Plant cell Nucleolus Rough ER Chromatin Smooth ER Ribosomes Golgi Central vacuole apparatus Microfilaments CYTOSKELETON Microtubules Mitochondrion Peroxisome Plasma membrane Chloroplast Cell wall Plasmodesmata Wall of adjacent cell © 2018 Pearson Education Ltd. Concept 7.3: The eukaryotic cell’s genetic instructions are housed in the nucleus and carried out by the ribosomes ▪ The nucleus contains most of the DNA in a eukaryotic cell ▪ Messenger RNA (mRNA) is transcribed from DNA as a template. ▪ Ribosomes use the information from mRNA to make proteins The Nucleus: Information Central ▪ The nucleus contains most of the cell’s genes and is usually the most clearly visible organelle under LM ▪ The nuclear envelope encloses the nucleus, separating it from the cytoplasm ▪ The nuclear envelope is a double membrane; each membrane consists of a lipid bilayer The Nucleus: Information Central ▪ Pores, lined with a structure called a pore complex, regulate the entry and exit of molecules from the nucleus ▪ The nuclear size of the envelope is lined by the nuclear lamina, which is composed of proteins and maintains the shape of the nucleus The Nucleus: Information Central ▪ In the nucleus, DNA is organized into discrete units called chromosomes ▪ Each chromosome contains one DNA molecule associated with proteins, called chromatin ▪ Chromatin condenses to form discrete chromosomes as a cell prepares to divide ▪ The nucleolus is located within the nucleus and is the site of ribosomal RNA (rRNA) synthesis Ribosomes: Protein Factories ▪ Ribosomes are complexes made of ribosomal RNA and protein ▪ Ribosomes carry out protein synthesis in two locations: ▪ In the cytosol (free ribosomes) ▪ On the outside of the endoplasmic reticulum or the nuclear envelope (bound ribosomes)  Concept 7.4: The endomembrane system regulates protein traffic and performs metabolic functions in the cell ▪ The endomembrane system consists of ▪ Nuclear envelope ▪ Endoplasmic reticulum (ER) ▪ Golgi apparatus ▪ Lysosomes ▪ Vacuoles ▪ Plasma membrane ▪ These components are either continuous or connected via transfer by vesicles  The Endoplasmic Reticulum: Biosynthetic Factory ▪ The endoplasmic reticulum (ER) accounts for more than half of the total membrane in many eukaryotic Smooth ER cells Rough ER Nuclear envelope ▪ The ER membrane is continuous with the nuclear envelope ▪ There are two distinct regions of ER: ▪ Smooth ER, which lacks ribosomes ER lumen Cisternae ▪ Rough ER, whose surface is Ribosomes Transitional Transport vesicle ER studded with ribosomes Functions of Smooth ER ▪ The smooth ER ▪ Synthesizes lipids Smooth ER ▪ Metabolizes carbohydrates Rough ER Nuclear ▪ Detoxifies drugs and poisons envelope ▪ Stores calcium ions ER lumen Cisternae Ribosomes Transitional ER Transport vesicle Functions of Rough ER ▪ The rough ER ▪ Has bound ribosomes, which secrete glycoproteins (proteins Smooth ER covalently bonded to Nuclear carbohydrates) Rough ER envelope ▪ Distributes transport vesicles, secretory proteins surrounded by membranes ER lumen ▪ Is a membrane factory for the cell Cisternae Ribosomes Transitional ER Transport vesicle  The Golgi Apparatus: Shipping and Receiving Center Golgi apparatus cis face ▪ The Golgi apparatus consists of (“receiving” flattened membranous sacs called side from ER) Cisternae cisternae ▪ The Golgi apparatus ▪ Modifies products of the ER ▪ Manufactures certain macromolecules ▪ Sorts and packages materials into trans face (“shipping” side of transport vesicles Golgi apparatus)  Nucleus 1 μm Lysosomes: Digestive Compartments ▪ A lysosome contains hydrolytic enzymes that can digest macromolecules ▪ Hydrolytic enzymes and lysosomal membranes are made by rough ER Lysosome and then transferred to the Golgi apparatus for further processing Digestive enzymes ▪ Phagocytosis is a process by Lysosome which cells engulf various large Plasma materials from outside of the cell. membrane Digestion (a) © 2018Phagocytosis Pearson Education Ltd.  