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Biology Section 3
Chapters 12-
| Term | Definition |
|---|---|
| Cell Division | Reproduction in single celled organisms |
| Chromatin | Unwound DNA in non-dividing cells -used for macromolecule synthesis -looks like SPAGHETTI |
| Chromosomes | Tightly packed DNA found during cell division -NOT used for macromolecule synthesis |
| Karyotype | an individuals collection of chromosomes |
| DNA replication occurs... | BEFORE mitosis |
| Phases of cell cycle | G2, G1, S, mitosis & cytokinesis |
| G2 | growth, protein synthesis, prep for division |
| G1 | growth, metabolism, prep for DNA synthesis |
| S phase | replication of DNA and centrosomes |
| Kineticohore | protein complex that attaches to the centromere of each chromatid -microtubules attach to kinetochore to help pull sister chromatid apart |
| Centrosomes | Microtubules organizing centers (also called spindle fibers) |
| Astral Microtubules | hold centrosomes in place at either end |
| Kinetochore microtubules | connect to sister chromatids at the kietochore |
| Mitotic Spindle | collection of microtubules that capture and retract chromosomes |
| Phases of Mitosis | prophase, pro-metaphase, metaphase, anaphase, telophase "Please Pass Me Another Tequilla" |
| Prophase | -Chromatin condenses into chromosomes -nucleolus disappears -microtubules assembly begins |
| Pre-Metaphase | -nuclear membrane breaks down -kinetochore microtubules form and attach to kinetochores -astral microtubules assemble to anchor centrosomes at poles |
| Metaphase | Chromosomes align at metaphase plate |
| Anaphase | -chromosomes break at the centromere into sister chromatids and move towards opposite poles -cohesin is degraded by the enzyme separase |
| Cohesin | protein that wraps around chromosomes in rings keeping them together |
| Seperase | Enzyme that acts like scissors by splitting cohesin rings |
| Telophase | -daughter chromosomes begin to decondense into chromatin -nuclear membranes begin to form around each set of daughter chromosomes -new cell wall begins to form (in plants) -clevage furrow forms (in animals) |
| Cell cycle control system | a cyclically operating set of molecules in the cell that both trigger and coordinate key events in the cell cycle -regulated by checkpoints |
| G1 Checkpoint | Check to see if there is any DNA damage and if the conditions are favorable for cell division |
| G0 Phase | cells exit the cell cycle and exist in a non-dividing state |
| Mature nerve cells and muscle cells... | NEVER divide |
| Liver cells... | can re-enter the cell cycle after injury |
| G2 Checkpoint | Checks to see if DNA was replicated correctly and triggers DNA repair enzymes |
| M Checkpoint | -checks to see if all chromosomes are attached to microtubules -prevent uneven separation of chromosomes -blocks anaphase by inhibiting separase |
| Cancer | disease where body cells grow uncontrollably and spread due to a loss of cell cycle check points -provide tumors with oxygen and nutrients allowing them to grow |
| Transformation | Change that a normal cell undergoes as it becomes malignant |
| Hematologic cancer | in blood cells -lukemia, lymphoma, and multiple myeloma |
| Solid tumor cancers | cancers in any other body organs or tissues -breast, prostate, lung, and colorectal cancers |
| Benign tumor | lump or growth that can only grow in one place and do NOT spread (non-cancerous) |
| Malignant Tumor | lump or growth that are cancer |
| Mestasis | spread of cancer cells to locations distant from the original site |
| Gene | segment of DNA that encodes a product and is carried on chromosomes |
| Locus | location of a gene of a chromosome |
| Asexual Reproduction | reproduce through mitosis producing clones |
| Somatic cells | mature cells of the body |
| Sexual Reproduction | two parents contribute half the genetic material |
| Gamates | cells with half the genetic material that fuse together to make somatic cells |
| Homologous Chromosomes | contain the same genes at identical loci -may have different versions of the same gene (different alleles) |
| Diploid organisms | contain two homologs |
| Karyotype | microscopic image of chromosomes |
| Sex Chromosomes | determines sex |
| Autosomes | non-sex chromosomes |
| # of chromosomes in a human cell | 46 |
| Life cycle | sexually reproducing organisms that alternate between haploid and diploid cells |
| Haploid cells | have one set of chromosomes (23) -sperm and egg cell |
| Diploid cells | arise from a combination of two haploid gamates (46 chrom) |
| Meiosis | Cell division that reduces the number of chromosomes in a cell -creates 4 haploid cells -has two steps/cycles |
| Meiosis 1 | Crossing over occurs in prophase 1, metaphase, anaphase, telophase, cytokinesis -Takes 1 diploid cell and turns it into 2 haploid cells |
| Meiosis 2 | Both cells from meiosis 1 go into meiosis 2 creating 4 haploid somatic cells |
| Genetic Variation | Meiosis creates offspring that are genetically different from parents through.... Crossing over and independent assortment |
| Crossing Over | DNA strands break and exchange with homologous strands -occurs in prophase 1 -adhered by chiasmata |
