Biology Of The Cell PDF

Biology Of The Cell Cell Structure By: Dr. Alaa Al Helaili Dr. Alaa Al Helaili © Credoweb.bg Objectives: • Introduce cells history. • List cells theory principles. • Categorize the unified structural features in the cells (similarities). • Describe the organization of prokaryotic cells. • Descr...

Biology Of The Cell Cell Structure By: Dr. Alaa Al Helaili Dr. Alaa Al Helaili © Credoweb.bg Objectives: • Introduce cells history. • List cells theory principles. • Categorize the unified structural features in the cells (similarities). • Describe the organization of prokaryotic cells. • Describe the organization of eukaryotic cells. • Identify the different parts of the endomembrane system of eukaryotic cells. • Study the functions of the internal membranes and compartments of eukaryotic cells. 2 Dr. Alaa Al Helaili © Cells • They are the smallest unit of life. • They are microscopic in size (can not be seen with our bare eyes). • They got discovered after the invention of microscope in the 17th century. • First cell observed by the English scientist Robert Hooke (1665). 3 Biography.com Dr. Alaa Al Helaili © Timetoast.com Bhphotovideo.com Cell Theory The cell theory includes the following three principles: 1. All organisms are composed of one or more cells within which life processes such as heredity occur. 1. Cells are the basic unit of life and smallest living things. 1. They arise (regenerated) only by division of a previously existing cells. Dr. Alaa Al Helaili © 4 Why Are Cells Small In Size? If cells were big in size: • More effort will be needed to diffuse nutrients across the cell membrane. • There will be too much demand for its DNA. • The amount of waste and the time needed to excrete it will increase. Smaller cells have larger thus better surface area to volume ratio Dr. Alaa Al Helaili © 5 • Other than egg cells, most cells are not visible to the naked eye. How do we Study cells that are too small to see? Dr. Alaa Al Helaili © 6 We need microscopes to visualize cells Dr. Alaa Al Helaili © 7 Types Of Microscopes Light microscope Electron microscope Edited from: Slideserve.com Edited from: Slideserve.com Uses visible light as their radiation Uses electron beam wavelength 8 Dr. Alaa Al Helaili © Why Do We Stain? • Stains are used to increase the contrast between different cellular components, thus enable better visualization of cells and cell parts under the microscope. Stained (left) vs. unstained (right) cells Visionlearning.com image © Judith Beekman Dr. Alaa Al Helaili © 9 • Two basic internal cell structures were recognized when cells were visualized under the microscope: • Prokaryotic (simple organization) • Eukaryotic (complex organization) Dr. Alaa Al Helaili © 10 Unified Structural Features • There are four major features all cells have in common: 1) 2) 3) 4) Plasma Membrane Cytoplasm Ribosomes Nucleoid/nucleus Dr. Alaa Al Helaili © 11 Unified Structural Features 1) Plasma Membrane • It surrounds the cell and separates its contents from the surroundings. with protein molecules planted • It is made up of phospholipid in it. bilayer Nslc.wustl.du Plasma Membrane Edited from: askabiologist.asu.edu Plasma Membrane Prokaryotic Cell Sciencing.com Dr. Alaa Al Helaili © Eukaryotic Cell 12 1)Plasma Membrane • Plasma Membrane structure: Phospholipid bilayer (hydrophilic heads & hydrophobic tails) with proteins planted in them, plus glycoproteins & cholesterol Edited from: biology.stachexchange.com Dr. Alaa Al Helaili © http://biology4alevel.blogspot.ro/2014/08/10-lipids.html 13 1)Plasma Membrane • It is called plasma membrane it encloses the cell and separate its components from the outer surroundings. • Its functions include: - Wrapping the cell - Isolating its interior from the exterior environment - Controls what moves in and out of the cell - Maintains electrical potential of the cell Dr. Alaa Al Helaili © 14 Plasma membrane or Cell membrane? 