Slide 1 / 141 Slide 2 / 141 7 th Grade PSI Inheritance and Variation of Traits 2015-11-02 www.njctl.org Slide 3 / 141 Slide 4 / 141 Table of Contents: Inheritance and Variation of Traits Click on the topic to go to that section Mendelian Genetics · Mendelian Genetics Using Punnett Squares · Test Crosses · Genetic Mutations · Return to Table of Contents Slide 5 / 141 Slide 6 / 141 Heredity Frequently Asked Questions Did you ever notice how much children look like their parents and I am sure that questions like these have crossed your mind before: their siblings? Are children ever identical to their parents? · Why do some people look more like their dad and some look · more like their mom? How do I get traits from my parents? · Why are some people born with birth defects or diseases? · As you can see, it's not only something that happens in humans! These questions (and more) will be answered in this unit! This is true about all living things on Earth.
Slide 7 / 141 Slide 7 (Answer) / 141 Genetics & Heredity Genetics & Heredity Here are two related terms that will show up quite a few times in this Here are two related terms that will show up quite a few times in this section. Try to define them with your table and then pull the tab for the section. Try to define them with your table and then pull the tab for the definition: definition: Genetics Genetics A branch of biology that studies genes , heredity , and variation of organisms Answer Heredity Heredity The passing of traits from parent to offspring (children) [This object is a pull tab] Slide 8 / 141 Slide 9 / 141 Review: Cells Review: Mitosis Earlier this year, we talked about the parts of the cell. Mitosis is the process that helps individual cells reproduce. We also talked about mitosis and meiosis and how these processes In mitosis, one "parent cell" reproduces its DNA and then splits into two help organisms live and reproduce. identical "daughter cells". The daughter cells are completely identical to the parent cell. The Stages: Permission Granted: Jeff Sale - San Diego St Univ Slide 10 / 141 Slide 11 / 141 Review: Meiosis 1 Where is all of the genetic information (DNA) found in the cell? Meiosis occurs in all animals that reproduce sexually (2 parents). In meiosis, the cell splits in two individual sex cells without duplicating its DNA.This means that after meiosis, the sex cells have A nucleus half of the DNA as a normal body cell. B cytoplasm The human cell on the left has all 23 After meiosis, the pairs of C cell membrane pairs of chromosomes (one pair is chromosomes split. shown). D mitochondria This means that each sex cell ends Click on the cell to see what happens up with 23 individual chromosomes after meiosis! (1/2 of what they started with)!
Slide 11 (Answer) / 141 Slide 12 / 141 1 Where is all of the genetic information (DNA) found in the 2 The process of creating new cells from existing cells is called mitosis. cell? True A nucleus Answer False B cytoplasm A C cell membrane D mitochondria [This object is a pull tab] Slide 12 (Answer) / 141 Slide 13 / 141 2 The process of creating new cells from existing cells is 3 The purpose of mitosis is _______________. called mitosis. A growth of organisms True B repair of damaged tissue Answer True False C both A and B are true D Neither A nor B are true [This object is a pull tab] Slide 13 (Answer) / 141 Slide 14 / 141 3 The purpose of mitosis is _______________. 4 Each cell in the human body has 23 pairs of chromosomes. How many chromosomes total will each daughter cell have after mitosis? A growth of organisms B repair of damaged tissue Answer C C both A and B are true D Neither A nor B are true [This object is a pull tab]
Slide 14 (Answer) / 141 Slide 15 / 141 4 Each cell in the human body has 23 pairs of 5 Each cell in the human body has 23 pairs of chromosomes. How many chromosomes total will each chromosomes. How many chromosomes total will each daughter cell have after mitosis? sex cell have after mitosis? Answer 46 total [This object is a pull tab] Slide 15 (Answer) / 141 Slide 16 / 141 5 Each cell in the human body has 23 pairs of 6 Meiosis leads to: chromosomes. How many chromosomes total will each sex cell have after mitosis? A Four offspring cells B Genetic Variation Answer 23 total (1/2 of what was C Cloning originally there!) D Both A and B are true E A, B, and C are true [This object is a pull tab] Slide 16 (Answer) / 141 Slide 17 / 141 6 Meiosis leads to: 7 After meiosis, the number of chromosomes is the same in the parent and offspring cells. A Four offspring cells True B Genetic Variation Answer D False C Cloning D Both A and B are true E A, B, and C are true [This object is a pull tab]
Slide 17 (Answer) / 141 Slide 18 / 141 Gregor Mendel 7 After meiosis, the number of chromosomes is the same in the parent and offspring cells. In the 1800s, an Austrian monk named Gregor Mendel conducted a series of True experiments that were designed to uncover False. The number of how traits are passed on from parent to False Answer chromosomes in the offspring. offspring is 1/2 the parent cell. His experiments were aimed at addressing one of the most fundamental issues concerning heredity: [This object is a pull tab] What are the basic patterns of heredity? Slide 19 / 141 Slide 20 / 141 Two Prevailing Original Hypotheses Two Prevailing Original Hypotheses At Mendel's time, there were 2 popular (and incorrect) ideas to 2. Inheritance of mutations: This idea stated that traits present in explain heredity: parents are modified as they are used or not used, and passed on to their offspring in the modified form. 1. The “blending” hypothesis : This idea stated that genetic material from the two parents blends together ex: A giraffe has a long neck ex: a red flower and a white flower will produce a pink flower because her parents kept stretching their own necks out to reach the leaves in the trees, and the long neck trait was passed on. Slide 21 / 141 Slide 22 / 141 Mendel's Experiments Mendel's Experiments In order to complete his experiment, Mendel needed to choose an How many living things can you think of that fulfill these guidelines? organism that had the following characteristics: Make a list with the person sitting next to you. - Usually small Click below to see what Mendel chose to work with. - Has a short life span - Inexpensive to take care of - Produce many offspring in a relatively short period of time - Easy to experiment with The garden pea Why do you think these traits would be important to scientists? Talk about each one at your table and be prepared to share your thoughts.
Slide 23 / 141 Slide 24 / 141 The Traits of Pea Plants Mendel's Choice: The Pea Plant Mendel chose pea plants for his experiment because: There are many varieties with distinct traits (such as color). · He could easily control the matings through cross-pollination. · Each pea plant has both the male and female reproductive organs. · Mendel chose to track 7 traits (or "observable characteristics") that only came in one of two forms. Slide 25 / 141 Slide 25 (Answer) / 141 8 Pea plants were particularly a good choice for use in 8 Pea plants were particularly a good choice for use in Mendel's experiments for all of the following reasons Mendel's experiments for all of the following reasons except that... except that... A Peas show easily observed variations in a number A Peas show easily observed variations in a number of characters, such as pea shape and flower color. of characters, such as pea shape and flower color. B It is possible to completely control matings between B It is possible to completely control matings between Answer D different pea plants. different pea plants. C It is possible to obtain large numbers of offspring C It is possible to obtain large numbers of offspring from one cross. from one cross. [This object is a pull D Peas live for an unusually long time. D Peas live for an unusually long time. tab] Slide 26 / 141 Slide 27 / 141 Monohybrid Cross Experiment #1: Monohybrid Cross One of Mendel's experiments looked at flower color. A pea plant can Mendel then mated two of the either have purple or white flowers. purple offspring plants. This cross produced 929 plants. For this experiment, he crossed a purple flower with a white one. Results: This is called a monohybrid cross 705 of the 929 plants had purple because the parent plants differ in only flowers and 224 had white flowers one trait, their flower color. Use a calculator - What percentage of Results: these flowers were purple? All of the offspring had purple flowers. _____________________% "mono" = one
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