Name: ___________________________Period: _______

Bio Science Week #28Week of: March 9 - 13

Day Root Words In-Class Homework

3/9: Monday

Word:Definition:

As in:-

Picture: -Grade Graph-Goals-Finish Pink Notes-Planarian Lab

3/10: Tuesday

Word:Definition:

As in:-

Picture:

- Planarian Conclusion

3/11: Wednesday

Word:Definition:

As in:-

Picture:-Late Arrival- Sex Pre-Test- Notes on Mitosis vs. Meiosis

3/12: Thursday

Word:Definition:

As in:-

Picture:

-Finish Notes-Meiosis Flipbook

3/13: Friday

Word:Definition:

As in:-

Picture:

-Week #28 Quiz-Google Classroom

Need Help? Talk to me in class. I’m available during periods 4, 5 and 8. You can call me at 708-434-3616 or email clundgren@oprfhs.org Also, Mr. Hill is in the Tutoring Center before school on Tuesdays and Thursdays. Be sure to use the website

mrlscience.weebly.comMitosis Vs. Meiosis Notes

Problem: How do we make babies with the correct number of chromosomes? ____________________________________________________________________________________________________________________________________________

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Name: ___________________________Period: _______Evidence:New Vocab:

Word DefinitionGametes

Somatic Cells

Haploid

Diploid

Homologous ChromosomesMitosis

Meiosis

Fertilization

Name Mitosis MeiosisDescription

What cells go through

itPicture

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Name: ___________________________Period: _______

Purpose

Stages

Haploid Vs. Diploid

Conclusion: Which is a better type of cell division is better to ensure that all babies have the correct number of chromosomes? Why? __________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

Gametes (Sex Cells) With Half a Copy of ChromosomesWhy is it important for the sex cells to have only half a copy of the set of chromosomes? As you may have guessed, you received half of your genes from your mother and half from your father. Every cell in your body (except your sex cells) has a double copy of your chromosomes. This means every cell in your body has 46

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Name: ___________________________Period: _______total chromosomes held in their nucleus. 23 of those chromosomes come from your mother and 23 of the other chromosomes come from your father. It is important for your sex cells to have only half the copy of chromosomes since they fuse to create the offspring. If there were more than half the copy (more than 23), the resulting offspring would have a chromosomal disorder. Any human offspring created with more or less chromosomes than the number 46 have a chromosomal disorder by definition. The chromosomal number and the genes they contain vary per species of organism. See the diagram on the human life cycle.

Why do gametes have only one copy of chromosomes?________________________________________________________________________________What is the process that produces gametes? __________________________What happens if your chromosome number is not 46? _______________________________________________________________________________How does the zygote change from a single cell into a multi-cellular organism?____________________________________________________________

Mitosis Vs. MeiosisProblem: What are the similarities and differences between Mitosis and Meiosis?

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Name: ___________________________Period: _______Use the chart below to answer the following questions.

Event Mitosis MeiosisFour new cells are formed from each original cellThis type of cell reproduction helps you growThis makes cells with the same number of chromosomes as the originalThis type of cell reproduction makes egg cells and sperm cellsThis makes cells with half the original number of chromosomesNew skin cells are made this wayTwo new daughter cells are formed from one original cellThe original cell replicates its DNA one time (during interphase)

The original cell will go through 1 cell division totalThe original cell will go through 2 cell divisionsCrossing over takes place during this processThe cell will go through prophase, metaphase, anaphase, and telophaseThe cell will go through cytokinesis

Complete the Venn diagram below for asexual and sexual reproduction.

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1 cell division haploid cells DNA replication

2 cell divisions diploid cells sexual reproduction

cell division 2 daughter cells asexual reproduction

4 daughter cells crossing over genetic diversity

Name: ___________________________Period: _______

Conclusion: Which provides more genetic diversity mitosis or meiosis? Why? ____________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________

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1 cell division haploid cells DNA replication

2 cell divisions diploid cells sexual reproduction

cell division 2 daughter cells asexual reproduction

4 daughter cells crossing over genetic diversity

Mitosis Meiosis

Name: ___________________________Period: _______

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Name: ___________________________Period: _______

Meiosis ReadingGenesGeneticists in the early 1900s wondered where genes might be located. Genes are factors that are passed from parents to offspring. They determine what traits you will express, how your body is built, and how you will look. They expected genes to be carried on structures inside the cell, but which structures? We now know that genes are held on our chromosomes – organized DNA held in the nucleus of our cells. Remember the nucleus is like the “brain” of our cells. We are Eukaryotic, which means we have nuclei in our cells. Prokaryotes, like bacteria, do not have nuclei. They still have genetic info, but it is floating around the inside of their bodies.

