Anatomy and Physiology Answer Key

2 required answer in bold the dna must be replicated

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Unformatted text preview: e; still part of the same chromosome as an extra chromatid. B. Late prophase: Chromosomes condense (coil and fold up) into visible form. Centrioles move to opposite ends of the cell. C. Metaphase: Spindle fibers form between the centrioles. Chromosomes attach to the spindle fibers at the cell ‘equator’. D. Late anaphase: Chromatids from each chromosome are pulled apart and move in opposite directions, towards the centrioles. E. Telophase: Chromosomes begin to unwind again. Two new nuclei form. A cleavage furrow forms across the midline of the parent cell, pinching it in two. F. Cytokinesis: Cell cytoplasm divides to create two distinct ‘daughter cells’ from the original cell. It is in this form for most of its existence, and carries out its designated role (normal function). Cancer: Cells out of Control (page 31) 1. 2. 3. Cancerous cells have lost control of the genetic mechanisms regulating the cell cycle so that the cells become immortal. They also lose their specialized functions and are unable to perform their roles. The cell cycle is normally controlled by two types of gene: proto-oncogenes, which start cell division and are required for normal cell development, and tumorsuppressor genes, which switch cell division off. Tumor suppressor genes will also halt cell division if the DNA is damaged and, if it cannot be repaired, will bring about a programmed cell suicide (apoptosis). Normal controls over the cell cycle can be lost if either the proto-oncogenes or the tumor suppressor genes Tissues and Organs (page 33) 1. (a) Diffusion. (b) Phagocytosis. 2. (a) (b) (c) (d) 3. (a) Muscle tissue: Dense tissue comprising highly specialized contractile cells called fibers held together by connective tissues. (b) Nervous tissue: Tissue comprising densely packed nerve cells specialized for transmitting electro-chemical impulses. Nerve cells may be associated with supportive cells (e.g. Schwann cells), connective tissue, and blood vessels. (c) Connective tissues: Supporting tissue of...
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