Reproduction Mr. Gluckin 01-14-2013 http://www.cellsalive.com/puzzles/index.htm Ground rules Please close all other apps & web pages. No Facebook, games, music, etc. No off topic chat Be respectful of each other Don t share personal information I can see all chat even private chat Ohio Content Standards Life Science 1: Describe that asexual reproduction limits the spread of detrimental characteristics through a species and allows for genetic continuity Life Science 2: Recognize that in sexual reproduction new combinations of traits are produced which may increase or decrease an organism s chances for survival Life Science 3: Explain how variations in structure, behavior or physiology allow some organisms to enhance their reproductive success and survival in a particular environment At the end of class Wednesday I will be able to describe the difference between asexual and sexual reproduction I will be able to recognize the significance of reproduction to the continuation of a species I will describe and define 2 types of sexual reproduction and at least 2 types of asexual reproduction The question we are here to answer! Aphids are a common plant-pest insect. They alternate between asexual and sexual reproduction. During the summer, aphid populations grow quickly by asexual reproduction. As winter approaches, aphids switch to sexual reproduction. What advantage does the switch to sexual reproduction give the aphids? A)Sexual reproduction maintains a constant level of variation in the population and requires less energy. B)Sexual reproduction decreases variation in the population & prevents the spread of harmful mutations. C)Sexual reproduction increases variation in the population and provides for adaptability in a changing environment. D)Sexual reproduction produces individuals that are clones and allows rapid population growth under stable environmental conditions. 1
Purpose of Reproduction To make sure a species can continue. Definition: Reproduction is the process by which an organism produces others of its same kind. When reproduction is not taking place fast enough, organisms become endangered When reproduction is not taking place at all, organisms become extinct Reproduction & Survival Reproduction is nature s way of allowing a species to survive. A male and a female of a species mate in order to pass their genetic information on to their offspring. Those offspring will then mate and pass on their own genetic information. The more a species reproduces, the larger its population becomes. The larger a species population, the more the species can reproduce to build an even larger population. A large population gives a species a better chance of survival. Sexual & Asexual Reproduction Asexual Reproduction There are two main categories of reproduction: Asexual reproduction - a single organism creates an offspring that contains the same genes as its parent This form of reproduction is generally used by simple organisms, such as bacteria, because only one parent is required. There are several types. All of the offspring are genetically identical to the parent. Not including reproduction in bacteria, all other forms of asexual reproduction involve mitosis. Mitosis is a form of cell division that produces daughter cells that are identical to the parent cell. Sexual reproduction form used by most higher animals, requires sex cells called gametes (sperm/eggs), usually requires two parents. Chromosomes in the Larger Scheme 2
Major Events in Mitosis Mitosis in Onion Root Tip Types of Asexual Reproduction Types of Asexual Reproduction Budding - offspring grows out of the body of the parent organism, i.e. sponges and hydras Binary Fission - singlecelled organisms divide to create two new organisms, i.e. amoeba Fragmentation - parts of an organism break off to form new life, i.e. starfish or planaria Asexual Reproduction A new organism (sometimes more than one) is produced from one organism. The offspring will have hereditary material uniform with the hereditary material of the parent organism. This means they will be genetically alike. Budding Regeneration Fission (Binary fission) 3
Sexual Reproduction Sex cells produced by the females must combine with sex cells produced by the males in a process called fertilization. During fertilization, egg cells and sperm cells fuse to produce an offspring. Fertilization can be internal or external. Internal fertilization egg and sperm combine inside of an organism usually takes place in the female mammals, reptiles, birds, some amphibians and fish External fertilization takes place outside of an organism most amphibians and fish Sexual Reproduction Sexual reproduction is used by most complex organisms, such as humans. A sexually-reproducing organism produces unique sex cells called gametes. Gametes are created from a process known as meiosis. During meiosis, the amount of genetic material is cut in half. Major Events in Meiosis Sexual Reproduction Requires two sex cells egg and sperm The egg and sperm join to form an entirely new organism Different from the parent organism Features of an offspring that result from genes passed on by parents are called inherited traits, or characteristics Mitosis and Meiosis Compared Advantages and Disadvantages http://www.pbs.org/wgbh/nova/body/howcells-divide.html 4
IMPORTANT! Asexual reproduction results in offspring that are genetically identical to the parent organism Sexual reproduction results in offspring that are genetically different from the parent organisms Mini Quiz Asexual organisms, as compared to sexual organisms, tend to be smaller, have shorter life spans, and produce little or no genetic variability between generations. This makes it harder for an individual asexual organism to survive and reproduce. What is one advantage that asexual organisms have that helps them to overcome these disadvantages? A. They have higher reproductive rates B. They never need to sleep C. They are able to find food easier D. They use energy more efficiently Mini Quiz The question again. Aphids are a common plant-pest insect. They alternate between asexual and sexual reproduction. During the summer, aphid populations grow quickly by asexual reproduction. As winter approaches, aphids switch to sexual reproduction. What advantage does the switch to sexual reproduction give the aphids? A)Sexual reproduction maintains a constant level of variation in the population and requires less energy. B)Sexual reproduction decreases variation in the population & prevents the spread of harmful mutations. C)Sexual reproduction increases variation in the population and provides for adaptability in a changing environment. D)Sexual reproduction produces individuals that are clones and allows rapid population growth under stable environmental conditions. The Answer Aphids are a common plant-pest insect. They alternate between asexual and sexual reproduction. During the summer, aphid populations grow quickly by asexual reproduction. As winter approaches, aphids switch to sexual reproduction. What advantage does the switch to sexual reproduction give the aphids? A)Sexual reproduction maintains a constant level of variation in the population and requires less energy. B)Sexual reproduction decreases variation in the population & prevents the spread of harmful mutations. C)Sexual reproduction increases variation in the population and provides for adaptability in a changing environment. D)Sexual reproduction produces individuals that are clones and allows rapid population growth under stable environmental conditions. Additional Resources Cell Biology http://bio-alive.com/animations/cellbiology.htm http://www.cellsalive.com/cells/3dcell.htm 5
FILE TRANSFER Today s Slides 1. 3. Reminder: See you Wednesday Remember to complete your Island lessons! This week I would like you to complete: (8th grade) 3b. Reproduction as well as 3c. Heredity Don t forget to do your Pathway assignments in Math and Reading daily! 2. Remember a recording of this class will remain on your daily plan so you can watch it again if needed. Upcoming Science events: Science Zone is open Tuesdays and Thursdays from 4-5pm. Please join your Science teachers if you need help with your science material by clicking on the link in your newsletter. QUESTIONS? Raise your hand. No mic? Type in your question in advance, then press Enter when it s your turn. If you have no questions, you may go. Thanks for joining us today! 6