| Synaptonemal Complex | Connects homologs and facilitates crossing over |
| Chiasmata | bridges where crossovers are -seen in metaphase 1 -breaks during anaphase 1 |
| Independent Assortment | Sperm or eggs get random assortment of chromosomes -mother and father chromosomes randomly line up and are split |
| Non-disjunction | Failure to separate chromosomes during meiosis (anaphase) -lethal for all but a few chromosomes EX: down syndrome.. trisomy 21 |
| Pangenisis | Gemmules(seeds) released from cells & collect in the gamates -we gain our parents traits |
| Preformation | -Individuals grow directly from gamates -uniparental inheritance |
| Blending | offspring are average of both parents |
| Gregor Mendel | Australian Monk that artificially crossed pea plants discovering the monohybrid cross and alleles |
| Alleles | Alternative version of the same gene EX: tall or short, purple or white |
| Dominant allele | Displayed in F1 (heterozygous) EX: DD |
| Recessive allele | masked in F1 EX:dd |
| Law of Segregation | -all parents contain two distinct alleles -alleles segregate during meiosis -only one allele is passed on to offspring |
| Homozygous | -two identical alleles -Dominant or Recessive EX: DD or dd |
| Heterozygous | -two different alleles EX: Dd |
| Genotype | combination of alleles W/ in an individual |
| Phenotype | observed traits in an individual EX: blonde hair, purple flower |
| Punnett square | -grid that protects the outcome of crosses -known genotype is 'segregated' to show potential offspring |
| Testcross | -determine unknown genotype by crossing with a homozygous recessive |
| Dihybrid cross | -Mendel's second experiment evaluated if characters are linked (inherited together) or independent (inherited separately) EX: pea color |
| NonParental Traits | -In-dihybrid cross, Mendel observed traits not seen in the P generation -Confirmed that genes are independent of each other |
| Law of Independent Assortment | -2 genes assort independent of one another -possible because genes are located on different chromosomes |
| Loss of function mutation | -mutation that renders an allele inactive -creates an absent or deformed protein -commonly inherited as recessive traits |
| Incomplete Dominance | -heterozygotes display an intermediate phenotype |
| Co-dominance | -two alleles equally contribute to phenotype -heterozygotes are a district phenotype |
| Antigen | something that emits an immune response |
| Epistasis | -one gene will influence the phenotype of a second gene -phenotype is usually the result of several genes |
| Polygenic Inheritance | multiple genes combine to make a single phenotype |
| Environmental Influence | -phenotype is a combination of genotype and environment -genes are flexible and can be altered depending on environment |
| Pedigree Chart | Family history reveals inheritance patterns of genetic traits in humans |
| Dominant Pattern | affected offspring will have at least one affected parent |
| Recessive Pattern | affected offspring may arise from two unaffected parents -'skip' generations |
| Carriers | Unaffected heterozygotes 'carry' the recessive allele |
| Over-dominance | -heterozygotes for some genes have an advantage under some circumstances -explains why recessive alleles persist in a population even when they cause early death |
| Chromosome theory of Inheritance | -genes are carried on chromosomes and lead to an individuals unique traits |
| Sex Determination | Can be determined several different ways including: temperature, X-Y, X-0, 2-W, and Haploid-diploid system |
| Temperature based system | temperature determines sex too hot or cold: male warm: female |
| X-Y system | presence of a Y chromosome determines Sex |
| X-0 system | found in insects, females have XX and males have only one X chromosome |
| Z-W system | the genetic sex of an offspring is determined by a pair of sex chromosomes, always a Z from the father, and either a Z or W from the mother |
| Haploid-Diploid system | some species have 16 chromosomes a set -If you inherit 1 set you're male and if you inherit 2 sets you're female |
| X-linked traits | -genes carried on the X chromosomes -males inherit only 1 copy |
| X-chromosome Inactivation | females inactive extra X-chromosome |
| Barr Body | highly condensed X-chromosome that becomes inactive |
| Linkage Disequilibrium | -genes located on the same chromosome will not cross over at same frequency |
| Chromosome Mutation | Several different types including deletion, duplication, inversion, and translocation |
| Deletion | chunk of information is removed from chromosome -looses information |
| Duplication | chunk of chromosome is duplicated making a longer chromosome -gains information |
| Inversion | chunk of chromosome is reversed/inverted -neither looses or gains information |
| Translocation | segment of one chromosome is moved to a non-homologous chromosome -neither looses or gains information |
| Non-disjunction | -failed separation of chromosomes during meiosis -creates either monosomes or trisomies in embryos |
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