1/15 Daily Catalyst Pg. 69 Meiosis 1. Predict the effect of a checkpoint existing after S phase that prevents the cell from moving into G2 phase. 2. Describe where in humans we see asexual reproduction. 3. A cell with 10 chromosomes undergoes mitosis. How many daughter cells are created? ___ Each daughter cell has ___ chromosomes. a. 2, 10 b. 10, 2 c. 1, 10 d. 2, 20
1/15 Daily Catalyst Pg. 69 Meiosis 1. Predict the effect of a checkpoint existing after S phase that prevents the cell from moving into G2 phase. Cells with abnormal amounts of DNA 2. Describe where in humans we see asexual reproduction. Mitosis- 2 exact daughter cells 3. A cell with 10 chromosomes undergoes mitosis. How many daughter cells are created? ___ Each daughter cell has ___ chromosomes. a. 2, 10 b. 10, 2 c. 1, 10 d. 2, 20
1/15 Class Business Pg. 69 Meiosis Quiz #16 on Friday Tutoring after school, during 4th period, and during lunch Schedule tutoring sessions with me Mitosis packet due on Friday ALL OF THE PACKET NEEDS TO BE COMPLETED
Study Assignment New studying assignment You are required to study a certain amount of hours per week independently AND with a group/partner per month Independently= 6 hours per week Group/partner= 4 hours per month Sheet is due at the end of each month on the last Friday (Jan. 30th) Name(s) Date Time Topic(s) Covered Notes Signature
1/15 Agenda Pg. 69 Meiosis Daily Catalyst Class Business Meiosis notes Mitosis worksheet (if time permits)
Sexual Reproduction Definition: Two parents give rise to offspring that have UNIQUE combinations of genes. Genetic variation
Chromosomes in human cells Homologous Chromosomes: Two chromosomes with the same length and centromere position Both carry genes controlling the same inherited characteristic
Sex Chromosomes Sex Chromosomes Everything else are autosomes! Females (XX) Males (XY) Everything else are autosomes!
**Not all cells will have the same chromosome number** Chromosome Sets Key Point #1: Number of chromosomes in a set is represented by n. Diploid Haploid Key Point #2: Two chromosome sets 2n Humans= 46 (2n=46) Key Point #3: One chromosome set n Humans= 23 (n=23) **Not all cells will have the same chromosome number**
Why we need N? When it is time to make sex cells you DON’T want the cells to have 2N (2 sets of chromosomes). It would mess everything up when an egg and sperm combined, there would be too many chromosomes! 2N N Sperm and egg cells 4N 2N 2N N
Meiosis is very similar to Mitosis From looking at the stages, we can see that meiosis is very similar to mitosis. In meiosis, the cells grow through duplication and cytokinesis twice! What is the end result of meiosis? To make haploid cells or cells with one set of chromosomes
Meiosis goes through ONE MORE round of cell division MEIOSIS I MEIOSIS II 1N 1N 1N 1N 1N 1N
Meiosis Key Point #4: Meiosis goes through 2 cell divisions and ends with 4 genetically DIFFERENT cells. Why different? Genetic information between chromosomes gets switched. The chromosomes are made of tightly packed DNA and DNA is our genetic information. The DNA has sections we call genes. The genes are all of our traits- the eye color and hair color. We get all of our DNA from our parents. Our parents copy their DNA through meiosis and when the egg and sperm meet, they have a full set of DNA and you are YOU! Germ Cell in Interphase Prophase I Metaphase I Anaphase I Telophase I
2N N N N N In mitosis, the cells have a 2N or two sets of DNA. In meiosis, 4 cells are created and each have a haploid number of chromosomes or one set. Use this page to show them that the original 2N cell has twice as much DNA as each of the 4 products of meiosis. N N
Meiosis Phase 1 Anaphase Prophase Chromosomes condense and pair up (homologous) Anaphase Chromosomes move towards the poles Sister chromatids remain attached In meiosis phase 1, the chromosomes duplicate. The chromosomes pair up with one another forming a tetrad. The tetrad line up in the middle of the cell then during anaphase, the tetrads are pulled apart, so in other words the chromosomes are moved to the opposite ends of the cell. During telophase, the cell pinches off and forms two new cells with diploid number of chromosomes. This is just like mitosis!!! Metaphase Homologous chromosomes line up in the middle Kinetochores are attached to aster Telophase Division of cells Haploid set of chromosomes Interphase Same interphase as before
Crossing Over Key Point #5: Crossing over During prophase, DNA molecules from non-sister chromatids break off and “cross over” to other’s DNA Tetrad
Meiosis I At the end of meiosis I: 1 2 cells Haploid number of chromosomes 46 23
Meiosis II Chromosomes lines up in the middle Because of crossing over, chromatids maybe different Nuc. Membrane forms, chromosomes uncondense Cell divides Spindle forms Chromosomes are still sister chromatids Chromatids separate Chromatids move as individuals Meiosis II
Meiosis II At the end of meiosis II: 2 2 cells each = 4 cells Genetically UNIQUE
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Take a step back 1. What is the purpose of mitosis? 1. What is the purpose of meiosis? What’s the difference between haploid and diploid cells? Regrowth and repair To create gametes and sex cells! Haploid is half set of chromosomes or half N Diploid is a full set of chromosomes or two set of chromosomes 2N
1/16 Daily Catalyst Pg. 70 Compare M&M 1. 2. 3.
1/16 Agenda Pg. 70 Compare M&M Daily Catalyst Class Business Meiosis review Concept check Bozeman Video Compare and contrast M & M Quiz #16
Whiteboard Review Time! When I say “show,” hold up your whiteboards This is a mitosis or meiosis review Depending what I put on the screen, write Mitosis or Meiosis
Used for sexual reproduction Meiosis Sex cells undergo meiosis- sperm and eggs
Has 2 cell divisions Meiosis Meiosis has 2 cells divisions and end with haploid cells or one set of chromosomes.
Produces two IDENTICAL daughter cells Mitosis
Has 1 cell division Mitosis
Creates gametes Meiosis
Creates haploid cells Meiosis Guided Practice Creates haploid cells Meiosis meiosis
Creates cells with 2N chromosomes Mitosis Guided Practice Creates cells with 2N chromosomes Mitosis mitosis
Creates diploid cells Mitosis Guided Practice Creates diploid cells Mitosis mitosis
Produces four DIFFERENT daughter cells Meiosis Guided Practice Produces four DIFFERENT daughter cells Meiosis meiosis
Genetic information between chromosomes gets switched Meiosis
Creates cells with n chromosomes Meiosis
Used for growth Mitosis
Used to make somatic cells Meiosis mitosis
With a tablemate Complete concept check 13.3 with your tablemates. These answers need to be discussed and only write down what you need. https://www.youtube.com/watch?v=2aVnN4RePyI
Compare and Contrast M & M In your notes on today’s page, 70 compare and contrast mitosis and meiosis. You may use your book for help and pay special attention to chromosomes versus chromatids.
Quiz #16 Directions: Silently and independently complete the quiz. Turn your quiz into the basket when you are finished. Pick up the math in science homework. Time: 15 minutes Noise: 0 (silent)
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