Name: Hour: Teacher: ROZEMA Inheritance & Mutations Connected to Speciation
Let s Review What We Already Know:
What Have We Learned?
Lesson 26: PI 1 (Projected Image) - Human Karyotype (image from https://en.wikipedia.org/wiki/karyotype#/media/file:nhgri_human_male_karyotype.png) This is a karyotype of the chromosomes found in a human body cell (somatic cell):
Name: Period: Date: Lesson 26: Are the UCSD juncos a now a separate species from the mountain juncos? Part 1: - Comparing Alleles in the Offspring to the Parents In the model below, the different locations (loci) of three genes (A, B, and C) are shown across three pairs of chromosomes in different individuals. Each gene has four different possible alleles for it. for gene A these alleles can be A 1, A 2, A 3, or A 4 for gene B these alleles can be B 1, B 2, B 3, or B 4 for gene C these alleles can be C 1, C 2, C 3, or C 4 The karyotype for a mom and her offspring for these three chromosomes and the corresponding alleles at the loci for these genes are shown below. Q1: Which male, must be the biological parent of this offspring? Q2: In the diagram above, males 1 through 5 belong to one population, males 6 through 10 belong to a second population, and males 11 through 15 belong to third population. Are any of the four alleles for each gene missing from any of the three populations? Explain.
Talk with a partner: How could comparing all the alleles found in the mountain junco populations to all the alleles found in the UCSD population help us determine if a baby bird had a dad that was from the mountain population or a dad that was from the UCSD population? Do you think it would be necessary to sample all of the birds in the population to collect that DNA or could scientists compare DNA from a smaller sample of birds from both areas and still draw reliable conclusions? Part 2- Q3: How does the continued absence of certain alleles in the UCSD population help support the claim that there have been very little (or no) cross-breeding between males from the mountains and UCSD females since the founding event? Next Steps Q5: Our model for how DNA is passed on from parent to offspring in sexually reproducing organisms assumes that all the DNA that a child inherits is 100% identical to the DNA found in mom and dad (50% from each). Do you think it is ever possible that a child ends up with some DNA that isn t completely identical to the DNA of their parents? Explain. Q6: What sources of data would you need in order to investigate these ideas and these questions further?
Lesson 26: Article: Is there a relationship between the alleles in the Lagunas (mountain) males and the alleles in the UCSD offspring? Reading is adapted from the article Genetic and morphological evolution following a founder event in the dark-eyed junco, Junco hyemalis thurberi by C. A. Rasner, P. Yeh, L. S. Eggert, K. E. Hunt, D. S. Woodruff and T. D. Price Smaller isolated populations of organisms often differ genetically from their larger ancestral populations. A team of researchers wanted to determine if this was the case between juncos living on the University of California at San Diego (UCSD) campus and the juncos from the nearby mountains. Juncos were first observed breeding on the campus in 1983 and a resident breeding population became established there. As of 2002, there were about 70 breeding pairs. It is known that small flocks from the nearby mountain populations over-winter at UCSD and it is thought that the founders of the campus juncos probably originated from one of the migrating flocks. The researchers mentioned above used mist nets and potter s traps to catch juncos on campus (20) and in the mountains (156). A total of 176 birds were genotyped. Of that number, 157 were males. At least 10 birds were collected in each sample, at the following locations:
DNA comparison Blood samples were taken from each bird in order to analyze the DNA. One bird died before a blood sample could be drawn, so DNA was extracted from heart tissue in this case. This team of researchers chose to examine five loci (a loci is a gene location on a chromosome) that had multiple alleles/locus. They looked at the alleles found there to determine if the UCSD population was genetically different from the mountain populations. Four of the five loci showed a decrease in the number of alleles in the UCSD population as compared to the other populations of mountain birds. One allele (208) at locus Gf05 was found in 62.5% of the campus birds, while the allele was found at very low frequencies across the mountain populations and not found at all in some populations (see Fig. 4). This team of researchers compared the genotype of an additional 41 UCSD birds for a different loci (Gf01b), for a total of 61 UCSD individuals. With the addition of these individuals the researchers found a total of 12 alleles in the UCSD population compared to 22 alleles found in 157 mountain birds. For this comparison they concluded that: The UCSD population has less genetic diversity in its population than the mountain population. The original founders of the UCSD population were estimated to have included a minimum of 7 individuals. In cases like this, where a founding population has lost genetic diversity, that genetic diversity would typically be replenished by subsequent immigration and interbreeding, unless something is preventing that from happening. The fact that the UCSD population retains the lower number of alleles that they do for various loci, despite currently numbering about 70 breeding pairs, suggests that there was fairly rapid population growth in the early generations and/or that there have been few subsequent immigrants and no or little interbreeding since the founding event. They were unable to detect the presence of any immigrants among a sample of 20 UCSD birds.
