WARM UP: March 31 st / April 1 st T-1: How could doctors use inheritance patterns? What information would be important to them?

Let’s make some predictions for the next generation…

Lesson 4 Data Summary….Purple or Non-Purple, that is the question!

This is what we should be looking at….

Instead, we will fill in the pedigrees based on how we know they would turn out. TYPE “A”TYPE “B”TYPE “C”TYPE “D”TYPE “E”TYPE “F” PURPLE X PURPLE NON- PURPLE X NON- PURPLE X NON- PURPLE TYPE “A” OFFSPRING X TYPE “A” OFFSPRING TYPE “B” OFFSPRING X TYPE “B” OFFSPRING TYPE “C” OFFSPRING X TYPE “C” OFFSPRING

EXIT SLIP – TYPE 2! Why can’t non-tasters have taster offspring?

April 2 nd & 3 rd Warm up: Type 1: Why do you think that Mendel used plants to study patterns of heredity?

In reading 4.3, we read about Gregor Mendel and his work with the pea plants. Can his ideas help with the question of how two organisms can appear the same on the outside, but have different instructions on the inside? (For example, some purple plants produced non- purple offspring, some tongue roller parents produced non-tongue roller offspring…) Let’s review what he learned.

WHAT DID MENDEL LEARN? The inheritance of traits is determined by units or factors that are passed on to offspring unchanged. An individual inherits one factor from each parent for a trait. A trait may not show up in an individual, but can still be passed on to the next generation Some traits are dominant over others. By this he meant that if a plant had a purple and a white factor, it would appear purple because the purple is dominant.

Now, let’s discuss the exit slip from last class… Why can’t non-tasters have taster offspring?

Activity 5.1 How do I get new cells? You will need to do this activity on a blank sheet of paper. Feel free to make any notes you want to study from on this same paper – you may need 2 sheets! In this activity, we will compare the division of somatic cells to sex cells. Somatic cells = NOT SEX CELLS, cells that make up your body. Sex cells = “gametes” or “sperm or egg”

Remember this picture from before…. CELL, NUCLEUS, CHROMOSOME, DNA… - Remember, the chromosomes are compressed strands of DNA. Are the chromosomes “organized” in the cell? Can you tell how many there are?

Scientists studying chromosomes find it difficult to study them the way they appear in The cell, so they make charts that organize all the chromosomes found in the cell. These charts are called karyotypes. Karyotypes allow scientists to compare individuals and analyze chromosomal behaviors. A karyotype of the chromosomes in a human cell would look like this…

How do you think scientists group the chromosomes?

Scientists put the ones that are alike together. When you use size, you can see that they are organized in pairs. Different sizes may be connected to different traits. There are different traits to keep track of in an organism.

Copy this diagram on the front of your paper. Not only human chromosomes are organized in pairs. Plants have pairs of chromosomes as well. This diagram represents the chromosomes in the plants we have been talking about in class. (Plant cells have more than three pairs of chromosomes, but this diagram has been simplified. Mendel’s pea plants, for example have 14 chromosomes.)

HOW CAN PLANTS LOOK THE SAME ON THE OUTSIDE, BUT CARRY DIFFERENT INSTRUCTIONS ON THE INSIDE? (WHEN WE CROSSED TYPE C PURPLE PLANTS WE GOT SOME NON-PURPLE OFFSPRING.) Imagine these are chromosomes for three different traits in type A offspring. The TRAIT for color is on pair “2.” Color in the pair “2” chromosomes with the instructions you think the plants would have for color. If you want part of the chromosome to not have purple instructions, leave it blank. Now, repeat the process for type B & C. Re-draw the shapes and fill in the colors.

KEY IDEA! Something is different about the third cross – the type “C” plants? The plants were all purple on the outside, but something must be different on the inside because they produced offspring that were purple and non-purple. QUESTION: Where did the type C plants get it’s chromosomes? How do you think that works?

Let’s review what we know about plant reproduction from Lesson 2. Plants have both male and female parts. Plants have eggs in the ovaries. Plants have pollen, which is like sperm and needed to fertilize the egg. The seed is a fertilized egg. Fertilization happens when the pollen from one plant reaches the ovary of another. Plants produce offspring that have traits similar to their parents.

QUESTIONS:  Where are the instructions for stem color located?  Where did the chromosomes come from in the new plant?

Remember, an egg cell in the ovary of a plant was fertilized by a pollen cell. Since we know that every cell has chromosomes, there must be chromosomes in the egg and pollen too. If each plant has two chromosomes for each trait, how come the offspring don’t have four copies of the chromosomes when the egg and sperm cell combine?

