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Heredity Review. Heredity. The passing on of physical or mental characteristics genetically from one generation to another. They can be considered the “blueprints” of the human body. What are “Blueprints”. Every living organism needs a set of “Blueprints” that specify its traits
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Heredity The passing on of physical or mental characteristics genetically from one generation to another. They can be considered the “blueprints” of the human body.
What are “Blueprints” Every living organism needs a set of “Blueprints” that specify its traits Traits= A genetically determined characteristic or condition Traits can be… Physical- eye color, tail length, ear shape, etc. Behavioral- eating habits, location, etc.
Where are “Blueprints” y x The blueprints of an organism are found in the chromosomes Humans have 23 pairs of chromosomes One of the pairs is the sex chromosome which determine the sex of the offspring x x x y x y x x x x Females have 2 X chromosomes and males have one X and Y the Punnet Square above shows the possible outcomes of their offspring
Chromosomes • Chromosomes are made up of many genes joined together • Humans have up to 30,000 different genes on 23 pairs of chromosomes • In a pair of chromosomes, one chromosome is from the female parent and the other is from the male parent
Genes • Genes are heredity factors that are carried on chromosomes • This idea is called the Theory of Inheritance developed by Sutton with the help of Mendel • According to the chromosome theory of inheritance, genes are carried from parents to their offspring on chromosomes Video to watch on heredity: http://www.youtube.com/watch?v=7CMHzVNnh1I
Chromosomes in other organisms • Many other organisms have chromosomes as well • Silkworms have 56 chromosomes • Dogs have 78 chromosomes
Sexual and Asexual Reproduction • Most mammals and fish reproduce sexually. This means they need to find a mate to reproduce, and the genes combine to form the offspring • Unlike mammals and fish, other organisms such as plants, bacteria, and small insects such as spiders reproduce asexually • Unlike sexual reproduction, these organisms produce offspring on their own, no mate necessary • However, they're are advantages and disadvantages to each reproductive form. Each organism will do what is most naturally beneficial to them
Advantages and Disadvantages Sexual Reproduction Asexual Reproduction
Types and Process of Sexual and Asexual Reproduction • Asexual reproduction comes in different forms. Some organisms grow offspring from their body, while others release a mass of cells, called gemmules • Sexual reproduction comes in two forms. One kind is syngamy, when there is a fusion of genes, such as a human case (fertilization) • The other kind is conjugation, where there is only a temporary fusion, such as with the DNA in bacteria • Asexual reproduction occurs without a member of the same species, and the chromosomes of the organism copy, producing offspring • Sexual reproduction requires a male and female of the same species to combine genetic material. When the cells of the male and female combine, they produce offspring
Review Questions 1.What are traits? What do they have to do with chromosomes? 2.How many chromosomes does the human body have? 3.Compare and contrast sexual and asexual reproduction. 4.What is one benefit of asexual reproduction? 5.What is the Theory of Inheritance? What does it have to do with the appearance of the offspring? 6. What chromosomes to males and females have? What is the chance their baby will be a boy?
Sources • http://science.yourdictionary.com/trait • http://www.diffen.com/difference/Asexual_Reproduction_vs_Sexual_Reproduction • Cronkite, Donald, Ph.D. Science Explorer; Cells and Heredity. Needham: Prentice Hall, 2000. Print. • http://www.youtube.com/watch?v=7CMHzVNnh1I