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Developmental Biology Exam: Embryogenesis and Cleavage Patterns, Exams of Developmental biology

A comprehensive overview of key concepts in developmental biology, focusing on embryogenesis and cleavage patterns. It includes definitions of essential terms, explanations of different stages of development, and detailed descriptions of cleavage types. The document also presents questions and answers, making it a valuable resource for students studying developmental biology.

Typology: Exams

2024/2025

Available from 12/20/2024

Nursebrahim01
Nursebrahim01 🇺🇸

358 documents

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DEVELOPMENTAL BIOLOGY EXAM

WITH CORRECT ANSWERS

Embryogenesis - CORRECT ANSWER-Collective name for the stages of development between fertilization and hatching Stages of embryogenesis - CORRECT ANSWER-Fertilization, cleavage, gastrulation, organogenesis, metamorphosis, and gametogenesis Zygote - CORRECT ANSWER-Fertilized egg, a single cell which divides mitotically to produce all the cells of the body Fertilization - CORRECT ANSWER-Fusion of gametes which stimulates development and initiates a new individual Cleavage - CORRECT ANSWER-Series of rapid mitotic divisions following fertilization, cytoplasm of zygote divided into smaller cells (blastomeres), and by the end formation of the blastula Blastula - CORRECT ANSWER-Early-stage embryo consisting of a sphere of cells surrounding an inner fluid-filled cavity, the blastocoel Blastomeres - CORRECT ANSWER-Any of the cells resulting from the cleavage of a fertilized ovum during early embryonic development that together form the blast Blastocoel - CORRECT ANSWER-The fluid-filled cavity within the blastula

Blastopore - CORRECT ANSWER-The invagination point where gastrulation begins. For deuterostomes= anus and protostomes= mouth This is the dimple that becomes a ring through which cells migrate. Those inside will become the mesoderm Gastrulation - CORRECT ANSWER-Stage where blastomeres undergo dramatic movements and change their positions relative to one another, results in formation of three germ layers Gastrula - CORRECT ANSWER-The stage of the embryo following gastrulation in which the three germ layers are formed Organogenesis - CORRECT ANSWER-Germ layers interact with one another and rearrange themselves to produce tissues and organs Gametogenesis - CORRECT ANSWER-Development of gametes, usually not complete until the organism is physically mature Vegetal hemisphere - CORRECT ANSWER-Bottom portion of the egg which contains the yolk Animal hemisphere - CORRECT ANSWER-Upper half of the egg Notochord - CORRECT ANSWER-Mesodermal rod in the most dorsal portion of the embryo, important role in inducing and patterning the nervous system Neurula - CORRECT ANSWER-The embryo while the neural tube is forming Neural tube - CORRECT ANSWER-Embryonic precursor to central nervous system, i.e. the brain and spinal chord

Ectoderm - CORRECT ANSWER-Generates outer layer of embryo, produces epidermis of the skin, forms the brain and nervous system Endoderm - CORRECT ANSWER-Becomes innermost layer of the embryo, produces epithelium of digestive tube and its associated organs (including the lungs) Mesoderm - CORRECT ANSWER-Generates blood, heart, kidney, gonads, bones,muscles, and connective tissues Epithelial cells - CORRECT ANSWER-One of two major types of cells in the embryo, are tightly connected to one another in sheets or tubes Mesenchymal cells - CORRECT ANSWER-One of two major types of cells in the embryo, are unconnected to one another and operate as independent units Cell lineage - CORRECT ANSWER-Series of cell types stating from an undifferentiated, pluripotent stem cell through stages of increasing differentiation, to the terminally differentiated cell type Fate map - CORRECT ANSWER-Diagram mapping larval or adult structures onto the region of the embryo from which they arose Chimeric embryos - CORRECT ANSWER-Embryos made from tissues of more than one genetic source, useful to trace cell lineages by fate maps Homologous structures - CORRECT ANSWER-Organs whose underlying similarity arises from their being derived from a common ancestral structure

Analogous structures - CORRECT ANSWER-Those whose similarity comes from their performing a similar function rather than their arising from a common ancestor What causes the different cleavage patterns observed? - CORRECT ANSWER-Cleavage patterns are influenced by the amount and distribution of yolk and by cytoplasmic factors How does the embryo achieve rapid divisions without growth? - CORRECT ANSWER-The cleavage cell cycle lacks G1 and G phases What are the molecular machines that divide cells? - CORRECT ANSWER-Mitosis: karyokinesis (nuclear division) Cytogenesis ( cytoplasmic division) What regulates the end of cleavage? - CORRECT ANSWER- Mid-blastula transition is the point when zygomatic genomes are activated Holoblastic cleavage - CORRECT ANSWER-Complete cleavage. First cleavage always occurs along the vegetal-animal axis of the egg, the second cleavage is perpendicular to the first. Two types: Isolecithal (small yolk distribution) and Mesolecithal (moderate yolk distribution)

  1. Radial- echinoderms
  2. Spiral - flatworms
  3. Bilateral- tunicates
  4. Rotational- mammals Isolecithal cleavage - CORRECT ANSWER-Complete cleavage. (small amount of evenly distributed yolk)
  5. Radial- echinoderms
  6. Spiral - flatworms
  7. Bilateral- tunicates
  8. Rotational- mammals

Mesolecithal cleavage - CORRECT ANSWER-Complete cleavage. (moderate vegetal yolk disposition) Radial- amphibians Meroblastic cleavage - CORRECT ANSWER-Incomplete cleavage. In the presence of a large amount of yolk in the fertilized egg cell, the cell can undergo partial, or meroblastic, cleavage. Two major types of meroblastic cleavage are discoidal and superficial. Teloecithal cleavage - CORRECT ANSWER-Incomplete cleavage. (dense yolk throughout most of the cell) Bilateral- cephalopod Discodial- fish Centrolecithal - CORRECT ANSWER-Incomplete cleavage. (yolk in center of egg) Superficial - most insects Inner cell mass - CORRECT ANSWER-Give rise to the embryo and some extraembryonic structures Trophoblast cells - CORRECT ANSWER-Give rise to the chorion - part of the placenta What is the function of the blastocoel? - CORRECT ANSWER- Prevents contact between vegetal and animal cells and provides space for gastrulation movements Invagination - CORRECT ANSWER-The infolding of a portion of the outer layer of a blastula in the formation of a gastrula Involution - CORRECT ANSWER-Inturning of cell sheet over the basal surface of an outer layer.

Ingression - CORRECT ANSWER-Migration of individuals cells into the embryo Delamination - CORRECT ANSWER-Splitting or migration of one sheet into two sheets Epiboly - CORRECT ANSWER-The expansion of one cell sheet over other cells Convergent extension or Intercalation - CORRECT ANSWER- Cells intercalate to narrow the tissue and at the same time move it forward. Mechanism for elongation Cadherin - CORRECT ANSWER-...