Biology 1052 - Evolution PDF

Week 2: Study of Life & Evolution of Life Charles Darwin (Father of Evolution): ​ Initially believed that species had remained unchanged since the time of creation. ​ During his 5-year voyage, he collected and recorded the geological and biological diversity. ​ While travelling to the G...

Week 2: Study of Life & Evolution of Life Charles Darwin (Father of Evolution): ​ Initially believed that species had remained unchanged since the time of creation. ​ During his 5-year voyage, he collected and recorded the geological and biological diversity. ​ While travelling to the Galapagos Islands, Darwin observed differences in the size and shape of beaks between finches on different islands. Theory of Evolution: ​ EVOLUTION: any evolved trait that helps an organism be more suited to its environment. Natural Selection: ​ Individual organisms in a species exhibit variation that is BLANK. -​ Can be passed from one generation to the next. ​ Organisms compete for available resources. -​ Individuals in a population produce more offspring than the environment can support ​ Some individuals in a population have favorable traits that enable them to better compete for limited resources (survival of the fittest) -​ Will have greater reproductive success. ​ Organisms become adapted to environmental conditions, as traits that are favorable will increase in a population due to increased reproductive success. -​ Descent with modification Theory of Evolution: ​ One scientist that influenced Darwin was a predecessor named Jean-Baptiste de Lamarck. ​ Lamarck developed the theory of inheritance of acquired characteristics. -​ The environment can bring about an inherited change. Lamarck Darwin Inheritance of acquired characteristics Evolution by Natural Selection ​ The example used by Lamarck was ​ Darwin’s theory would predict that that the long neck of the giraffe giraffe populations would include developed over time because giraffes individual giraffes with longer necks stretched their necks to reach food in than others. trees. ​ Individuals with longer necks could ​ They then passed gradually longer reach more leaves, acquire more necks to their offspring. energy, and potentially produce more offspring that inherited the long neck trait. ​ Over time, the trait would be more common in a population (adaptation to the environment). Think, Pair, Share: ​ What are some examples of adaptations that have evolved in living organisms? -​ The shape of a bird’s beak -​ The color of a mammal’s fur -​ The thickness or thinness of the fur -​ That shape of the ears or nose ★​ Help for survival Evidence of Evolution - Fossils: ​ Some fossils serve as transitional links between groups. -​ They have some traits like their ancestors and others like their descendants. Evidence of Evolution - Biogeographical: ​ CONTINENTAL DRIFT: the position of the continents and oceans has shifted throughout Earth’s history. ​ Australia has many distinct species because it has been geographically isolated for about 50 million years. Evidence of Evolution - Anatomical: ​ HOMOLOGOUS STRUCTURE: anatomically similar because they are inherited from a common ancestor. -​ Forelimbs of different species share same general structure but different function ​ ANALOGOUS STRUCTURE: NOT anatomically similar; not from a common ancestor. -​ Similar function because of similar environments. Evidence of Evolution - Biochemical: ​ Humans and chimpanzees have a high degree of similarity in DNA sequences.  -​ 97% related Terminology: ​ GENE: a segment of DNA information for one specific trait/protein. ​ ALLELES: variation in a gene. Processes of Evolution: ​ EVOLUTION is the change in traits that are heritable. -​ Evolutionary change occurs in populations over many generations. ​ We now understand evolution in terms of genetic inheritance, as genes interact with the environment. -​ A gene is a segment of DNA that codes for a trait. -​ Traits are passed from one generation to the next via alleles (alternate forms of a gene). Mutations: ​ MUTATIONS are changes in the DNA. -​ Change in segment of chromosomes -​ Variations in alleles -​ Sequences of DNA -​ Environmental factors ​ The only source of new inheritable variation in a population. ​ Mutations are random events. -​ A mutation does not arise because the organism “needs” one. ​ Some are beneficial (provide a survival advantage), and some are harmful.. ​ New mutations can cause variation of genes in a population. -​ Nature has more options. Genetic Drift: ​ GENETIC DRIFT refers to a change in small population’s allele frequency due to a random chance. -​ Change of variation → narrows the variation  ​ It’s not based on fitness but pure luck of any natural disaster or random event. ​ NATURAL DISASTERS: hurricane, volcano, tsunami, earthquake, fire etc. ​ RANDOM EVENTS: stepped on, ran over, picked up etc. ​ FOUNDERS EFFECT: part of the original population colonized a new area. ​ BOTTLENECK EFFECT: a natural disaster happens leaving few survivors from an original population. Gene Flow: ​ GENE FLOW is the movement of alleles between populations. -​ Increase in the variation. -​ Individuals or their gametes migrate from one population to another and breed in the new population. ​ Gene flow mixes genetic diversity. -​ More diversity. Natural Selection: ​ Some individuals in a population have favorable traits that enable them to better compete and survive (survival of the fittest). ​ Over the years, nature’s actions select populations with favorable traits that are passed onto the future generation/descendents. Non-random Mating: ​ NON-RANDOM MATING occurs when individuals are selective about choosing a mate with a preferred trait. -​ Less diversity. ​ Random mating is never observed in natural populations, because most sexually reproducing organisms select mates based on some trait. ​ ARTIFICIAL SELECTION is a human-controlled breeding to increase the frequency of desired traits. Microevolution: ​ Within species variation. -​ Same species ​ EX: Different breeds of dogs, due to artificial selection. Macroevolution: ​ The process of evolution on a large scale. -​ Results in the formation of a new species. ​ SPECIATION: when one species gives rise to two species -​ Recall: species – a group of similar, interbreeding organisms.  -​ They are reproductively isolated from other species. ​ Ex. New species of salamanders, in California, evolved from a Northern species Populations are reproductively isolated by the geographical barrier. Week 3: Cell Structure and Function Cells Cell: ​ The CELL is the structural and functional unit of an organism, the smallest structure capable of performing all the functions necessary for life. ​ All cells have 3 things in common: 1.​ Cell/Plasma Membrane 2.​ Cytoplasm 3.​ Genetic Material (DNA) Cell Theory: ​ Cells are the basic units of life. ​ All living organisms are composed of one or more cells. ​ All cells come only from previously existing cells. Types of Cells: ​ PROKARYOTIC CELLS lack membrane enclosed structures. ​ EUKARYOTIC CELLS possess membrane enclosed structures. Plasma Membrane and Cytoplasm: ​ All cells are surrounded by a PLASMA MEMBRANE. ​ The material inside of a cell is the CYTOPLASM.  ​ The plasma membrane regulates what enters and exits a cell. ​ Head → polar ​ Tail → nonpolar → hydrophobic ​ Intro → inside ​ Inter = between Learning Check: ​ Which of the following organelles is the principal and distinguishing feature of the eukaryotic cell? a)​ Mitochondria b)​ Chloroplast c)​ Nucleus d)​ Ribosomes e)​ Lysosomes Surface Area/Volume Ratio ​ Not all cells are the same size. ​ The fact that cells are so small is a great advantage for multicellular organisms. ​ The amount of surface area affects the ability to get materials in and out of a cell. ​ As cells increase in volume, the proportionate amount of surface area decreases. ​ All three have the same volume, but the group on the right has four times the surface area. Prokaryotes: ​ Structurally simple.  ​ Metabolically diverse. ​ Adapted to most types of environments. ​ Felagella = plural ​ Pili = plural ​ Pilus = singular ​ Plasmid = small circular DNA ​ Protein factory of cells. ​ Not linear. Eukaryotes (Animal and Plant): ​ Are structurally complex. ​ Have a nucleus. ​ Possess membrane-bound organelles. ​ Examples are animals, plants, fungi and protists. Nucleus: ​ Stores DNA. ​ Nucleolus. ​ Nuclear Envelope. -​ Double membrane, continuous with endoplasmic reticulum, disappears during cell division. -​ Nuclear pores → bidirectional transport of proteins and ribosomal subunits Ribosomes: ​ Site of protein synthesis. ​ Two subunits (large and small). -​ Subunits consist of rRNA and protein molecules. ​ Polyribosomes. -​ Several ribosomes with a single mRNA molecule. Endoplasmic Reticulum:  ​ Consists of membranous channels and saccules (flattened vesicles). ​ Rough ER. -​ Processing and modification of proteins. -​ 3D protein functional ​ Smooth ER. -​ Synthesizes phospholipids. -​ Produces lipids. Golgi Apparatus: ​ Post office of the cell. ​ Collects, sorts, packages, and distributes materials such as proteins and lipids. ​ Proteins made in Rough ER have tags that serve as “zip codes” to direct Golgi apparatus where to send them. Lysosomes: ​ Contain hydrolytic digestive enzymes that break down unwanted, foreign substances or worn - out parts of cells. ​ Considered the garbage disposal of the cell. ​ Only in plant cells. Vacuoles: ​ Membranous sacs that store substances. ​ EX: water, pigments, toxins ​ Only in plant cells. Peroxisomes: ​ Membrane bound vesicles containing enzymes. ​ The enzymes break down molecules (fatty acids) and as a result produce hydrogen peroxide (H2O2). ​ H2O2 is then broken down to water and oxygen. ​ Peroxisomes found in liver cells ​ In both plant and animal cells. Endomembrane System: ​ Nuclear envelope ​ Endoplasmic reticulum ​ Golgi apparatus ​ Vesicles Learning Check:  ​ The ______ function(s) in the packaging, storage, and distribution of molecules produced by the ER. a)​ Golgi apparatus b)​ Lysosome c)​ Nucleus d)​ Mitochondria e)​ Centrioles Energy-Related Organelles: ​ Chloroplasts use solar energy to synthesize carbohydrates. ​ Carbohydrates are broken down in Mitochondria. Chloroplasts: ​ Site of photosynthesis. ​ Structure: -​ Double-membrane -​ Stroma -​ Grana ↳​ Thylakoids ​ Chloroplasts contain: -​ Their own DNA -​ Ribosomes -​ Enzymes Mitochondria: ​ Found in all eukaryotic cells. ​ Site of cellular respiration. ​ Structure: -​ Double-membrane -​ Matrix -​ Cristae ​ Mitochondria contain… -​ Their own DNA -​ Ribosomes -​ Enzymes Cytoskeleton: ​ Maintains cell shape. ​ Assists in movement of cell and organelles. ​ Assemble and disassemble as needed.  ​ Three types of macromolecular fibers: 1.​ Actin Filaments 2.​ Intermediate Filaments 3.​ Microtubules Actin Filaments: ​ Smallest among all three cytoskeletal fibers. ​ Are long, extremely thin (7nm), flexible fibers. ​ 2 filaments wrapped around each other. ​ Mechanical support. ​ Determines cell shape. ​ Allows movement of the cell surface: -​ Enabling cells to migrate. -​ Engulf particles. ​ Play a role in animal cell division. ​ Anchored to the plasma membrane. ​ Allows intestinal microvilli to expand and contract. ​ Play a role in animal cell division, cell movement.