15 Dr. Alaa Al Helaili © Mybio.ie 29 Cell Membrane proteins • The proteins planted in the plasma membrane are responsible for controlling what moves in and out of the cell (controls cells interaction with the environment) Just like doors. • Some proteins allow molecules and ions to move in or out of the cell (called transport proteins: channels proteins & carrier proteins) • Some proteins causes a changes inside the cell in response to binding to a specific molecule such as hormones (called receptor proteins) Learn.genetics.Utah.edu Dr. Alaa Al Helaili © 17 Unified Structural Features 2) Cytoplasm • It is a semifluid (Jell-O like) medium fills the interior of the cell. • It is thick because of the high concentration of the macromolecules (sugar, protein…) and the organelles it carries. • It has a part that contains organic molecules and ions that is called the cytosol. Cytoplasm Cytoplasm Prokaryotic Cell Dr. Alaa Al Helaili © Eukaryotic Cell 18 2) Cytoplasm Cytoplasm = Cytosol + Organelles + Inclusions The inside of the cytoplasmic membrane where most cellular activities occur Jell-O like fluid where various elements are suspended little organs that performs functions for the cell (the metabolic machinery of the cell) Stored nutrients and secretory products ex. Sugars, amino acids, & proteins 19 Dr. Alaa Al Helaili © Unified Structural Features 3) Ribosomes • They are made of rRNA (ribosomal RNA) and protein. • They are the site of protein synthesis. • They are floating freely in the prokaryotic cells (no membrane around them). • Eukaryotic ribosomes are larger in size. Edited from: askabiologist.asu.edu Ribosomes Ribosomes Prokaryotic Cell Sciencing.com Dr. Alaa Al Helaili © Eukaryotic Cell 20 Unified Structural Features 4) Nucleoid/Nucleus • They are the centrally located genetic material (DNA). • In prokaryotic cells, there is no membrane that separates the nucleoid from the rest of the cell’s internal environment. • In eukaryotic cells, the nucleus is surrounded by a double-membrane structure (nuclear envelope). Nuclear envelope Edited from: askabiologist.asu.edu Nucleus Nucleolus Nucleoid (DNA) Prokaryotic Cell - Eukaryotic Cell Sciencing.com Nucleoid: is prokaryotic DNA that exist only in the prokaryotic cells Nucleus: is a membrane bound organelle found in almost every eukaryotic cell Dr. Alaa Al Helaili © 21 Prokaryotic Cells Prokaryotes Domains Imperial collage of science, technology and medicine Savannahthecell.weebly.com • Bacteria (discovered 1676) • Archaea (discovered 1990) Bacteria Archaea There are small differences between them in: ● The nature of membrane lipids ● The process of molecular (DNA & Ribosome) activities Dr. Alaa Al Helaili © 23 Prokaryotic cells • Prokaryotic cells are simple organisms that have simple cellular organization. They are consisted of: (From the inside towards the outside) Scientific American. Springer Nature • Interior compartments that include: the nucleoid, plasmids and ribosomes. • Cytoplasm • Plasma membrane • Cell envelope made up of: - Cell wall - Flagella and pili - Cytoskeleton (capsule) >> sometimes 24 javatpoint.com/bacteria-cell Prokaryotic cells Nucleoid Ck12.org Dr. Alaa Al Helaili © 25 Prokaryotic cells are like one room cabin Owlcation.com tripadvisorllc Couch, bed, oven, dining table all in one place (no walls in between) 26 Name the functions of each organelle in the Prokaryotic cell: istockphoto 27 Dr. Alaa Al Helaili © Prokaryotes Roles • Good roles: ✔ Photosynthesis (use light and CO2 to produce organic molecules such as petroleum) ✔ Decomposing (break down dead organisms and return CO2 to the atmosphere) • Bad roles: ✔ Cause diseases (ex. Salmonella) Dr. Alaa Al Helaili © 28 Khanacademy.org Eukaryotic Cells Eukaryotic Cells • Eukaryotic cells are more complex than prokaryotic cells. • They are distinguished by their compartmentalization (divided into sections) that is occurring due to having: -Extensive endomembrane system - Membrane bound organelles within which biochemical processes can occur. • Eukaryotic cells include: plants, animals, protists, and fungi. Dr. Alaa Al Helaili © 30 Eukaryotic Cells:Animal And Plant Cells They are living cells with common general structure that