Biology 1 – Cells, Molecular Biology and Genetics (Biol 1000) Past Paper PDF

Biology 1 – Cells, Molecular Biology and Genetics (Biol 1000) Professor: Dr. Michael Cardinal-Aucoin Winter 2025  Evolution Major unifying theories in biology Darwinian evolution – Natural selection Some evidence and examples...

Biology 1 – Cells, Molecular Biology and Genetics (Biol 1000) Professor: Dr. Michael Cardinal-Aucoin Winter 2025  Evolution Major unifying theories in biology Darwinian evolution – Natural selection Some evidence and examples Biol 1000 - Dr. M. Cardinal-Aucoin 2  Some major unifying concepts of Biology 1. Theory of Evolution by Natural Selection 2. Cell Theory 3. Genetics 4. Homeostasis Biol 1000 - Dr. M. Cardinal-Aucoin 3  A Note about Theories Everyday Use: Theory means a guess, or “untested speculation”. “In theory I should do fine in this course” In science: A theory Is a broad explanation based on many lines of evidence Aids in the generation of new hypotheses Has withstood rigorous scientific testing Biol 1000 - Dr. M. Cardinal-Aucoin 4  Two major unifying concepts of Biology 1. Theory of Evolution by Natural Selection Characteristics of a population change over time. (pattern) Individuals with certain heritable traits produce more offspring than those without those traits. (mechanism)  All species are related by descent from a common ancestor. & All species come from (descend) from other pre-existing species. 2. Cell Theory All organisms are made up of cells. (pattern) All cells come from pre-existing cells. (mechanism)  All single-cell organisms in a population related to a common ancestor. & All cells in a multi-cellular organism descend from an ancestral cell. Biol 1000 - Dr. M. Cardinal-Aucoin 5 Two major unifying concepts of Biology All organisms are made from cells!!!!!!! A single idea that unites all living things!!!!!! Biol 1000 - Dr. M. Cardinal-Aucoin 6 Two major unifying concepts of Biology All cells are related!!!!! All cells arise from other cells. Through evolution (sharing Through development common ancestors). (embryology). Biol 1000 - Dr. M. Cardinal-Aucoin 7  Modern Cell Theory 1. A cell is the smallest self-reproducing unit of life. 2. Cells make up all living things. 3. New cells arise from pre-existing cells. 4. The activity of an organism depends on the total activity of independent cells. 5. Energy flow (metabolism and biochemistry) occurs within cells. 6. Cells contain the hereditary information in the form of DNA and RNA. 7. Cells of similar organisms share similar chemical composition. Biol 1000 - Dr. M. Cardinal-Aucoin 8  Cells All cells share certain properties, but not all cells are identical. Biol 1000 - Dr. M. Cardinal-Aucoin 9  Different Types of Cells 4 Basic features of ALL cells: Plasma membrane Semifluid substance called cytosol Genetic material (at some point) Ribosomes (to make proteins) Plus metabolism (chemical pathways to convert various forms of energy into biochemical work) Biol 1000 - Dr. M. Cardinal-Aucoin 10 Units of Measure μm - Micrometer 1,000,000 micrometers = 1 meter Strand of hair has a diameter of ~ 20-180 μm 106 nm - Nanometer 1,000,000,000 nanometers = 1 meter 109 Wavelength of visible light (400-700 nm) Ǻ - Angstrom 10,000,000,000 Angstroms = 1 meter 1010 Used to measure the size of atoms/bond lengths Length of a C-H bond in methane is ~1 Angstrom Biol 1000 - Dr. M. Cardinal-Aucoin 11 https://learn.genetics.utah.edu/content/cells/scale/ Introduction to the Cell With about 37 trillion cells in the human body, each cell must be really tiny! Biol 1000 - Dr. M. Cardinal-Aucoin 12 Why study cells? Cells are the fundamental functional unit of all living things. Cell theory is a unifying principle in biology. Understanding cells allows us to understand how organisms function. Plants, animals, parasites, fungus, etc. Knowledge of cells is critical to understanding human health and disease as well as for disease treatment. Biol 1000 - Dr. M. Cardinal-Aucoin 13 “Nothing in biology makes sense except in the light of evolution.” -Theodosius Dobzhanksy Along with cell theory, evolution is one of the main unifying themes in biology. Explains many seemingly disparate facts, observations, and experimental results. All living things are the result of evolution, including you.  Natural selection is one mechanism that drives evolution Other mechanisms include: – Artificial selection (by humans) – Sexual selection (competition for mates) – Genetic drift (changes due to random chance) – Gene flow (movement between populations) Biol 1000 - Dr. M. Cardinal-Aucoin 15  Evolution by Natural Selection If a population has 1. Differences between individuals – Mutations (raw material), meiosis (sexual reproduction) mixes things up… 2. That are heritable – Traits can be passed from one generation to the next. 3. And result in differential survival and reproduction – Some individuals leave more offspring than others. Then with time evolution will occur. Biol 1000 - Dr. M. Cardinal-Aucoin 16 Biol 1000 - Dr. M. Cardinal-Aucoin 17 Evidence for the theory of evolution by natural selection. Biol 1000 - Dr. M. Cardinal-Aucoin 18  Darwinian Evolution Descent with Modification How Natural Selection Works 1. Environmental resources are limited. Organisms will have to compete for space, food, mates, etc. 2. Members of a population vary extensively in their characteristics. This is easily observable. 