Introduction to Cells: BIO 101 Lecture Notes PDF

Introduction to Cells BIO 101_LECTURE 4 and 5 1 Supplementary materials Read the information on the link provided for detailed explanations https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/...

Introduction to Cells BIO 101_LECTURE 4 and 5 1 Supplementary materials Read the information on the link provided for detailed explanations https://rwu.pressbooks.pub/bio103/chapter/introduction-to-cells/ 2 Cell 3 Microscopy for visualising cells Light Microscope Electron Microscope 4 Microscopy for visualising cells 5  Cell ▪ A cell is the smallest unit of a living thing, that can carry on all life processes. 6  History of cells ▪ First cells seen where cork cells in 1665 by Robert Hooke https://education.nationalgeographic.org/resource/history-cell-discovering-cell/ 7 Cell Theory ▪ All living things are composed of one or more cells ▪ The cell is the basic unit of life in all living things ▪ All cells come from existing cells 8 Two main classification of cells ▪ Plants Eukaryotic Cells ▪ Animals ▪ Fungi ▪ Protists/Protoctists ▪ Bacteria Prokaryotic Cells ▪ Archaea 9  Similarities of all cells They all contain 1. Cell/Plasma membrane: an outer covering that separates the cell’s interior from its surrounding environment 2. Cytoplasm: Consisting of a jelly-like cytosol within the cell in which other cellular components are found 3. Hereditary material (DNA): Genetic material of the cell 4. Ribosomes: Synthesize proteins 10 Cell Sizes 11 Prokaryotic cells ⬧ Include bacteria ⬧ DO NOT HAVE A NUCLEUS ⬧ Have long circular DNA ⬧ No membrane bound organelles ⬧ Contain ribosomes to make proteins. ⬧ Most prokaryotes have a peptidoglycan cell wall ⬧ Rod shaped, spherical, and spiral 12  Prokaryotic cells ⬧Reproduction: Usually Asexual ⬧ Binary Fission: an organism duplicates its DNA and then divides into two parts, with each new organism receiving one copy of DNA. ⬧ Conjugation: Exchange of DNA between bacteria (not Asexual) https://www.britannica.com/video/154218/DNA-another-cell-conjugation-transduction-processes https://byjus.com/biology/monera/ 13 Prokaryotic cells 14  Prokaryotic cells ⬧ Either classified as eubacteria or archaea. ⬧ Eubacteria: Commonly found ⬧ Archaea: Live in extreme environments (hot springs, salt lakes, and submarine volcanic habitats) ⬧ Halophiles ⬧ methanogens ⬧ thermoacidophiles 15 Prokaryotic cells: The Good Ones ⬧ Bioremediation: organisms are added to water to convert toxic pollutants, such as oil, into harmless substances. ⬧ Food Production: Butter, Cheese, Yogurt, Sauerkraut, Beer, Pickles, Olives, Chocolate, Coffee, Soy sauce, meats, etc. ⬧ Decompose dead organisms ⬧ Digesting food ⬧ Fix Nitrogen for Plants 16 Prokaryotic cells: The Bad Ones ⬧ Food Spoilage ⬧ Can cause disease in plants and animals ⬧ Produce Toxins 17 Eukaryotic cells 18 Eukaryotic cells ⬧ More complex & larger than prokaryotes ⬧ Have membrane bound organelles ⬧ HAS A NUCLEUS ⬧ Has more DNA than prokaryotes ⬧ DNA is linear ⬧ Animal, plant, fungi 19  Eukaryotic cells Movement for Unicellular Eukaryotes like the Protist ⬧ Flagella: tail-like projections ⬧ Pseudopod: false-foot ⬧ Cilia: finger-like projections (some non-motile) 20 Structure of Eukaryotic cells ▪ The Plasma Membrane ▪ The Cytoplasm ▪ Organelles ▪ The Nucleus ▪ Ribosomes ▪ Mitochondria ▪ Peroxisomes ▪ Vacuoles and Vesicles 21  Before we look at the Structure of Eukaryotic cells, Let’s look at organic molecules of the cell 22 Organic Molecules of the cell ▪ Carbohydrates ▪ Nucleic acids ▪ Proteins ▪ Lipids 23  Proteins Most diverse and complex macromolecules in the cell Used for structure, function and information Made of linearly arranged amino acid residues “folded” up with “active” regions 24 Protein types and function ▪ Enzymes – catalyzes covalent bond breakage or formation. Amylase ▪ Structural – collagen, elastin, keratin, etc. ▪ Motility – actin, myosin, tubulin, etc. ▪ Regulatory – bind to DNA to switch genes on or off ▪ Storage – ovalbumin, casein, etc. ▪ Hormonal – insulin, nerve growth factor (NGF), etc. ▪ Receptors – hormone and neurotransmitter receptors ▪ Transport – carries small molecules or irons ▪ Special purpose proteins – green fluorescent protein, etc. 25 26  Lipids Hydrophobic molecules Energy storage, membrane components, signal molecules Triglycerides (fat), phospholipids, waxes, sterols 27 Lipids 28 Saturated and Unsaturated fatty acids 29  Carbohydrates Sugars, storage (glycogen, starch), Structural polymers (cellulose and chitin) Major substrates of energy metabolism 30 Carbohydrates and Glycolysis 31  Nucleic Acids DNA (deoxyribonucleic acid) RNA encode genetic information for synthesis of all proteins Building blocks of life 32 Nucleic Acids 33 Structure of Eukaryotic cells Plasma Membrane 34  Structure of Eukaryotic cells Plasma Membrane Properties Made of hydrophobic and hydrophilic components Semi-permeable: allows some materials to pass while excluding others Fluid-like phospholipid bilayer Functions It selectively isolates the content of the cell of the external atmosphere (encloses cell and cell organelles) It regulates the exchange of substances between the cytoplasm and the external environment. (organic molecules, ions, water, oxygen, CO2 etc) Communicates with other cells. 