And after that, as you know, after the hunter time, then people went int agriculture and the cities began to form. Then there was a surplus of grain a...полностью>>
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- The mitochondria has an egg shape structure. The mitochondria consists of an inner and outer membrane. The outer membrane is what shapes the organelle to its egg like shape. The inner membrane which folds inward makes a set of “shelves” or cristae that allow the reactions of the mitochondria to take place.
- Cells are composed of oxygen, hydrogen, carbon, and nitrogen, which contain most important organic compounds in a cell are proteins, nucleic acids, lipids, and carbohydrates,Water makes up 60 to 65 percent of the cell.Some cells are complete organisms, as the unicellular bacteria and protozoa; others, such as nerve, liver, and muscle cells, are components of multicellular organisms,Cells range in size from the smallest bacteria like mycoplasmas, which are 0.
- Cells are some of the smallest organisms around. All living things consist of cells, and yet they are invisible to the naked eye. How and why are they so small? Well, cells are the basic structural and functional units of life. As life on earth has evolved into organisms of different species and living things, two basic laws of nature have dictated why cells have remained so small.
- The rough endoplasmic reticulum contains ribosomes which are not present in the smooth endoplasmic reticulum. The rough endoplasmic reticulum allows the cell to produce proteins.
- Prokaryotic cells have a simple structure and they are usually smaller than eukaryotic cells. Also, most prokaryotic cells contain a cell wall. In addition to having the basic cell parts, eukaryotic cells also contain a membrane-bounded nucleus and cell organelles.
- This biological kingdom is composed of bacteria and cyanobacteria, one-celled (sometimes colonial) organisms whose cells lack a nuclear envelope, mitochondria, or plastids. They reproduce asexually through fission (splitting in two) and mainly gain their nutrition by absorbing it from their environment (though some species are chemoautotrophs or photosynthetic).
- Living things make up the world as we know it. Living things are involved in our life constantly, seeing that we are alive. There are five characteristics that are common to all living things. Living things are made up of one or more cells. Each cell is made up of living matter and is separated by a barrier that encloses the cell from its surroundings.
- however Darwin’s findings marked a revolution of thought and social upheaval unprecedented in Western consciousness challenging not only the scientific community, but the prominent religious institution as well.
- Cyanobacteria is any of a large, heterogeneous group of prokaryotic, principally photosynthetic organisms. Cyanobacteria resemble the eukaryotic algae in many ways, including morphological characteristics and ecological niches, and were at one time treated as algae, hence the common name of blue-green algae.
- Mitosis is the process that facilitates the equal partitioning of replicated chromosomes into two identical groups. Before partitioning can occur, the chromosomes must become aligned so that the separation process can occur in an orderly fashion. The alignment of replicated chromosomes and their separation into two groups is a process that can be observed in virtually all eukaryotic cells.
- Mitochondria are tiny organelles found in nearly all eukaryotic cells. They are rather large organelles ranging from 0.5+m to 10+m in length and 1+m in diameter. The mitochondria are the energy factories of the cell and are located in the cytoplasm. They are the sites of cellular respiration.
- CONVERGENT EVOLUTION ………………….. 39 CONCEPT OF ADAPTATION ………………………………. 41 PUNCTUATED EQUILIBRIUM ………………………………43 VALUE/LIMITATIONS: THE THEORY OF BIOLOGICAL EVOLUTION …. 45 ALTERNATE EXPLANATIONS OF BEING ……………………… 47 CONCLUSIONS ……………………………………….
- To understand how this creation of life from abiotic material occured, we have to consider a critical idea. Life originated from its abiotic surroundings. Thus, it is important for us to learn about the physical and chemical environments of the primitive Earth.
- Plague, was a term that was applied in the Middle Ages to all fatal epidemic diseases, but now it is only applied to an acute, infectious, contagious disease of rodents and humans, caused by a short, thin, gram-negative bacillus. In humans, plague occurs in three forms: bubonic plague, pneumonic plague, and septicemic plague.
