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is the transmission of traits from one generation to the next.

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Presentation on theme: "is the transmission of traits from one generation to the next."— Presentation transcript:


2 is the transmission of traits from one generation to the next.

3 Who was Gregor Mendel? Gregor Mendel was born in 1822 in Heinzendorf, Austria. Mendel grew up on a farm and learned a lot about flowers and fruit trees. When he was 21 years old, he entered a monastery. The monks taught science and performed many scientific experiments. Mendel was sent to Vienna where he could receive training in teaching. However, Mendel had trouble taking tests. Although he did well in school, he was unable to pass the final exam. He returned to the monastery and put most of his energy into research. Mendel discovered the principles of heredity in the monastery garden by studying pea plants.

4 From his previous work with plants, Mendel knew that the patterns of inheritance were not always clear. For example, sometimes a trait that appeared in one generation was not present in the next generation. In the third generation, though, the trait showed up again. Mendel noticed these kinds of patterns in several other living things too. Mendel wanted to learn more about what was causing these patterns. To keep his investigation simple, Mendel decided to study only one kind of organism. Because he had studied garden pea plants before, they seemed like a good choice. Like many good ideas, Gregor Mendels ideas were not understood at first. In 1865, Mendel wrote about his studies, but it wasnt until after his death, more than 30 years later, that he finally got the recognition he deserved. Once Mendels ideas were found and understood, the door was open to modern genetics.

5 are characteristics or features of an organism that are inherited (passed from parent to offspring). Examples eye color nose shape hair type and color

6 Some traits are passed on and others are not Dominant traits are traits that hide other traits when passed on to offspring Recessive traits are the traits that get hidden by dominant traits blue eyes Recessive trait Brown Eyes Dominant trait

7 Which traits do you have that are dominant? Which are recessive? Lets take a look at a few examples. Thumb ShapeEarlobes Straight Dominant Hitchhikers Recessive Hanging free Dominant Attached Recessive

8 Why are some traits passed on and others are not? The answer lies in our Cells. Scientist began to experiment with plants and animals to learn how traits are passed on from parents to offspring.

9 Vocabulary Review The cell is a membrane covered structure that has all the materials necessary for life. Nucleus - contains all the genetic information for all life processes. Chromosomes are long molecules of DNA; found in the nucleus of eukaryotic cells. DNA - deoxyribonucleic acid; heredity material that controls all the activities of a cell.

10 Not all organisms have a nucleus, but all organisms have genes. Genes are contained in DNA. basic unit of heredity determines a persons traits (characteristics) passed on from parent to offspring through asexual or sexual reproduction

11 –nucleus - chromosomes –DNA - genes - traits Chromosomes Cells

12 Alleles are the different forms of a gene. Alleles come in pairs, one set from your father the other set from your mother. Geneticists use letters to represent alleles. Example: Alleles come in pairs, and the allele for having a Widow's Peak is thought to be dominant, so you only need one copy present to have the trait. Straight hairline Widows peak

13 Genotype vs Phenotype Genotype is the combination of alleles an organism inherits from its parents (genes). Phenotype is the organisms appearance (physical). ww Straight hairline WW, Ww Widows peak

14 Genotype vs Phenotype Other Examples:

15 Punnett Square The Punnett square is a diagram that is used to predict the outcome of a particular cross or breeding experiment. It is named after Reginald C. Punnett,Reginald C. Punnett and is used by biologists to determinebiologists the probability of an offspring having aprobability particular genotype. The Punnettgenotype square is a summary of every possible combination of one maternal allele withallele one paternal allele for each gene being studied in the cross.


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