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 |
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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 contents that look dark & dense. |
functions of lysosomes | fusing with membranes of damaged organelles, enzymes are activated forming secondary lysosomes which break down lysosomal contents; 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 contents 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 contents 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- ½ of all cancers are associated with abnormal forms of p53) |
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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 | structures@chromosome 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. |