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How Cells Divide

How Cells Divide
share By Rick Groleau Posted 10.09.01 NOVA Most of the time, when a cell in our bodies divides, each new cell carries a complete set of chromosomes. The cells involved with human reproduction, however, carry only half after division occurs. In this step-by-step explanation, learn about mitosis and meiosis, the two types of cell division. This feature originally appeared on the site for the NOVA program 18 Ways to Make a Baby. Background on Meiosis and Mitosis As viewed from a human perspective, nature seems to have done ingenious engineering to overcome obstacles. Asexual reproduction relies on a process called mitosis, in which the nucleus of a cell divides to create two new nuclei, each containing an identical copy of DNA. Meiosis, on the other hand, is the process by which certain sex cells are created. How exactly does meiosis halve and mix chromosomes?

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LabBench Study this small section of a slide of Sordaria to determine if crossing over has occurred in the asci designated by an X. If the ascospores are arranged 4 dark/4 light, count the ascus as "No crossing over." If the arrangement of ascospores is in any other combination, count it as "Crossing over." Resources, Animations, Interviews, + Tools We are enhancing our most popular resources by building collections around them. First up: Polymerase Chain Reaction! The DNA Learning Center has been developing multimedia animation programs since 1990. These popular programs feature some of the most common molecular processes such as PCR, sequencing, and DNA restriction. View online or download for play from your computer. Stunning three-dimensional visualizations of cellular and molecular processes.

Parts of the Cell - Cells Alive! For life all cells have basic needs. Cells have diverged in their structure and function to accommodate these survival requirements. Here are some KEY TERMS to help you think, explore and search for similarities and significant differences that have become the characteristics of eukaryote (animal, plant) and prokaryotic (bacteria) cells. Examples might be searching: eukaryote prokaryote reproduction or animal plant cell energy. Chromosome Behavior and Gene Linkage - BIOL110F2012 - Confluence Previously we examined the relationship between gene segregation and meiosis. As you should now know, Mendel was able to infer independent assortment between different genes because they were located on different chromosomes (each of which assorts randomly during meiosis). We also mentioned that genes located on the same chromosome may segregate together because they are linked. Next, you will learn why they may, or may not, segregate together. Moreover, you will learn how the frequency at which they become unlinked can be used to construct a genetic map of each chromosome.

What is the strongest muscle in the human body? (Everyday Mysteries: Fun Science Facts from the Library of Congress) There are three types of muscles in the human body: cardiac, smooth and skeletal. Cardiac muscle makes up the wall of the heart and is responsible for the forceful contraction of the heart. Smooth muscles make up the walls of the intestine, the uterus, blood vessels, and internal muscles of the eye. Skeletal muscles are attached to the bones and in some areas the skin (muscles in our face). Contraction of the skeletal muscles helps limbs and other body parts move. Most sources state that there are over 650 named skeletal muscles in the human body, although some figures go up to as many as 840.

Small Movies of Cell Bio Topics Interactive tutoring on the toughest topics in biology Have you ever wished for an effective tool to help your students visualize tough topics like a tour of the plant and animal cell, cellular respiration, photosynthesis, mitosis, meiosis, protein synthesis, or how neurons work? Our new 3-minute animations allow instructors to show 3D, fluid movement and dramatic "zoom" sequences that bring difficult-to-teach biological concepts to life during lectures. Each animation is accompanied by a PowerPoint® slideshow with screenshots identifying the main components of the animation.

Differences Between Cancer and Normal Cells Updated December 16, 2014. Written or reviewed by a board-certified physician. See About.com's Medical Review Board. Human Sense Organs - The Five Senses Aristotle (384 BC - 322 BC) is credited with the traditional classification of the five sense organs: sight, smell, taste, touch, and hearing. As far back as the 1760's, the famous philosopher Immanuel Kant proposed that our knowledge of the outside world depends on our modes of perception. In order to define what is "extrasensory" we need to define what is "sensory".

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