Study of life

1. Study of life Premedical course - Biology

2. Biology includes among other • two different approaches • understanding all via study on the smallest level of life • Continuity of life is based on genetic information. • Orderliness, structure and functional coupling is encoded in the DNA molecule • understanding diversity and unity via study evolutionary processes

3. Organisms Populations Communities Ecosystems The Biosphere Molecules Organelles Cells Tissues Organs+Organ Systems Levels of Biological Organization

4. Organization • The cell is the basic structural and functional unit of the organism. • The cell is the lowest level structure, which is able to carry out all life processes. • Unicellular organism • Single cell – • Bacteria and Protista • - Amoebas

5. Multicellular organisms Structure and function are interrelated at all levels of organisation. Form fits function. Schizosaccharomyces pombe Caenorhabditis elegans Xenopus laevis Drosophila melanogaster

6. 2. Metabolism • Organisms are open systems • the flow of energy –photosynthesis in producers(plants, algae (photosynthetic protist), some bacteria) convertssolarenergy into energy of chemical bondsforconsumers (animal feeding on plants) • CELLS manage endless belt of chemical reactions, chemicals and energy is converted into cellular components

7. The cell compose, decompose and alter nutritive substances as aminoacids, lipids, sugars, nucleotides, proteins and other. • Catabolic reactions – degradation of nutrients to small molecules; the cell use some of them as building stones, • useful form of energy is released • Anabolic reactions use the same energy for biosynthesis

8. 3. Homeostasis: regulation of the internal environment to maintain a constant state Temperature, water, pH, electrolytes Regulatorstry to maintain the parameter at a constant level over possibly wide ambient environmental variations. endothermic animals - mammals and birds Conformers allow the environment to determine the parameter. exothermic (both ectotherm and poikilotherm) – reptiles and some sea animals

9. Many biological processes are self-regulating, they operate by a mechanism called feedback, in which an output or product regulates that process. Negative feedback – inhibition, level of glucose and insulin temperature in birds and mammals

10. Positive feedback - blood precipitation, the function of blood platelets Schema to illustrate the positive feedback loop (heavy arrows) whereby activated platelets accelerate thrombin generation, and thrombin in turn increases platelet aggregation.

11. 5. Evolutionary adaptation Evolution is the fundamental theme of biology. The ability to change over a period of time in response to the environment. This ability is fundamental to the process of evolution . Ursus arctos horribilis Ursus maritimus

12. 4. Growth and development • Maintenance of a higher rate of anabolism than catabolism. A growing organism increases in size in all of its parts, rather than simply accumulating matter. • Cell growth – proliferation: cell development and division

13. Bacterial growth is binary fission, bacterial growth in batch culture • can be modeled with four different phases Kingdom Protista Subkingdom Protozoa Phylum Ciliophora Paramecium - binary fission

14. Plants • Rely on soil primarily for support and water • Obtain compounds of nitrogen, phosphorus, and other nutrients • Require oxygen in the atmosphere and for respiration • Fungal growth • as hyphae on or in solid substrates • Human, Animal development • The zygote undergoes rapid cell divisions with no significant growth (a specific process known as cleavage) and cellular differentiation, leading to development of an embryo.

15. 6. Response to stimuli • can take many forms • the contraction of a unicellular organism to external chemicals • complex reactions involving all the senses of multicellular organisms • A response is expressed by motion, • for example, the leaves of a plant • turning toward the sun (phototropism) • and by chemotaxis.

16. 7. Reproduction The ability to produce new individual organisms, either asexually from a single parent organism, or sexually from two parent organisms. Asexual reproduction is notlimited to single-celled organisms. Most plants have the ability to reproduce asexually. - binary fission- Bacteria - budding - yeasts and Hydras (invertebrates of the order Hydroidea) budding yeast (arrows)

17. - conjugation- bacteria may exchange genetic information • Donor’s plasmid(sexual plasmid) F+ • passes into acceptor’s cell F-,F-pili • on surface of one bacteria strain – F+, • through conjugative bridge • parthogenesis, fragmentation and • spore formation that involves only mitosis. • - hermaphroditic species can self-fertilize.

18. Parthenogenesis occurs naturally in some species, including lower plants (where it is called apomixis), invertebrates (e.g. water fleas, some bees and parasitic wasps), and vertebrates (e.g. some reptiles,fish, and very rarely, birds and sharks). Wingless female giving birth Aphis Aphid Green-fly) baby hammerhead

19. Sexual reproduction by combination of genetic material contributed from two different members of the species Each contributes half of the offspring's genetic makeup by creating haploid gametes. In anisogamous species, the two sexes are referred to as male (producing sperm or microspores) and female (producing ova or megaspores).

20. Sexually reproducing organisms have two sets of genes for every trait (called alleles). Offspring inherit one allele for each trait from each parent, thereby ensuring that offspring have a combination of the parents' genes. Autogamy Self-fertilization (also known as autogamy) occurs in hermaphroditic organisms Allogamy describing the fertilization of an ovum from one individual with the spermatozoa of another.

21. Characteristics of the living systems: high organization, orderliness dynamic system,maintain homeostasis metabolism - ability of energy consumption and transformation growin terms of kind ability of development and adaptation in time – evolutional adaptation answer to outer stimulus - opened system exchange of molecules and energy ability of reproduction, life come from life

22. Thank you for your attention Campbell, Neil A., Reece, Jane B., Cain Michael L., Jackson, Robert B., Minorsky, Peter V., Biology, Benjamin-Cummings Publishing Company, 1996 –2010.