Cell Structure (Topic A2.2)

Essential Idea(s): Cells are the smallest functional unit of living organisms, and come with a wide range of shapes, sizes, and functionalities.

Unit Length: 3 Lessons (+2 AHL)

Guiding Questions

◊ What are the features common to all cells and the features that differ?

◊ How is microscopy used to investigate cell structure?

Materials:

Self-Teaching Slides (SL) / Self-Teaching Slides (AHL)	Quizlet Vocab Set (SL and HL)
Teaching Slides (SL) / Teaching Slides (AHL)	Notes Template (SL) / Notes Template (AHL)

IB Statement(s) and Objective(s)
A2.2.1: Cells as the basic structural unit of all living organisms State the three parts of the cell theory NOS Concept: Deductive reason can be used to generate predictions from theories A2.2.2: Microscopy skills Define micrograph Label the parts of a light microscope Demonstrate how to focus the microscope on a sample Define magnification Given the magnification of the ocular and objective lenses, calculate the total microscope magnification Measure the field of view diameter of a microscope under low power. Calculate the field of view diameter of a microscope under medium or high power Estimate the size of a sample in the microscope field of view Use a formula to calculate the magnification of a micrograph or drawing A2.2.3: Developments in microscopy Define resolution Compare the functionality of light and electron microscopes Outline the process of producing images of cell surfaces using freeze-fracture electron microscopy Define fluorescence Describe the use of fluorescence in microscopy Outline immunofluorescence and its uses in biology research Outline the use of cryogenic electron microscopy Give one example of microscopy demonstrating the concept “technology begets discovery” A2.2.4: Structures common to cells in all living organisms Outline the function of structures that are common to all cells A2.2.5: Prokaryote cell structure State the two primary types of cells found in living organisms Outline the major differences between prokaryotic and eukaryotic cells List the functions of the following structures of a prokaryotic cell: cell wall, plasma membrane, cytoplasm, naked DNA and 70S ribosomes Define “extracellular” Contrast the size of eukaryotic and prokaryotic ribosomes Describe the structure and function of nucleoid DNA Compare the genetic material of prokaryotes and eukaryotes Outline the structural diversity of prokaryotes A2.2.6: Eukaryote cell structure State the meaning and advantages of eukaryotic cells being “compartmentalized” Outline the function of the following structures in the eukaryotic cell: plasma membrane, cytoplasm, 80s ribosomes, nucleus, mitochondria, chloroplast, endoplasmic reticulum, Golgi apparatus, vesicles, vacuoles, lysosomes, cytoskeleton of microtubules and microfilaments A2.2.7: Processes of life in unicellular organisms Discuss the differences between something that is living and something that is non-living Outline the 7 functional features of life A2.2.8: Differences in eukaryotic cell structure between animals, fungi and plants Compare and contrast the structures of plant, animal and fungal cells, with reference to cell walls, vacuoles, chloroplasts, centrioles, cilia and flagella Describe the function of plastids A2.2.9: Atypical cell structure in eukaryotes Give 3 examples of atypical cell structures in eukaryote cells Describe features of skeletal muscle fibers that make them an atypical cell Describe features of aseptate fungal hyphae that make them an atypical cell Describe features of red blood cells that make them an atypical cell Describe features of phloem sieve tube elements that make them atypical cells A2.2.10: Cell types and cell structures viewed in light and electron micrographs Define micrograph Recognize features and identify structures in micrographs of prokaryotic cells, inclusive of the plasma membrane, nucleoid region, ribosomes and cell wall. Recognize features and identify structures in micrographs of eukaryotic cells, inclusive of the plasma membrane, nucleus, mitochondrion, chloroplast, vacuole, rough and smooth endoplasmic reticulum, Golgi apparatus, secretory vesicle, ribosomes, cell wall, cilia, flagella and microvilli A2.2.11: Drawing and annotation based on electron micrographs Demonstrate how to draw cell structures seen with a microscope using sharp, carefully joined lines and straight edge lines for labels
Additional Higher Level Topics A2.2.12: Origin of eukaryotic cells by endosymbiosis State the endosymbiosis theory Outline the major events in the origin of eukaryotic cells Describe the evidence for the endosymbiotic theory NOS Concept: The strength of a theory comes from the observations it can explain and the predictions it supports Explain why endosymbiosis can be regarded as a valid scientific theory A2.2.13: Cell differentiation as the process for developing specialized tissues in multicellular organisms Define tissue, organ, organ system, and organism Define differentiation Describe the relationship between cell differentiation and gene expression Outline two examples of environmental influence on gene expression A2.2.14: Evolution of multicellularity Contrast multicellular organisms to unicellular organisms State 2 kingdoms with both unicellular and multicellular organisms State that multicellularity has evolved repeatedly Outline the steps in the evolution of multicellularity

IB Statement(s) and Objective(s)

A2.2.1: Cells as the basic structural unit of all living organisms

State the three parts of the cell theory
NOS Concept: Deductive reason can be used to generate predictions from theories

