Basal Humanbiologi Cytologi

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Basal Humanbiologi

Cytology

Lipid: any of various substances that are soluble in nonpolar organic solvents.

Nucleus: directs overall cell activities by housing the genetic mat.
Chromatin: a complex of nucleic acid basic protein, usually dispersed in the interphase nucleus and condense to chromosomes;contain information of synthesizing proteins.
Nucleolus: dense, composed of protein + RNA, spherical body of nucleus, enlarges during protein synthesis and form ribosome.

Cytoplasm: Organelles in cytoplasm divide the labour of the cell, where cell activity mainly occurs, nutrients are received, processed and used.
Organelles: a specialized cellular part (as a mitochondrion, lysosome, or ribosome)
Cytosol: the fluid portion of the cytoplasm exclusive of organelles and membranes
Cytoskeleton: protein rods and tubules that form a framework.


Organelles:

Centrosome: adjacent to nucleus, two rodlike centrioles, function in the formation of the spindle apparatus during cell division, and consist of a cylinder with nine microtubules arranged peripherally in a circle, and distribute chromosomes to newly formed cells.
Cilium: short hair like process, one on a cell that is capable of lashing movement and serves especially in free unicellular organisms to produce locomotion or in higher forms a current of fluid
Endoplasmic Reticulum: complex organelle composed of vesicles. Provides attachment for ribosome - rough ER synthesizes protein, then move through tubules to Golgi apparatus. Smooth ER contains enzyme synthesize lipid; transport mats within cell.
Flagella: primary organ of motion of many micro organisms. (sperm)
Golgi Apparatus: a cytoplasmic organelle consists of a stack of smooth membranous saccules and associated vesicles and active in the modification and transport of protein to glycoprotein.
Mitochondria: membranous sacs with inner partitions, produce energy for the cell through cellular respiration, and are rich in fats, proteins, and enzymes, transform energy into usable form, ATP.
Lysosome: membranous sacs, contains various hydrolytic enzymes, break down nutrients and foreign particles.
Microfilament: tiny rods of actin protein, active in muscular contraction, provide cellular mobility, maintenance of cell shape.
Microtubule: tubules that are composed of the globular tubulin proteins and form an important component of the cytoskeleton, mitotic spindle, cilia, and flagella
Peroxisome: membranous sacs, contains enzymes which act in oxidative reactions and especially in the production and decomposition of hydrogen peroxide – detoxification of alchohol.
Ribosome: Composed of protein + RNA molecules, synthesize protein from ammo acid.

Cell membrane:

Function: determines which substance enters or leaves the cell; signal transduction; adhere to each other to form tissue; maintaining cell integrity.
S: Composed of protein, lipids, carbohydrate; bilayer of phospholipid molecules (P40), a phosphate group and two fatty acids bound to a glycerol molecule. Cholesterol molecules embedded in membrane – less water permeable, rigid, stabilize membrane.
Membrane protein:

  1. Receptors on cell surface bind hormones etc start signal transduction;
  2. selective channel allow particular ion to enter or leave;
  3. anchor membrane to rods and tubules;
  4. outer layer, identification of cell – functioning of immune system;
  5. CAMs. (maintain integrity of cell and controls passage of mats into and out of cell)


Diffusion: process by which molecules or ions scatter or spread spontaneously from regions where they are in higher concentration towards where they are in lower concentration. If and only if (1) cell membrane permeable (2) concentration gradient exist.
Facilitated diffusion: med hjælp uden energi, carrier molecules. (glucose through cell membrane)
Osmosis: movement of solvent through semi permeable membrane into a solution of higher solute concentration, that tends to equalize the concentration of solvent on the two sides of membrane.
Filtration: molecules forced from regions of higher pressure to lower pressure through membrane.
Active Transport: carrier molecules moves ions or molecules from regions of lower concentration to regions of higher concentration.
Endocytosis:

  1. Pinocytosis: membrane engulfs droplets of liquid from surroundings.
  2. Phagocytosis: membrane engulfs particles from surroundings.
  3. Receptor-mediated endocytosis: receptors bind specific ligands, and they are drawn into the cell.

Exocytosis: vesicle fuses with membrane to expel substances from cell.

Mitosis: process that takes place in the nucleus of a dividing cell, involves typically a series of steps - prophase, metaphase, anaphase, and telophase, and results in the formation of two new nuclei each having the same number of chromosomes as the parent nucleus.
Prophase: condensation of chromosomes consisting of two chromatids, disappearance of the nucleolus and nuclear membrane, and formation of mitotic spindle
Metaphase: chromosomes become arranged in the equatorial plane of the spindle
Anaphase: chromosomes move toward the poles of the spindle
Telophase: spindle disappears and the nuclear envelope reforms around each set of chromosomes
Cytokinesis: starts during anaphase till telophase, cytoplasmic division.

Differentiation: the process in each cells develop different characteristic in structure and function.
Apoptosis: genetically determined destruction of cells from within due to activation of a stimulus or removal of a suppressing agent, programmed cell death.

Characteristic of Cancer:

  1. Hyperplasia: uncontrolled cell division, due to telomerase that continually rebuild chromosomes, thus not signalled to stop dividing due to shortening of chromosome tips.
  2. Dedifferentiation: reversion of specialized structure to a more primitive condition, lose functions of the normal type of cell from which it descend. Grow into disorganized masses.
  3. Invasiveness: tend to spread through basement membranes, invade healthy tissues.
  4. Angiogenesis: induce formation of blood vessels, nourish and remove waste.
  5. Metastasis: transfer of a disease-producing agency from the site of disease to another part of the body, eg via blood stream.