3. Some characteristics (from 2) provide an advantage in the competition for resources (from 1). 4. Therefore some individuals will live longer and produce more offspring than others. Differential survival and reproduction. 5. If those characteristics are heritable then over time the advantageous characteristics will become more common in the population. The population changes over time – it evolves. Biol 1000 - Dr. M. Cardinal-Aucoin 19  Evolution by Natural Selection If a population has 1. Differences between individuals – ✓ (trait = colour) Mutations (raw material), meiosis (sexual reproduction) mixes things up… 2. That are heritable – ✓ Traits can be passed from one generation to the next. 3. And result in differential survival and reproduction – Some individuals leave more offspring than others. ✓ ✓ Then with time evolution will occur. Biol 1000 - Dr. M. Cardinal-Aucoin 20 It is not the strongest of the species that survives, nor the most intelligent that survives. It is the one that is most ADAPTABLE to change. -C. Darwin Biol 1000 - Dr. M. Cardinal-Aucoin 21 How natural selection works Natural selection occurs through interactions between individual organisms and their environment, but individuals do not evolve. A population is the smallest group that can evolve. Evolutionary change is measured as changes in relative proportions of heritable traits in a population over successive generations. Natural selection can act only on heritable traits, traits that are passed from organisms to their offspring. Environmental factors vary from place to place and from time to time. A trait that is favorable in one environment may be useless or even detrimental in another environment. Selective force (e.g. predation by birds) Biol 1000 - Dr. M. Cardinal-Aucoin 22 Evolution by Natural Selection Biol 1000 - Dr. M. Cardinal-Aucoin 23  Natural selection acts “sees” phenotype Genotype: – the genetic constitution of an individual organism environment Phenotype: – The set of observable characteristics of an individual organism. Biol 1000 - Dr. M. Cardinal-Aucoin 24  Darwinian Evolution Evolution = genotype phenotype environment Biol 1000 - Dr. M. Cardinal-Aucoin 25  Macroevolution = Microevolution x Time “Climbing Mount Improbable” Cumulative effects of many incremental modifications over the millions of years of evolution can result in major changes. With enough time you might be able to take a more gradual Jumping directly path to the reach the peak. to summit is impossible. Biol 1000 - Dr. M. Cardinal-Aucoin 26 The Vastness of Evolutionary Time The Earth is about 4 600 000 000 years old: Or about 115 000 000 human generations; Or about 9 200 000 000 mouse generations; Or about 115 000 000 000 fly generations; Or about 46 000 000 000 000 bacteria generations!! Biol 1000 - Dr. M. Cardinal-Aucoin 27  Macroevolution = Microevolution x Time “Climbing Mount Improbable” Over time phenotypic differences accumulate producing major transitions in evolution. And if you’re still wondering how evolution can produce something as complex as a human being starting from a single cell… Biol 1000 - Dr. M. Cardinal-Aucoin 28  Macroevolution = Microevolution x Time “Climbing Mount Improbable” …remember that you did it yourself in just 9 months! Biol 1000 - Dr. M. Cardinal-Aucoin 29  Evolution Decent with Modification Evidence for Evolution is Extensive: Homology Universal genetic code Fossil record Genomics Insecticide resistance Biogeography Genetics Microevolution Vestigial structures Comparative anatomy and physiology Embryology Comparative biochemistry Etc. Biol 1000 - Dr. M. Cardinal-Aucoin 30  Darwinian Evolution Five broad categories of evidence: 1. Natural Selection in action (examples) 2. Homology (anatomy, development and molecular) 3. Convergent evolution (Analogous features) 4. Biogeography 5. Fossils Biol 1000 - Dr. M. Cardinal-Aucoin 31  Darwinian Evolution Evidence for Darwin’s Theory 1. Natural Selection in Action: Antibiotic Resistance The use of drugs selects for pathogens that, through chance mutations are resistant to the drugs’ effects (antibiotic resistant bacteria and drug resistant HIV). Also e.g. insecticide resistance. Biol 1000 - Dr. M. Cardinal-Aucoin 32  Evolution Descent with Modification Disease-causing bacteria and other microbes are increasingly evolving to resist our drugs. Biol 1000 - Dr. M. Cardinal-Aucoin 33  Darwinian Evolution Evidence for Darwin’s Theory 2. Homology Homology: similarity resulting from common ancestry Different types of homologies: Anatomical Embryological/developmental Genetic/molecular Homologies result when organisms diversify from an ancestor as they adapt to new conditions/environments – divergent evolution. Biol 1000 - Dr. M. Cardinal-Aucoin 34  Darwinian Evolution Evidence for Darwin’s Theory 2. Homology: Genetic/Molecular Universal genetic code!! All organisms use same triplet code! Many conserved sequences of amino acids in proteins and of nucleotides in DNA. Shared genes and proteins among organisms. Biol 1000 - Dr. M. Cardinal-Aucoin 35  Darwinian Evolution Evidence for Darwin’s Theory 2. Homology: Vestigial Genetic/Molecular Icefish are a group of fish Icefish species that live in the frigid waters of the ocean around Antarctica. Only vertebrates that lack https://www.thoughtco.com/antarctic-or-crocodile-icefish-2291921 Trout gills Icefish gills hemoglobin. – Thinner blood as adaptation to extreme environment? Biol 1000 - Dr. M. Cardinal-Aucoin 36  Darwinian Evolution Evidence for Darwin’s Theory 2. Homology: Vestigial Genetic/Molecular Despite absence Cod hemoglobin of hemoglobin gene icefish still have part of the hemoglobin Icefish https://www.thoughtco.com/antarctic-or-crocodile-icefish-2291921 gene! hemoglobin – From ancestor gene that had hemoglobin. Biol 1000 - Dr. M. Cardinal-Aucoin 37  Darwinian Evolution Evidence for Darwin’s Theory 2. Homology: Vestigial Genetic/Molecular All great apes have 24 pairs of chromosomes except humans which have 23. – If we share a common ancestor with the other great apes where did the https://www.thoughtco.com/antarctic-or-crocodile-icefish-2291921 24th chromosome pair go? – Complete loss unlikely because carries too much information. Biol 1000 - Dr. M. Cardinal-Aucoin 38  Darwinian Evolution Evidence for Darwin’s Theory 2. Homology: Vestigial Genetic/Molecular When human genome was published could search for missing chromosome. Extra Discovered that centromere! chromosome 2 was the result of end-to-end Vestigial fusion of two ancestral telomeres! chromosomes. – With vestigial telomeres! Biol 1000 - Dr. M. Cardinal-Aucoin 39  Darwinian Evolution Evidence for Darwin’s Theory 3. Convergent Evolution When characters are similar, but are not derived from a common ancestor = Analogous. Analogous features demonstrate that organisms with separate ancestors may adapt in similar ways to similar environment. Independent evolution of similar structures in distantly related organisms. Usually superficially similar. E.g. wings of bird, bat, and bee. Biol 1000 - Dr. M. Cardinal-Aucoin 40  Darwinian Evolution Evidence for Darwin’s Theory Divergent evolution Convergent evolution Adaptive radiation result of Similar selective different selective pressures. pressures. Homology Analogy Biol 1000 - Dr. M. Cardinal-Aucoin 41  Cells Evolve Divergent evolution Convergent Evolution Prokaryotic ATPases flagellum Kishikawa J-i, Ibuki T, Nakamura S, Nakanishi A, Minamino T, Miyata T, et al. (2013) Common Wikimedia Commons Evolutionary Origin for the Rotor Domain of Rotary Atpases and Flagellar Protein Export Apparatus. PLoS ONE 8(5): e64695. https://doi.org/10.1371/journal.pone.0064695 Biol 2021 - Dr. M. Cardinal-Aucoin 42  Darwinian Evolution Evidence for Darwin’s Theory 4. Biogeography Species distributions can be explained by their evolution. Species tend to be more closely related to other species from the same area than to species that live farther away. Suggests a common ancestor adapts to nearby habitats. Combine with geology: Break up of Pangea supercontinent (plate tectonics) stranded most marsupials in Australia. Placental mammals evolved after split and could not reach Australia until more recently. Biol 1000 - Dr. M. Cardinal-Aucoin 43  Darwinian Evolution Evidence for Darwin’s Theory 5. Fossil record Oldest fossil from around 4 bya. Cyanobacteria or "blue-green algae," fossils as far back as Precambrian. oldest cyanobacteria-like fossils are Stromatolites today. nearly 3.5 bya. Cyanobacteria are larger than most bacteria, and may secrete a thick cell wall. Often form large layered structures, called stromatolites (if more or less dome- shaped) or oncolites (if round). Stromatolite fossils. Biol 1000 - Dr. M. Cardinal-Aucoin 44  Darwinian Evolution Evidence for Darwin’s Theory 5. Fossil record First fossil single cell eukaryotes ca. 1.8 bya (Parfreya et al. 2011). Therefore, prokaryotes were the only cellular Early fossil eukaryotes form of life for 2.1 billion years! True multicellularity (i.e. tissues, extracellular matrix, etc.) very soon after (around 1.8-1.5 bya). Multiple independent origins: Plants, animals, fungus, red algae, brown algae, myxomycetes, etc. Grypania, possibly earliest multicellular life. Biol 1000 - Dr. M. Cardinal-Aucoin 45  How is evolution relevant to cell biology? 