Let’s take a look at the process of fertilization and the egg and sperm to see if we can figure out what happens. **We will be using a simplified diagram using only two pairs (four chromosomes) and it will not include all of the steps in the process. Remember, in 7 th grade you learned that body cells divide for growth and repair. Let’s start by watching a brief video clip! nes+genetics+and+dna

Follow along while I draw out the process for you, you will have a chance to copy the picture in the end.

Look at the bands on the chromosomes, they are next to each other. They are positioned in the same place on each of the chromosomes. What do you think these bands are?

In this picture, one chromosome of a pair has been extended. Notice the pink section, This represents a “GENE”. Genes produce different traits.

Remember – a chromosome is a compressed strand of DNA. A DNA molecule consists of distinct segments called genes. A gene for a specific trait appears at the same place on both copies of the chromosome. This location is called the “locus”. This picture is a representation of a chromosome that carries the trait for stem color in plants. The band Represents the gene. The color represents the “allele” – the variation Of the trait. In the case of the plants, The “instructions” for the chemical reaction that produces anthocyanin (the chemical that will cause a purple stem) are present on the chromosome. The stem color was determined by the instructions for Producing anthocyanin.

KEY IDEAS! Each allele is a version of the gene that carries the instructions for a chemical that will result in a variation of a particular trait. One allele comes from one parent and one 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 you observed in the chromosomes in the karyotype.

Let’s turn to activity 5.2: How can parents produce offspring with different traits? How could the instructions for offspring that all inherited one copy of genes from their mother and one copy of their genes from their father look different?

How may chromosomes are in a human cell? After cell division in a somatic cell (mitosis), how many chromosomes are in the new cells? After cell division in a sex cell (meiosis), how many chromosomes are in the new cells? Why?

In activity 5.2, we will see that each gamete produced during cell division of a sex cell will produce different combinations of chromosomes. To look at what happens when each gamete is produced by cell division, we will look at a fictional organism with just a few chromosomes and figure out the different things that could happen when it makes its gametes.

The fictional organism is the yllis. The yllis has only six chromosomes (3 pairs) and only one trait per chromosome. Each trait has two alleles (variations). These genes carry instructions for the shape of the mouth, nose, and eyes. Turn to page 56, follow the instructions to see how many combinations you will come up with. Be sure to answer the making sense questions on page 58.

EXIT SLIP – TYPE 2: What is the difference between mitosis and meiosis?

Warm up = April 8 th and 9th In the green book assignment, you learned two new terms: genotype & phenotype. Please make a comparison between the two words.

Activity 6.1 Beginning the Model Purpose: Develop a model to explain how traits are passed from parents to offspring. WHAT IDEAS DO YOU HAVE ABOUT WHAT FORM THE MODEL SHOULD TAKE? HERE’S WHAT WE ALREADY KNOW….  There are two copies of the information for each trait.  One copy comes from each parent.

Can you remember models you have constructed in previous IQWST units? In 6 th grade: “How can I smell things from a distance?” you constructed a particle model of matter. Also in 6 th grade: “Can I believe my eyes?” you constructed a model of light and seeing. Those models were diagrams to explain data. This is the same type of model as whatwe will make. It will be a set of “rules” that say what to do when we have different combinations of alleles.

What do the rules for the model need to do? The rules need to fit all of the data collected so far. (Models need to fit the evidence.) The rules need to answer these questions: 1.How can two purple plants behave differently when having offspring? 2.How can an organism pass on a trait that it doesn’t show? 3.How do organisms go from genotype to phenotype?

The question at the end of lesson 4 was: “How can two organisms appear the same on the outside, but not carry the same instructions on the inside?” This question can be restated: “How can two organisms with the same phenotype have different genotypes?” In lesson 5 we learned that there are instructions that are passed that result in the variation of a trait that can be seen. We also learned that there are a pair of instructions for each trait, one from each parent.

Using those ideas, we will figure out how to go from genotype to phenotype. Remember – we are trying to answer the following: How can two plants behave differently when having offspring? How can an organism pass on a trait that it doesn’t show?

We have been studying plants with two variations for stem color. Remember, in these plants, there are only two alleles that can be passed from parent to offspring for the stem variations: purple and non purple. Combinations of the alleles produce the phenotypes we were hoping to observe in our seedlings. GENOTYPE (instructions)PHENOTYPE (what you see) TYPE “A”TYPE “B”TYPE “C”TYPE “D”TYPE “E”TYPE “F” PURPLE X PURPLE NON- PURPLE X NON- PURPLE X NON- PURPLE TYPE “A” OFFSPRING X TYPE “A” OFFSPRING TYPE “B” OFFSPRING X TYPE “B” OFFSPRING TYPE “C” OFFSPRING X TYPE “C” OFFSPRING

EXIT SLIP: Type 2 (Look at the pedigree we completed on page 72 to answer this question. USE THE WORDS GENOTYPE, PHENOTYPE and ALLELES properly to answer the question) QUESTION: Why were the F1 generation plants all purple?