- BIOLOGY 2 1. ORAGANELLES2. TYPES OF CELLS3. OSMOSIS/ DIFFUSION4. CELL THEORY 1. ORGANELLES small structures embedded in the cytoplasm e.g. plastids, vacuoles, mitochondria, lysosomes, centrosomes, endoplasmic reticulum (e.r.) 2. TYPES OF CELLS A. Prokaryotic Cells 3.
- Fungi is a group of single celled or multicellular organism which obtain their food by the absorption of nutrient from it s surrounding environment. Food is dissolved by the enzymes from which the fungi excrete and is later absorbed by the fungi s cell walls.
- . The adult fern plant in its dominate generation (sporophyte) develops sporangium on one side of its leaf. When meiosis is finished inside the sporangia and the spores are completed the annulus dries out releasing the spores.
- Scientists have formulated many theories about the origin of life and how it evolved into the various forms known today. These ideas come from the evidence of the fossil record, from laboratory simulations of conditions on the earth, and from consideration of the structure and function of cells.
- O, sulfate Chemosynthesis – process where certain bacteria obtain energy from oxidation of inorganic compounds and obtain C from CO - Bacterial Structure - Lypopolysaccharide – polysaccharide chain with lipids attached - Molecules of it deposited over layer of gram positive – forming outer membrane - Makes gram negative bacteria resistant to many antibiotics to which gram positive bacteria are susceptible - Capsule – gelatinous layer surrounding cell - Bacilli – straight, rod-shaped bacteria - Cocci – spherical bacteria - Spirilla – spirally coiled bacteria - Spores – single-celled bodies that grow into new bacterial individuals - Some bacteria change into stalked structures, grow long, branched filaments or form erect structures that release spores - Bacterial cells have simple structures - kinds of cell walls – gram negative/positive - Cytoplasm of a bacterium contain no internal compartments/organelles & is bound by a membrane encased w/i a cell wall composed of 1/more polysaccharides - Pili – other kinds of hairlike outgrowths that occur on some bacteria cells – shorter than flagella - Help bacterial cells to attach to appropriate substrates - Endoscopes – resistant to environmental stress; may germinate & form new bacterial individuals after decades/centuries - Bacterial Variation - processes lend variability to bacterial reproduction - Mutation - Because of the short generation time of bacteria whose populations often double in a few min., mutation plays important role in generating genetic diversity - Genetic Recombination - Transfer of genes from one cell to another as portions of viruses, plasmids, other DNA fragments *Intestinal bacterium: typhoid, dysentry, other diseases - Bacterial Ecology and Metabolic Diversity - Bacteria most abundant organisms in most environments - Obligate anaerobes – organisms cannot grow in presence of O - Facultative anaerobes – organisms that function as anaerobes/aerobes - Aerobes – organisms that require O - Autotrophic bacteria - Heterotrophs – get energy from organic material formed by other organisms (most bacteria) - Autotrophs – obtain energy from nonorganic sources - Photosynthetic bacteria – contain chlorophyll but not held in plastids *Cyanobacteria, green/purple sulfur bacteria, purple nonsulfur bacteria - Different colors caused by photosynthetic pigments - Chemoautotrophic bacteria – derive energy from the oxidation of inorganic molecules (N, S, Fe compounds, gaseous H) - Heterotrophic bacteria - Saprobes – bacteria that obtain nourishment form dead organic material - Autotrophic bacteria, capable of making their own food, obtain energy from light or the oxidation of inorganic molecules - Heterotrophic bacteria obtain energy from breaking down organic compounds made by other organisms - By-products of bacterial metabolism - Antibiotics – valuable - Botulism – food poisoning - Salmonella – gastrointestinal disease - N-fixing bacteria - N