Bio Cheat Sheet for Exam PDF

Preview

Summary

A cheat sheet for the first bio exam...

Description

Cell Cycle: Mitotic (M) Phase (mitosis & cytokinesis), Interphase (90% of cycle, cell growth & copying of chromosomes in preparations for cell division) sub-phases: G1 (firs gap), S Phase (synthesis - chromosomes are duplicated), G2 Phase (second gap). Crossing over occurs in early Prophase 1 when each chromosome pairs with its homolog. The sister chromatids are held together by proteins called cohesins. The non sister chromatids are broken at precisely corresponding positions. A zipper-like structure called the synaptonemal complex holds the homologs together tightly. DNA breaks are repaired, joining DNA from one non sister chromatid to the corresponding segment of another. All the DNA in a cell constitutes the cell’s genome. Sister chromatids are joined copies of the original chromosome attached along their lengths by cohesins. Genes (region of DNA that can be expressed to produce a final functional product that is either a polypeptide or an RNA molecule) are the units of heredity and are made up of segments of DNA. They are passed to the next generation via reproductive cells called gametes (sperm and eggs). In asexual reproduction, a single individual passes all of its genes to its offspring without the fusion of gametes. In sexual reproduction, two parents give rise to offspring that have unique combinations of genes inherited from the two parents. A karyotype is an ordered display of the pairs of chromosomes from a cell. A homologous chromosome (homologs) are the two chromosomes in each pair. They are the same length and shape and carry genes controlling the same inherited characters. Sexual life cycle increases the genetic variation in a species through the behavior of chromosomes during meiosis and fertilization: independent assortment of chromosomes, crossing over, random fertilization. Independent assortment of chromosomes: homologous pairs o chromosomes orient randomly at metaphase 1 of meiosis. Each pair of chromosomes sorts maternal and paternal homologs into daughter cells independently of the other pairs. Number of combinations possible when chromosomes assort independently into gametes is 2^n (n=haploid number). For humans (n=23), there are more than 8 million possible combinations of chromosomes. DNA can transform bacteria through transformation: a change in genotype and phenotype due to assimilation of foreign DNA. Conclusion of the experiment: the living R bacteria had been transformed into pathogenic S bacteria by unknown, heritable substance from the dead cells that enabled the R cells to make capsules. Oswald Avery and colleagues announced that the transforming substance was DNA. DNA molecules are made up of two strands forming a double helix: two outer sugar-phosphate backbones, with the nitrogenous bases paired in the molecule’s interior. The backbones are antiparallel (their subunits run in opposite directions). Adenine (A)

rRNA is the most abundant type of RNA.The cells in a non-dividing stage are in G0 phase. DNA polymerase i enzyme removes RNA nucleotides of primer from 5’ end and replaces them with DNA nucleotides. Exons are the coding segments of a stretch of eukaryotic DNA. Ensures the DNA sequence in the genome remain accurate: proofreading during DNA replication, mismatch repair, excision repair, complementary base pairing during DNA replication....