BSC2011 Exam 1 Review I II III IV V VI Introduction Gene Expression Fertilization Cleavage Gastrulation Organogenesis Slide Set I Introduction Gene Expression Types of Science Deductive hypothesis driven experimental Inductive reasoning generalize from a large body of consistent observations Steps of the Scientific Process 1 Observe something 2 Ask a question 3 Formulate a hypothesis 4 Make a prediction 5 Experiment test 6 Revise hypothesis Hypothesis a proposed explanation for an observed phenomenon that leads to a certain prediction Null Hypothesis a statement that negates a hypothesis Theory a hypothesis or set of hypothesis that is consistent with virtually all of the available evidence Junk Science the selective enlistment of science to serve a political and or economic agenda Pseudoscience fake science false evidence etc Good experimental design should aim to disprove the null hypothesis Central Dogma the flow of genetic information is basic to all living things I DNA mRNA Transcription DNA mRNA Protein i Occurs in a ribosome in the cytoplasm Translation mRNA Protein i Codons code for specific amino acids ii Multiple codons may code for the same amino acid because of 3rd base wobble The majority of an organism s genes code for proteins 50 i Enzymes catalyze reactions ii Structural support iii Transport other molecules iv Hormones coordinate cell activity v Receptors respond to and bind to chemical stimuli vi Defense antibodies vii Storage of amino acid reserves The DNA sequences of most of an organism s chromosomes carry information for the production of specific proteins What does it mean when we say a gene is expressed It is has been transcribed and translated II Mutations Large scale sections of chromosomes get rearranged Small scale point mutation Change in just one nucleotide in a gene Substitution may or may not change the amino acid that was originally coded for i Silent no amino acid change ii Missense amino acid changes Insertions Deletions reading frame cause a frameshift mutation by altering the codon i Nonsense early or not stop signal no protein A non functional protein is likely to arise from a nonsense mutation What does it mean when we say a gene is expressed It is has been transcribed and translated Slide Set II Fertilization Cleavage I Animal Reproduction a Asexual b Sexual II Animal Gametes Life Cycles III IV General Pattern animal development a Fertilization b Cleavage c Gastrulation morphogenesis d Organogenesis V Animal Fertilization a Sperm b Egg c Steps VI Animal Cleavage a Definition terms b Purposes c Note d Egg types cleavage types i Sea urchin ii Frog iii Chick iv Human i Contact ii Acrosomal Reaction iii Cell membrane depolarization fast block iv Cortical Reaction fertilization envelope slow block v Entry of sperm nucleus I Animal Reproduction a Asexual one parent no fertilization of egg by sperm i Advantage quick ii Disadvantage carries mutations since offspring are clones iii Types 1 Binary fission 2 Budding 3 Fragmentation regeneration 4 Parthenogenesis no sperm 5 Gynogenesis all female activated but not fertilized by sperm b Sexual 1 egg and 1 sperm i Types 1 External by spawning sea urchins spray sperm 2 Internal by insemination ii Development types 1 External a Oviparous embryo gets food from yolk and later hatches chickens a Ovoviparous live birth food still from yolk 2 Internal b Viviparous live birth food from placenta some snakes humans iii Advantage genetic diversity iv Disadvantage must find mate slower II Animal Gametes a Gametes sex cells i Meiotic cell division ii Half of chromosomes haploid iii Oogenesis production of haploid eggs iv Spermatogenesis production of haploid sperm b Somatic Cells body cells i Mitotic cell division ii Full of chromosomes diploid iii Can be arranged into pairs of homologous chromosomes III Life Cycles a Diplontic most animals b Haplontic fungi protists c Alternations of generations plants some algae IV General Pattern animal development 1 Fertilization Zygote 2 Cleavage Blastula 3 Gastrulation morphogenesis Gastrula 4 Neurulation Organogenesis Embryo V Animal Fertilization a Sperm i Acrosome vesicle at the tip of the sperm head that contains hydrolytic enzymes to digest the outer jelly coat of the egg ii Bindins gamete recognition proteins b Egg i Outer Jelly coat cumulus ii Middle Vitelline Layer zona pellucida iii iv Yolk v Cytoplasmic Determinants Inner cell membrane has cortical granules c Steps 1 Contact i Sperm s hydrolytic enzymes digest through outer jelly coat 2 Acrosomal Reaction Sperm ejects acrosomal process Protein receptors on the egg recognize and bind to the sperm s bindin molecules 3 Fusion of egg sperm cell membranes Na flows in causing egg cell membrane depolarization Causes Fast Block of Polyspermy temporary 1 3 seconds 4 Cortical Reaction Caused by release of Ca from E R This causes cortical granules to rupture Cortical enzymes degrade remaining receptors Then the C M and Vitelline Layer detach Then the fertilization envelope forms and acts as a slow block of polyspermy permanent 5 Sperm nucleus enters egg and nuclei fuse i ii i ii i ii iii iv v d Note on Cortical Reactions i The Ca is important because it activates the egg Eggs can be artificially activated by injecting Ca ii Parthenogenesis in some all female species eggs develop asexually without sperm iii Gynogensis sperm is only used for activation Not for fertilization VI Animal Cleavage a Cleavage a rapid series of mitotic cell divisions that occur in the absence of cell growth b Purposes i Produce many cells quickly ii Create blastocoel cavity iii Regulates how CD s get partitioned early cell determination b Note i Morula solid ball of 16 64 cells ii Blastula hollow ball of a coupe thousand cells Blastocoel hollow fluid filled cavity Blastomere each in cell in a blastula c Egg types cleavage types The amount and distribution of yolk in the egg will affect cleavage and blastocoel formation i Sea urchin o Microlecithal egg little yolk o Holoblastic Cleavage cells divide completely and synchronously o Spherical Blastocoel ii Frog o Mesolecithal egg moderate amount of yolk Unevenly distributed Animal Pole mostly cytoplasm w nucleus Vegetal Pole mostly dense yolk o Holoblastic Cleavage cells divide completely but at different rates Yolk rich cells divide slower First 2 cleavages are vertical 2nd division begins before the 1st is finished 3rd cleavage is horizontal o Blastocoel is reduced and offset towards the animal pole iii
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