fixation – carried out by nodule-forming bacteria - Bacteria releases fixed N (when they break down proteins) - N cycle carried out exclusively by bacteria - Bacteria as plant pathogens - Most plant diseases caused by bacteria - Most bacteria that cause plant diseases are from a group of rod-shaped bacteria called pseudomonads * Citrus canker (Florida) – destroy citrus seedlings - Bacteria as human pathogens - Cholera, leprosy, tetanus, bacterial pneumonia, whooping cough, diptheria - Many diseases dispersed in food/water - Legionnaires?s Disease - Severe pneumonia – fatal in 15- 0% of victims if untreated - Caused by legionella – small, flagellated, rod-shaped, gram/-, bacteria w/ pointed ends - Common in water - Attacks monocytes (type of white blood cell) - Destroyed with erythromycin treatment - Sexually Transmitted Diseases - Gonorrhea, syphilis – controlled w/ antibiotics (syphilis – penicillin) - Infections caused by Chlamydia trachomatis (bacteria) - Painful symptoms – causes sterility - Controlled w/ antibiotic tetracycline - Causes arthritis in young people - Dental Caries (decay) - Causes cavities in dental plaque (film on teeth) - Plaque consists of bacteria cells surrounded by polysaccharide matrix - Caused by diets high in sugar - Prevented w/ antibiotics - Bacterial Diversity - Archaebacteria – distinctive membranes, unusual cell walls, unique metabolic cofactors - Eubacteria – kingdom Archaebacteria belongs in - Methanogenic – prominent Archaebacteria - Produce methane from CO & H to obtain energy - Source of marsh gas - Reduce S to form hydrogen sulfide - Archaebacteria ancient group of prokaryotes that are different from eubacteria – seem to be direct ancestors of eukaryotes - Omnibacteria – rigid, rod-shaped, heterotrophic, gram/+ - Vibrios – comma-shaped that have single terminal flagellum - Obligate parasites – organisms that can live only as parasites - Rickettsias – bacteria causing Rocky Mountain spotted fever - Cyanobacteria – photosynthetic bacteria – bring about increase of free O in the atmosphere (crucial for eukaryotic evolution) - Produce accumulation of limestone deposits (stromatolites) - Phycobilins – accessory pigments that are blue & red & water soluble - Only in cyanobacteria, red algae, & cryptomonads - Mucilaginous sheath that can be different colors (blooms in H3O) - Fix atmospheric N in cells called heterocysts (especially important in rice fields) - Chloroxybacteria – photosynthetic bacteria - Fixes N - Biochemical characteristics give rise to chloroplasts of green algae - Mycoplasmas – Aphragmabacteria (phylum name) - Cause diseases in mammals & birds *Premature labor in women *Pneumonia - Treated with antibiotics - Spiroplasmas – cause plant diseases *Aster yellow - Both (spiro-/myco- plasmas) lack cell walls & cells bounded by 3-layered lipid membrane - Resistant to antibiotics & penicillin working to inhibit cell growth - Spirochaetes – long spirilla where flagella are inserted beneath outer lipoprotein membrane of gram/- outer cell wall - Agents of syphilis & yaws (disfiguring eye disease) *Lyme disease (inflammatory ailment)- treated w/ penicillin/tetracycline -Pseudomonads – straight/curved gram/- rods w/ 1/more flagella at one ent - Soil/water – break down organic compounds (autotrophic) - Plant pathogens – infections to people who eat the plants -Actinomycetes – produce spores by division of terminal, erect branches into chains of small segments - N fixing molecules formed at roots of flowering plants - Dental plaque, leprosy, tuberculosis - Ivermectin – antiparasitic agent,
- An emerging hypothesis is that the up regulation or reexpression of telomerase is a critical event responsible for continuous tumor cell growth. In contrast to normal cells, tumor cells show no loss of average telomere length with cell division. Through this suggestion immortalization may occur through a mutation of gene in the telomerase repression pathway allowing the expression of telomerase in cancer cells.