Science 7 Unit 7: Introduction to Cells PDF
Document Details
Uploaded by MesmerizingSuccess4954
Tags
Summary
This is a study guide for Science 7, Unit 7: Introduction to Cells, Lesson 1. It covers cellular structure and observation, with learning competencies, learning targets, knowledge kickstarter, warm-up activities and questions.
Full Transcript
Science 7 Unit 7: Introduction to Cells esson 1 L ellular Structure and Observation C Table of Contents Introduction...
Science 7 Unit 7: Introduction to Cells esson 1 L ellular Structure and Observation C Table of Contents Introduction 1 Learning Competency 2 Learning Targets 2 Knowledge Kickstarter 2 Warm-Up 4 Learn about It 8 Types of Cells 10 Cellular Structures and Functions 11 Key Points 14 Check Your Understanding 15 Self Assessment 16 Reflection 16 References 17 Answer Key 18 0 Science 7 Unit 7: Introduction to Cells 1 Cellular Structure and Observation Figure 1. An onion peel stained and viewed under the microscope Introduction Haveyoueverwonderedwhatyouaremadeof?Cellsarethetinybuildingblocksof alllivingthings.Theyaresosmallthatyouneedamicroscopetoseethem!Imagine abustlingcity,withdifferentpartsworkingtogether—thatislikeacell!Fromthetiny bacteria to the leaves on trees, cells are everywhere and crucial to life. 7.1.Cellular Structure and Observation 1 Science 7 Unit 7: Introduction to Cells Learning Competency Attheendofthislesson,thelearnersshouldbeabletousepropertechniquesinobserving and identifying the parts of a cell with a microscope, such as the cell membrane,nucleus, cytoplasm, mitochondria, chloroplasts, and ribosomes. Learning Targets In this lesson, you should be able to do the following: Observe and identify key parts of a cell. Utilize a microscope for detailed observation. Knowledge Kickstarter Choose the best answer for each question. Write the letter of the correct answer before the number. _______1. Who first discovered the existence of cells in 1665? A. Isaac Newton B. Antonie van Leeuwenhoek C. Robert Hooke D. Marie Curie _______2. Which of the following statements is a fundamental principle of cell theory? A. Cells are the basic units of life. B. Cells can only be seen with a microscope. C. Only animal cells are important. D. Cells do not divide. 7.1.Cellular Structure and Observation 2 Science 7 Unit 7: Introduction to Cells _______3. Where is DNA primarily located in a cell? A. cell wall B. Golgi apparatus C. nucleus D. cytoplasm _______4. What would happen if the cell membrane was damaged? A. increased energy production B. decreased cell growth C. improved DNA replication D. uncontrolled substance entry and exit _______5. What would the mitochondria represent if you compared a cell to a city? A. city hall B. power plant C. public library D. roads _______6. In a real-life scenario, how does being knowledgeable about cells help doctors? A. designing buildings B. creating medicines C. teaching history D. programming computers _______7. What role does the nucleus play in a cell? A. It generates energy. B. It stores genetic information. C. It produces proteins. D. It digests food. 7.1.Cellular Structure and Observation 3 Science 7 Unit 7: Introduction to Cells _______8. Evaluate the role of organelles. Which isnotfoundin prokaryotic cells? A. DNA B. mitochondria C. ribosomes D. cytoplasm _______9. Which process would be most affected in analyzing cell functions if the Golgi apparatus was removed? A. energy production B. nutrient transport C. protein modification D. waste removal _______10. When evaluating cell sizes, why are smaller cells more efficient? A. They have more DNA. B. They reproduce faster. C. They have a higher surface area-to-volume ratio. D. They consume less energy. Warm-Up Tiny Cell Experiment Materials gelatin powder a ruler food coloring a sharp knife salt measuring spoon a shallow baking dish or tray 7.1.Cellular Structure and Observation 4 Science 7 Unit 7: Introduction to Cells Procedure 1. Prepare the gelatin in the shallow dish according to package instructions, adding a few drops of food coloring. 2. Once set, use the ruler and knife to cut the gelatin into cubes of different sizes (e.g., 1 cm, 2 cm, and 3 cm on each side). 3. Place the cubes on a flat surface. 4. Sprinkle the same amount of salt on each cube. 5. Start a timer and observe the changesovertime(e.g.,at5-minuteintervals for up to 30 minutes). 6. Recordhowthesaltaffectseachcubesize,focusingontherateofshrinkage or any other changes. 