Name: Period: Date: Lesson 26: Home learning Data Packet A: Mutation Rate. Scientists have investigated how often mutations occur in many organisms. How often a mutation appears in the DNA of the organism or in the gene pool of a larger population of that organism is referred to as the mutation rate. They have also identified all the possible number of locations that could undergo a mutation in the DNA. The smallest sub-unit of genetic information in the structure of the DNA is referred to as a base pair (bp). And they have identified the number of genes that each of these organisms has in its entire set of DNA in its cells (its genome). Some of the DNA contains genes, while other parts of it do not. The mutation rate of an organism, can be determined by comparing the DNA between lots of individuals, often across generations. They have found that the mutation rate is approximately constant per year and largely similar among genes. And they have also found that there is a great deal of similarity of mutation rates among mammals. Q1: Compare using the estimated mutation rates of these organisms to humans to complete the calculations in the table below. Organisms A. Fruit Flies (D. melanogaster) B. Mice (M. musculus) C. Humans (H. sapiens) D. Bacteria (E. coli) 1. Approximate # of genes in its genome 13600 20210 32,000 4288 2. Estimated mutation rate ~1 in every 10,000 genes ~1 in every 10,000 genes ~1 in every 10,000 genes ~1 in every 100,000,000 genes 3. Estimated # of mutations that would be found in the genes of each offspring (1.36 on average) = between 1 and 2 4. % of offspring s genes that are new ones not found in the parents (due to mutations) % = part whole * 100 part whole * 100 1.36 13600 * 100.01% 5. % of offspring s genes that are found in the parent(s) (nonmutated) = 100% - % from above = 100% -.01% = 99.99% Q2: So does a child really inherit 50% of all its DNA from mom and 50% from dad?
Data Packet B: Mitochondrial DNA. Images and text adapted from https://en.wikipedia.org/wiki/mitochondrial_dna Scientists have investigated where all the DNA is found in humans and other mammals.the entire set of genes on all that DNA is found inside each of the cells of these animals.this is referred to as its genome. The entire genome in all body cells in people contain approximately 32,000 genes. Although most of these genes are found on DNA that is packaged in chromosomes within the nucleus (in the form of 23 pairs of chromosomes), some DNA is found in a different part of the cell. That additional DNA is found in a structure inside our cells called the mitochondria. Mitochondria are structures within cells that convert the energy from food into a form that cells can use. The genetic material found in mitochondria is known as mitochondrial DNA or mtdna. The structure of this mtdna forms a closed loop. Mitochondrial DNA contains 37 genes, all of which are essential for normal mitochondrial function. But there are also part mitochondrial DNA that contain no genes. Q3: Out of 32,000 genes in an entire human cell, what percentage are in the mitochondria? Q4: Is this a relatively large percent or relatively low percent? In sexual reproduction, mitochondria are normally inherited exclusively from the mother; the mitochondria in mammalian sperm are usually destroyed by the egg cell after fertilization. Also, most mitochondria are present at the base of the sperm's tail, which is used for propelling the sperm cells; sometimes the tail is lost during fertilization. Q5: So does a child really inherit 50% of all their DNA from mom and 50% from dad? Explain:
Data Packet C: Y chromosomes. Images and text adapted from https://en.wikipedia.org/wiki/mitochondrial_dna and https://en.wikipedia.org/wiki/xy_sex-determination_system All animals have DNA that codes for genes present on their chromosomes. The genes that each of these organisms has in its entire set of DNA is referred to as its genome. The entire genome in all body cells in people contain approximately 32,000 genes. In humans, most mammals, and some other insect species, such as the fruit fly, two of the chromosomes, called the X chromosome and Y chromosome, code for sex. In these species, one or more genes are present on their Y- chromosome that determine maleness. In this process, an X chromosome and a Y chromosome act to determine the sex of offspring, often due to genes located on the Y chromosome that code for maleness. Offspring have two sex chromosomes: an offspring with two X chromosomes will develop female characteristics, and