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Molecular Biology 1-1


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Life and Evolution: The images have big font size and reduced background color. Useful for smartphone,classroom and printouts. The rest is standard stuff.

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Molecular Biology 1-1

  1. 1. Molecular Biology 1-1 put together by: Linda Fahlberg-Stojanovska Disclaimer: I put these together for my kid for his smartphone. However, I found most images had very small type and increased thefont size. I am posting it because another teacher might find this useful. The sources are given. If I have used anything illegally, write me and I will take it off. 1
  2. 2. Contents• Life• Evolution
  3. 3. KEYWORDSLife is the primary characteristic of organisms.Organism is any connected living system capable of • response to stimuli, • reproduction, • growth and development • adaptation to environment • homeostasisHomeostasis is the property of organisms • regulates its internal environment • maintains a system of stable constant conditions like • temperature or pH. 3
  4. 4. KEYWORDSCell is the basic structural and functional unit of an organism. The main purpose of cell is to organize.Organelle is a subunit within a cell with a specific function. It is usually membrane-bound.Tissue is a layer of cells that are alike and work together for a specific function. Tissue is the cellular organizational level between cells and a complete organ.Organ is a• functional group of multiple tissues• relatively independent part of the body• carries out one or more special functions 4
  5. 5. Organismscan be classified as: - single-cellular - multi-cellularProkaryotes: bacteria and archaeaEukaryotes: all other organisms!Viruses are not organisms or cells. 5
  6. 6. Prokaryotes • unicellular • no cell nucleus • no mitochondria • no membrane-bound organellesNeither their DNA nor sites of metabolic activity arecollected together in a discrete membrane-enclosedarea.Instead, everything is openly accessible within thecell, some of which is free-floating. 6
  7. 7. Prokaryotes vs. Eukaryotes 7 c
  8. 8. Developmental Eras• Earth is probably 4.5 billion years old• 3.8 billion years of simple cells (prokaryotes = bacteria and archaea)• 3 billion years of photosynthesis,• 2 billion years of complex cells (eukaryotes),• 1 billion years of multicellular life,• 600 million years of simple animals, 8
  9. 9. Cell SizeBacteria • microbacteria ~150 nm • E. coli 1,5 µm x 5 µm • Exceptional: ~10 µm up to >100 µmHuman Cells: • erithrocytes ~ 8 µm • ovum (egg) ~ 100 µm • nerve cells ~ 4 µm – 100 µm 9
  10. 10. CELLCell is the basic structural and functional unit of an organism.Humans contain about 10 trillion (1013) cells.Most plant and animal cells are • between 1 and 100 µm • Visible only under the microscope. 10 OilImmer.htm
  11. 11. Relative Sizes 11
  12. 12. KEYWORDSEvolution is a science that investigates the development of species.Creationism is the belief that life on Earth was created directly by a supernatural being.Phylogeny is the science that studies the evolutionary relationships between groups of organisms (populations, species, ...).Taxonomy is a system of classification of organisms into groups according to their relationships and evolutionary development 12
  13. 13. Evolution and MutationStart with:• Common origin of species.• Genetic changes accumulate and lead to the emergence of new characteristics.• Genetic changes are the result of mutations, introduction of new genes or recombination of genes.• New characteristics are inherited.• Natural selection: the environment represents a selection pressure to force only characteristics that represent an advantage for survival and reproduction.• When populations are separated, different characteristics are selected and new species develop. 13
  14. 14. Evolution and Mutation 14
  15. 15. Classification Organisms - DomainsCategory: DomainThere are 3 domains. - Bacteria - Archaea - EukaryotesIn 1990, the category “Domain” was added after C. R. Woesedistinguished Bacteria and Archaea based on differences in theirrRNA 16SThe three-domain system adds the level of classification Domainsabove the level of Kingdoms. 15
  16. 16. TaxonomyDOMAIN Eukaryota 16
  17. 17. Kingdoms = 6Prokaryotes: eubacteria, archaebacteriaEukaryotes: protista, plants, animals, fungiHistory of KingdomsLinnéas: 2 (animals and plants) ~1960: 4 basic divisions prokaryotes and eukaryotes ~1969: 5 (fungi is added) ~1980: 6 17
  18. 18. History of TaxonomyOn the Earth there are 5-100 million different species of organisms.They differ in morphology, biochemical and genetic characteristics.The first really successful attempt at grouping of organisms wascarried out by Linnaeus with the introduction of species and genera.Species representing "all instances of creatures” that are each equalto the smallest details of physical structure.Darwin: " “all true classification is genealogical”Ernst Mayer (~ 1940): biological species is a population or set ofpopulations who can breed with each other and have fertileoffspring. 18
  19. 19. Keywords• Morphology (biology): the study of the form or shape of an organism.• Biochemical Characteristics: characteristics which describe the chemical substances and vital processes occurring in living organisms.• Genetic Characteristics: characteristics which are related to heredity and the variation of inherited characteristics among similar or related organisms. 19
  20. 20. Genotype vs. PhenotypeGenotype: All of the genetic code of an organism.Phenotype: All of the properties of an organism.Phenotype reflects the genotype, as well as environmental influences (diet, climate, injuries, lifestyle, …). 20
  21. 21. Phylogenic TreePhylogenic tree can be drawn on the basis of:- similaritiesbetween organisms (fosils and their age, anatomy,…)- differences between their amino acids and proteins- differences between nucleotides in their DNA and RNA Differences based on molecular biology is called molecular phylogeny. A node (taxa) joined together in the tree implies “descended from a common ancestor”. 21
  22. 22. Phylogenetic Tree for the 3 Domains 22
  23. 23. Dots indicate common ancestor. Numbers indicate “relative” amount of change in genome.Phylogenetic tree based on similarities between genome sequences. The genome is an organism’s complete set of DNA. 23