biology2
Terms
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- chromatin
- Network of fibrils consisting of DNA and associated protiens, observed w/in a nucleus that isn't dividing.
- diploid(2n)number
- cell condition in which 2 of each type of chromosome are present.
- haploid (n) number
- cell condition in which only 1 of each type of chromosome is present.
- centromere
- constriction where sister chromatids of a chromosome are held together.
- centrosome
- central microtubual organizing center of cells. It contains 2 centrioles.
- centriole
- 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.
- aster
- short radiating fibers produced by the centrosomes in animal cells.
- spindle
- microtubual structure that brings about chromosomal movement during nuclear division.
- prophase
- mitotic phase during which chromatin condenses so that chromosomes appear; chromosomes are scattered.
- kinetochores
- Disc shaped structure w/in the centromere of a chromosome to which spindles, microtubuals become attached during mitosis & meiosis.
- prometaphase
- spindle is in process of forming and kinetochores of chromosomes are attaching to kinetochore spindle fibers.
- metaphase plate
- a disc formed during metaphase in which all of a cells chromosomes lie in a single plane at right angles to spindle fibers.
- anaphase
- daughter chromosomes (each consisting of 1 chromatid) are moving toward the poles of the spindle.
- telophase
- daughter cells are forming as nuclear envelopes & nucleoli appear. Chormosomes will become indistinct chromatin.
- cell plate
- newly formed plasma membrane that expands outward until it reaches the old plasma membrane and fuses w/ it.
- carcinogenesis
- development of cancer
- metasthesis
- the spread of cancer from the place of orgin throughout the body; caused by the ability of cancer cells to migrate & invade tissues.
- angiogenesis
- formation of new blood vessels; 1 mechanism by which cancer spreads.
- proto-oncogenes
- normal gene that can become an oncogene through mutation.
- tumor suppression genes
- gene that codes for a protein that ordinarily suppresses cell division; inactivity can lead to a tumor.
- telomere
- tip of the end of a chromosome that shortens with each cell division & may thereby regulate the # of times a cell can divide.
- oncogene
- cancer causing gene.
- luekemia
- cancer of blood forming cells and lymphiod tissues.
- nucleoid
- region of prokaryotic cells where DNA is located; it is not bounded by a nuclear envelope.
- asexual reproduction
- production that requires only one parent, and doesn't require gametes.
- meiosis
- type of nuclear division that occurs as part of sexual reproduction, in which the daughter cells receive the haploid # of chromosomes in varied combinations.
- sexual reproduction
- reproduction involving meiosis, gamete formation, & fertilization; produces off spring w/ chromosomes inherited from each parent w/ a unique combination of genes.
- gamete
- haploid sex cell. i.e. sperm & egg.
- homologous chromosomes (homologues)
- member of a pair of choromosomes that are alike & come together in synapsis during prophase of the 1st meotic division.
- genetic recombination
- process in which new genetic info. is incorporated into a chromosome/ DNA fragment.
- crossing over
- exchange of segment b/w nonsister chromotids of a bivalent during meiosis.
- fertilization
- fussion of sperm & egg nuclei producing a zygote that develops into a new individual.
- independent assortment
- alleles of unlinked genes segregate independently of each other during meiosis so that gametes contain all possible combinations of alleles.
- spores
- asexual reproductive/resisting cell capable of developing into an individual w/o fussion w/ another cell in contrast to a gamete.
- spermatogenesis
- production of sperm in males by process of meiosis & maturation.
- oogenesis
- production of eggs in females by a process of meiosis & maturation.
- secondary oocyte
- oogenesis, the functional product meiosis 1; becomes the egg.
- polar body
- in oogenesis, a nonfunctional product; 2 to 3 meotic products are of this type.
- bacteriophages
- virus that infects bacteria.
- purine
- type of nitrogen- containing base, such as adenine, guanine, having a double ring structure.
- adenine
- ...composes the structure of DNA & RNA.
- guanine
- composes the structure of DNA & RNA pairs w/ cytosine.
- pyrimidines
- nitrogen- containing base such as cytosine, thymine, & uracil; having single ring structure.
