General-Biology-1st-Quarter.pdf

History of the Cell Hans and Zacharias Janssen Invented the first primitive Microscope Hans and Zacharias Janssen were glass makers (Hans as the father and Zacharias as the son) allowed Robert Hooke to view the cell walls of a cork in 1665 2 1 2 feet, magnified 5-...

History of the Cell Hans and Zacharias Janssen Invented the first primitive Microscope Hans and Zacharias Janssen were glass makers (Hans as the father and Zacharias as the son) allowed Robert Hooke to view the cell walls of a cork in 1665 2 1 2 feet, magnified 5-10 x the size of the specimen with Concave and Convex Lenses William Boreel, a family friend, wrote a letter to inform the French King about the Invention Marcelo Malphigi (1660) was the first to observe blood capillaries in fish tails considered the precursor of Embryology observed red blood cells through capillaries and found the connection between arteries and veins Robert Hooke (1665) discovered the cell in 1665 by examining a thin slice cork and seeing a multitude of little pore He coined the term cell, because of the appearance similar to jail cells did not know the structure, function, nucleus, and other organelles found in cells Francesco Redi (1668) He refuted the theory of spontaneous generation (This is the theory of Louis Pasteur which states that living creatures could arise from nonliving matter and that such processes were common place and regular. ) experimented to see if rotting meat turns into flies found out that flies can make other flies, but meat can't Anton van Leeuwenhoek (1683) taught himself how to polish and grind glass of great curvature up to 270x diameters, which he then used to create the first practical microscope first to see and describe bacteria, yeast, plants, the life in a drop of water and the circulation of corpuscles in capillaries.  Coined the term "Animalcules" In 1674, described the algae Spirogyro. Robert Brown (1839) discovered the nucleus in plants scrutinized the epidermis of an orchid with his microscope found that the cell had an opaque spot (areola) Theodore Schwann (1839) Matthias Jakob Schleiden had found that all plants are composed of cells and communicated his findings with Schwann who had found similar structures in animal cells He concluded "All living things are made up of cells and cell products" Matthias Jakob Schleiden (1839) stated that different parts of plants are composed of cells and communicated it with Schwann recognized the importance of cell nucleus and its importance with cell division. Rudolf Virchow (1855) "Omnis cellula e cellula" All cells arise from a pre-existing cell Gregor Johann Mendel (1865) he discovered the laws of inheritance which are: law of segregation, law of independent assortment and law of dominance Walter Fleming (1882) was a pioneer of cytogenetics was the first to conduct systemic study of chromosomes during division and called this process mitosis Thomas Hunt Morgan (1915) confirmed Mendelian laws of inheritance and the hypothesis that genes are located on chromosomes. did this by extensively breeding the common fruit fly  published the Mechanism of Mendelian Heredity in 1915 In 1933, he received the Nobel Prize in Physiology or Medicine Francis Crick and James Watson (1953) with Maurice Wilkins solved the structure of DNA their findings were published in Nature in April 1953 it was actually Rosaline Franklin who discovered the structure of DNA because Photograph 51, which was the sole photograph that solved the structure of DNA, belonged to her. Maurice Wilkins gave Photograph 51 to Francis Crick and James Watson without Rosaline's knowledge. Cell Theory 1. All living organisms are composed of one or more cells (Theodore Schwann and Matthias Jakob Schleiden, 1838-1839) 2. The cell is the basic structural and functional unit of life (Theodore Schwann and Matthias Jakob Schleiden, 1838-1839) Schleiden proposed that new cells arise from within the old cells, specifically from the nucleus. This was corrected by Rudolf Virchow who proposed "Theory of cell lineage" stating that "omnis cellulae e cellula" (all cells arise from pre-existing cells) 3. In 1855, Rudolf Virchow concluded that all cells come from pre - existing cells Modern Cell Theory 1. The cell contains hereditary information DNA which is passed on from cell to cell during cell division 2. All cells are basically the same in chemical composition and metabolic activities 3. All basic chemical and physiological functions are carried out inside the cells. (digestion, movement etc.) 4. A cell depends on the activities of subcellular structures within the cell (organelles, plasma membrane etc. ) Exceptions to the Cell Theory Viruses are considered alive by some, yet they are not made up of cells. Viruses have many features of life, but by definition of cell theory, they