A2.2.2: Microscopy skills

Define micrograph
Label the parts of a light microscope
Demonstrate how to focus the microscope on a sample
Define magnification
Given the magnification of the ocular and objective lenses, calculate the total microscope magnification
Measure the field of view diameter of a microscope under low power.
Calculate the field of view diameter of a microscope under medium or high power
Estimate the size of a sample in the microscope field of view
Use a formula to calculate the magnification of a micrograph or drawing

A2.2.3: Developments in microscopy

Define resolution
Compare the functionality of light and electron microscopes
Outline the process of producing images of cell surfaces using freeze-fracture electron microscopy
Define fluorescence
Describe the use of fluorescence in microscopy
Outline immunofluorescence and its uses in biology research
Outline the use of cryogenic electron microscopy
Give one example of microscopy demonstrating the concept “technology begets discovery”

A2.2.4: Structures common to cells in all living organisms

Outline the function of structures that are common to all cells

A2.2.5: Prokaryote cell structure

State the two primary types of cells found in living organisms
Outline the major differences between prokaryotic and eukaryotic cells
List the functions of the following structures of a prokaryotic cell: cell wall, plasma membrane, cytoplasm, naked DNA and 70S ribosomes
Define “extracellular”
Contrast the size of eukaryotic and prokaryotic ribosomes
Describe the structure and function of nucleoid DNA
Compare the genetic material of prokaryotes and eukaryotes
Outline the structural diversity of prokaryotes

A2.2.6: Eukaryote cell structure

State the meaning and advantages of eukaryotic cells being “compartmentalized”
Outline the function of the following structures in the eukaryotic cell: plasma membrane, cytoplasm, 80s ribosomes, nucleus, mitochondria, chloroplast, endoplasmic reticulum, Golgi apparatus, vesicles, vacuoles, lysosomes, cytoskeleton of microtubules and microfilaments

A2.2.7: Processes of life in unicellular organisms

Discuss the differences between something that is living and something that is non-living
Outline the 7 functional features of life

A2.2.8: Differences in eukaryotic cell structure between animals, fungi and plants

Compare and contrast the structures of plant, animal and fungal cells, with reference to cell walls, vacuoles, chloroplasts, centrioles, cilia and flagella
Describe the function of plastids

A2.2.9: Atypical cell structure in eukaryotes

Give 3 examples of atypical cell structures in eukaryote cells
Describe features of skeletal muscle fibers that make them an atypical cell
Describe features of aseptate fungal hyphae that make them an atypical cell
Describe features of red blood cells that make them an atypical cell
Describe features of phloem sieve tube elements that make them atypical cells

A2.2.10: Cell types and cell structures viewed in light and electron micrographs

Define micrograph
Recognize features and identify structures in micrographs of prokaryotic cells, inclusive of the plasma membrane, nucleoid region, ribosomes and cell wall.
Recognize features and identify structures in micrographs of eukaryotic cells, inclusive of the plasma membrane, nucleus, mitochondrion, chloroplast, vacuole, rough and smooth endoplasmic reticulum, Golgi apparatus, secretory vesicle, ribosomes, cell wall, cilia, flagella and microvilli

A2.2.11: Drawing and annotation based on electron micrographs

Demonstrate how to draw cell structures seen with a microscope using sharp, carefully joined lines and straight edge lines for labels

Additional Higher Level Topics

A2.2.12: Origin of eukaryotic cells by endosymbiosis

State the endosymbiosis theory
Outline the major events in the origin of eukaryotic cells
Describe the evidence for the endosymbiotic theory
NOS Concept: The strength of a theory comes from the observations it can explain and the predictions it supports
Explain why endosymbiosis can be regarded as a valid scientific theory

A2.2.13: Cell differentiation as the process for developing specialized tissues in multicellular organisms

Define tissue, organ, organ system, and organism
Define differentiation
Describe the relationship between cell differentiation and gene expression
Outline two examples of environmental influence on gene expression

A2.2.14: Evolution of multicellularity

Contrast multicellular organisms to unicellular organisms
State 2 kingdoms with both unicellular and multicellular organisms
State that multicellularity has evolved repeatedly
Outline the steps in the evolution of multicellularity


