Biology2

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chromatin

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Network of fibrils consisting of DNA and associated protiens, observed w/in a nucleus that isn't dividing.

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diploid(2n)number

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cell condition in which 2 of each type of chromosome are present.

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haploid (n) number

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cell condition in which only 1 of each type of chromosome is present.

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sister chromatids

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1 of 2 genetically identical chromosomal units that are the result of DNA replication & are attached to each other @ the centromere.

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centromere

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constriction where sister chromatids of a chromosome are held together.

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centrosome

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central microtubual organizing center of cells. It contains 2 centrioles.

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centriole

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cell organelle existing in pairs that occurs in the centrosome and may help organize a mitotic spindle for chromosome movement during an animal cell division.

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aster

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short radiating fibers produced by the centrosomes in animal cells.

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spindle

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microtubual structure that brings about chromosomal movement during nuclear division.

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prophase

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mitotic phase during which chromatin condenses so that chromosomes appear; chromosomes are scattered.

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kinetochores

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Disc shaped structure w/in the centromere of a chromosome to which spindles, microtubuals become attached during mitosis & meiosis.

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prometaphase

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spindle is in process of forming and kinetochores of chromosomes are attaching to kinetochore spindle fibers.

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metaphase

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chromosomes(each consisting of 2 sister chromatids) are @ the metaphase plate(center of fully formed spindle).

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metaphase plate

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a disc formed during metaphase in which all of a cells chromosomes lie in a single plane at right angles to spindle fibers.

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anaphase

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daughter chromosomes (each consisting of 1 chromatid) are moving toward the poles of the spindle.

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telophase

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daughter cells are forming as nuclear envelopes & nucleoli appear. Chormosomes will become indistinct chromatin.

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cell plate

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newly formed plasma membrane that expands outward until it reaches the old plasma membrane and fuses w/ it.

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carcinogenesis

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development of cancer

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tumor

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cells derived from a single mutated cell that has repeatedly undergone cell division. Benign tumors remain @ the site of orgin while milignant tumors metastisize.

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metasthesis

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the spread of cancer from the place of orgin throughout the body; caused by the ability of cancer cells to migrate & invade tissues.

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angiogenesis

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formation of new blood vessels; 1 mechanism by which cancer spreads.

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proto-oncogenes

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normal gene that can become an oncogene through mutation.

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tumor suppression genes

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gene that codes for a protein that ordinarily suppresses cell division; inactivity can lead to a tumor.

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telomere

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tip of the end of a chromosome that shortens with each cell division & may thereby regulate the # of times a cell can divide.

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oncogene

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cancer causing gene.

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luekemia

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cancer of blood forming cells and lymphiod tissues.

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nucleoid

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region of prokaryotic cells where DNA is located; it is not bounded by a nuclear envelope.

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asexual reproduction

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production that requires only one parent, and doesn't require gametes.

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meiosis

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type of nuclear division that occurs as part of sexual reproduction, in which the daughter cells receive the haploid # of chromosomes in varied combinations.

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sexual reproduction

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reproduction involving meiosis, gamete formation, & fertilization; produces off spring w/ chromosomes inherited from each parent w/ a unique combination of genes.

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gamete

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haploid sex cell. i.e. sperm & egg.

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homologous chromosomes (homologues)

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member of a pair of choromosomes that are alike & come together in synapsis during prophase of the 1st meotic division.

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genetic recombination

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process in which new genetic info. is incorporated into a chromosome/ DNA fragment.

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crossing over

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exchange of segment b/w nonsister chromotids of a bivalent during meiosis.

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fertilization

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fussion of sperm & egg nuclei producing a zygote that develops into a new individual.

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independent assortment

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alleles of unlinked genes segregate independently of each other during meiosis so that gametes contain all possible combinations of alleles.

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spores

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asexual reproductive/resisting cell capable of developing into an individual w/o fussion w/ another cell in contrast to a gamete.

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spermatogenesis

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production of sperm in males by process of meiosis & maturation.

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oogenesis

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production of eggs in females by a process of meiosis & maturation.

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secondary oocyte

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oogenesis, the functional product meiosis 1; becomes the egg.

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polar body

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in oogenesis, a nonfunctional product; 2 to 3 meotic products are of this type.

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bacteriophages

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virus that infects bacteria.

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purine

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type of nitrogen- containing base, such as adenine, guanine, having a double ring structure.