are not considered alive The first cell did not originate from a pre-existing cell  Mitochondria and Chloroplasts have their own genetic material, and reproduce independently from the rest of the cells Prokaryotes Vs. Eukaryotes Characteristics Prokaryotes Eukaryotes size 0.2 - 2.0 µm, 1-10 µm 10 - 100 µm membrane-bound None Mitochondria, Golgi apparatus, Lysosomes, organelles Vacuoles, Chloroplasts, Nucleus, smooth & rough Endoplastic Reticulum Flagella Made of Flagellin Made of Microtubules Glycocalyx ✓ present in some that lack cell wall Cell wall bacteria- plants - cellulose, fungi - chitin peptidoglycan/murein Plasma/Cell ✓ ✓ Membrane Cytoplasm ✓ ✓ Chromosomes Single Circular Multiple & Linear (DNA) Cell division Binary Fission Mitosis Sexual Transfer of Dna Meiosis Recombination Animals Vs. Plant Cells Characteristics Prokaryotes Animals Plants Cell wall/Cell membrane ✓ Bacteria - X ✓ Plants - Cellulose peptidoglycan/murein Plasma Membrane ✓ ✓ ✓ Flagella/Cilia ✓ ✓ X Except in sperm of a few species of fern Nucleus X Nucleoid Region ✓ ✓ Chromosomes (DNA) Singular/Single Circular Multiple/Linear Multiple/Linear Ribosomes 70 svedbergs (s) 80 svedbergs 80 svedbergs (s) (s) Centrioles X ✓ ✓ Characteristics Prokaryotes Animals Plants Chloroplasts X X ✓ Golgi X ✓ ✓ Apparatus/Complex Endoplasmic Reticulum X ✓ ✓ (Smooth/Rough) Mitochondria X ✓ ✓ Lysosomes X ✓ ✓ Peroxisomes X ✓ ✓ Vacuoles X Small Large Microtubules X ✓ ✓ Prokaryotes Domain Bacteria/Eubacteria (Kingdom Bacteria/Eubacteria) disease causing pathogens to photosynthesizes or symbiotes Domain Archaea (Kingdom Archaea) None pathogenic Live/Thrive in extreme environments Thermophiles - Thrives in extreme temperature (60° - 140° Celsius ). Found in Sediments of Volcanoes; Deep Sea Hydrothermal vents Methanogens - microorganisms which produce methane as a byproduct Halophiles - microorganisms that thrive in high saline/salinity environments Psychrophiles - Microorganisms that thrive in extremely cold environments Eukaryotes Domain Eukarya Kingdom Plantae Ferns, Trees, Flowers Kingdom Animalia Elephants, Hippos, Dogs, Cats Kingdom Fungi Mushroom, Yeast (Saccharomyces cerevisiae) Kingdom Protista Euglena, Paramecium Eukaryotic Organelles Nucleus The organelle responsible for DNA synthesis and RNA synthesis Smooth Endoplasmic Reticulum Lipid synthesis; carbohydrate metabolism in liver cells; detoxification in liver cells; calcium ion storage It is called smooth because of the absence of ribosomes Rough Endoplasmic Reticulum Synthesis of membrane proteins, secretory proteins and hydrolytic enzymes Ribosomes are present Golgi Apparatus Consisting of stacks of flat membranous sacs Temporary storage and transport of macro molecules; formation of lysosomes and transport vesicles Ribosomes A complex of rRNA and protein molecules Polypeptide (protein) synthesis Lysosomes A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists Digestion of nutrients, bacteria, and damaged organelles Mitochondria Conversion of chemical energy of food to chemical energy of Adenosine triphosphate (ATP) uses oxygen to breakdown organic molecules and synthesize ATP Chloroplasts Conversion of light energy to chemical energy of sugars Plasma Membrane Also called the cell membrane, is the membrane found in all cells that separates the interior of the cell from the outside environment Cytoplasm is a thick solution that fills each cell and is enclosed by the cell membrane provides shape to the cell Cytosol The fluid portion of the cytoplasm Microtubules are polymers of tubulin that form part of the cytoskeleton and provide structure and shape to eukaryotic cells Vesicle a structure within or outside a cell, consisting of liquid or cytoplasm enclosed by a lipid bilayer Intermediate Filament Are cytoskeletal structural components found in the cells of vertebrates, and many invertebrates Peroxisome contains enzymes that oxidize certain molecules normally found in the cell, notably fatty acids and amino acids produces hydrogen peroxide as a by-product then converts it to water. Nucleolus is a region found within the Nucleus that is concerned with producing and assembling the cell's ribosomes Centriole a cylindrical organelle composed mainly of a protein called tubulin. Used for organizing microtubules Flagella a lash-like appendage that protrudes from the cell body of certain cells. Used for cell movement Nuclear Envelope The double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm Chromatin The complex DNA and proteins that makes up eukaryotic chromosomes When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope. The lose form of DNA; Normal State of DNA Chromatids Half of the duplicated chromosomes Chromosomes Condensed form of Chromatin Microvilli One of many fine, finger like projections of the epithelial cells in the lumen of the small intestine