7. Here is how to compute the gelatin cubes’ surface area, volume, and their ratio: a. Surfacearea:Tocalculatethesurfaceareaofacube,usetheformula: surface area = 6 × (side length)². This means you first multiply the length of one side of the cube by itself. Then, multiplythisby6.For example,ifacube’ssideis6cmlong,itssurfaceareais6×(6cm)²= 216 cm². b. Volume:Tocalculatethevolumeofacube,usetheformula:volume= (side length)³. This means you multiply the length of one sideofthe cubebyitselfthreetimes.Forexample,ifacube’ssideis6cmlong,its volume is (6 cm)³ = 216 cm³. c. Ratio: To find the surface area to volume ratio, simply divide the surface area by the volume. For instance, if the surface area is 216 cm² and the volume is 216 cm³, the ratio is 216 cm² / 216 cm³ = 1:1. 7.1.Cellular Structure and Observation 5 Science 7 Unit 7: Introduction to Cells Observation Table Table 1.Cell size simulation: surface area to volumeratio in gelatin cubes 1 cm cube 2 cm cube 3 cm cube Surface Area (cm²) Volume (cm³) Surface Area to Volume Ratio Initial Observation Observation after 5 min Observation after 10 min Observation after 15 min Guide Questions 1. Which gelatin cubes showed a more noticeable reaction to the salt? Consider the surface area to volume ratio in your answer. 7.1.Cellular Structure and Observation 6 Science 7 Unit 7: Introduction to Cells 2. Howdoesthisexperimenthelpusunderstandtheimportanceofcellsizeinrelation to their function in living organisms? 3. Ifcellswerelarger,howmighttheirabilitytoabsorbnutrientsandremovewastebe affected? Relate this to your observations of the gelatin cubes of different sizes. Essential uestion Q How does the surface area to volume ratio of a cell influence its efficiency in performing vital functions, and what might be the implications for larger or smaller organisms? 7.1.Cellular Structure and Observation 7 Science 7 Unit 7: Introduction to Cells Learn about It Cells, the basic units oflife,werefirstobservedbyRobertHookein1665.Heuseda compound microscope to look at thin slicesofcork,adriedpartofsomeplants.He saw tiny rectangular spaces in the cork. Not only that, but he compared these to a monk’scellularroomandcalledthesestructures,cells.Thisgroundbreakingdiscovery led to the development of cell theory, which is central to our understanding of biology. Cell theory includes three important points: All living things are made up of cells. Cells are the smallest units of life. New cells come from pre-existing cells through cell division. Thistheoryhighlightstheimportanceofcellsinallorganisms'structure,function,and reproduction. Figure 2. Development of cell theory Do you know why cells are small? Let us consider how a scentspreadsinroomsof different sizes. Imagine you light a scented candle in a small room. You will notice 7.1.Cellular Structure and Observation 8 Science 7 Unit 7: Introduction to Cells that the scent fills the space quickly, enveloping theroominapleasantaroma.This happensbecause,inasmallerspace,scentparticleshavelessareatotravel,allowing them to diffuse rapidly. Conversely, if you light the same candle in a much larger room, the scent will take significantlylongertobenoticeableacrosstheentirearea.Thisisduetothelargerair volume that the scent particles must move through, making the diffusion process slower. Thisprincipleofdiffusionindifferentspacesdirectlytiesintowhycellsaresmalland why surface area to volume ratio is important. As demonstrated in our "Tiny Cell Experiment," smaller gelatin cubes, representing cells, reacted more quickly to salt duetotheirlargersurfacearearelativetotheirvolume.Thisexperimenthighlightsa crucialbiologicalconcept:smallcellshaveahighersurfaceareatovolumeratio.This makes them more efficient in transporting nutrients and wastematerials.Similarto how the scent diffuses more quickly in a small room, small cells can exchange substances more rapidly and efficiently. This illustrates the practical implications of cell size on their function. Figure 3. Smaller objects have high surface area to volume ratio as compared to larger objects. 7.1.Cellular Structure and Observation 9 Science 7 Unit 7: Introduction to Cells Types of Cells Prokaryotic and eukaryotic cells are the two primary types of cells that make up all living organisms. The key difference between them lies in theirstructuralcomplexity and organization. The term prokaryotic is derived from Greek, where pro means "before" and karyon means "nut" or "kernel," referring to the nucleus. Prokaryotic cells, therefore, are cellsthatlackatruenucleus.Thesecellsaregenerallysmallerandsimplerinstructure. They are commonly found in bacteria and archaea. Their genetic material is not enclosedwithinamembrane-boundnucleus;instead,itistypicallyinasingle,circular strand of DNA located in