Anatomy & Physiology Chapter 3: The Cellular Level of Organization

Cells

Building blocks of all plants and animals; smallest living units in the body

Two types of cells

Sex cells (germ cells) and Somatic cells

Sex cells

Reproductive cells, male sperm, female oocyte

Somatic cells

All body cells except sex cells

Extracellular fluid (a watery medium)

Surrounds the cell

Cytoplasm

Intracellular structures collectively known as organelles (cell contents )

Plasma Membrane (aka cell membrane)

Separates the cytoplasm from the extracellular fluid

Plasma membrane functions

Physical isolation, regulates exchange with environment, monitors the environment and structural support

Phospholipid bilayer

Makes up the Two layers of phospholipids are arranged in a way that their hydrophobic fatty-acid tails are projecting to the interior whereas their hydrophilic heads are projecting the exterior. It is a barrier to ions and water ---- soluble compounds

Location of integral proteins

Within the membrane (they are part of the membrane structure & cannot be removed without damaging or destroying the membrane)

Location of peripheral proteins

Bound to inner or outer surface of the membrane (easily separated from it)

Types of membrane proteins

Anchoring proteins, recognition proteins, enzymes, receptor proteins, carrier proteins, channels

Anchoring proteins

Stabilizers; attach to inside or outside structures

Recognition proteins

Identifiers; label cells as normal or abnormal

Enzymes

Catalyze reactions

Receptor proteins

Bind and respond to ligands (ions and hormones)

Carrier proteins

Transport specific solutes through membrane

Channels

Regulate water flow and solutes through membrane

Cytoskeleton

Network of supporting filaments in the cytoplasm (proteins are bound to this): micro filaments, intermediate filaments and microtubules

Cytosol

Intracellular fluid; (dissolved materials, high potassium/low sodium, high protein, high carbohydrate/low amino acid and fat)

Organelles

Structures with specific functions (suspended within the cytosol, these perform functions within the cell)

Nonmembranous organelles

No membrane, direct contact with cytosol; includes: cytoskeleton, microvilli, centrioles, cilia, ribosomes, and proteasomes.

Membranous organelles

Covered with plasma membrane, isolated from cytosol; includes: endoplasmic reticulum (ER), the Golgi apparatus, lysosomes, peroxisomes, and mitochondria

Microvilli

Increase surface area for absorption, attach to cytoskeleton; (nonmembranous)

Centrioles in the Centrosome

Centrioles form spindle apparatus during cell division / centrosome: is the cytoplasm surrounding centriole; (nonmembranous)

Cilia

Small hair-like extensions, move fluids across the cell surface; (nonmembranous)

Ribosome

Build polypeptides in protein synthesis; two types: Free Ribosomes in cytoplasm (manufactures protein for cell), Fixed Ribosome attached to to ER (manufacture proteins for secretion); (nonmembranous)

Proteasomes

Contain enzymes -(proteases), disassemble damaged proteins for recycling; (nonmembranous)

Endoplasmic reticulum (ER)

Network of membranous channels extending throughout the cytoplasm; functions: synthesis of proteins, carbohydrates, and lipids, storage of synthesized molecules and materials, transport of materials, detoxification; there is a rough er and a smooth er; (membranous)

Rough endoplasmic reticulum

Has ribosomes bound to membrane; responsible for modification and packaging of newly synthesized proteins; (membranous)

Smooth endoplasmic reticulum

Lacks attached ribosomes; responsible for synthesis of lipids and carbohydrates (phospholipids and cholesterol, steroid hormones, gylcerides, glycogen); (membranous)

Cisternae

Storage chambers within membranes

Golgi apparatus

Stackable plates of protein, "traffic directors"; functions: storage, modification, and packaging of secretory products for exocytosis; vesicles enter forming and exit mature; (membranous)

Lysosomes

Vesicles containing digestive enzymes; intracellular removal (clean up) of damaged organelles or pathogens, "digestive demolition crews"; carry enzymes to cytosol; 2 types: primary and secondary; (membranous)

Autolysis

Self-destruction of damaged cells; lysosome membranes break down, digestive enzymes released, cell decomposes, cellular materials recycle

Peroxisomes

Vesicles containing degradative enzymes; catabolism of fats and other organic compounds; neutralization of toxic compounds - cleans up dangerous free radicals; (membranous)

Mitochondria

Double membrane with inner membrane folds (cristae) enclosing important metabolic enzymes; takes chemical energy from food (glucose), produces 95% of the ATP required by the cell, known as the cell "power house", store energy packets; can self replicate; (membranous)

Aerobic metabolism

Aka- cellular respiration; aerobic means oxygen dependent and aerobic metabolism refers to an energy-generating system under the presence of oxygen; mitochondria use oxygen to break down food and produce ATP

Nucleus

Largest organelle, the cell's control center; contains nucleosomes (DNA coiled around histones), chromatin (loosely coiled DNA - cells not dividing) and chromosomes (tightly coiled DNA - cells dividing); stores information