1. What are

genes?______________________________________________2. How are they found in Eukaryotes versus Prokaryotes? __________________

____________________________________________________________

Passing Traits

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Name: ___________________________Period: _______To follow a certain pattern of inheritance, there are two things that must happen for genes holding traits to pass from generation to generation. First, an organism with two parents must inherit a single copy of every gene from each parent. Second, when that organism produces gametes (gametes are sex cells – egg and sperm), those two sets of genes must be separated so that each gamete contains just one set of genes. As it turns out, chromosomes—those strands of DNA and protein inside the cell nucleus—are the carriers of genes. The genes are located in specific positions on chromosomes.

3. What two things must happen to pass traits from one generation to the next?________________________________________________________________________________________________________________________

4. What are gametes?_____________________________________________

ChromosomesA body cell in an adult human has 46 chromosomes. 23 of the chromosomes come from the male parent, and 23 come from the female parent. These two sets of chromosomes are homologous (hoh MAHL uh gus), meaning that each of the 23 chromosomes from the male parent has a corresponding chromosome from the female parent. Body cells contain both sets of homologous chromosomes while some cells contain only one copy of the homologous chromosomes. Cells with one copy of chromosomes are the gametes, or sex cells (the egg and sperm).

5. How many total chromosomes do humans have in their body cells?__________

6. Where do those chromosomes originate?_________________________________________________________________________________________

7. What are homologous chromosomes? ____________________________________________________________________________________________

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Name: ___________________________Period: _______

8. What cells contain both copies of

the

homologous chromosomes?___________9. What cells contain one copy of the homologous chromosomes?

____________

MeiosisRemember the cell cycle including mitosis is the process that produces our body cells. Meiosis is a process similar to mitosis except meiosis produces the gametes (sex cells) instead of body cells. There are also two important differences in meiosis than mitosis. In meiosis, the sex cells have half the amount of chromosome copies than do body cells. Also, the sex cells produced by meiosis are genetically unique. To summarize, meiosis produces genetically unique sex cells that have half the chromosome copy number of body cells.

10. What type of cells does meiosis produce?_________________________________________________________________________________________

Genetically Unique Gametes (Sex Cells)Why is genetic diversity important? Genetic diversity plays a very important role in survival and adaptability of a species. A species that has a large degree of diversity among its population will have more variations from which to choose those that are best adapted to the environment. With very little gene variation within the species, healthy reproduction becomes increasingly difficult, and offspring often deal with similar problems to those of inbreeding. The vulnerability (weakness) of a population to certain types of diseases can also increase with reduction in genetic diversity. Therefore, genetic diversity is very important and crucial for the survival of a species!

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Name: ___________________________Period: _______

11. Why is genetic diversity important? _____________________________________________________________________________________________

As mentioned before, meiosis is the process that produces genetically diverse gametes. In male animals, these gametes are called the sperm. In female animals, these gametes are called the egg. Usually one sperm fertilizes one egg in humans. Even plants have gametes though. Plant pollen is essentially male plant sperm! Think of that next time you have seasonal allergies. The diagram below is an overview of meiosis. You can see that one cell starts and creates four genetically diverse cells with half as many chromosome copies by the end.

12. What type of

cells are at the beginning of meiosis compared to the ones at the end? ________________________________________________________________________________________________________________________

Meiosis involved two distinct cycles. The first is titled “Meiosis I” while the second follows as “Meiosis II”. You can notice the homologous chromosomes

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Name: ___________________________Period: _______mix genes during Meiosis I. While the chromosome number is cut in half during Meiosis II. The diagram above shows the phases of Meiosis I and Meiosis II. You may recognize them as Interphase, Prophase I, Metaphase I, Anaphase I, Prophase II, Metaphase II, Anaphase II, and Telophase II. These are the same phases as seen in mitosis, except the phases are repeated in meiosis producing four cells instead of two.

13. What is one way that meiosis differs from mitosis? _________________________________________________________________________________

One of the most important phases of meiosis occurs during Meiosis I – Prophase I. During this phase, crossing over occurs. The diagram below shows the details of crossing over. This allows the gametes to exchange some genes producing genetic diversity. Some sections of each homologous pairs of genes exchange with each other, mixing the genes and theirs traits that will be passed on to their offspring.

14. What is the purpose of crossing over?___________________________________________________________________________________________

15. When does crossing over occur? ___________________________________

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