that increase its surface area. Cytoskeleton  A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical transport, and signaling functions. Central Vacoule In a mature plant cell, it is a large membranous sac with diverse roles in growth, storage, and sequestration of toxic substances Plasmodesma An open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger. molecules to pass between the cells. Gap Junctions Equivalent to Plasmodesma in function; found in animal cells Circulatory and Communication between cells Amyloplast is a colorless organelle that stores starch (amylose), particularly in roots and tubers. Prokaryotic Cell Difference DNA The DNA in prokaryotes is contained in a central area of the cell called the nucleoid, which is not surrounded by a nuclear membrane Somatic Vs. Gametes Somatic Cells Gametes Body Cells Sex Cells Diploid (2h) Haploid (h) 23 pairs of Chromosomes with a total of 46 Chromosomes Single Set of 23 Chromosomes Ex. Blood Cells, Skin Cells, Stem Cells, Nuerons, Muscles Egg & Sperm Cell Cells, etc. Produced through Mitosis Produced Through Meiosis Parts of Dyads (Chromosome) P Arm (Petite Arm) short arm of the chromosome Q Arm Long arm of the chromosome Centromere contains DNA; Binds sister chromatid Kinetochore (protein) spindle fiber attaches Sister Chromatids Two chromatids that are in the same chromosome Non-Sister Chromatids Two chromatids that are from different chromosomes Two Non-Sister Chromatids exchange genetic material in Meiosis Homologue/Homologous Chromosome paired chromosomes Cell Cycle The Cell cycle control system is driven by a built in clock that can be adjusted by external stimuli (i.e. chemical messages) An orderly sequence of events from the time a cell divides to form 2 daughter cells to the time those daughter cells divide again Lasts for 24 hours/1 day Checkpoint - a critical point in the Cell cycle where "stop" and "go-ahead" signals can regulate the cell cycle Animals cells have built in "stop" signals that halt the cell cycle and checkpoints until overridden by "go-ahead" signals Three Major checkpoints are found in the G1, G2 and M phases of the Cell Cycle Interphase This is the time when a cell's metabolic activity is very high Chromosomes duplicate during this period Many cell parts are made Cell does most of its growing Lasts for at least 90% of the total time required for the cell cycle G1 Phase Refers to the Hap between cell division and DNA synthesis  is a time when the cell increases its supply of proteins, increases the numbers of many of its organelles (such as mitochondria and ribosomes), and grows in size The G1 Checkpoint (Restriction point) ensures that the cell is large enough to divide and that enough nutrients are available to support the resulting daughter cells. If a cell receives a "go-ahead" signal, it will exit the Cell Cycle and switch to a non dividing stage called G0 Most of the cells in the human body are in the G0 phase S phase DNA synthesis occurs At the beginning of the S phase, each chromosome is single At the end of this phase, the chromosomes are double, each consisting of two sister chromatids G2 Phase spans the time from the completion of DNA synthesis to the onset of cell division Among the proteins synthesized during G2 are some that are essential to cell division G2 Phase Checkpoint ensures that DNA replication in S phase has been successfully completed The Metaphase Checkpoint ensures that all of the chromosomes are attached to the mitotic spindle by a kinetochore Kinase a protein which activates or deactivates another protein by phosphorylating them. Kinases give the "go-ahead" signals at the G1 & G2 checkpoints. The kinases that drive these checkpoints must themselves be activated The activating molecule is cyclin, a protein that derives its name from its cyclically fluctuating concentration in the cell. Because of this requirement, these kinases are called cyclin-dpendent kinases or CDKs Cyclins - accumulate during the G1, S and G2 phases of the cell cycle By the G2 checkpoint, enough cyclin is available to form MPF complexes (aggregations of  CDK and cyclin) which initiate Mitosis. M Phase Mitotic Phase Mitosis - the nucleus and its contents, including the duplicated chromosomes divide and are evenly distributed to form two daughter nuclei Cytokinesis- The cytoplasm is divided into two Mitosis (apparent division) is nuclear division; the process by which the nucleus divide to produce two new nuclei results in two daughter cells that are genetically identical to each other and to the parental cell from which they came. Cytokinesis is the division of the cytoplasm. Both mitosis and cytokinesis last for around one to two hours. Prophase Within the nucleus, the chromatin fibers become more tightly coiled and folded forming discrete chromosomes The nucleoli disappear Each duplicated