Activities: ⓟ = podcast / ⍰ = inquiry 5 / ⓦ = Write it / Ӕ = The academy / Ⓡ = Read it
Ⓛ (recommended): Practicing Micrograph Analysis One of the rights of passage for any budding biologist is to become really good at recognizing micrographs. Fine-tune your skill of recognizing key structures of microscope images. Complete the following worksheet. Ӕ: Virtual Tour Guide Through Cells (💁) Screencast a recording of the following interactive 3D models: bacterial cell / plant cell / animal cell. Take us on a virtual tour of each, highlighting the key features of both prokaryotic and eukaryotic cells (and their organelles), then comparing/ contrasting the features of each. Include as much from this unit as possible (e.g. the characteristics of living things). Ⓛ: The Dirtiest Things at This School (👫 max 2) Look around you – what surface is home the most bacteria? Design an experiment to test this out (watch this for inspiration). Simply request that our wonderful lab technician prepare you some agar plates. Then grab some cotton swabs, swipe a few surfaces, and see how the bacteria grow. Prepare a video or written summary of your work, in which you briefly describe an outline of your experiment, including the following: Variables – what are your independent and dependent variables? What are your control variables? What would a good research question be? In a few sentences — What is a good hypothesis? If you really want to get into the 8-10 mark range, also outline a brief step-by-step method. (Go here for help with any of these tasks.) Ⓛ: Pond Scum, under the Microscope (👬 max: 2) Find a local water source and collect a small sample. Use the light microscope to see if you can find any paramecium, then photograph it (or use an online photo) and highlight the parts of the cell that enable it to carry out the functions of life. If you choose this one, you’ll get the best results if you: Use a clean jar Add a little dirt and a little grass to the pond water Seal it with a lid Let it sit in some sunlight for a couple days (you can leave it at RISS for this part).Then do the following: Sketch 2-3 organisms that you observe under your microscope. Indicate the magnification level used to observe each microorganism. Indicate the magnification OF YOUR SKETCH Use labels to indicate visible structures, including body parts (e.g. mouthparts or legs on water fleas), any key cell structures (e.g., nucleus, chloroplast, cell wall, or membrane). ⍰: “Inquiry 5”: Q&A on Prokaryotes and Eukaryotes (💁/ 👭max 2) Create a list of 5 inquiry questions related to prokaryotes and antibiotics. Remember that good inquiry questions are conceptual / open-ended… Such as*: “How can killing infectious bacteria be both a good and bad thing?* NOT: “What is the function of pili on prokaryotic cells?” If working solo, write out answers to your own questions; if working in pairs, record yourselves asking each other your 5 questions. Lab – ⓟ/ⓦ/Ӕ: How Good are Those Antibacterial Products? (👫 max 2 [lab work and podcast only]) Design an investigation to compare the efficacy of various antibacterial products. The products can either be natural OR human-made products (e.g. natural: ginger, lemon, tea tree oil, etc.; human-made: soaps, hand wipes, alcohol gels, etc). Use agar plates to grow bacteria, using your chosen product to see how effectively it inhibits growth. ⓟ/ⓦ: Tell the Story of Life’s Origin (💁 / 👬max 2 [podcast only]) We’ve learned quite a mix of bio history, theory, and content in our first weeks. Now is your chance to tie it all together in one short and informative story. Use this link to read about all the connections between cell theory, Anton van Leeuwenhoek, endosymbiosis, and more — and tell the story of the origin of life. Emphasize the points that compare prokaryotes vs. eukaryotes – and make it creative! ⓟ/ⓦ: The Ultimate Social Network (💁 / 👬max 2 [podcast only]) Microbes in the human body outnumber our own body cells at a rate of about 10:1. Read this article about the endless bacteria that populate nearly every nook and cranny of our body. Then, either in a podcast or an individual writeup, discuss: 1) The symbiotic role of prokaryotes in multicellular organisms (such as humans); 2) How microbes form such large numbers in the human gut; and 3) How the use of antibiotics might be leading to unforeseen consequences in human health. ⓟ/ⓦ: Your Gut – Microbe Paradise (💁 / 👬max 2 [podcast only]) We are just beginning to understand the role of the 100 trillion prokaryotes (that’s 100,000,000,000,000) inside your gut. The developed world is experiencing a surge of diseases related to imbalances in our microbiomes. Watch this Ted Talk explaining the situation, and come up with a list of inquiry-based questions to discuss. Here are some suggestions to get you started: What are microbes? How do microbes in your gut fulfill the 7 characteristics of life? How do scientists study gut microbes? What is the symbiotic role of prokaryotes in complex animals (such as humans)? Why can sudden changes in our microbiomes be a bad thing? ⓟ/ⓦ: (+NOS link): This Podcast Will Kill You (From 37:45 – 55:15) (💁 / 👬max 2 [podcast only]) “Travel back to a time before humans knew microbes even existed to discover alongside Leeuwenhoek a whole new world of animalcules like giardia.” Listen to this podcast and learn about the discovery of the micro-world, and development of microscopes. Respond in either a podcast or a written report, discussing: 1) How science evolved to allow us to study, and understand, the microscopic world; and 2) What we discovered after the invention of the microscope; 3) How inventions of apparatus have enabled us to develop a greater understanding of biology. Then round off the assignment with a few questions of your own. *Extra stuff (all optional):* Scale of the Universe 📄: Old School Worksheet Print out (or complete digitally) this worksheet that compares prokaryotes vs. eukaryotes. This will be a fantastic resource for you to use when studying! 📄Old School Worksheet – Calculating Size with Microscopes How can we know the size of the things we look at under a microscope? Grab a scope and some slides, and practice measuring size with the microscope. Complete this worksheet and submit it on Google Classroom. Game Time: Quizziz A game of organelle matching — it’s very Kahoot-like