Cset Subtest Ii: Science 100% Solutions

CSET SUBTEST II: SCIENCE 100% SOLUTIONS Morphogenesis - ANSWER When cells divide, the cell will change shape/organization many times by going through a succession of stages -A single-celled egg develops into a complex, multi-cellular organism by dividing and going through many stages in this process Order of Embryological Development - ANSWER Morula--Blastula--Gastrula-- Neurla Zygote-Cleavage--Morula-Blastula, Gastrula, Neurla, Organogenesis Fertilization triggers the zygote to go through a series of rapid cell divisions called cleavage - ANSWER Fertilization triggers the zygote to go through a series of rapid cell divisions called cleavage Cleavage - ANSWER The mitotic division of zygote after fertilization. -At this stage, the embryo doesn't grow. Cells just keep dividing to form a solid ball called a MORULA Blastula - ANSWER Stage after forming a morula -As the cells continue to divide, they press against each other and produce a fluid-filled cavity called BLASTOCOEL -Blastulation: the hollow ball of cells produced by cleavage of a fertilized ovum Gastrula - ANSWER -Stage after blastula -The process that produces embyronic germ layers is gastrulation -During gastrulation, zygote begins to change its shape. Cells now migrate into the blastocoel and differentiate into 3 germ layers that give rise to various organs and systems in the body -Outer layer becomes ectoderm -Middle layer becomes mesoderm -Inner layer becomes endoderm -Ectoderm produces the epidermis (skin), the eyes, nervous system -Endoderm produces the inner linings of digestive/respiratory tract and accessory organs -Mesoderm gives rise to everything else (e.g. bones/muscles) What do the 3 germ layers give rise to? - ANSWER -Ectoderm produces the epidermis (skin), the eyes, nervous system -Endoderm produces the inner linings of digestive/respiratory tract and accessory organs -Mesoderm gives rise to everything else (e.g. bones/muscles) Neuralation & Organogenesis - ANSWER Neurla stage begins with the formation of 2 structures: -notochord-a rod-shaped structure running beneath the nerve cord -neural tube cells-develop into CNS During this time, organogenesis (the formation of all of the organs/structures) also takes place Provides food for the embryo - ANSWER Yolk Sac Forms a fluid-filled sac that protects the embryo - ANSWER Amnion Is involved in gas exchange; stores uric acid - ANSWER Allantois Surrounds all the other extraembyonic membranes - ANSWER Chorion During embyronic development, some tissues determine the fate of other tissues in a process called ________. - ANSWER Induction Homeotic genes control the development of the embryo. Some homeotic genes, called homeobox genes, consists of homeoboxes (short, nearly identical DNA sequences) that encode proteins that bind to DNA. These proteins tell cells what type of structures to make. Hox genes, which are a subset of homeobox genes, specify the position of body parts in the developing embryo - ANSWER Homeotic genes control the development of the embryo. Some homeotic genes, called homeobox genes, consists of homeoboxes (short, nearly identical DNA sequences) that encode proteins that bind to DNA. These proteins tell cells what type of structures to make. Hox genes, which are a subset of homeobox genes, specify the position of body parts in the developing embryo What are the 2 key phases of the cell cycle? - ANSWER Interphase (growing) & Mitosis (dividing) -Most of the life of a cell is spent in interphase Every cell has a life cycle, the period from the beginning of one division to the beginning of the next. The cell's life cycle is called the cell cycle - ANSWER Every cell has a life cycle, the period from the beginning of one division to the beginning of the next. The cell's life cycle is called the cell cycle Interphase - ANSWER The Growing Phase -It is the time span from one cell division to another -The cell hasn't started to divide. The cell carries out its regular activities. All the proteins/enzymes it needs to grow are produced during interphase -3 stages: G1, S, G2 -The S Phase is when the cell replicates its genetic material. During interphase, every single chromosome, which contains the organism's DNA blueprint, in the nucleus is duplicated before undergoing mitosis -Replication occurs during the S phase -During G1/G2, the cell produces proteins/enzymes, including those required for DNA replication. This is when growth and preparation for mitosis occur -Once duplication has been completed, the cell is ready for mitosis The cell cycle consists of 2 periods: interphase and mitosis. During the S phase of interphase, the chromosomes replicate. Growth and preparation for mitosis occur during the G1/G2 stages of interphase - ANSWER The cell cycle consists of 2 periods: interphase and mitosis. During the S phase of interphase, the chromosomes replicate. Growth and preparation for mitosis occur during the G1/G2 stages of interphase Single Chromatid ---