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UMass Amherst MICROBIO 160 - Genes

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MICROBIO 161 1st Edition Lecture 3Outline of Last LectureI. The Nature of Disease II. Categories of Diseases III. The Scientific MethodIV. Experiments and TheoriesV. InfectiousDiseases a.Factors VI. Life ExpectancyOutline of Current LectureI. Cells a. Organization ofCells II. The Cell Cycle a. The CellCheckpoints III. GrowthFactors IV. Cell Function and Cancer a. Characteristics of a Normal Cell andCancer Cell V. Protein Production VI. Genetic Code VII.DNA Replication These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is bestused as a supplement to your own notes, not as a substitute.Current LectureEvery cell has the same DNA• The average adult has approximately 100 trillion cells in total - 210 types of cells in the human body Organization of cells:• Tissues: groups of cells that perform a similar function • Organ: groups tissues which perform the same function • Organ systems: groups of related organs - Digestive System 1. Stomach A. Acid secreting cells (gland) B. Mucus secreting cells (gland) 2. Intestines C. Muscle cells (muscle) D. Nutrient absorbing cells (mucosa) The Cell Cycle:G1 (first growing phase): Where most cells spend most of their life• Creates proteinS (synthesis phase): When a cell is big enough it begins the process of cell divisionG2 (second growing phase): Growth in this has only occurs if the cell notices that it doesn’t have all the required components to divideM (mitotic phase): Actual cell divisionThe Cell Checkpoints: Cells have checkpoints to regulate the cell cycle— set of questions— if any answers to the questions are no, the cell cycle pauses until there are enough changes that the answer becomes a yes— if yes isn’t possible, the cell can exit the cycle or begin apoptosis (process of programmed cell death)G1 Checkpoint: Is the cell big enough? (cell growth),Is the environment favorable?G2 Checkpoint: Is all the DNA replicated? (DNA replication machinery), Is the cell big enough?, Is the environment favorable?M Checkpoint: Are all chromosomes aligned on spindle? (mitosis machinery)Growth Factors: proteins that stimulate cell growth and division• Can be self produced or come from another cell • Growth factors attach to a growth receptor and start a signal cascade (signaling molecules between cells)—results in transcription factor activation— further results transcription of growth related genes •The blue dots resemble the different proteins that eventually turn on the orange transcribing genesDNA holds the recipes for making proteins— everything a cell needs to survive is coded in its DNA• Chromosomes: the cookbooks containing protein recipes • Gene: an individual protein recipe Protein ProductionProteinProductionRNAPOLYMERASERIBOSOMESTRANSCRIBEDTRANSLATED AMINO ACIDS(Protein)Deoxyribonucleic Acid RibonucleicAcid(messenger RNA)Transcription copy of DNA—RNA translated to Amino AcidsDNA and RNA are nuclear chains of nucleotides (letters in the DNA/RNA genetic alphabet)•DNA Bases: T—A, C—G•RNA Bases: U—A, C—GGenetic Code: DNA sequence of a gene= a sentence of 3 letter words (codon)• Thedogwasstuckoutinthesunalldaywaitingforhisfamily- Separated into 3 letter bits (codons): the protein code would read: Thedog was stuck out in the sun all day waiting for his family— the sentence represents a gene, each letter corresponds to a nucleotide base, each word represents acodon— together they code for a specific order of amino acids (building blocks— peptides— for proteins—a polypeptide)Genotype: the process of determining the genetic constitution by examining their DNAsequence.Messenger RNA (mRNA): a large family of RNA molecules that convey genetic information from DNA to the ribosome, where they specify the amino acid sequence ofthe protein products of gene expression.Polypeptide: chains of amino acids Phenotype: the appearance of an organism resulting from the interaction of the genotype and the environmentDNA Replication: the process of producing two identical strands from one original DNA molecule• When cells divide, each daughter cells needs a complete copy of the DNA • DNA polymerase is the protein that makes the copy • Once DNA polymerase makes a copy of the DNA, the cell can moveforward in the cell cycle DNA reads, synthesizes, and proofreads• Bases have assignments A—G, C—G, if they don’t go to the correct onethen it will more than likely change to the correct one Cell Function and Cancer:• Every cell in an organism has the same genetic information (DNA) butcells perform different roles • Their roles depend on their function which is determined by the tissueor organ to which they belong - A cell’s function is guided by a specific set of instructions (genes) in itsnucleus - Expression of genes is controlled by transcription factors— help cellsperform their daily functions and regulate cell growth by controllinggene expression- When the instructions (genes) relating to cell growth and death are wrong (mutated), the cell may start dividing uncontrollably, not die when it should and cancer results Characteristics of a Normal cell:• Reproduce themselves exactly • Stop reproducing at the right time • Stick together in the right place • Become specialized or mature (differentiate) • Self destruct if they are damaged (apoptosis) Characteristics of a Cancer cell:• Don’t reproduce themselves exactly • Don’t stop reproducing at the right time • Don’t stick together in the right place • Don’t become specialized or mature (differentiate) • Don’t self destruct if they are damaged


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