Structured Study Sessions (SSS): Bio 120 - University of Saskatchewan - PDF
Document Details
Uploaded by ChivalrousMossAgate1187
University of Saskatchewan
2024
Tags
Summary
This presentation provides a structured study session overview for Bio 120 at the University of Saskatchewan, covering topics like macromolecules, microscopy types, and cell theory. It includes questions for self-assessment.
Full Transcript
University Library Structured Study Sessions (SSS): Bio 120 Janelle and Steve Sept 17, 2024 Please note: This material has been...
University Library Structured Study Sessions (SSS): Bio 120 Janelle and Steve Sept 17, 2024 Please note: This material has been developed by your awesome Structured Study Sessions Peer Mentor and not your course professors! Selection of session materials is based on your peer mentor’s knowledge and experiences with taking the course and input from the SSS Peer Mentor Team. University Library What is SSS? SSS stands for structured study sessions It is a weekly session where we go over course material and you will be given opportunities to ask questions and gain a better understanding of topics covered in class We offer four 80-minute sessions each week, and you can attend one or more! It is not your lab or your lecture, but rather a place where you can deepen your understanding of lecture material Peer mentors are fellow students like you who have taken bio 120 and done well! University Library Icebreaker Say your name, your program, and your favourite thing about university so far University Library In This Session: Macromolecules Early microscopy Cell theory § Types of microscopy and their uses § What are cells small? Features common to all cells Prokaryotic vs eukaryotic cells University Library Let’s see what you already know! University Library Question 1: Which one of the following is a part of the cell theory? A. All organisms are composed of more than one cell B. Cells arise when pre-existing cells divide C. All cells have ribosomes, cytoplasm, and an endomembrane system D. Cells of multicellular organisms are all specialized to perform specific jobs University Library Question 1: Which one of the following is a part of the cell theory? A. All organisms are composed of more than one cell B. Cells arise when pre-existing cells divide C. All cells have ribosomes, cytoplasm, and an endomembrane system D. Cells of multicellular organisms are all specialized to perform specific jobs University Library Question 2: What best describes magnification? A. The ratio of the object as you see it under the microscope to its real size B. The number of times the object could fit across your field of vision in the microscope C. The minimum distance 2 points in the specimen could be separated and still distinguished as 2 separate points D. The actual size of the object University Library Question 2: What best describes magnification? A. The ratio of the object as you see it under the microscope to its real size B. The number of times the object could fit across your field of vision in the microscope C. The minimum distance 2 points in the specimen could be separated and still distinguished as 2 separate points D. The actual size of the object University Library Question 3: Which of the following is not found in prokaryotic cells A. Nucleus B. Nucleoid C. Cytoplasm D. Pili University Library Question 3: Which of the following is not found in prokaryotic cells? A. Nucleus B. Nucleoid C. Cytoplasm D. Pili University Library Macromolecules Life is made up of four macromolecules: Proteins – monomer is amino acids Nucleic acid (DNA/RNA) – monomer is nucleotides Carbohydrates – monomer is monosaccharides Lipids – not made of monomers This Photo by Unknown Author is licensed under This Photo by Unknown Author is This Photo by Unknown Author is CC BY-SA-NC licensed under CC BY This Photo by Unknown Author is licensed under licensed under CC BY CC BY-SA-NC University Library Hooke and van Leeuwenhoek § Hooke - first to use a microscope to observe cells § Van Leeuwenhoek - first to use a microscope to observe living organisms. He observed pond water and bacteria from scrapings off his teeth! University Library Cell Theory The cell theory came about in the middle of the 19th century, after people were able to use microscopes to observe cells and make some generalizations about all cells. The cell theory consists of these 3 ideas: § All organisms are made of one or more cells § The cell is the basic structural and functional unit of all living organisms § Cells only arise when pre-existing cells divide University Library Overview of Cells § Cells carry out essential life processes § Cells can only be viewed with a microscope because they are very small § All cells have a central region that contains DNA surrounded by cytoplasm § Cells have DNA and RNA (genetic information, contains the instructions for building proteins) § Cells use energy, respond to changes in environment, reproduce, and pass on genetic information (DNA) § There are two types of cells: prokaryotic and eukaryotic University Library Light Microscopy § Uses light (photons) to illuminate the specimen § Advantages: the specimen can be alive, this type of microscopy is much less expensive § Ideal specimens: living organisms such as bacteria and protists, as well as other larger cells. You will be able to see features such as the plasma membrane, nucleus, and larger organelles like the mitochondria and chloroplasts. University Library Types of Light Microscopy Bright field microscopy § Light passes directly through the specimen § You can stain the specimen to increase contrast of cellular structures, but this will typically kill the cell University Library Types of Light Microscopy Dark field Phase contrast microscopy Nomarski (differential microscopy Density differences within the interference contrast) § The specimen is specimen causes light to bend This is very similar to illuminated by light in different ways – which contrast microscopy, at an angle, and we results in contrast between where the cell appear 3D are only able to see different structures due to density differences light that scatters University Library Types of Light Microscopy Confocal laser scanning microscopy § Lasers scan the specimen, and light is focused by a computer in such a way that only a very thin plane is observed § The specimen must be fluorescently stained. This can either be achieved using dyes or proteins that we add to the specimen, or just using fluorescent materials that are naturally present in the cell University Library Electron Microscopy § In electron microscopy, a beam of electrons is fired at the specimen § The specimen must be fixed (dead) and usually stained/coated with a metal § Has higher resolution than light microscopy University Library SEM § Stands for scanning electron microscopy § The specimen can remain whole, but needs to be coated with a heavy metal § Electrons become excited on the surface of the specimen, which gives the specimen a 3D appearance § Best for viewing the outside appearance of specimens such as insects, viruses, as well as structures like flagella University Library TEM § Stands for transmission electron microscopy § The specimen must be sectioned and stained with heavy metal § The regions of the specimen that we can see appear light due to electrons that have passed through § Ideal for viewing very small structures like organelles University Library Magnification § Magnification is the ratio of the image as seen under the microscope to its size in real life § The microscope lenses are responsible for magnification This Photo by Unknown Author is licensed under CC BY-NC University Library Resolution § The ability to distinguish 2 points in a specimen as separate § It depends on wavelength – if the light or electrons have a shorter wavelength, then the resolution will be higher University Library Contrast § This refers to how sharp the borders around the specimen appear § Keep in mind that increasing contrast will not increase resolution! University Library Question 4: Which of the following will increase resolution? A. Increase magnification B. Increase contrast C. Cut the specimen into smaller pieces D. Fix the specimen before observing it (kill the specimen) University Library Question 4: Which of the following will increase resolution? A. Increase magnification B. Increase contrast C. Cut the specimen into smaller pieces D. Fix the specimen before observing it (kill the specimen) University Library Question 5: Which method of microscopy would be best to observe a paramecium swimming in a sample of pond water? A. Bright field B. SEM C. TEM D. Confocal microscopy University Library Question 5: Which method of microscopy would be best to observe the behavior of a paramecium swimming in a sample of pond water? A. Bright field B. SEM C. TEM D. Confocal microscopy University Library Why are Cells So Small? § Thoughts? This Photo by Unknown Author is licensed under CC BY-NC University Library Why are Cells So Small? § Speed of diffusion § Easier to replace damaged cells when they are small, and damage won’t have as large of an effect § SA/Volume ratio University Library SA/Volume Ratio § Nutrients, wastes, and other materials get in and out of the cell via the plasma membrane § When a cell gets really big, it needs to bring more material in to keep up with its metabolic needs § However, surface area and volume do not increase proportionally § This means that cells either need to remain small or else change their shape in order to increase surface area University Library Are there any components that every living cell on earth would have? § Any thoughts? This Photo by Unknown Author is licensed under CC BY-NC University Library Components Common to all Cells Cells can be grouped into 2 categories: prokaryotic and eukaryotic. These components are common to both cell categories: § Ribosomes § Cytoplasm and cytosol § DNA and the central dogma § Plasma membrane § Cytoskeleton University Library DNA and the central dogma § All cells contain deoxyribonucleic acid (DNA) § All of an organism’s genetic information is encoded in the DNA in the form of genes § In order for the genes to be expressed, a few steps need to occur § Central dogma: DNA – RNA - protein University Library DNA and the Central Dogma – Prokaryotes vs Eukaryotes Prokaryotes Eukaryotes § DNA is in the form of a single DNA is in the form of multiple linear circular chromosome chromosomes § The circular chromosome is located DNA is stored in the nucleus – which in the nucleoid region is bound by 2 phospholipid bilayers Transcription occurs in the nucleus § Transcription and translation both and translation occurs in the occur in the cytoplasm. Translation cytoplasm – either on free-floating occurs on free-floating ribosomes ribosomes or on ribosomes anchored to the endoplasmic reticulum University Library Plasma membrane § The plasma membrane surrounds the cell and provides a semi- permeable barrier. This means that some molecules can pass directly through the membrane while others cannot § It is made up of a phospholipid bilayer with embedded membrane proteins that serve various functions § Phospholipids are amphipathic § Can be described using the fluid This Photo by Unknown Author is licensed under CC BY mosaic model University Library Plasma Membrane – Prokaryotes vs Eukaryotes § The plasma membrane is quite similar in prokaryotes and eukaryotes § There can be slight differences in the composition of membrane lipids/proteins and the methods that membrane