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 upon a farm and learned a lot about flowers and fruit trees. When he was 21years old, he entered a monastery. The monks taught science andperformed many scientific experiments. Mendel was sent to Vienna wherehe could receive training in teaching. However, Mendel had trouble takingtests. Although he did well in school, he was unable to pass the final exam.He returned to the monastery and put most of his energyinto research. Mendel discovered the principles of heredityin 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 onegeneration was not present in the next generation. Inthe third generation, though, the trait showed up again.Mendel noticed these kinds of patterns in severalother living things too. Mendel wanted to learn moreabout what was causing these patterns.To keep his investigation simple, Mendel decided to study onlyone kind of organism. Because he had studied garden pea plants before,they seemed like a good choice.Like many good ideas, Gregor Mendel’s ideas were notunderstood at first. In 1865, Mendel wrote about his studies, but it wasn’tuntil after his death, more than 30 years later, that he finally got therecognition he deserved. Once Mendel’s 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).Examplesnose shapeeye colorhair typeand color
6 Some traits are passed on and others are not Dominant traits are traits that hide othertraits when passed on to offspringRecessive traits are the traits that gethidden by dominant traitsblue eyesRecessive traitBrown EyesDominant traitBrown Eyes
7 Which traits do you have that are dominant? Which are recessive? Let’s take a look at a few examples.Thumb ShapeEarlobesStraightDominantHitchhiker’sRecessiveHanging freeDominantAttachedRecessive
8 Why are some traits passed on and others are not 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 geneticinformation for all life processes.Chromosomes are long molecules of DNA;found in the nucleus of eukaryotic cells.DNA - “deoxyribonucleic acid”; hereditymaterial that controls all the activities of acell.
10 Not all organisms have a nucleus, but all organisms have genes. Genes are contained in DNA.basic unit of hereditydetermines a persons traits(characteristics)passed on from parent tooffspring through asexual orsexual reproduction
12 Alleles are the different forms of a gene. Alleles come in pairs, one set from your father theother set from your mother.Geneticists use letters to represent alleles.Example: Alleles come in pairs, and the allelefor having a Widow's Peak is thought to bedominant, so you only need one copy presentto have the trait.Widow’s peakStraight hairline
13 Genotype vs Phenotype Genotype is the combination of alleles an organism inherits from itsparents (genes).Phenotype is the organismsappearance (physical).WW, WwWidow’s peakwwStraight hairline
15 Punnett Square The Punnett square is a diagram that is used to predict the outcome of aparticular cross or breeding experiment.It is named after Reginald C. Punnett,and is used by biologists to determinethe probability of an offspring having aparticular genotype. The Punnettsquare is a summary of every possiblecombination of one maternal allele withone paternal allele for each gene beingstudied in the cross.