How Do Traits Get Passed On? LESSON 4

Move to which corner you think is correct for each question Can offspring get instructions for the variation of a trait from either parent? Do all offspring from the same parents inherit identical variations of a trait? Can offspring sometimes show a variation of a trait that neither parent shows? If parents have different variations of a trait, does it seem that one is more likely to be passed on?

Activity 4.1 Log on to 4.1 Look at each pedigree and see if you can find the patterns that answers the questions in the data table Put a check in yes or no for each family Total the number of yes/no responses Go to Making Sense Questions

Making Sense When we first looked at pedigrees, you saw that two parents who tasted PTC could have offspring that taste or do not taste PTC. Did you see the same thing when looking at the pedigrees of multiple generations of a family? Does the data from the previous generations help you figure out how two parents who taste PTC could have offspring who do not taste PTC? Is there anything in the data from this lesson that helps figure out which tasters might be able to have offspring that do not taste?

Wrapping Up Were you surprised by variation shown by any of the offspring? Do you think you will see the same patterns for tongue rolling as you did for PTC tasting people? Do you think that these patterns can only be seen for the traits of PTC tasting and possibly tongue rolling? What pattern did you see evidence for in this lesson? Do you think this pattern is true for every organism? There are patterns in how traits appear to be passed from parents to offspring. Somehow information about traits can be passed on even if it cannot be seen in parents. This happens in both plants and animals in the pedigree data

Reading together 4.3 Mendel Are there any of Mendel’s ideas that you could investigate that might help with the question of how two organisms can appear the same on the outside but have different instructions on the inside? He said there are factors. Could you look for factors? Where would you look to see if there are factors? Where could you look to see if one factor comes from each parent?

Karyotypes Who can remind me what compressed forms of DNA are called? Karyotypes allow scientists to compare individuals and analyze chromosomal behaviors How do you think scientists could group the chromosomes? Not only human chromosomes are in pairs. Plants have pairs of chromosomes too

How are mitosis and meiosis similar? How are they different? Why would combining cells that results from mitosis not work for fertilization? What is the difference in the cells between mitosis and meiosis? How do sex cells in meiosis compare to the body cells at the end of mitosis?

If meiosis stopped here (the third step), what would you have? What has to happen to the sex cells before they become egg and sperm? Why are chromosomes in pairs in body cells? Where do chromosomes come from? How do you know they come from both parents?

Look at the bands on chromosomes 1, 9, and 16. What do you notice about their position on the chromosome? What do you think these bands are? Remember in your chemistry unit, you learned that proteins are large chains of what? The way that the amino acids are arranged, or the shape they are in determines how those proteins work in your body. DNA has the instructions for how the amino acids are shaped to make proteins.

NOTES TO TAKE A segment of DNA called a gene is an arrangement of amino acids to make one proteins, and the next gene section would be a different arrangement that makes a different protein. A DNA molecule consists of different parts called genes A gene instructs for the production of a single kind of protein

You are looking at a chromosome. A gene for a specific trait appears at the same place on both copies of the chromosome. The location the gene is at on a chromosome is called a locus. -This is a diagram of chromosomes that carry the trait for stem color in plants. The band on the chromosome is the gene. The color represents the variation of the trait. -A version of the gene that carries the instructions for a chemical resulting in a variation of a particular trait is called an allele.

One allele comes from one parent and one comes from the other parent. If the 2 chromosomes were place side by side, the alleles would be next to each other. This is the banding that we saw in the chromosomes in the karyotype.

Each allele is a version of the gene that carries the instructions for a chemical resulting in a variation of a particular trait. One allele comes from one parent and one comes from the other parent. If the two chromosomes were placed side by side (as in the diagram), the alleles would be next to each other. This is the banding that students observed in the chromosomes in the karyotype