NN+Development+HW

Human Life Cycle 16.1 p. 320 INSERTING FIGURES IS ALWAYS A GOOD THING. (1) How many chromosomes does a mother contribute to a new individual? A father?\ (2) Where does meiosis occur in males? in females? (3) Compare and egg cell to a sperm cell. (4) What is the difference between meiosis and mitosis.
 * Each parent contributes 23 chromosomes
 * Males: in the testes, chromosomes are divided up to where there are 23 chromosomes in the cell
 * Females: in the ovaries, cell division occurs to where there are 23 chromosomes in each cell
 * The egg cell is much larger than the sperm cell; and the sperm cell has a tail to help it "swim" to the egg cell, but the egg cell doesn't have a tail and simply sits and waits for a sperm cell to come and combine with it to make a child
 * Meiosis only occurs to produce the sex cells and the cells resulting from meiosis only has 23 chromosomes, whereas mitosis is the division of all the other cells and there are 46 chromosomes in each of the cells resulting from mitosis.

Development Chapter 17 17.1 (5) Describe in detail how fertilization occurs (6) What is polyspermy and how is prevented during fertilization? 17.2 (7) Describe the processes involved in development. (8) What are the extraembryonic membranes and what is their role? (9) What happens during pre-emrbyonic development? (10) What happens during embryonic development? (11) What are the primary germ layers and what body structures come from each layer?
 * Once the sperm enters the female, it swims into the ovary and finds an egg cell. From there the sperm cell has to penetrate the membranes surrounding the egg cell to fuse with the egg and deposit its DNA into the egg cell.
 * Polyspermy is when multiple sperm cells fuse with an egg cell. This condition is prevented by two major steps. The first is that the plasm membrane depolarizes. The second step is for that the cortical granules release enzymes to turn the zona pellucida into an impenetrable shield.
 * The first step is called cleavage, and this part is where the zygote starts to divide, and this division is mitotic.
 * The second step is growth, which is where the "daughter cells" become larger than their source cells
 * The third step is morphogenesis, a step that involves the embryo starting to take shape and certain cells starting to differentiate from other cells and moving to their appropriate places in the body
 * The fourth, and final, step is differentiation. Differentiation is the step where cells start to gain a structure and a function. The first distinguishable system is the nervous system.
 * Extraembryonic membranes are the membranes that surround the embryo. They perform functions such as providing nourishment to the embryo, collecting the waste of the fetus, and providing a protective fluid around the embryo.
 * During the first week after fertilization the zygote is mostly just dividing, creating the embryo.
 * Embryonic development is the development after the second week. During this stage the body mostly begins to create more cells and the cells differentiate to develop all the different systems.
 * Ectoderm: creates the epidermis, the lining of the oral cavity and rectum, and the nervous system
 * Mesoderm: creates te skeleton, muscles, dermis, cardiovascular system, urinary system, reproductive system, outer parts of the respiratory and digestive systems.
 * Endoderm: creates epithelial lining of the digestive tract and respiratory tract and the bladder