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Summary of Week 1 - Readings and Lecture

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Human Biology
Stephen Wright

Week 1 DNA – deoxyribonucleic acid Genetics: study of all aspects of genes Genes: fundamental units of biological info Genetics: 1. Molecular Genetics: works on few genes at a time 2. Genomics: study of the complete gene set (genome) Continuum of Genetic and Environmental Factors contributing to disease: it’s a gradient The Nature of Biological Information: - Chromosomes are hypothesized to hold information because they are passed down intact to a new generation through VERY PRECISE divisions. Diploid: two sets of the genome, 2 identical chromosome sets Ex: humans Haploid: one set (the haploid number is n = number of chromosomes in a set) Ex: fungi, bread mold Homologs/Homologous Chromosomes: - two identical chromosomes (paired in meiosis) – can be different alleles. - Not necessarily next to each other when not undergoing meiosis Introns: noncoding inserts in genes ** Gel Electrophoresis can separate DNA molecules Packing DNA: - DNA double-helix coils around a nucleosome Nucleosome: 8 histone proteins Chromatin: Nucleosomes and the DNA Centromere: constricted region acting as attachment point to move the chromosomes around Telomere: Tips of the chromosome – work like the aglet ** Mitochondria and Chloroplasts also have DNA Prokaryotes: - No nuclei - Genome is not bound - Single noncoiled chromosome in cytoplasm - Has plasmids (circular chromosomes) Proteins: 1. Structural: contribute to outward physical structure – hair, nails, muscles, cytoskeleton 2. Enzymatic: catalyze the reactions within the cells 3. Regulatory: turn gene activity on and off Transcription: - Stage I in protein synthesis - DNA is copied into RNA - RNA o Ribose sugar o Cytosine, Guanine, Adenine, and Uracil Nucleotides o Single linear strand o mRNA: removed introns, messenger o rRNA: ribosomal o tRNA: transfer – carry the amino acids in translation o can be reverse transcribed into DNA o Translation: - mRNA is translated into a polypeptide - 3 nucleotides make a codon - Codon: code for specific amino acid - A ribosome reads these codes and makes protein DNA Replication: - Helix is unzipped - Complementary strand formed - New strand is ligated Mutation: a mutation in egg or sperm cells can be passed down, a mutation in somatic cells either dies or grows into a tumor Epigenetic: nongenetic changes Natural Selection: - Homology: similarities due to common ancestry - Differences are due to natural selection (some individuals may produce more offspring) Constructing Evolutionary Lineages: - Branched diagram showing ancestry over time - Genetics show us that chimps are our closest living relatives - Race is not meaningful at the genetic level Forward Genetics: treat cells with normal genes with agents such as chemicals or radiation. Proceed by screening for mutants. Mutations will allow for the discovery of that gene’s function. Phenotype  Mutations  Gene for phenotype Reverse Genetics: A gene with no known function is taken and forced to mutate (or knockout), by studying the resultant effects, the function can be learned. Genotype  Mutations  gene function Manipulating DNA: 1. DNA Cloning: take DNA fragment, replicate and amplify 2. Modify DNA and reintroduce to organism or introduce to difference organism 3. Sequence the DNA Detecting Specific Sequences for DNA, RNA, and Protein: 1. Probing: used to detect specific macromolecules o Probe is labelled (radioactive or fluorescent) o Relies on specif
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