Unit 1 The fundamental properties of life that distinguish it from nonlife are: 1. Self reproduction 2. Self regulation 3. Self renewal Reproduction: The creation of new individuals of the same species by already existing organisms is called reproduction Heredity: Heredity is the transmission of characteristics from parents to progeny. Because of heredity, children are similar to their parents. Variation: Variation is ability of organism to acquire new traits (ability to change). Duse to this, children are never identical to their parents. Reproduction, heredity and variation cause evolution. The evolutional history of species development is its phylogenesis. Living organisms can grow. The individual development of an organism from the moment when its first cell is created to the death of the organism is called ontogenesis. Irritability is the capability of living matter to respond to the environmental stimuli. Homeostasis is dynamic constancy of organism’s internal environment (constant concentration of solutes in the blood, pH and etc.). Integrity means that the organism is functionally indivisible and should be considered as a solid functioning unit. Discretion means that any organism is composed of various parts and can be considered as a group of structural and functional units. Organization levels of Molecules,cell,tissue,organs,organism,population, biogeocenosis (community) and biosphere matter: Taxonomy of humans: phylum Chordates, subphylum Vertebrates, class Mammals, subclass Placentals, order Primates, suborder Anthropoids (narrow-nosed apes), family of Hominids (humans), genus Homo (man) and species Homo sapiens (wise man). Cytology: a science studying the structure, chemical composition and functions of cells, their multiplication, development and interaction in a multicellular organism. Resolution: ability of the optical system to distinguish two closely spaced points as separate objects. Another definition of resolution is the minimal distance at which two points are distinguishable by the optical system as two different objects Resolution of the human eye- 100 micrometres Resolution of a light microscope- 200nm Resolution of a electron microscope: 0.2nm Histochemistry: Common dyes are distributed throughout the cell and stain many structures nonspecifically, but there are special dyes that stain only certain substances. Such differential staining of cells is called histochemistry. Histochemical reactions reveal the sites of specific chemical reactions or specific cellular components. Fluorescent dyes (e.g., acridine orange, which stains nucleic acids) are also used in histochemistry. Fluorescent dyes are the dyes that absorb light of one wavelength and re-emit light at a longer wavelength. Immunohistoche Morphometry is a set of methods used to measure the size or count the number of histological structures. Measurements can be made with the help of ocular micrometers mistry allows detection of specific proteins with antibodies bound with dyes. Antibodies are proteins of the immune system which can recognize specific antigen (usually a protein) and bind to it. Cell fractionation (differential centrifugation): This method is used to separate (fractionate) cell components according to their size and density. Autoradiography: This method detects radiation from isotopes contained in an object of study with a photosensitive film Components of the cell theory: Cell is the smallest living unit of all living organisms. Cells of animals, plants and other organisms are similar in structure, chemical composition and functioning. Growth and development of organisms occur due to multiplication and development of cells. New cells appear only by means of division of already existing cells. A virus is an infectious agent consisting of nucleic acid (DNA or RNA) enveloped into proteins and in some cases lipids. The outer protein shell of viruses is called capsid. An entire virus particle, consisting of capsid and an inner core of nucleic acid is called a virion. The protein envelope surrounding the nucleic acid of a virus is called a capsid. The capsid protects the viral genome from external influences and takes part in viral entry into the cell. It consists of multiply repeating proteins called capsomers. The capsomers fit each other to assemble a capsid. The capsid can make virus rod-shaped or nearly spherical (rarely other shapes are possible). Some viruses (hepresviruses, influenza virus) are also covered with a lipid envelope called. It originates from the membrane of the infected cell (or the membrane of the nucleus). The lipid envelope also contains viral glycoproteins. Typical virus life cycle: Attachment of the viral particle to the cell surface. Entry of the virus into the cell. Synthesis of viral proteins nucleic acids. viral particles leave the cell. There are three possible patterns of viral genome replication: 1. DNA → DNA. If the viral DNA is double-stranded, its replication is similar to the replication of cellular genome. Such viruses commonly use DNA polymerase of the host cell. 2. RNA → RNA. Infected cells do not have the enzyme that can replicate RNA and most RNA viruses contain a gene encoding RNA replicase. 3. RNA → DNA → RNA. Some RNA viruses encode reverse transcriptase, an enzyme that makes DNA on the RNA template. The viral nucleic acid and capsid proteins spontaneously assemble into new viral particles, a process called self-assembly. For example, the tobacco mosaic virus can be "disassembled" in the laboratory. When the components of the virus are mixed, they spontaneously assemble into virions. Transposons Transposons are DNA sequences that can move from one location of the genome to another. They are found in both prokaryotes and eukaryotes. They are of two types: Transposons (or DNA transposons), which can move by a “cut-and-paste” mechanism. Retrotransposons, which can move by the "copy+paste" mechanism with reverse transcription. The enzymes necessary for this are encoded by the transposon itself. Viroids and prions Another class of plant pathogens are viroids. They are small, circular RNA molecules that do not encode proteins but replicate in the host plant cells. Viroids probably disrupt normal plant metabolism, by causing errors in the systems that control gene expression. Prions are defective (misfolded) forms of normal cellular proteins. When prions infect normal cells, they convert normal proteins into prions. X-ray crystallography allows to determine the three-dimensional structure of biomolecules. This method is based on the diffraction of X-rays passing through the crystal of the substance under study. Mathematical processing of the obtained data in combination with knowledge about the chemical properties of the substance helps to determine its three-dimensional structure. Microsurgery of cells is the method allowing removing and transplanting organelles of the cell. A cell culture is cells of any tissue grown in a laboratory dish in a special nutrient medium under controlled conditions. Focal distance- the point where far away light converges on passing through the lens.
