Passive. mechanisms. Active. mechanisms. Cell diffusion. Movement. Movement. Movement. Mechanisms that do not require cellular energy such as:

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1 Passive mechanisms Mechanisms that do not require cellular energy such as: Diffusion Facilitated diffusion Osmosis Filtration Active mechanisms Mechanisms that do require cellular energy such as: Active transport Endocytosis Exocytosis Cell diffusion A substance can only diffuse into or out of a cell if the cell membrane is permeable to the substance and if a concentration gradient exists

2 Dialysis A chemical technique that uses diffusion to separate small molecules from larger ones in a liquid Facilitated diffusion A process that moves molecules from regions of higher concentration toward regions of lower concentration Insulin A hormone that promotes facilitated diffusion of glucose through the membrane of certain cells

3 Osmosis A special case of diffusion that occurs whenever water molecules diffuse from a region of higher water concentration to a region of lower water concentration across a selectively permeable membrane Osmotic Pressure The ability of osmosis to generate enough pressure to lift a volume of water Isotonic Refers to a solution that has the same osmotic pressure as body fluids

4 Hypertonic Refers to a solution that has a higher osmotic pressure than body fluids causing the cells to shrink as water moves out of the cell Hypotonic Refers to a solution that has a lower osmotic pressure than body fluids causing the cells to swell and possibly burst as water moves into it Hydrostatic pressure Pressure created by the weight of water

5 Active transport Process that occurs when particles move from a region of lower concentration to a region of higher concentration Endocytosis Process by which particles that are too large to enter a cell by diffusion, facilitated diffusion, or active transport are conveyed with a vesicle formed from a section of the cell membrane Exocytosis Process by which particles stored in vesicles are secreted from the cell

6 Pinocytosis Process by which cells engulf tiny droplets of liquid from their surroundings as a small portion of the cell membrane indents Phagocytosis Process by which cells engulf particles from their surroundings as a small portion of the cell membrane indents Transcytosis Process that combines endocytosis and exocytosis to transport a particle or structure across a cell

7 Interphase The stage in the cell cycle where young cells grow, manufacture compounds, new organelles are made, and the chromosomes and centrioles replicate S phase of interphase The phase when the DNA of the cell is replicated in preparation for cell division G1 and G2 phases The phase when the cell grows and other structures are duplicated

8 Mitosis Division of the cell nucleus Each daughter cell receives an exact copy of the mother s genetic material Described as a series of four stages but the process is actually continuous Meiosis The division of sex cells resulting in two, and then four, daughter cells each containing the haploid number of chromosomes which is half of the parent cell s genetic information; mitosis is a phase of meiosis Prophase The first stage of mitosis when the DNA condenses into chromosomes, the nuclear envelope and the nucleolus disperse, and a spindle-shaped group of microtubules forms between the centrioles as they move apart

9 Metaphase The second stage of mitosis when the chromosomes line up in an orderly fashion about midway between the centrioles, and spindle fibers become attached to the centromere of the chromosome Anaphase The phase when the centromere of the chromatids separate and the chromatids become chromosomes, which are pulled apart toward opposite sides of the cell Telophase The final stage of mitosis when the chromosomes complete their migration toward the centrioles, the nuclear envelope reforms, and the chromosomes become invisible

10 Cytokinesis This phase begins during anaphase; cell membrane develops a cleavage furrow Contraction of a ring of microfilaments divides cytoplasm Ring pinches inward, separating the two nuclei and distributing half of the organelles New cells may differ slightly but contain identical genetic info Cell differentiation The process by which cells develop specialized characteristics in structure and function to reflect genetic control of the nucleus as certain genes are turned on while others are turned off Stem Cell Cells that retain the ability to divide repeatedly without specializing allow for continual growth and renewal; this cell divides mitotically to yield either two daughter cells like itself, or one daughter cell and one that becomes partially specialized

11 Apoptosis A form of cell death that is a normal part of development (Ex: Skin cells peeling away after a sunburn) Scavenger Cell A cell that engulfs and destroys cells that are undergoing apoptosis Cancer A group of closely related diseases resulting from gene mutations that alter the cell cycle; characteristics include: Hyperplasia Dedifferentiation Invasiveness Angiogenesis Metastasis