- thymine
- composes structure of DNA; pairs w/ adenine.
- cytosine
- composes the structure of DNA & RNA; pairs w/ guanine.
- complementary base pairing
- hydrogen bonding b/w particular purines & pyrimidines in DNA.
- DNA replication
- syntesis of new DNA double helix prior to mitosis & meiosis in eukaryotic cells & during prokaryotic fission in prokaryotic.
- template
- parental strand of DNA that serves as a guide for the complemantary daughter strand produced during DNA replication.
- semi-conservative replication
- duplication of DNA resulting in 2 double helix molecules, each having 1 parental & 1 new strand.
- DNA polymerase
- during replication an enzyme that joins nucleotides to a DNA template.
- replication fork
- in eukaryotes, the point where the 2 parental DNA strands separate to allow replication.
- genetic mutation
- alter gene whose sequence of bases differs from the previous sequence.
- proof reading
- process used to check the accuracy of DNA replication as it occurs & to replace a mispaired base w/ the right one.
- DNA repair enzyme
- 1 of the several enzymes that restore the original base sequence & in an altered DNA strand.
- capsid
- outer layer of a virus; composed of protein subunits.
- Lytic Cycle
- bacteriophage life cycle in which the virus takes over the operation of the bacterium immediately upon entering it, & subsequently destroys the bacterium.
- lycogeneic cylce
- bacteriophage life cycle in which the virus incorporates its DNA into that of a bacterium; occurs preliminary to the lytic cycle.
- retrovirus
- RNA virus containing the enzyme reverse transcriptase that carries out RNA/DNA transcription.
- prion
- infectious particle consisting of protein only & no nucleic acid.
- mad cow disease
- type of prion.
- prokaryote
- organism that lacks the membrane bounded nucleus & membranous organelles typical of eukaryotes.
- peptidoglycan
- unique molecule found in bacterial cell walls.
- flagella
- long, slender extension used for locomotion by some bacteria, protozoans, & sperm.
- fimbriae
- short bristle-like fibers that allow prokaryotes to adhere to surfaces.
- plasmid
- self-duplicating ring of accessory DNA in cytoplasm of bacteria.
- binary fission
- splitting of a parent cell into 2 daughter cells; serves as an asexual form of reproduction in bacteria.
- conjugation
- transfer of genetic material from one cell to another.
- transformation
- taking up of extraneous genetic material from the enviroment by bacteria.
- transduction
- exchange of DNA b/w bacteria by means of a bacteriophage.
- endospore
- spore formed w/in a cell; certain bacteria form endospores.
- obligate anaerobes
- prokaryote unable to grow in the presence of free oxygen.
- facultative anaerobe
- prokaryote that is able to grow in either presence/absense of gaseous oxygen.
- photoautotrophs
- organism able to synthesize organic molecules by using carbon dioxide as the carbon source & sunlight as the energy source.
- chemoautotrophs
- 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.
- chemoheterotrophs
- organism that is unable to produce its own organice molecules, & therefore require organic nutrients in its diet.
- saprotroph
- organism that secretes digestive enzymes & absorbs the resulting nutrients back across the plasma membrane.
- bacteria
- 1 of 3 domains of life; contains prokaryotic cells that differ from archaea b/c they have their own unique genetic biochemical & physological characteristics.
- symbiotic
- non-free living chemoheterotroph rely on mutualistic, commensalistic or parasitic relationships.
- cyanobacteria
- photosythetic bacterium that contains chlorphyll and releases oxygen; formerly called a blue-green alga
- lichens
- symbiotic relationship b/w certain fungi & algae, in which the fungi possible supply inorganic food/water & the algae provide organic food.
- archaea
- prokaryotic cells that often live in extreme habitats & have unique genetic, biochemical, & physological characteristics.
- methanogens
- archaea that lives in oxygen free habitats such as swamps & releases methane gas.
- halophiles
- arhaea that lives in extemely salty habitats.
- thermoacidophile
- archaea that lives in hot, acidic, aquatic habitats, such as hot springs/near hydrothermal vents.