THIS IS A STUDY GUIDE, NOT AN ALL INCLUSIVE REVIEW. THERE MIGHT BE THINGS NOT COVERED BY THIS STUDY GUIDE THAT MIGHT BE ASKED IN YOUR QUIZZES and PRACTICAL TESTS. STUDENTS ARE RESPONSIBLE FOR STUDYING THEIR MANUAL AND FOR ALL THE MATERIAL COVERED DURING THE LABORATORY PERIOD, AS PER THE COURSE SYLLABUS

Cytology Lab # 3

... Nucleus 1 Plasma membrane 2 Cytoplasm 3 -Organelles -Cytosol -Inclusions The Cell

Lysosome They digest old and worn out organelles and particles brought into the cell. Smooth endoplasmic reticulum It synthesizes lipids and helps to detoxify the cell. Microvilli It is the outermost part of the cell and it controls movements of substances into and out the cell. Plasma membrane or cell membrane Centrosome Pericentriolar material Centrioles They form the mitotic spindle for assisting the cell division They produce the ATP (energy) for cellular functions. Rough endoplasmic reticulum It receives the proteins produced by the ribosomes, modifies them, and transport them to the Golgi body. It processes, modifies, sorts and packages proteins and other substances within vesicles for transport and export from the cell. Mitochondrion -Chromatin -Nuclear envelope -Nucleolus Nucleus: Cytosol It is a gel-like fluid that supports organelles in the cell It contains the genetic material. It is where the ribosomes are assembled. The Cell Ribosomes Golgi body They are the site of protein synthesis. Peroxisomes They detoxify the cell from harmful chemicals produced by cellular reaction (ex: free radicals). They increase the cell surface for absorption It is the cell’s biosynthetic center.

PASSIVE TRANSPORTACTIVE TRANSPORT It moves ions or molecules across the plasma membrane with no expenditure of energy by the cell It requires that the cell expends energy, generally in the form of ATP Diffusion Filtration Osmosis

It is the passive net movement of ions or molecules from the region of higher concentration to the region of lower concentration. It is the difference between the high and low concentration areas Lower concentration Higher concentration Concentration Gradient: The tendency of ions and molecules in a concentration gradients is to move from the region of higher concen- tration to the region of lower concentration Diffusion: Diffusion tends to eliminate the concentration gradient Brownian Movement: It is the irregular movement of particles suspended in a liquid or gas caused by the kinetic energy of these particles No concentration gradient

Concentration Gradient: The natural tendency of a solute is to move down its concentration gradient, from higher concentration to lower concentration. It is the difference between the high and low concentration areas of a solute within a given medium 5- Membrane permeability :  permeability,  rate Factors affecting diffusion rate through a membrane 3- Temperature:  temp.,  motion of particles 1- Steepness of concentrated gradient:  difference,  rate 2- Molecular weight: larger molecules move slower 4- Membrane surface area:  area,  rate

Down gradient Larger molecules move slower Diffusion in a Concentration Gradient Substance A is larger (it has a higher molecular weight) than substance B A B

Impermeable Membrane It is a membrane through which none substance can pass

It is a membrane through which any substance can pass Freely Permeable membrane

Selectively Permeable Membrane It is a membrane that permits the free passage of some materials and restricts the passage of other The plasma membrane works as a selectively permeable membrane It allows some things through, such as nutrients and wastes, but usually prevents other things as proteins and phosphates, from entering or leaving the cell.

It is the passive net diffusion of solvent (water), across a selectively permeable membrane, toward the solution that has the higher concentration of solutes Osmosis: A Special Case of Diffusion AB Osmosis: OSMOSIS

Osmolarity and Tonicity Osmolarity is the total solute concentration in an aqueous solution Solution A has a lower osmolarity than solution B Solution B has a higher osmolarity than solution A Solution A is hypotonic in relation to solution B Solution B is hypertonic in relation to solution A OSMOSIS A B If two solutions of different tonicity are separated by a selectively permeable membrane, the solvent (water) will pass the membrane until equilibrium is attained and both solution contain equal concentration of solutes When equilibrium is attained, A and B are isotonic solutions

Hypertonic solution: A solution that has a higher concentration of solutes than other Hypotonic solution: A solution that has lower con- centration of solutes than other Isotonic solution: Two solutions that have equal concentrations of solutes ABCD OSMOSIS

Isotonic solution It is a solution with the same concentration of non-penetrating solutes as that found in the cells. (Intravenous solutions are isotonic solutions). Hypertonic solution It is a solution with a higher concentration non-penetrating solutes than that found in the cells. Hypotonic solution It is a solution with a lower concentration of non-penetrating solutes than that found in the cells. water

Osmotic Flow across a Plasma Membrane

Effects of Tonicity on RBCs Hypotonic, isotonic and hypertonic solutions affect the fluid volume of a red blood cell. Notice the crenated and swollen cells. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. (a) Hypotonic(b) Isotonic(c) Hypertonic © Dr. David M. Phillips/Visuals Unlimited Swollen cell Normal cell Crenated cell