35  Structure of Eukaryotic cells Cytoplasm The cytoplasm is the entire region of a cell between the plasma membrane and the nuclear envelope. It is made up of organelles suspended in the gel-like cytosol, the cytoskeleton, and various chemicals The cytoplasm consists of 70 to 80 percent water Functions Site for metabolic reactions 36 Organelles of a typical animal and plant cell 37  Structure of Eukaryotic cells Nucleus Properties The Nuclear membrane Chromosomes The Nucleolus Ribosomes Functions The nucleus houses the cell’s DNA and directs the synthesis of ribosomes and proteins 38  Structure of Eukaryotic cells Mitochondrion Properties Are oval-shaped, Double membrane organelles Have their own ribosomes and DNA. The inner membrane has folds called cristae that increase surface area Functions Mitochondria are often called the “powerhouses” or “energy factories” of a cell because they are responsible for making adenosine triphosphate (ATP), the cell’s main energy-carrying molecule 39  Structure of Eukaryotic cells Peroxisomes Properties Peroxisomes are small, spherical organelles enclosed by single membranes Many of these oxidation reactions release hydrogen peroxide, H2O2, which would be damaging to cells; however, when these reactions are confined to peroxisomes, enzymes safely break down the H2O2 into oxygen and water. Functions They carry out oxidation reactions that break down fatty acids and amino acids They also detoxify many poisons that may enter the body. Eg Alcohol 40  Structure of Eukaryotic cells Lysosomes Properties Lysosomes are small, spherical compartments that function as the digestive and organelle-recycling facility of animal cells. The enzymes in lysosomes are called acid hydrolases because they catalyze hydrolysis reaction and their optimal pH is around 4.5. Functions They contain hydrolytic enzymes that digest non-functioning organelles, macromolecules, and pathogens (disease-causing organisms). 41 Structure of Eukaryotic cells Lysosomes and Peroxisomes Importance Lysosomes, the cell's recycling centers, use acid hydrolases to break down waste into reusable parts. Peroxisomes protect cells by isolating and breaking down harmful hydrogen peroxide into water and oxygen. These organelles ensure efficient and safe cellular function. 42  Structure of Eukaryotic cells Vesicles and Vacuoles Properties The term “vacuole” means “empty space”. Vesicles and vacuoles are membrane-bound sacs that function in storage and transport. Vacuoles are larger than vesicles Functions They can store food or other nutrients required by a cell to survive. They also store waste products and prevent the entire cell from contamination Contractile vacuoles, contract to expel water from the cell. Vacuoles in plant cell help maintain water balance 43  Structure of Eukaryotic cells The Endoplasmic Reticulum Properties The endoplasmic reticulum (ER) is a series of interconnected membranous sacs and tubules The rough endoplasmic reticulum (RER) is so named because ribosomes attached to its cytoplasmic surface give it a studded appearance when viewed through an electron microscope. These bound ribosomes are in the process of translating proteins directly into the lumen of the RER The smooth endoplasmic reticulum (SER) is continuous with the RER but has few or no ribosomes on its surface. Functions of the SER include synthesis of carbohydrates, lipids, phospholipids, and steroid hormones and detoxification of medications and poisons 44  Structure of Eukaryotic cells The Endoplasmic Reticulum Functions Site for protein and lipid synthesis. The SER is generally used for the synthesis/ storage of lipids and steroids, while the RER plays a significant role in the synthesis of various proteins. 45  Structure of Eukaryotic cells The Golgi Apparatus (GA) Properties The GA is a series of flattened membranes, each forming a separate compartment Functions Vesicles containing proteins and lipids bud from the ER and transport their contents to the Golgi apparatus (GA). In the GA, proteins and lipids are sorted, packaged, and tagged so that they wind up in the right place. For this reason, the GA is sometimes called the post office of the cell. 46 Plant cells vs Animal cells: Differences 47  Cell wall in plant cell but not animal cell Properties A structure external to the plasma membrane While the chief component of prokaryotic cell walls is peptidoglycan, the major organic molecule in the plant cell wall is cellulose, a polysaccharide made up of glucose units. Fungus and some protist cells also have cell walls, which are made of other structural molecules. Functions The cell wall is a rigid covering that protects the cell, provides structural support, and gives shape to the cell. 48  Chloroplast in plant cell but not animal cell Properties Double membrane organelles Have their own ribosomes and DNA Chloroplasts have outer and inner membranes, but within the space enclosed by a chloroplast’s inner membrane is a set of interconnected and stacked fluid-filled membrane sacs called thylakoids Functions Chloroplasts are plant cell organelles that carry out photosynthesis. Photosynthesis is the series of reactions that use carbon dioxide, water, and 49 light energy to make glucose and oxygen  Large Central Vacuole in plant cell but not animal cell Properties Plant cells each have a large central vacuole that occupies most of the area of the cell Functions The central vacuole plays a key role in regulating the cell’s concentration of water in changing environmental conditions. The central vacuole also supports the expansion of the cell. When the central vacuole holds more water, the cell gets larger without having to invest a lot of energy in synthesizing new cytoplasm. 50  Lysosomes in animal cell but not Plant cell Functions Lysosomes are the cell’s “garbage/recycle disposal.” Enzymes inside lysosomes aid the breakdown of proteins, polysaccharides, lipids, nucleic acids, and even worn- out organelles. 51 Summary 52 Summary 53 Summary 54 The END 55