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adenine

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...composes the structure of DNA & RNA.

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guanine

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composes the structure of DNA & RNA pairs w/ cytosine.

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pyrimidines

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nitrogen- containing base such as cytosine, thymine, & uracil; having single ring structure.

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thymine

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composes structure of DNA; pairs w/ adenine.

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cytosine

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composes the structure of DNA & RNA; pairs w/ guanine.

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complementary base pairing

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hydrogen bonding b/w particular purines & pyrimidines in DNA.

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DNA replication

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syntesis of new DNA double helix prior to mitosis & meiosis in eukaryotic cells & during prokaryotic fission in prokaryotic.

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template

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parental strand of DNA that serves as a guide for the complemantary daughter strand produced during DNA replication.

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semi-conservative replication

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duplication of DNA resulting in 2 double helix molecules, each having 1 parental & 1 new strand.

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DNA polymerase

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during replication an enzyme that joins nucleotides to a DNA template.

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replication fork

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in eukaryotes, the point where the 2 parental DNA strands separate to allow replication.

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genetic mutation

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alter gene whose sequence of bases differs from the previous sequence.

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proof reading

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process used to check the accuracy of DNA replication as it occurs & to replace a mispaired base w/ the right one.

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DNA repair enzyme

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1 of the several enzymes that restore the original base sequence & in an altered DNA strand.

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capsid

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outer layer of a virus; composed of protein subunits.

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Lytic Cycle

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bacteriophage life cycle in which the virus takes over the operation of the bacterium immediately upon entering it, & subsequently destroys the bacterium.

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lycogeneic cylce

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bacteriophage life cycle in which the virus incorporates its DNA into that of a bacterium; occurs preliminary to the lytic cycle.

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retrovirus

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RNA virus containing the enzyme reverse transcriptase that carries out RNA/DNA transcription.

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prion

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infectious particle consisting of protein only & no nucleic acid.

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mad cow disease

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type of prion.

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prokaryote

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organism that lacks the membrane bounded nucleus & membranous organelles typical of eukaryotes.

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peptidoglycan

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unique molecule found in bacterial cell walls.

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flagella

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long, slender extension used for locomotion by some bacteria, protozoans, & sperm.

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fimbriae

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short bristle-like fibers that allow prokaryotes to adhere to surfaces.

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plasmid

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self-duplicating ring of accessory DNA in cytoplasm of bacteria.

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binary fission

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splitting of a parent cell into 2 daughter cells; serves as an asexual form of reproduction in bacteria.

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conjugation

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transfer of genetic material from one cell to another.

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transformation

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taking up of extraneous genetic material from the enviroment by bacteria.

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transduction

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exchange of DNA b/w bacteria by means of a bacteriophage.

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endospore

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spore formed w/in a cell; certain bacteria form endospores.

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obligate anaerobes

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prokaryote unable to grow in the presence of free oxygen.

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facultative anaerobe

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prokaryote that is able to grow in either presence/absense of gaseous oxygen.

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photoautotrophs

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organism able to synthesize organic molecules by using carbon dioxide as the carbon source & sunlight as the energy source.

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chemoautotrophs

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organism able to synthesize organic molecules by using carbon dioxide as the carbon source & the oxidation of an inorganic substance(such as hydrogen sulfide)as the energy source.

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chemoheterotrophs

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organism that is unable to produce its own organice molecules, & therefore require organic nutrients in its diet.

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saprotroph

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organism that secretes digestive enzymes & absorbs the resulting nutrients back across the plasma membrane.

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bacteria

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1 of 3 domains of life; contains prokaryotic cells that differ from archaea b/c they have their own unique genetic biochemical & physological characteristics.

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symbiotic

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non-free living chemoheterotroph rely on mutualistic, commensalistic or parasitic relationships.

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cyanobacteria

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photosythetic bacterium that contains chlorphyll and releases oxygen; formerly called a blue-green alga

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lichens

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symbiotic relationship b/w certain fungi & algae, in which the fungi possible supply inorganic food/water & the algae provide organic food.

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archaea

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prokaryotic cells that often live in extreme habitats & have unique genetic, biochemical, & physological characteristics.

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methanogens

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archaea that lives in oxygen free habitats such as swamps & releases methane gas.

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halophiles

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arhaea that lives in extemely salty habitats.

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thermoacidophile

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archaea that lives in hot, acidic, aquatic habitats, such as hot springs/near hydrothermal vents.