Also occurs in the absence of DNA damage as a mechanism to shuffle genes

Also occurs in the absence of dna damage as a

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Also occurs in the absence of DNA damage as a mechanism to “shuffle” genes between a pair of homologous chromosomes that carry the same genes (i.e., each member of the chromosome 15 pair will shuffle with one another, but not with other chromosomes from a different pair). This happens during gamete (egg and sperm) formation as a way to generate genetic diversity on each pair of chromosomes before they are passed to the next generation. Thus, two parents with various characteristics will likely see those “mixed up” in their children. Non-Homologous End Joining: Process in which damaged DNA with double-strand breaks is essentially stuck together in non-homologous ways. Is a rather extreme and problematic repair pathway. Because the DNA is joined without regard to a similar sequence, this type of repair can lead to an increase in mutations at the damage site, as well as chromosomal “mix up”. Usually used under circumstances of extreme DNA damage as a last resort by the cell to save the DNA. Mutated Enzymes in Repair Pathways Type(s) of DNA Damage Affected DNA polymerase is mutated and cannot fill in the gap after repair enzymes removed damaged nucleotides. Single damaged base Thymine dimers Mutated DNA repair enzymes in nucleotide excision repair do not recognized damaged regions of DNA. Thymine dimers Mutation in DNA polymerase prevents it from recognizing an incorrectly added base during DNA replication. Mismatch repair Mutation in the recombination machinery involved in DNA repair. Double stranded break INHERITANCE Key Concepts: F DNA is Organized into Chromosomes Genes: sections of DNA that code for a protein and are expressed depending on the needs of the cell.
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Histones: proteins that DNA wraps around to prevent tangling as well as promote coiling of the nucleosomes that it creates once combining the DNA and itself together into turning into a larger chromatin fiber. Chromatin fibers: fibers that are folded into large loops that eventually form highly compact DNA chromosomes that serve as a multilevel filing system for the genes. Genome: whole set of genes that a person has. Genotype: exact sequence of nucleotides present on each individual’s chromosomes; our complete set of genes. Phenotype: all the observable characteristics or traits of an individual, including ones that are not easily seen. Example: blood type or color blindness. Differences emerge from subtle differences in genotype as well as environmental factors such as the quality of our food , type of shelter we live in , and financial security . Alleles are Gene Variations: Alleles may have differences in the sequences of only one or a few DNA base pairs, but that small difference means that they produce different proteins than their counterpart genes. Somatic cell: any cell that isn’t a gamete. Contains two copies of every allele, one from each biological parent.
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  • Winter '19
  • DNA, DNA Damage

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