an area of the cell called thenucleoid. Incontrast,eukaryotic,alsooriginatingfromGreek,whereeumeans"true,"andkaryon againreferstothenucleus.Itdescribescellswithatruenucleusenclosedbyanuclear membrane. Eukaryotic cells are more complex and are typically larger than prokaryotic cells. They comprise various organisms, including animals, plants, fungi, and protists. Besides the distinct nucleus, eukaryotic cells also have other membrane-boundorganelleslikemitochondriaandchloroplasts(inplants),whichare absent in prokaryotes. This advanced compartmentalization allows for more specialized functions within the cell. Figure 4. Difference between prokaryotic and eukaryotic cells 7.1.Cellular Structure and Observation 10 Science 7 Unit 7: Introduction to Cells Cellular Structures and Functions Figure 5. Parts of animal (top) and plant (bottom) cell 7.1.Cellular Structure and Observation 11 Science 7 Unit 7: Introduction to Cells Table 2 offers a comprehensive overview of cellular components, called organelles, and their distinct functions within the cell. This table categorizes these organelles based on their location (exterior, interior, and endomembrane systems). The exterior group includes structures like the cell membrane and cell wall, which interact with the cell's external environment, protection,andmovement.Theinterior group, encompassing the cytoplasm, nucleus, ribosomes, centrioles, mitochondria, and chloroplasts, includes components that manage cellular processes like energy production, genetic material storage, and protein synthesis. Lastly, the endomembranesystem,comprisingtheendoplasmicreticulum,Golgiapparatus/body, lysosomes, and vacuoles, is involved in the synthesis, modification, and transport of cellular materials and waste processing. This categorization provides an organized framework to understand how each part contributes to the cell's overall function. It illustrates the remarkablecomplexityand coordinationwithineventhesmallestunitoflife.Thetablealsodescribeseachandits function and presence in different cell types (prokaryotic, eukaryotic,andspecifically within plant or animal cells). This tabular presentation is an invaluable resource for understanding the complexity and diversity of cellular functions and how these components work in harmony to maintain the cell's life processes. Table 2.Parts of the cell Present in Specific to Organelle/ Description Function Prokaryotic/ Plant/ Structure Eukaryotic Animal/ Both controls entry and protective outer exit of nutrients cell membrane both both layer and minerals in the cell eukaryotic (plant), provides support cell wall rigid outer layer prokaryotic plant and protection (some) 7.1.Cellular Structure and Observation 12 Science 7 Unit 7: Introduction to Cells Present in Specific to Organelle/ Description Function Prokaryotic/ Plant/ Structure Eukaryotic Animal/ Both gel-like site for chemical cytoplasm substance inside both both reactions the cell contains the controls cell nucleus cell's genetic eukaryotic both activities material (DNA) site of protein synthesizes ribosomes both both synthesis proteins eukaryotic cylindrical involved in cell centrioles (mostly animal animal structures division cells) powerhouse of produces energy mitochondria eukaryotic both the cell (ATP) endoplasmic network of synthesizes eukaryotic both reticulum membranes proteins and lipids stacks of modifies, sorts, Golgi apparatus/ flattened and packages eukaryotic both body membranes proteins contain break down waste lysosomes digestive eukaryotic mostly animal and cell debris enzymes contain convert solar chloroplasts chlorophyll for energy to eukaryotic plant photosynthesis chemical energy 7.1.Cellular Structure and Observation 13 Science 7 Unit 7: Introduction to Cells Present in Specific to Organelle/ Description Function Prokaryotic/ Plant/ Structure Eukaryotic Animal/ Both storage, waste both (large large fluid-filled vacuole disposal, growth, central vacuole in both sac and protection plants) Did You Know? The largest cell in the world is the ostrich egg, while the smallest is theMycoplasma genitalium, a type of bacteria. Key Points Cellsare the basic units of life, discovered by RobertHooke in 1665. Cell theorystates that all living things are madeof cells, cells are the smallest units of life, and new cells come from existing cells. Cells have ahigh surface area-to-volume ratio, makingthem efficient in transporting nutrients and waste. There are two main types of cells:prokaryotic(likebacteria, without a nucleus) and eukaryotic(like plant and animal cells, with a nucleus). Cells have different parts, calledorganelles, eachwith its own function. 