Cell Biology 222 Lecture 14 PDF

Cell Biology 222 Lecture 14 Developmental Biology Created by Dr. Najah AL-Baqami  none Asexual reproduction is simple and direct, it gives rise to offspring that are genetically f E identical to the pa...

Cell Biology 222 Lecture 14 Developmental Biology Created by Dr. Najah AL-Baqami  none Asexual reproduction is simple and direct, it gives rise to offspring that are genetically f E identical to the parent organism. Sexual reproduction, on the other hand, involves the mixing of genomes from two individuals to produce offspring that are genetically distinct from one another and from both their parents. Multicellular organisms arise through a process that begins with the fertilized egg and ends with a new individual. Page 652. 21 Tell The specialized cells that perform the central process the germ cells, or gametes— 0 are haploid; that is, they each contain only one set of chromosomes. Typically, two 5,02 types of gametes are produced. In animals one is large and nonmotile and is referred These haploid 001 to as the egg; the other is small and motile and is referred to as the sperm 0 germ cells are generated when a diploid cell undergoes meiosis. TEST During meiosis the chromosomes of the double chromosome set are partitioned T out, in fresh combinations, into single chromosome sets. Page 652 a Page 653  SEE The early cell divisions of the fertilized egg. The fertilized egg divides into two daughter cells called blastomeres. These two blastomeres divide into four blastomeres, the four blastomeres divide into eight, and so on. Terloo  see Prad Morula: hundred cells arranged as a STEST solid ball of blastomeres. Blastula: The cells of the morula rearrange themselves into a single safe layer of cells surrounding a fluid- filled central cavity  00 Is the folding of the blastula cells. The resulting gastrula is a double-layer cup of cells. d The three germ layers: 1- Ectoderm : The outer layer. 2- Endoderm: The Inner layer. 3- Mesoderm: The layer between the ectoderm and endoderm in most animals These are three germ layers from which all cells, tissues and organs develop. oooo STEFFI re