Genetics Test 1 (got 94% in the course)

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Biological Sciences
BIOL 2153
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Chapter 1DNA structurephosphatesugar backbone connected by base pairs AT GCDNAs function is replication and gene expression Replication depends on base pairing and preservation of the sequence of basesmRNA Contains all the invormation needed for the synthesis of a polypeptide RNA transcript eventually separates from its DNA template and is altered by the addition deletion or modification of nucleotidesThe finished molecules are mRNA important in gene expressionGene expression the process by which genes affect the phenotypeConverts sequence of nucleotides to sequence of amino acids in a protein via transcription and translationTranscription process through which RNA is formed along a DNA template A pairs to T G pairs to CTranslation protein polypeptide synthesis directed by a specific messenger RNA occurs on ribosomesAt this stage the genes mRNA acts as a template for the synthesis of a polypeptideEach of the genes codons now present in the sequence of the mRNA specifies the incorporation of a particular amino acid into the polypeptide chain fig 17 Human beta globin gene expressionThe amino acid sequence of a protein determines its structure and functionMuch of an organisms phenotype results from protein functionMutation changes in the DNA sequence of a gene change the sequence of the encoded protein therefore mutations can alter protein structure and function Hemoglobin sicklecell mutationA change in one of the base pairs can cause a serious mutation of a geneAlthough it seems like a small change the outcome can be drasticChapter 2Each chromosome consists of one doublestranded DNA molecules plus an assortment of proteinsEukaryotic somatic cells possess two copies of each chromosome diploid and the gametes have only one copy of each chromosome haploidCell Cycle in eukaryotesG1SG2MIn this progression S is the period in which the chromosomes are duplicated an event that requires DNA synthesisThe M phase is the time when the mother actually dividesThis occurs in two phases Mitosis process that distributes the duplicated chromosomes equally and exactly to the daughter cells and cytokinesis which is the process that physically separates the two daughter cells from each other The G1 and G2 phases are gaps in between the S and M phasesMitosis makes my toes When mitosis begins each chromosome has already been duplicatedThese sister chromatids are joined at the chromosomes centromereThese chromatids are exact copies of the original chromosomeG1 2n 2cG2 2n 4cAfter cytokinesis 2n 4c both daughter cells are diploidStages of mitosisInterphase centrosome duplicates chromosomes begin to condense and become visableProphase condensing chromatids to become chromosome held together at centromere daugher cells begin to move apartThe initiation of spindle formation and the condensation of duplicated chromosomes from the diffuse network of chromatinprophaseMetaphase Attachment of spindle microtubules to the kinetochores indicates the cell is entering metaphaseThe Chromosome are aligned at metaphase plate halfway between the polesEach sister chromatid is connected to a different poleThis polar alignment is crucial for the equal distribution of genetic material to the daughter cells
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