Question Answer
Cell Theory (Hooke)= Cells are building blocks of all plants & animals All cells come from the division of preexisting cells. Cells are the smallest units that perform all vital physiological functions. Each cell maintains homeostasis at the cellular level.
Sex cells: germ cells or reproductive cells; either sperm or oocytes
Somatic cells: all other cells (excludes only sex cells)
functions of plasma membrane Physical Isolation Regulation of exchange with the environment Sensitivity to the environment Structural support
Integral proteins: part of the membrane structure & cannot be removed without damaging or destroying the membranes; most span the width of the membrane one or more times, thus are known as transmembrane proteins.
receptor proteins in the membrane are sensitive to the presence of specific extracellular molecules called ligands.
Glycocalyx: layer formed by the extension of the carbohydrate portion beyond the outer surface of the membrane.
cytoplasm general term for the material located between the plasma membrane & membrane surrounding the nucleus; contains many more proteins than the extracellular fluid; contains organelles & cytosol.
cytosol vs extracellular fluid Concentration of potassium ions higher in the cytosol Fluid&concentration of sodium ions is lower Concentration of proteins is higher in cyto and contains small amounts of carb & AA,lipids ECF is a transport medium only & no reserves are there.
interstitial fluid) *which is in both cytosol and extracellular fluid within tissue contain masses of insoluble materials known as inclusions; most common inclusions are nutrients such as glycogen.
Nonmembranous organelles: not completely enclosed by membranes & all their components are in direct contact with the cytosol; cytoskeleton, microvilli, centrioles, cilia, ribosomes, proteasomes.
Microtubules found in most cells; hollow tubes built from globular protein tubulin;
tubulin is a ____ protein that builds up microtubules
Fixed ribosomes are attached to the endoplasmic reticulum (ER).
Smooth ER: refers to the fact that no ribosomes are associated
ribosomes associated with the rough ER surface are fixed ribosomes;
Golgi Apparatus: looks like a stack of dinner plates; receives transport vesicles from the ER; typically consists of 5 or 6 flattenedmembranous sacs (cisternae); single cells may have several oftennear the nucleus
functions of golgi *Modifies & packages secretions, such as hormones or enzymes for release through exocytosis *renews or modifies plasma membrane *packages special enzymes within vesicles for use in the cytoplasm.
lysosomes special vesicles that provide an isolated environment for potentially dangerous chemical reactions; small dense often spherical bodies with sat_flash_1s that look dark & dense.
functions of lysosomes fusing with membranes of damaged organelles, enzymes are activated forming secondary lysosomes which break down lysosomal sat_flash_1s; cytosol reabsorbs released nutrients & wastes R removed by exocytosis essential cleanup & recycling
Peroxisomes smaller than lysosomes & carry different enzymes; produced by growth & subdivision of existing peroxisomes; enzymes produced at free ribosomes; transported from cytosol into peroxisomes by carrier proteins.
functions of peroxisomes absorb, break down fatty acids&other organiccompounds making hydrogen peroxide potentially dangerous free radical within the peroxisome,catalase breaks down the hydrogen peroxide to oxygen & water protecting the cell from effects of free radicals produced
cristae Inner membrane contains numerous folds that increase the surface area for reactions:
Matrix: fluid sat_flash_1s of mitochondria surrounding the cristae
Nucleoli: several dark-staining areas in the nucleus; synthesize ribosomal RNA; assemble ribosomal subunits that reach cytoplasm by carrier-mediated transport at the nuclear pores; composed of RNA, enzymes & proteins called histones;
gene functional unit of heredity; contains all the DNA triplets needed to produce specific proteins
In the RNA processing, nonsense regions___________ are snipped out & remaining segments_________are spliced together. (introns) exons
Selectively permeable: because the permeability of the cell’s plasma membrane is somewhere in between, it is said to be selectively permeable; permits free passage of some materials & restricts the passage of others.
Freely permeable: membrane through which any substance can pass without difficulty.
osmosis is the diffusion of water molecules across a selectively permeable
Isotonic: solution that does not cause an osmotic flow of water into or out of a cell.
Hypotonic: solution with the least solute concentration.
Hemolysis: event of a RBC swelling with fluid so it may burst when the RBCs are placed in a hypotonic solution.
Hypertonic solution: solution with the greatest solute concentration; cells places in a hypertonic solution will lose water & shrivel.
Crenation: shrinking of RBCs when placed in a hypertonic solution.
Ion pumps: carrier proteins which actively transport cations – Na+, K+, Ca+2, Mg+2, across plasma membranes; other specialized cells can transport I-, Cl-, Fe+2
Exocytosis functional reverse of endocytosis; vesicle created inside the cell fuses with, becomes part of the plasma membrane releasing the vesicle sat_flash_1s into the extracellular environment
Transmembrane potential: potential difference across a plasma membrane.
Apoptosis: genetically controlled death of cells
G0: not preparing for cell division, but performing all of the other functions appropriate for that particular type of cell.
G1 : Normal cell function plus cell growth, duplication of organelles, protein synthesis
S: DNA Duplication & synthesis of Histones occurs during this stage. G2: Protein synthesis
Metaphase begins as the chromatids move to a narrow central zone called the metaphase plate; ends when all the chromatids are aligned in the plane of the plate.
Anaphase: begins when the centromere of each chromatid pair splits & the chromatids separate; the 2 daughter chromosomes are now pulled toward opposite ends of the cell along the chromosomal microtubules.
Cytokinesis: division of the cytoplasm; begins with a cleavage furrow & continues throughout Telophase; completion of cytokinesis marks the end of cell division.
Stem cells: special cells that maintain cell populations through repeated cycles of celldivision. Stem cells are relatively unspecialized; only function is to produce daughter cells
Repressor genes: genes that inhibit cell divison (ex, p53- ? of all cancers are associated with abnormal forms of p53)
Tumor (neoplasm): mass or swelling produced by abnormal cell growth & division
Benign tumor: usually remain in the epithelium or connective tissue capsule; seldom threatens an individual’s life; can be easily removed by surgery if it disturbs surrounding tissue.
Metastasis: process of malignant cells traveling to distant tissues & organs establishing secondary tumors; Makes the cancer difficult to control
telomeres [email protected] level regulates#of cell divisions performed terminal seg of DNA w/ proteins segments bend&fold repeatedly 2 form caps @ the ends of chromosomes function 2 attach chromosomes 2 nuclear matrix
telomeres 2 protect ends of chromosomes from damage during mitosis r subject 2wear&tear when 2 short the repressor gene signals the cell 2 stop dividing
nucleoli form around portions of DNA that contain the instructions for producing ribo proteins & RNA when those instructions of amino acids
function of smooth er synthesis of phospholipids & cholesterol needed for growth & maintenance of plasma membrane, ER, nuclear envelope & Golgi apparatus Synthesis of steroid hormones ( androgens & estrogens)
function of smooth er Synthesis & storage of glycerides esp triglycerides in liver cells & adipocytes. Synthesis & storage of glycogen in skeletal muscle & liver cells.
function of smooth er In muscle cells, neurons, & other types of cells, SER adjusts composition of cytosol by absorbing & storing ions (ex. Ca+2) larger molecules; also, SER in liver & kidney cells, responsible for detoxification or inactivation of drugs.