genetics exam review.docx

37 Pages

Molecular Biology and Genetics
Course Code
MBG 1000
Georgevander Merwe

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GeneticsandSocietyTermTestReviewInformationfromLecturesCells The Basic Unit of LifeOrganisms can be single cells or collections of many cells Mutations errors in the DNA affect whether the cell functions normallyTypes of CellsProkaryotic cellsLack a nucleusAlmost all prokaryotic cells are single cells bacteria and green algaeThey have DNA and RNA and genetic material but it is not contained within a special compartment in the cell nucleus DNA is nakedEukaryotic cellsContain a nucleus and other complex organelles DNA and RNA contained in a membrane bound compartment within a cell nucleusHumans are eukaryotesDNA is coiled Human CellsHuman cells are divided into 260 cell typesWithin those 260 types they are divided into 4 categories1Epithelial skin line all of our external cavities2Muscle 3Nerve cells carry electrical impulses4Connective tissues tendons ligaments bones cartilage blood and blood elementsMacromolecules in CellsCells are made up of a substance called protoplasm Protoplasm is a collection of molecules some gases and minerals in water A thick waterbased gelThere are 4 basic classes of macromoleculesCarbohydrates sugars starchesenergy source we burn themLipids fats oilsmembranes major component in all cell membranesProteinseg Actin all eukaryotic cells collagen outside of the cellstructures enzymes structure of cell or organism can be enzymesNucleic acidsDNA RNAgenetic materialexamples examplesMutations affect the major macromolecules Can affect directly proteins or indirectly lipids carbohydrates Mutation causes protein to not be able to fold properly it cant functionAnimal CellsSurrounded by the plasma membraneContains nucleoplasm nucleus and cytoplasm with other specialized organellesNucleus is separated from the rest of protoplasm by 2 membranes Those 2 membranes are called the nuclear envelope This is important because it separates the nuclear material from the rest of the protoplasm allowing eukaryotic to impose more complicated regulations The nuclear envelope is the difference between prokaryotic and eukaryotic cellsLysosomes degrade macromolecules Mitochondria have a double envelope as wellCell Division and DeathAre required for normal growth and developmentMitosis produces new cellsMitosis occurs in somatic cells all cells but egg and spermApoptosis is cell death that is part of normal development controlledNecrosis is uncontrolled cell death in response to injuryCell division occurs in 3 stages1 Division of the chromosomesmitosis2 Division of the nucleus karyokinesis3 Division of the cytoplasmcytokinesisThe Cell Cycle The sequence of events associated with cell divisionS phase DNA synthesisreplicationG phase gap for growth M phase mitosis nuclear divisionCell division or cytokinesis is part of G1Replication of ChromosomesProcess of duplicating a chromosomeDNA replication occurs prior to division Produces sister chromatidseach contains one DNA strandHeld together at centromeresThe new copy of a chromosome is formed by DNA synthesis during SphaseOverview of MitosisProduces two daughter cells with identical chromosome setsOccurs in most body cellsContinuous process divided into1Prophase2Metaphase3Anaphase4TelophaseCytogeneticsSub discipline within genetics Focuses on chromosome variationsAbnormal number of copies of genes or chromosomes can lead to genetic abnormalitiesHuman Chromosome Complement2n464422 pairs AUTOSOMESo2 SEX CHROMOSOMESfemale similarXXomale dissimilarXYNB A small number of genes at the end of the short arm of the X are homologous ie the same locus to the genes at the end of the long arm of the Y chromosome Portrait of a ChromosomePrimarily DNA and protein chromatinDescribed by size and shapeHeterochromatin darkEuchromatin lightContains oTelomereoCentromereHeterochromatin Hch is darkly staining contains no active genesEuchromatin Ech contains active gene proteinsTelomeres chromosome tips are always Hch Centromere constriction of the chromosome where spindle fibers attach are always HchCentromere PositionAt tiptelocentric arent any in humansClose to end acrocentricDisplaced from centersubmetacentric At midpointmetacentricLong arm qShort arm p
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