Vesicle containing two 1 μm Lysosomes: Digestive damaged organelles Compartments Mitochondrion fragment Peroxisome fragment ▪ Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy Lysosome Peroxisome Mitochondrion Digestion Vesicle (b) Autophagy  Vesicle containing two 1 μm damaged organelles Peroxisomes: Oxidation Mitochondrion fragment Peroxisome fragment ▪ Peroxisomes are specialized metabolic compartments bounded by a single membrane layer Lysosome ▪ Peroxisomes are involved in Peroxisome detoxification of oxidative stress. e.g. free radicals ; single unpaired electron in Mitochondrion Digestion Vesicle valence electron. (b) Autophagy Vacuoles: Diverse Maintenance Compartments Central vacuole ▪ Vacuoles are large vesicles derived from the ER and Cytosol Golgi apparatus ▪ Contractile vacuoles, found in many freshwater protists, Central pump excess water out of Nucleus vacuole cells Cell wall ▪ Central vacuoles, found in Chloroplast many mature plant cells, hold 5 μm organic compounds and water Concept 7.5: Mitochondria and chloroplasts change energy from one form to another ▪ Mitochondria are the sites of cellular respiration, a metabolic process to generate ATP ▪ Chloroplasts, found in plants and algae, are the sites of photosynthesis  Mitochondria: Chemical Energy Conversion ▪ Mitochondria are found in nearly all eukaryotic cells Mitochondrion ▪ They have a smooth outer membrane and Intermembrane space Outer an inner membrane folded into cristae membrane ▪ The inner membrane creates two DNA compartments: intermembrane space and Free Inner mitochondrial matrix membrane ribosomes in the Cristae ▪ Some metabolic steps of cellular mitochondrial Matrix matrix 0.1 μm respiration are catalyzed in the (a) Diagram and TEM of mitochondrion mitochondrial matrix ▪ Cristae present a large surface area for enzymes that synthesize ATP Chloroplasts: Capture of Light Energy Stroma Ribosomes Inner and outer membranes Granum DNA Thylakoid Intermembrane space 1 μm (a) Diagram and TEM of chloroplast ▪ Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis ▪ Chloroplasts are found in leaves and other green organs of plants and in algae Chloroplasts: Capture of Light Energy Stroma Ribosomes Inner and outer membranes Granum DNA Thylakoid Intermembrane space 1 μm (a) Diagram and TEM of chloroplast Chloroplast structure includes - Thylakoids, membranous sacs, stacked to form a granum - Stroma, the internal fluid The chloroplast is one of a group of plant organelles, called plastids  The Evolutionary Origins of Mitochondria and Chloroplasts ▪ Mitochondria and chloroplasts have similarities with bacteria: ▪ Enveloped by a double membrane ▪ Contain free ribosomes and circular DNA molecules ▪ Grow and reproduce somewhat independently in cells ▪ These similarities led to the endosymbiosis Endoplasmic Nucleus reticulum Nuclear ▪ The endosymbiosis suggests envelope Engulfing of oxygen- that an early ancestor of using nonphotosynthetic prokaryote, which eukaryotes engulfed an oxygen- becomes a mitochondrion using nonphotosynthetic Ancestor of prokaryotic cell eukaryotic cells (host cell) ▪ The engulfed cell formed a Engulfing of Mitochondrion relationship with the host cell, photosynthetic becoming an endosymbiont prokaryote Chloroplast At least ▪ The endosymbionts evolved into Mitochondrion one cell Nonphotosynthetic mitochondria eukaryote ▪ At least one of these cells may have then taken up a photosynthetic prokaryote, which evolved into a chloroplast Photosynthetic eukaryote  Prokaryotes vs Eukaryotes Prokaryotes Eukaryotes Type of Cell Always unicellular Unicellular and multi-cellular Cell membrane Double membranes (inner membrane Single membrane and outer membrane) Cell size Ranges in size from 0.2 μm – 2.0 μm in Size ranges from 10 μm – 100 μm in diameter diameter Cell wall Usually present; chemically complex in Usually absent, but when present, nature chemically simple in nature Nucleus Absent. Instead, they have a nucleoid Present region in the cell Ribosomes Present. Smaller in size Present. Comparatively larger in size DNA arrangement Circular Linear Mitochondria Absent Present Cytoplasm Present, but cell organelles absent Present, cell organelles present Endoplasmic reticulum Absent Present Lysosome absent present Cell division Through binary fission Through mitosis Reproduction Asexual Both asexual and sexual Example Bacteria and Archaea Plant and Animal cell  Think-Pair-Share Question: Insulin is a hormonal protein secreted by the pancreas to decrease high blood sugar. Let’s assume that you start monitoring subcelluar localizations of insulin from the DNA in a single cell. Please indicate subcelluar organelles that Insulins can travel from the beginning to the end inside of the cell in the order of time and explain each step briefly. Step 1. Insulin-encoding DNA makes its corresponding mRNA in Nucleus. Step 2. Insulin mRNA is released through nuclear pores (please add additional steps here) Step 3…. Step 4….... Final step: Insulin reaches blood vessels and starts decreasing high blood sugar High Insulin Normal blood sugar secreted blood sugar Reading Assignment: Chapter 8.