Final exam big concepts units 1 3 Unit 1 I Genomic equivalence all different cell types in an organism contain identical DNA but are different because each cell expresses different genes 1 Regulated through gene regulation and gene expression cell differentiation II Cell potency 1 Totipotent totally potent i Potential for a cell to become an entire individual organism ii No genes have been irreversibly turned off i Cell can become any part of an organism but not an entire Ex early embryonic stem cells 2 Pluripotent partially potent organism ii Some genes have been turned off Ex mature embryonic stem cells 3 Multipotent maybe potent i Cells are already differentiated limited potential Ex adult stem cells 4 Stem cell relatively undifferentiated cells that can be induced through cell signaling to differentiate i Used for research III EMBRYONIC DEVELOPMENT Fertilization Cleavage Gastrulation Morphogenesis organogenesis Zygote morula blastula gastrula embryo 1 Fertilization sea urchin i Contact 1 Sperm s acrosome releases hydrolytic enzymes that digest egg s outer jelly layer ii Acrosome reaction 1 Sperm releases acrosomal process containing binding 2 Egg protein receptors recognize and bind to sperm proteins proteins a Species specific b Like BINDIN iii Membrane fusion 1 Egg membrane depolarizes fast block a No other sperm can penetrate b Occurs within the first three seconds lasts up to iv Cortical reaction 1 minute 1 Wave of Ca2 ions activate the eggs at the sperm site a Cortical enzymes are released out of the egg 2 Vitelline space swells hardens and forms a fertilization envelope slow block a Permanent block v Fusion of nuclei 1 Egg and sperm nuclei fuse to create a diploid zygote 2 Cleavage division of cells formation of blastula blastoderm URCHIN Microlecithal little yolk FROG Mesolecithal medium yolk Spherical blastocoel Offset blastocoel CHICK Macrolecithal lots of yolk Elongated blastocoel Holoblastic cleavage even and uniform Zygote 4 cell morula blastula Toward animal pole Cortical rotation establishes grey crescent cells Holoblastic cleavage First 2 cleaves vertical Third horizontal Zygote 2 cell 4 cell morula blastula Meroblastic cleavage only through cytoplasmic disk not through yolk Zygote blastoderm formation of 3 germ layers endo meso ecto and 3 Gastrulation archenteron i Urchin 1 Ingression inner mesenchyme cells at vegetal pole lose adhesion detach and move into blastocoel enchyme mesoderm a Mes b Must be induced through cytoplasmic determinants 2 Invagination Outer cells at vegetal pole pinch inward by changing shape a Form the blastopore future anus b Begins archenteron formation 3 Elongation a Archenteron guided by filipodia of mesenchyme cells to reach other end of blastula forms mouth a Outer cells change shape push into blastocoel b Forms blastopore and dorsal lip 2 Involution a Outer cells continue to divide and roll inward from all directions into blastopore b Creates archenteron and inner germ layers mesoderm and endoderm ii Frog 1 Invagination iii Chick Upper epiblast cells converge to the midline and move inward along a primitive streak Primitive streak blastopore Some cells move downward to become endoderm Other cells move sideways to become mesoderm iv Three germ layers 1 Endoderm inner layer a Thyroid thymus pancreas liver tonsils b Digestive and respiratory tract 2 Mesoderm middle layer Inner skin cartilage connective tissue a Skeletal system b c Circulatory system spleen d Reproductive system e Excretory system f Muscles and notochord a Outer skin b Nervous system and sense organs c Glands pituitary sweat mammary d Hair nails and teeth e Facial and ear bones 3 Ectoderm outer layer 4 Organogenesis Neurulation i Frog 1 Notochord induces surface ectoderm cells a Ectoderm cells harden and change shape forming the neural plate 2 Formation of neural folds grooves a Changes in cell shape cause uplifting of cells i Microtubules extend to elongate ii Microfilaments contract to turn cells into 3 Neural tube formation wedge shape a Neural folds meet to form tube i Cell adhesion changes pinches off neural tube from under overlying cells b Neural tube becomes spinal cord and brain 4 Somites form vertebrae ribs and muscles a Somite paired blocks of mesoderm b Rest of mesoderm splits and forms body cavity 5 Neural crest cells migrate to form other cell types coelem a Nerves teeth skull b IV Genetic and molecular mechanisms used in induction 1 Cells are guided through development via molecular signals that induce changes i Molecular signals maternal cytoplasmic determinants 1 Regulate gene expression and influence early 2 development If CD are distributed asymmetrically cells receiving different CDs signals will have different instructions and different embryonic fates 3 Signals determine three body axes a Anterior posterior b Dorsal ventral c Right left 4 CD in grey crescent cells convey dorsal info for the embryo and induce differentiation V Morphogens 1 Substance that provides positional information in the form of a concentration gradient along an embryonic axis i BICIOD affects the fate of the anterior posterior axis 1 In fruitfly ii SHH sonic hedge hog affects the fate of the anterior posterior limb development Unit 2 I Phases of the cell cycle mitosis and meisos and their checkpoints a Cell cycle series of events that take place in a cell leading to its division and duplication i Cell growth Interphase ii Mitosis diploid to diploid 2n 1 Prophase 1 G1 cell growth cellular contents excluding chromosomes duplicated a G1 restriction checkpoint growth is completed successfully after G1 makes sure i Successful passes through checkpoint into S ii If not goes to G0 to hang out and finish maturing do its job or to fix what is wrong 1 fixed matures then goes to S 2 not fixed apoptosis signaled 2 S chromosomes duplicated 3 G2 cell double checks the duplicated chromosomes making any needed repairs a G2 checkpoint successful asseses if DNA replication was If yes goes into M mitosis i ii Uses MPF maturation promoting factor a cyclin CDK complex a Centrosomes move to opposite sides b Spindle microtubules lengthen c Nuclear membrane dissolves d DNA begins to condense into sister chromatids 2 Prometaphase 3 Metaphase a Kinetochore appears and aster forms a Spindle microtubules move the chromosomes b Line up in the middle of the cell 4 Anaphase a Centromeres contract and split the sister chromatids to opposite poles of cell 5 Telophase cytokinesis a Spindle disassembles b
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