DNA

Deoxyribonucleic acid is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses; sequence of bases - A, T, C, G; alpha helix shape

Protein synthesis

Transcription (copes instructions from DNA to mRNA in nucleus), translation (ribosome reads code from mRNA in cystoplasm, and assembles amino acids into polypeptide chain, processing (by RER and Golgi apparatus produce protein); a gene is transcribed to mRNA in three steps - gene activation, DNA to mRNA and RNA processing

RNA

Ribonucleic acid, translates and transcribes, sequence of bases: A, U, C, G ; single strands

Permeability

Determines what moves in and out of a cell

Impermeable

Lets nothing in or out

Freely permeable

Lets anything pass

Selectively permeable

Restricts movement; may restrict materials based on size, electrical charge, molecular shape, or lipid solubility

Osmosis

Special case of diffusion, is the diffusion of water across the cell membrane

Active transport

Requires energy and ATP, going uphill against the concentration gradient (think of sodium potassium pump)

Passive transport

No energy required

Diffusion

The movement of atoms or molecules from an area of higher concentration to an area of lower concentration. Atoms and small molecules can move across a cell membrane by diffusion; a function of the concentration gradient; is a passive process

Concentration

The amount of solute (the stuff) in a solvent (the liquid)

Concentration gradient

More solute (stuff) in one part of a solvent than another

Osmotic pressure

Force with which H20 moves a solution (inside pushing out)

Hydrostatic pressure

The opposing pressure, prevents osmotic flow of H20 into the solution (outside pushing in); makes sure they don't get too big

Osmolarity

the total solute concentration of a solution

Isotonic

A solution that does not cause osmotic flow of water in or out of a cell

Hypotonic

Has less solutes, water rushes into cell, cells swell and burst

Hypertonic

Has more solutes, water rushes out of cells, cells shrink

Cell tone

Is the shape of the cell; isotonic = homeostasis, hypotonic = cells burst, example is edema, hypertonic = cells shrink, example is dehydration

Facilitated diffusion

Passive, needs help getting across but still flowing high to low

Cotransport

One way; two substances move in the same direction at the same time

Countertransport

Opposite ways; one substance moves in while another moves out

Sodium-potassium exchange pump

Active transport, carrier mediated; sodium ions (Na+) out, potassium ions (K+) in

Secondary active transport

A free ride, Na+ concentration gradient still drives, one substance gets across via active transport, a second one rides along for free; ATP energy pumps Na+ back out

Vesicular transport

Aka bulk transport; materials move into or out of cell in vesicles

Endocytosis

Is active transport using ATP; receptor mediated, pinocytosis, phagocytosis

Exocytosis

Granules or droplets are released from the cell; vesicles engulf bad stuff in the cell then discharge it outside the cell; reverse of endocytosis

Pinocytosis

Cell drinking, drinks extracellular fluid / consuming liquid in cell (type of endocytosis)

Phagocytosis

Cell eating, macrophages eat debris, bacteria and other abnormal material that don't belong; consuming solid in cell (type of endocytosis)

Transmembrane potential

Unequal charge across the plasma membrane

Interior of plasma membrane charge

Slightly negative

Outside of plasma membrane charge

Slightly positive

Interphase

The non dividing period of a cells life, cells grow and mature; most of a cells life is spent here

Prophase

The first stage of cell division, before metaphase, during which the chromosomes become visible as paired chromatids and the nuclear envelope disappears.

Mitosis

Divides duplicated DNA into two sets of chromosomes - daughter cells (these are indentical); DNA coils tightly into chromatids, chromatids connect at a cetromere

Kinetochore

Protein complex around centromere

Metaphase

The second stage of cell division, between prophase and anaphase, during which the chromosomes become attached to the spindle fibers; Chromatids line up in middle on equator

Anaphase

The stage of meiotic or mitotic cell division in which the chromatids move away from one another to opposite ends of the cell

Telophase

In this stage the two separate cells form but are still connected

Cytokinesis

The division of the cell cytoplasm; the cells split apart; afterwards the process begins again

Life span of exposed cells (skin and digestive tract)

Live only days or hours

Rate of division of muscle and neuron cells

These rarely divide, takes a great deal of time

Steps of cancer development

Abnormal cell, primary tumor, metastasis, secondary tumor; (Uncontrolled cell multiplication)

Neoplasm

Tumor; enlarged mass of cells, abnormal cell growth and division; a new and abnormal growth of tissue in some part of the body, especially as a characteristic of cancer

Benign tumor

Contained, not life threatening

Malignant tumor

Spreads into surrounding tissues (invasion), starts new tumors (metastasis)

Cell differentiation

Only reads certain genes directions, turns off the other genes directions that doesn't need, but still carries all genes. Does this to form tissues (liver cells, fat cells, and neurons); depends on what genes are active and which are inactive

The number of chromosomes somatic cells contain

46 chromosomes