includes: Nuclei • Cell membrane Organelles • Cytoplasm • Nuclei (DNA) • Organelles Cell membrane Edited from: biologywise.com Dr. Alaa Al Helaili © Cytoplasm 31 Eukaryotic Cells (Nucleus) • It is the control center of the cell. • It has a large structure in the center called the nucleolus. • It contains chromatin that carries the genetic material (DNA) • Surrounded by a membrane (nuclear envelope) that has nuclear pores • Easy to see under the microscope • There is usually one per cell (exceptions: fungi cells may have multiple, mature red blood cells in mammals has no nucleus ) Dr. Alaa Al Helaili © Edited from: vmed.info chromatin pores Nucleolus 32 33 Nuclear envelope Eukaryotic Cells (Nucleus) • What is the nucleolus? - The center of the nucleus. - Made up of nucleic acids and proteins. - The cite of DNA transcription into mRNA - the cite of ribosomes synthesis Biologywise.com 33 Dr. Alaa Al Helaili © Eukaryotic Cells (Nucleus) What is the genetic material (DNA)? ● It is the molecule that stores genetic information. ● This genetic information is the hereditary information that determines cell structure and function. ● DNA is tightly curled up around proteins (histones) forming chromatin. ● Chromatin loops around itself forming chromosome. Dr. Alaa Al Helaili © 34 Eukaryotic Cells (Nucleus) • What are the nuclear envelope and nuclear pores? - The nuclear envelope is the surface of the nucleus - It is made up of two phospholipid bilayer membrane (the outer layer is continuous with the endoplasmic reticulum) - The membrane (nuclear envelope) contains openings called nuclear pores - Nuclear pores functions: - Allow material exchange between the nucleus and the cytoplasm - Allow ribosomes to move into the cytoplasm Dr. Alaa Al Helaili © 35 Differences? ● Nucli ● Nucleus ● Nucleolus ● Neclioed 36 Animal Cells Eukaryotic Cells: Animal Cells Animal cells have: • Only plasma membrane that encloses the cell (no cell wall). • Cytoskeleton (support system) • Various organelles. • Some have microvilli, cilia, or flagella. 38 Dr. Alaa Al Helaili © Thinglink.com Microvilli, Cilia, and Flagella 39 Eukaryotic Cells: Organelles (The Endomembrane System) • It is the membrane that: - divide the cell into compartments. - Channel the passage of molecules through the interior of the cell (like roads) - Provides a surface for synthesizing lipids and some proteins • It is divided into: - Endoplasmic reticulum (ER) - Golgi apparatus - Lysosomes - Microbodies (peroxisomes) - Vacuoles (in plants only) Dreams.metroeve.com Dr. Alaa Al Helaili © 40 Eukaryotic Cells: Organelles (The Endomembrane System) -Endoplasmic Reticulum (ER) • It is fluid filled tubules for carrying substances. • It comes in two types according to their structure: 1)Rough endoplasmic reticulum (RER) that: - It is filled with ribosomes (making it rough). - synthesizes proteins. 2)Smooth endoplasmic reticulum (SER) that: ● is filled with enzymes that are involved in the synthesis of carbohydrates, lipids including phospholipids and steroid hormones. ● stores intracellular calcium Ca2+. ● Detoxifies the cell from drugs and pesticides. Dr. Alaa Al Helaili © 41 Dr. Alaa Al Helaili © 42 Eukaryotic Cells: Organelles (The Endomembrane System) -Golgi Apparatus• It is complex that has flattened sacks of membranes. • Each individual sack is called cisternae. • Golgi apparatus functions include: - collecting, packaging and distributing synthesized materials to different parts of the cell. - Modifying proteins and lipids that are manufactured in the ER. - Synthesizing cell wall components (in plants). • The different types of packages that Golgi apparatus produces include: (secretory vesicles, cell wall components, & lysosomes) Dr. Alaa Al Helaili © 43 Slideplayer.com Dr. Alaa Al Helaili © 44 Eukaryotic Cells: Organelles (The Endomembrane System) -Lysosomes• They are spherical (round) membrane bound bags that arise from Golgi apparatus. • They contain high levels of (degrading) digestive enzymes. • They breakdown macromolecules, waste, nonfunctional, or foreign materials (ex. viruses) within the cell. • Uncontrolled release of lysosomes content into the cytoplasm can lead to cell death (necrosis). Dr. Alaa Al Helaili © 45 Eukaryotic Cells: Organelles (The Endomembrane System) -Lysosomes- Copyright © 2009 Pearson education, inc. Lysosome fusing with food vacuole and digesting food Dr. Alaa Al Helaili © 46 Eukaryotic Cells: Organelles (The Endomembrane System) -Microbodies: peroxisomes• They are enzyme bearing (carrying) membrane bound vesicles. • Involved in the oxidative breakdown of fatty acids (in animal cells). • Responsible for protecting the cell from the toxic hydrogen peroxide it produces as a result of killing germs (e.g. In white blood cells WBCs) WBCs produce hydrogen peroxide to kill bacteria, the oxidative enzymes in peroxisomes breaks down hydrogen peroxide into oxygen and water Cell secretions like hormones and neurotransmitters are packaged in secretory vesicles at the Golgi apparatus that get transported to the cell surface for release. Dr. Alaa Al Helaili © 47 48 Macmillanhighhered.om Dr. Alaa Al Helaili © 49 Eukaryotic Cells: Organelles (Centrosomes and Centrioles) • Centrosomes are the microtubule organizing center. • Each centrosome contains two centrioles (the region surrounding the centrioles). • Centrioles are barrel shaped pairs. • Exist in animal cells. • Play a role during reproduction. Google.sites.com https://cnx.org/contents/ [email protected] Dr. Alaa Al Helaili © 50 51 Eukaryotic Cells: Organelles (Mitochondria) • Sausage shaped organelles. • Found in every eukaryotic cell. • Bounded by two membranes: - A smooth outer membrane. - An inner folded membrane (the folds are called cristae). • Inside the cristae exist the matrix. • Outside the cristae exist the intermembrane space. Dr. Alaa Al Helaili © 52 Eukaryotic Cells: Organelles (Mitochondria) • They have their own DNA that produces proteins that are essential for oxidative metabolism (acts as a cell within a cell). • Mitochondria replicate by division, an activity that is aided by the genes in the nucleus. Dr. Alaa Al Helaili © 53 Plant Cells Eukaryotic Cells: Plant Cells • Things that only plant cells contain: - Hard cell wall: supports & protects the cell and gives it square or rectangular shape. - Central vacuole: stores food, water, and waste and keep cells in shape. - Chloroplasts: where photosynthesis takes place. - Plasmodesmata: openings in the cell walls for cytoplasmic connections between plant cells. Dr. Alaa Al Helaili © 55 Pmgbiology.com Dr. Alaa Al Helaili © 56 Eukaryotic Cells: Organelles (The Endomembrane System) -Vacuoles (in plants only)• They are large, water-filled, sacs in plant cells (very small or absent in animal cells). • They temporary store water and other needed materials (like sugars and ions) and waste. • The central vacuole involved in cell growth as it expand to increase the size of the cell. • It is used to maintain water balance in the plant cell. Sbio.info Dr. Alaa Al Helaili © 57 Eukaryotic Cells: Organelles Chloroplast • Found in plant cells. • They can manufacture their own food. • They contain chlorophyll (the photosynthetic pigment) that gives the plant its green color. • Surrounded by two membranes and contains DNA. • Larger and more complex than mitochondria. Dr. Alaa Al Helaili © 58 Eukaryotic Cells: Organelles Chloroplast • It has closed compartments of stacked membranes called grana. • Each granum contains disk shaped structures called thylakoids (the light capturing photosynthetic pigments). • Around the thylakoids exists fluid matrix called stroma (where the enzymes used to synthesis glucose during photosynthesis are). Sicascienceclass.wordpress.com Dr. Alaa Al Helaili © 59 Eukaryotic Cells: Organelles (Mitochondria & Chloroplast) Cites.google.com • Mitochondria and chloroplast are both surrounded by a double membrane. • They both contain their own DNA and synthesis machinery. • They both provide energy to the cell (the power centers of the cell) Rbpaonline.com • Mitochondria exists in animal cells while chloroplasts exist in plant cells. • Mitochondria