7.1.Cellular Structure and Observation 14 Science 7 Unit 7: Introduction to Cells Check Your Understanding Match the terms on the left with their correct description on the right. Draw a line connecting each term to its description. Column A Column B _______1. Robert Hooke A. the largest cell in the world _______2. cell theory B. discovered cells in 1665 _______3. prokaryotic cells C. controls entry and exitofsubstancesin _______4. eukaryotic cells cells _______5. cell membrane D. the powerhouse of the cell, producing _______6. mitochondria energy _______7. nucleus E. stores and protects the cell's genetic _______8. cytoplasm material _______9. endoplasmic F. jelly-like substance that holds cell parts reticulum in place _______10. Golgi apparatus G. involved in protein and lipid synthesis _______11. surface area to H. modifies and transports proteins volume ratio I. explains the importance of cells being _______12. DNA small _______13. ostrich egg J. genetic material found in cells _______14. chloroplast K. cells without a nucleus _______15. cell size efficiency L. cells with a nucleus and organelles M. involved in photosynthesis N. describes that alllivingthingsaremade of cells O. demonstrates how cell size affects function 7.1.Cellular Structure and Observation 15 Science 7 Unit 7: Introduction to Cells Self Assessment I think I need I have a minimal I am confident Skills more time and understanding of that I can do this assistance. it. with ease. I can observe and identify key parts of a cell. I can utilize a microscope for detailed observation. Reflection I find______________________the most interestingbecause________________________________. I need to improve on________________________because___________________________________. I need to practice_________________________because______________________________________. I plan to___________________________________________________________________________________. 7.1.Cellular Structure and Observation 16 Science 7 Unit 7: Introduction to Cells References Alberts, Bruce, Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts, and Peter Walter. 2015. Molecular Biology of the Cell. 6th ed. New York: GarlandScience. Campbell, Neil A., and Jane B. Reece. 2015.Biology.10th ed. Boston: Pearson. Lodish, Harvey, Arnold Berk, Chris A. Kaiser, Monty Krieger, Anthony Bretscher, Hidde Ploegh, Angelika Amon, and MatthewP.Scott.2016.MolecularCellBiology.8thed.NewYork:W.H. Freeman. 7.1.Cellular Structure and Observation 17 Science 7 7.1. Cellular Structure and Observation Answer Key Knowledge Kickstarter 1. C. Robert Hooke 6. B. creating medicines 2. A. Cells are the basic units of life. 7. B. It stores genetic information. 3. C. nucleus 8. B. mitochondria 4. D. uncontrolled substance entry 9. C. protein modification and exit 10. C. They have a higher surface 5. B. power plant area-to-volume ratio Warm-Up 1. Which gelatin cubes showed a more noticeable reaction to the salt? Consider the surface area to volume ratio in your answer. Thesmallergelatincubesshowedamorenoticeablereactiontothesaltbecause theyhaveahighersurfacearea-to-volumeratio.Thismeansalargerproportionof the cube's volume is exposed to salt, leading to more efficient water loss and shrinkage. In larger cubes, less surface area is exposed relative totheirvolume, slowing down the process. 2. Howdoesthisexperimenthelpusunderstandtheimportanceofcellsizeinrelation to their function in living organisms? Thisexperimentillustratestheimportanceofcellsizeinrelationtotheirfunction. Cells are small to maximize their surface area relative to their volume, allowing efficient exchange of materials like nutrients and waste. If the cells were larger, this exchange would be less efficient, similar to how the larger gelatin cubes showed less reaction to the salt. 7.1.Cellular Structure and Observation 18 Science 7 7.1. Cellular Structure and Observation 3. Ifcellswerelarger,howmighttheirabilitytoabsorbnutrientsandremovewastebe affected? Relate this to your observations of the gelatin cubes of different sizes. If cells were larger, their ability to absorb nutrientsandremovewastewouldbe less efficient. This is because larger cells would have a smaller surface area relative to their volume, making the exchange of materials slower and less effective.Intheexperiment,thelargergelatincubesshrunklessthanthesmaller ones, demonstrating how size affects the rate of material exchange. Check Your Understanding 1. B 2. N 3. K 4. L 5. C 6. D 7. E 8. F 9. G 10. H 11. I 12. J 13. A 14. M 15. O 7.1.Cellular Structure and Observation 19