1. Explain how cells evolved, where they came from, their history, the diversity of cells and their common features. 2. Explain the structure and function of cells, and how they have adapted to different environments and circumstances. Biol 1000 - Dr. M. Cardinal-Aucoin 46  Present day. So what does the fossil record tell us about the history of life on Earth? Formation of planet Earth about 4.6 billion years ago. Biol 1000 - Dr. M. Cardinal-Aucoin 47  Minor insignificant details (i.e. evolution of humans). Evolution of life, prokaryotes, eukaryotes and multicellularity. Biol 1000 - Dr. M. Cardinal-Aucoin 48  Present day. 6) Colonization of land 5) Animals 6 major events in the 4) Multicellularity history of life. 3) Eukaryotes Great oxidation event (GOE) 2) Prokaryotes 1) Abiogenesis (first life) Formation Earth Biol 1000 - Dr. M. Cardinal-Aucoin 49 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes 5. Endosymbiogenesis 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 50 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes 5. Endosymbiogenesis 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 51 Abiogenesis Prebiotic synthesis The molecules of life can be formed spontaneously under ‘prebiotic conditions.’ No fossil record but can study in lab by replicating early earth conditions and searching for molecules of life. Living things are composed of 4 classes of biological macromolecules: 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids Biol 1000 - Dr. M. Cardinal-Aucoin 52 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes 5. Endosymbiogenesis 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 53 Protocells Once certain types of lipids (phospholipids) form their chemical properties result in the instantaneous formation of micelles and liposomes in aqueous solution (water). Hydrophilic heads together. Hydrophobic tails together. Biol 1000 - Dr. M. Cardinal-Aucoin 54 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes 5. Endosymbiogenesis 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 55 RNA World RNA has properties of both DNA (information storage) and proteins (enzymes). Because of this many scientists think that RNA, not DNA, was the original information storage molecule in the earliest forms of life on Earth. Has gained support in recent years from experiments demonstrating that RNA can perform self-cleavage and autocatalyze its own synthesis (Johnston et al. 2001). Biol 1000 - Dr. M. Cardinal-Aucoin 56 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes 5. Endosymbiogenesis 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 57 Prokaryotes Small, “simple” cells with no nucleus or internal compartments. Alone for 2.1 billon years During this time prokaryotes evolved most of the biochemistry present in all forms of life: DNA replication, the genetic code, protein synthesis via transcription and translation, photosynthesis, and anaerobic and aerobic metabolism. And split into eubacteria and archaea. Biol 1000 - Dr. M. Cardinal-Aucoin 58 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes Between 3.9 and 5. Endosymbiogenesis 1.8 billion yrs ago 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 59 Endosymbiogenesis The ancestors of some organelles (e.g. mitochondria and chloroplasts) were free-living prokaryotes that were engulfed by larger cells (likely archaea) and gradually incorporated permanently into the host cells. Biol 1000 - Dr. M. Cardinal-Aucoin 60 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes 5. Endosymbiogenesis 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 61 Eukaryotes Compartmentalization Membrane-bound organelles specialized for different functions. Cellular trafficking Endomembrane system for protein sorting, packaging, delivery, secretion. More complex. Bigger Larger cells True multicellularity Multiple chromosomes Mitosis and meiosis Sexual reproduction – increased genetic diversity for natural selection Biol 1000 - Dr. M. Cardinal-Aucoin 62 Main Events in the Evolution of Cells 1. Abiogenesis 2. Protocells 3. RNA world 4. Prokaryotes 5. Endosymbiogenesis 6. Eukaryotes 7. Multicellularity Biol 1000 - Dr. M. Cardinal-Aucoin 63  Multicellularity First multicellular organisms arose about 2.7 bya. Took off around 1 bya, just before Cambrian Explosion. Multicellularity arose multiple times. Strong selective advantage Advantages: Size – there’s always room at the top Competition for food Protection from predators Division of labour Increased complexity Overcome limits to cell size (SA:V) Biol 1000 - Dr. M. Cardinal-Aucoin 64 Eukaryotes "The eukaryotic cell is evolution's major achievement: multicellular life is merely a crude elaboration." -Simon Conway Morris Biol 1000 - Dr. M. Cardinal-Aucoin 65  Next time… Biological Macromolecules Biol 1000 - Dr. M. Cardinal-Aucoin 66