General Biology 1 Fall 2024 PDF

General Biology 1 Fall 2024 The cells part 1 Prof : Dr. Vincent Gagnon Book Raven, Biology, 13th edition  The cells Study guide: Topic Ref...

General Biology 1 Fall 2024 The cells part 1 Prof : Dr. Vincent Gagnon Book Raven, Biology, 13th edition  The cells Study guide: Topic References (13th Ed) Summarize the Cell Theory and list the key properties common to all cells Section 4.1 Discuss the impact of surface-to-volume ratios on cell size, and on Section 4.1, biological processes in general Figure 4.1 Distinguish between prokaryotic and eukaryotic cells. Section 4.2 & 4.3 Draw, and/or label diagrams of typical plant and animal cells as seen Figures 4.6 & 4.7. Lab through light and electron microscopes diagrams Identify and/or provide a simple explanation or function of the various Diagrams of Section cellular structures (organelles) found within typical eukaryotic cells. 4.4-4.7. Table 4.2 Table 4.3, Lab Compare the structural aspects of cells found in bacteria, protists, plants, Observations animals and fungi p. 561-563 Briefly study about the possible origins of life. Review the properties of life. Section 25.2 & 25.3 Describe features that must have been present in the earliest cells Section 25. 5, p. 534 Describe the endosymbiotic theory of the origins of eukaryotic organelles fig. 25.10 pp. 587-589 and the evidence supporting it. fig. 28.2, 28.3 & 28.4  How life began on Earth We really don't know how life began on Earth One scenario for the origin of life is that it originated in this dilute, hot, smelly soup of ammonia, formaldehyde, formic acid, cyanide, methane, hydrogen sulfide and organic hydrocarbons.  How life began on Earth Long before there were cells with the properties of life, organic molecules formed from inorganic molecules. Organic compound is any compound containing the element Carbon (C)* and you don’t need living thing to make organic compound. The formation of amino acids, nucleic acids, carbohydrates and lipids were essential, but by themselves not sufficient for life. The evolution of cells required early organic molecules to assemble into a functional, interdependent unit. *One exception to this rule is the molecule carbon dioxide (CO2), which is considered inorganic, even though it Nitrogenous contains carbon. base Amino acids  How life began on Earth Origin of the organic molecules 1. Extraterrestrial origins: − Hundreds of thousands of meteorites and comets are known to have slammed into the early Earth. − Recent findings suggest that at least some meteorites may have carried organic materials. Tagish Lake meteorite that landed in British Columbia in 2000, found that nearly 3% of the weight was organic matter.  How life began on Earth Origin of the organic molecules 2. Earth origins: − It is hypotheses that the early atmosphere was composed: ▪ Carbon dioxide (CO2) ▪ Nitrogen gas (N2) ▪ Water vapor (H2O) ▪ Hydrogen gas (H2) ▪ Hydrogen sulfide (H2S) ▪ Ammonia (NH3) ▪ Methane (CH4)  How life began on Earth Origin of the organic molecules 2. Earth origins: − American chemists Stanley L. Miller and Harold C. Urey recreated the primitive oceans and reducing atmosphere (little oxygen) of Earth in the lab. − Providing a natural source of energy by simulating lightning in the form of sparks. − Their experiment and others were able to produce a lot of the basic molecule for life. Amino acids Nitrogenous base  How life began on Earth The evolution of cells required early organic molecules Amino acids Nitrogenous base (building bloc of protein) (part of the building bloc of RNA/DNA) However, those organic molecules need to be assemble into a specific functional way to create self replicating organism (aka Life!). Proteins are shown in purple and the single RNA chain in beige. Ribosomes  How life began on Earth Hypothesis that life emerge from a random event So how a mismatch organic molecules creates a living organisms? We don’t know, but even the unprobeable can happen leaving enough time. Here an example of putting LEGO bricks in a washing machine by Mathematician Ingo Althöfer from Friedrich-Schiller University in Germany.  How life began on Earth So how a mismatch organic molecules creates a living organisms? We don’t know, but even the unprobeable can happen leaving enough time. Here an example of putting LEGO bricks in a washing machine by Mathematician Ingo Althöfer from Friedrich-Schiller University in Germany.  How life began on Earth So how a mismatch organic molecules creates a living organisms? We don’t know, but even the unprobeable can happen leaving enough time. Here an example of putting LEGO bricks in a washing machine by Mathematician Ingo Althöfer from Friedrich-Schiller University in Germany. Life could have occurred by the random organization of those organic molecule over millions on years  How life began on Earth Panspermia hypothesis Life came from an extraterrestrial origins: − Life may have originated elsewhere in the solar system or galaxy and arrive on Earth. − In this theory, we would be all descendant of extraterrestrial ☺  The Cells Little history Cells are generally too small for you to be able to see. Because cells are so small, they were not discovered until the invention of the microscope in the 17th century. English natural philosopher Robert Hooke was the first to observe cells in 1665, naming the shapes he saw in cork cellulae (Latin, "small rooms"). Robert Hooke Early studies of cells were conducted by: Anton van Leeuwenhoek: first observed living cells Mathias Schleiden: plants are made of cells. Theodor Schwann: all animal tissues are mare of individual cells. Schleiden and Schwann proposed the Cell Theory. Robert Hooke microscope  The Cells Cell theory 1. All organisms are made of 1 or more cells. 