fluidity is regulated between prokaryotes and eukaryotes, but for our purposes right now they are quite similar This Photo by Unknown Author is licensed under CC BY University Library Ribosomes § Ribosomes are the machinery needed to express a gene § They consist of both rRNA (ribosomal RNA) and proteins and consist of 2 subunits. One subunit is large, and one is small § They read the genetic sequence encoded in mRNA and build the corresponding protein § The process of building a protein is called translation This Photo by Unknown Author is licensed under CC BY-SA University Library Ribosomes – Prokaryotes vs Eukaryotes Prokaryotic Eukaryotic § Ribosomes are smaller and are § Ribosomes are larger and can be suspended freely in the cytoplasm anchored to the endoplasmic reticulum or suspended freely in the cytoplasm University Library Cytoplasm and Cytosol § Everything inside the plasma membrane (excluding the central region of the cell) is considered the cytoplasm. § The cytoplasm contains the cell’s organelles, cytosol, and cytoskeleton § The cytosol is the liquid portion of the cytoplasm and contains a variety of molecules such as ions and organic molecules University Library Cytoplasm and Cytosol – Prokaryotes vs Eukaryotes Prokaryotic Eukaryotic § There are no cellular organelles – § Cytoplasm is broken up into the cytoplasm consists mainly of compartments by various internal cytosol membranes. These compartments are the organelles – a major component in the eukaryotic cytoplasm University Library Cytoskeleton § The cytoskeleton is made up of different types of proteins Functions: § Supporting and protecting the cell and helping it to maintain its shape § Cell movement and response to stimuli § Anchoring various cellular organelles (in eukaryotes) § Assisting in cell division (in eukaryotes) University Library Cytoskeleton – Prokaryotes vs Eukaryotes § The cytoskeleton is much simpler in prokaryotes than eukaryotes § The eukaryotic cytoskeleton serves some extra purposes – anchoring organelles and aiding in cell division § It was originally thought that prokaryotes didn’t have a cytoskeleton but that has since been proven false This Photo by Unknown Author is licensed under CC BY University Library Prokaryotic Cells - Overview § Divided into 2 kingdoms: bacteria and archaea § They are all unicellular organisms § Initially, they were referred to as prokaryotes, but now the term is more commonly used to describe the prokaryotic cells themselves. This is because archaea and bacteria actually do not have a close evolutionary relationship – archaea are more closely related to humans than bacteria § They can often survive in extreme conditions – especially archaea § One cell carries out all of the functions needed for life. There are no specialized cells like in the human body University Library Prokaryotic Cells – Other features Nucleoid region: Prokaryotic cells do not have a nucleus like eukaryotic cells do. Instead, they have a nucleoid region where their DNA is stored. Circular chromosome: Instead of multiple linear chromosomes like in eukaryotes, prokaryotic cells have one circular chromosome that contains all the cell’s DNA Cell wall: Almost all prokaryotic cells have a cell wall Glycocalyx: This is a layer of carbohydrates coating the cell wall. When loose it is called a slime layer, but when it is more firmly attached it is called a capsule. Flagella: Many prokaryotic cells have flagella, which helps them move in various media Pili: Some bacteria have pili – smaller and less motile projections from the cell that help the cell adhere to surfaces and other cells, and even exchange genetic information with other cells Plasmids: Small sections of self-replicating DNA University Library Eukaryotic Cells - Overview Consist of four kingdoms: § Plants § Animals § Protists § Fungi § While some eukaryotes are unicellular (these would typically be protists), most are multicellular and thus have specialized cells that perform various functions in the body University Library Eukaryotic Cells - Summary Nucleus: This is the organelle where DNA is stored in the form of linear chromosomes. It is surrounded by 2 lipid bilayers with embedded nuclear pore complexes Organelles: Eukaryotes have organelles with various functions such as modifying proteins, transporting materials, and generating energy. Cell wall: Some eukaryotes can have a cell wall. These include plant cells and protists § Eukaryotic cells are bigger than prokaryotic cells, and they can be specialized to perform various functions in a multicellular organism University Library Summary § Life is made up of macromolecules § Microscopy has allowed us to come up with generalizations about all cells. Different microscopy techniques have different advantages § Cells can be divided into two categories: prokaryotic and eukaryotic. Eukaryotic cells are larger and more complex. However, there are some features that are common to both cell categoreis University Library Kahoot! https://play.kahoot.it/v2/?quizId=6196c5c2-927c-41bb-8e91- 366361712468 University Library Your university library is here to help library.usask.ca University Library Bibliography https://media.cheggcdn.com/media/082/082559be-5aeb-443f-b33f- 65f177b589f6/phpbb2Nyw.png https://cdn.shopify.com/s/files/1/1634/0335/files/s54_DSC_0068_480x 480.jpg?v=1623702742 https://moticmicroscopes.com/cdn/shop/articles/Euglena.jpg?v=161833 2840 https://upload.wikimedia.org/wikipedia/commons/4/47/Micrasterias_rad iata.jpg https://www.photometrics.com/wp- content/uploads/2020/02/Neuron_in_tissue_culture-1024x804.jpg University Library § https://www.shutterstock.com/image-photo/transmission-electron- microscope-tem-micrograph-260nw-537787375.jpg § https://www.tf.uni-kiel.de/matwis/amat/iss/kap_4/illustr/s4_1_1b.html