metabolizes sugar to generate energy while chloroplast uses light to generate energy. Dr. Alaa Al Helaili © 60 Mitochondria metabolizes sugar to generate energy while chloroplast uses light to generate energy Rbpaonline.com Mitochondria and chloroplast are both surrounded by a double membrane Cites.google.com Dr. Alaa Al Helaili © 61 Compare between mitochondria and chloroplast: (the differences) Mitochondria Chloroplast In both plant and animal cells Only in plant cell Uses sugar (glucose) Makes sugar (glucose) Metabolizes sugar to generate energy Uses sunlight to generate energy Compare between photosynthesis and cellular respiration Cellular respiration Photosynthesis It takes place in mitochondria It takes place in chloroplast Glucose and oxygen react to produce CO2, water, and energy ATP Chemical energy in glucose changes to chemical energy in ATP CO2 and water reacts using sunlight to produce glucose and oxygen Light energy from the sun changes to chemical energy in glucose Dr. Alaa Al Helaili © 62 Ib.bioninja.com.au Dr. Alaa Al Helaili © 63 Eukaryotic Cells: Organelles (Cytoskeleton: a cells scaffold) • A network of protein fibers that comes in three subunits: Crossfithartford.com - Actin filaments (microfilaments) - Microtubules - Intermediate tubules (Absent in plants) • Their functions include: - Supporting the shape of the cell. - Anchoring (holding in place) organelles to fixed location. - Helping with endocytosis (uptake of external material) - Involved in cell movement and growth (it can move materials inside the cell). Dr. Alaa Al Helaili © 64 Eukaryotic Cells: Organelles (Cytoskeleton: a cells scaffold) Microtubules Actin filaments (microfilaments) Intermediate tubules 65 Dr. Alaa Al Helaili © Opentextbc.ca Eukaryotic Cells Extracellular Structure Extracellular structures include: 1. Cell walls (in plants’, fungi, and some protists’ cells) 1. Extracellular matrix (in animal cells) Dr. Alaa Al Helaili © 66 Eukaryotic Cells Extracellular Structure 1) Cell Wall • The cell wall in plants’, fungi, and some protists’ cells is different in cellulose structure than that in prokaryotic cells: -In plants the cell wall is made up of fibers and the polysaccharide -In fungi cell walls are made of chitin (a carbohydrate) • Cell walls functions include: -providing and maintaining the shape of the cells. -Serving as a protective barrier. Dr. Alaa Al Helaili © 67 Eukaryotic Cells Extracellular Structure 2) Extracellular Matrix (ECM) • It is a mixture of glycoproteins (proteoglycan, fibronectin) and proteins (collagen) that cells secrete into the space around them. • It exists in animals. • EMC is linked to the cytoskeleton via a protein called integrin (hock-like) • Its function mainly is to: - Gives tissue strength and elasticity (mechanical support). -Separate different tissue. -Substrate for cell migration and development. -Coordinate cell behavior by altering gene expression. 68 Dr. Alaa Al Helaili © Khanacademy.org Healthline.com Eukaryotic Cells Cell Movement • Moving strategies: - Crawling (with the help of actin filaments and microtubules) it occurs during inflammation, clotting, wound healing and spread of cancer (e.g. White Blood Cells WBC) cilia Flagellum - Flagella and cilia aid movement Thoughtco.com Biologydiscussion.com - ECM (cells migrate through the extracellular matrix) e.g. migrating embryonic cells Dr. Alaa Al Helaili © 69 Point out the following cell compartments: Dr. Alaa Al Helaili © 70 Point out the following cell compartments: Dr. Alaa Al Helaili © 71 Sliderbase.com Dr. Alaa Al Helaili © 72 Comparison between prokaryotic cells and eukaryotic cells Structure Prokaryotes Eukaryotes Nucleus No Yes Mitochondria No Yes Chloroplasts No Plants only Ribosomes Yes Yes Cytoplasm Yes Yes Cell Membrane Yes Yes Capsule Sometimes No Golgi Apparatus No Yes Endoplasmic Reticulum No Yes Flagellum Sometimes Sometimes in animals Cell Wall Yes (not cellulose) Plants and Fungi only Dr. Alaa Al Helaili © 73 Please watch the following: • https://www.youtube.com/watch?v=URUJD5NEXC8 Dr. Alaa Al Helaili © 74