chromosome appears as two identical sister chromatids joined together In the cytoplasm, the mitotic spindle begins to form as microtubules rapidly grow out from the centrosomes. Prometaphase The nuclear envelope breaks into fragments Within the nuclear envelope gone, microtubules emerging from the centrosomes at the pole (ends) of the spindle can reach the chromosomes At the centromere region, each sister chromatid has a protein structure called kinetochore Some of the spindle microtubules attach to the kinetochore, throwing the chromosomes into agitated motion Other spindle microtubules make contact with microtubules coming from the opposite pole Forces exerted by protein "motors" associated with spindle microtubules move the chromosomes toward the center of the cell Mitosis Prophase is the preparatory stage  Centrioles move toward the opposite side of the nucleus The initially indistinct chromosomes begin to condense into visible threads. Chromosomes first become visible during early prophase as long, thin, and intertwined filaments but by late prophase, chromosomes are more compacted and can be clearly discerned as much shorter and rod-like structures Metaphase At metaphase, the mitotic spindle is fully formed, with its poles at opposite ends of the cell The chromosomes convene on the metaphase plate, an imaginary plane equidistant between the two poles of the spindle The centromeres of all the chromosomes are lined up on the metaphase plate For each chromosome, the kinetochores of two sister chromatids face opposite pole of the spindle The microtubules attached to a particular chromatid all come from one pole of the spindle and those attached to its sister chromatid come from the opposite pole Mitosis Metaphase - is when chromosomes become arranged so that their centromeres become aligned in one place, halfway between the two spindles poles. The long axes of the chromosomes are 90 degrees to the spindle axis. The plane of alignment is called the metaphase plate Anaphase Anaphase begins when the two centromeres of each chromosome come apart, separating the sister chromatids. Once separate, each sister chromatid is considered a full-fledged (daughter) chromosome Motor proteins of the kinetochores, powered by ATP, "walk" the daughter chromosomes centromere-first along the microtubules toward opposite poles of the cell As this happens, the spindle microtubules attached to the kinetochores shorten However, the spindle microtubules not attached to chromosomes lengthen The poles are moved farther apart, elongating the cell Anaphase is over when the equivalent and complete chromosomes have reached the two poles of the cell Anaphase is initiated by the separation of sister chromatids at their junction point at the centromere The daughter chromosomes move toward the poles Telophase is roughly the reverse of prophase The cell elongation that started in anaphase continues daughter nuclei appear at the two poles of the cell as nuclear envelopes form around the chromosomes Mean while, the chromatin fiber of each chromosome, uncoils, and nucleoli reappear At the end of the telophase, the mitotic spindle disappears Mitosis, the equal division of one nucleus into two genetically identical daughter nuclei is now finished Cytokinesis (Animal Cell) The division of the cytoplasm usually occurs along with telophase, with two daughter cells completely separating soon after the end of mitosis In animal cells, cytokinesis occurs by a process known as cleavage The first sign of cleavage is the appearance of cleavage furrow, which begins as a shallow groove in the cell surface In animals cells, cytokinesis involves a cleavage furrow, which pinches the cell in two At the site of the furrow, the cytoplasm has a ring of microfilaments mad of actin, a protein that functions in several types of cellular contraction The ring contracts much like the pulling of drawstrings, deepening the cleavage furrow and eventually pinching the cell in two. Cytokinesis (Plant Cell) First, membrane-enclosed vesicles containing cell wall material collect at the middle of the parent cell The vesicles then fuse, forming a membrane-enclosed disk called the cell plate The cell plate grows outward, accumulating more cell wall materials as more vesicles fuse with it Eventually, the membrane of the cell plate's contents join the parental cell wall The result is two daughter cells each bounded by its own continuous plasma membrane and cell wall Mitosis Telophase - is when daughter chromosomes complete their migration to the opposite poles The two set of progeny chromosomes are arranged into two groups at opposite ends of the cell Chromosomes uncoil and assume their extended form during interphase A nuclear membrane then forms around each chromosome group and the spindle microtubules disappear. Soon, the nucleolus reforms.