an offspring with an X and a Y chromosome will develop male characteristics. Q6: Which chromosome appears shorter in the fruit fly diagram above, the X or the Y? The two chromosomes that make up each of the 22 out of 23 pairs in a human karyotype, are the same length. In other words, both #2 chromosomes are the same length. Both #8 chromosomes are the same length (but #2 chromosomes are not the same length as #8 chromosomes). If the person is female, both #23 chromosomes will be the same length. But if the person is male, then the 23rd pair of chromosomes will be of different lengths. Q7: The karyotype shown to the right is the one your class looked at in the last lesson. The pair of chromosomes in the bottom right corner are the 23rd pair. Was this person born male or female? Q8: The chromosome that carries the fewest number of genes in humans is the Y chromosome. The Y chromosome carries only about 344 genes. Some of the DNA in the Y chromosome has no genes in it. Out of all the genes within a cell, what percentage of them are on the Y chromosome? Q9: Human females can pass on either one of the their two X chromosomes to an offspring, but a dad can pass on either an X chromosome or a Y chromosome. So does a child really inherit 50% of all their DNA from mom and 50% from dad? Explain:
Q10: Summarize your discoveries from these data packets and complete the questions below. Data Source How did each data packet help answer the question: Do offspring always end up with 50% of their mom s DNA and 50% of their dad s DNA? Data packet A Data packet B Data packet C Q11: Brainstorm: How could these new ideas about how DNA is inherited, be used to help determine whether someone is the biological mother or father of a child? Q12: Brainstorm: Do you think comparing DNA also help determine if someone is the grandfather or greatgreat grandmother of a child? Explain
Name: Period: Date: Lesson 27: Home Learning: Part A How can our new discoveries about how DNA is inherited help us figure out how closely related two different juncos are? The map below shows the breeding ranges of the juncos you looked at in the last lesson, as well as the breeding ranges of some other populations of juncos found in Mexico and other regions further south on the North American continent. The name of each population is referred to by four initials (e.g., PSJU). Predict: Consider these three different pairs of juncos populations: a) SCJU and ORJU b) SCJU and RBJU c) SCJU and VOJU Q1. Which of these two populations of birds do you think are more closely related? Q2. Which of these two populations of birds do you think are least closely related? Q3. Why? Explain your reasoning. image above from http://www.indiana.edu/~kettlab/fieldsites.html
Q4. How might comparing mutations in mitochondrial DNA between these different juncos help us determine how many generations ago they last shared a common ancestor? Q5. How might comparing mutations in mitochondrial DNA across other types of organisms help us determine how long ago their ancestors started to diverge into separate species from a common ancestor?
Name: Period: Date: Lesson 27: Home Learning: Part B these different populations of juncos? How could natural selection lead to all Q1. The video claimed that changes in glaciation around 20,000 years ago led to the diversification of juncos across North America. Here is map of the type of vegetation 15,000 to 25,000 years ago, when glaciers, thousands of feet thick covered parts of North America. When the glaciers receded (melted), what other changes do you think also occuring in: The average yearly temperature of across North America Source of water available for drinking. The type of plants that started growing in lands previously covered by ice were places
Q2. How could this environmental change in combination natural selection led to all these different populations of juncos? image above from http://www.indiana.edu/~kettlab/fieldsites.html Q3. Brainstorm: If natural selection removes trait variations from populations that give organisms a competitive disadvantage, and sexual reproduction simply reshuffles a sub-set of alleles that already in the population, it seems like over really long periods of time, variation should eventually disappear from populations. And yet, there is still a large amount of variation in each juncos population and between juncos populations. Do you think there is any way that new heritable trait variations (new alleles) can appear that were never in the population before? Explain.