2. Cells are smallest living things – basic unit of life. 3. Cells only arise by division from a pre-existing cell. Mathias Schleiden Theodor Schwann  The Cells Why are we made of billion of cells…? Why not just big one ?  The Cells Why are we made of billion of cells…? Why not just big one ? O2 CO2 Most cells are relatively small due to a reliance on diffusion of substances in and out of cells Rate of diffusion affected by: ▪ Surface area available. ▪ Temperature. ▪ Concentration gradient. ▪ Distance.  The Cells Why are we made of billion of cells…? Why not just big one ?  The Cells Why are we made of billion of cells…? Why not just big one ? Organism made of many small cells has an advantage over an organism composed of fewer, larger cells. As a cell’s size increases, its volume increases much more rapidly than its surface area. Some cells overcome limitation by being long and skinny – like neurons.  The Cells Once you were only one cell! Ovule (n) Spermatozoid (n) Meiosis Fertilization YOU ! 100 um Ovary Testicle Zygote (2n)  The Cells Once you were only one cell! First cell division of an embryo Ovule (n) Spermatozoid (n) Meiosis Fertilization Ovary Testicle Zygote (2n) Cell divide by mitosis with an average 3.72 x 1013 cell in an adult (Bianconi et al. 2013)  The Cells Once you were only one cell! Cells are the basic structural and functional units of an organism. Heart of Brick Sculpture by Nathan Sawaya Yellow https://avantgallery.com/nathan-sawaya/  The Cells Cell is composed of 3 main parts: 1) Plasma Membrane Flexible outer surface Separates cell’s internal environment from its external environment.  The Cells Cell is composed of 3 main parts: 1) Plasma Membrane Flexible outer surface Separates cell’s internal environment from its external environment. 2) Nucleus* DNA contains all the information of the cell is surrounded by a membrane. * in prokaryote there is no membrane, only a circular DNA that is called nucleoid  The Cells Cell is composed of 3 main parts: 1) Plasma Membrane Flexible outer surface Separates cell’s internal environment from its external environment. 2) Nucleus* DNA contains all the information of the cell is surrounded by a membrane. 3) Cytoplasm All parts inside the plasma membrane. ▪ Cytosol: liquid portion of cytoplasm (water + solutes) * in prokaryote there is no membrane, only a ▪ Organelles: biological machines. circular DNA that is called nucleoid The Cells  Cell structure Cell is like a medieval city Library: Nucleus Inside the wall: Cytoplasm Wall: Plasma Membrane Cell structure: Plasma Membrane Plasma Membrane  Plasma Membrane Function: The plasma membrane encloses a cell and separates its contents from its surroundings. This separation permit to maintain a stable chemistry inside the cell. Allow some substances to move into and out of cell but stops others (selective permeability). Transmits signals between intra and extracellular spaces.  Plasma Membrane Structure: Lipid bilayer (back to back layers made up of phospholipids). The thickness of the bilayer is about 5 to 10 nm. fatty acid tails Hydrophobic Lipid bilayer Water Water Water Water  Plasma Membrane Structure: Within the plasma membrane there are proteins (channels, carriers, receptors).  Organelles Organelles: Specialized structures inside cells. Each has a characterized shape and specific function. 8 main organelles of interest. Analogy: Cell is like a city and organelles are the part that keep it running. Cell structure: Nucleus Library Nucleus Plasma Membrane  Nucleus Function: Stores genetic material DNA (blueprint). “Information centre”. Contains nucleolus.  Nucleus Function: Stores genetic material DNA (blueprint). Where ribosome “Information centre”. are made ☺ Contains nucleolus. Ribosome In eukaryotes, the DNA is divided into multiple linear chromosomes.  Nucleus Structure: Largest organelle in cell (round). Is surround by a nuclear envelope which is compose of two phospholipid bilayer membranes. The outer layer of the nuclear envelope is connected to the Endoplasmic Reticulum (ER). The nuclear pores allows ions and small molecules to diffuse freely, while controlling the passage of proteins and RNA-protein complexes. Cell structure: Ribosome Ribosome Library Nucleus Plasma Membrane  Ribosomes Function: - Site of protein synthesis - “Builder” Each ribosome is composed of two subunits, each of which is composed of a combination of RNA, called ribosomal RNA (rRNA) and proteins. Ribosomes subunit proteins (purple) and rRNA (orange).  Ribosomes Made within the nucleus (nucleolus) Ribosome can be attached to endoplasmic reticulum or free in cytosol. Ribosomes  Ribosomes The ribosome take the m-RNA coming from the nucleus and make a polymer of amino acids name protein. The sequence of the protein being synthesized determines if the ribosome will become associated with the ER or remain in the cytosol Cell structure: Endoplasmic Reticulum Ribosome Library Rough Endoplasmic Reticulum Nucleus Smooth Endoplasmic Reticulum Plasma Membrane  Endoplasmic Reticulum (ER) Structure: Network of folded membranes attached to the nucleus Function: “Assembly line” Synthesis Intracellular transport  Endoplasmic Reticulum (ER) 2 types of E.R.: Rough E.R.: ▪ Covered with ribosomes ▪ Involved in protein synthesis ▪ Proteins can be modified by the addition of short-chain carbohydrates to form glycoproteins. ▪ Those proteins bound for secretion are separated from other products and packaged into vesicles that move to the Golgi for further modification and packaging for export.  Endoplasmic Reticulum (ER) 2 types of E.R.: Smooth E.R.: ▪ Has no ribosomes ▪ Involved in lipid and carbohydrate synthesis ▪ The majority of membrane lipids are assembled in the smooth E.R. ▪ Store Ca2+ which keeps the cytoplasmic level low, allowing Ca2+ to be used as a signaling molecule (muscle contraction). ▪ Detoxification of foreign substances (medication, drugs, alcohol, etc.)  Endoplasmic Reticulum (ER) Smooth E.R Rough E.R