1 / 70

Bellwork

Bellwork. Domestic horses have 64 chromosomes. How many chromosomes should be in an egg cell of a female horse? A. 16 B. 32 C. 64 D. 128. Bellwork.

paley
Download Presentation

Bellwork

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Bellwork Domestic horses have 64 chromosomes. How many chromosomes should be in an egg cell of a female horse? A. 16 B. 32 C. 64 D. 128

  2. Bellwork In a sample of double-stranded DNA, 30% of the nitrogenous bases are thymine. What percentage of the nitrogenous bases in the sample are adenine? • 20% • 70% • 30% • 40%

  3. Agenda 5/3- Cell Cycle, Division (Mitosis) • Bellwork • New Information: Cell Cycle, Mitosis • Virtual Lab- Identifying Stages of the Cell Cycle

  4. Cell Cycle and Cell Division (Mitosis) • What is mitosis? Why is it important?

  5. Cell Division 3 reasons for mitotic cell division (mitosis): Growth Repair Replacement Parent cell divides into two identical daughter cells

  6. Cell Division Cells divide to make new cells- DNA is replicated so each daughter cell gets an exact copy. DNA condenses into chromosomes during mitosis.

  7. Cell Division • Humans have 46 chromosomes, 23 from each parent. • Haploid cells: only one of each chromosome (n) • Diploid cells: two of each chromosome (2n)

  8. Cell Cycle(click for video clip) G1 phase M phase S phase G2 phase

  9. Interphase- longest • G1 Phase • Cell growth • S Phase • DNA replication • G2 Phase • preparation for mitosis • M Phase • mitosis and cytokinesis Allium G1 M phase S G2

  10. Interphase • Nucleus and nuclear envelope are visible. • One or more nucleoli are visible. • The rest of the nucleus is filled with chromatin.

  11. Figure 10-5 Prophase Interphase Cytokinesis Metaphase Telophase Anaphase

  12. Prophase pro- = first; first stage of mitosis • Nuclear envelope breaks down • Chromatin condenses into chromosomes • Centrioles move to opposite poles of the cell • Spindle fibers attach to chromosomes at the centromere.

  13. Metaphase • Chromosome line up in the Middle of the cell • Chromosome centromeres are attached to the spindle at the poles of the cell

  14. Anaphase • Chromosome centromeres separate and sister chromatids move Apart to the opposite ends of the cell

  15. Telophase • Chromosomes precipitate back into strands of DNA (chromatin) • A new nuclear envelope begins to form around each of the two new clumps of DNA

  16. Cytokinesis (“cell splitting”) • Same time as Telophase • Animal Cells: • cytoplasm splits as the cell membrane draws inward (cleavage furrow) and splits the cell in two • Plant Cells: • cytoplasm splits as a cell plate forms between the two new nuclei, then a new cell membrane

  17. Cell Cycle and Mitosis • I • P • M • A • T • C • Interphase • Prophase • Metaphase • Anaphase • Telophase • Cytokinesis • I • Protect • Mothers • And • Their • Children

  18. Cell Cycle and Mitosis Virtual Lab • Go to http://www.biology.arizona.edu/cell_bio/activities/cell_cycle/cell_cycle.html • Make a table like the one you’ll see before the activity begins. • Answer the following questions: • Which phase of the cell cycle is longest? How do you know? Which is shortest, and how do you know?

  19. Bellwork 5/4 • What are the 4 phases of the cell cycle? • What are the 4 phases of mitosis? • What phases are shown below?

  20. Agenda 5/4- Cell Cycle and Cancer • Bellwork • Notes- Cell Cycle Control and Cancer • Lab- Mitosis in Onion Root Tip Cells • HW- finish lab questions, study for test (Fri)- DNA structure and replication, cell cycle, and mitosis

  21. Binary Fission • Prokaryotes (bacteria) reproduce by a type of cell division called binary fission. • In binary fission the single bacterial chromosome replicates and the two daughter chromosomes actively move apart.

  22. G1 phase M phase S phase G2 phase

  23. G1 checkpoint Control system S G1 G2 M M checkpoint Figure 12.14 G2 checkpoint The Cell Cycle Control System • The events of the cell cycleare directed by a cell cycle control system, similar to a clock.

  24. G0 G1 checkpoint G1 G1 (b)If a cell does not receive a go-ahead signal at the G1checkpoint, the cell exits the cell cycle and goes into G0, a non-dividing state. (a) If a cell receives a go-ahead signal at the G1 checkpoint, the cell continues on in the cell cycle. Figure 12.15 A, B The Cell Cycle Control System • There are specific checkpoints where the cell cycle stops until a go-ahead signal is received.

  25. Normal mammalian cells. The availability of nutrients, growth factors, and a substratum for attachment limits cell density to a single layer. (a) Cells anchor to dish surface and divide (anchorage dependence). When cells have formed a complete single layer, they stop dividing (density-dependent inhibition). If some cells are scraped away, the remaining cells divide to fill the gap and then stop (density-dependent inhibition). Figure 12.18 A 25 µm Control of Cell Division • In density-dependent inhibition crowded cells stop dividing. • Most animal cells also exhibit anchorage dependence in which they must be attached to a substratum to divide.

  26. Cancer cells do not exhibitanchorage dependence or density-dependent inhibition. (b) Cancer cells. Cancer cells usually continue to divide well beyond a single layer, forming a clump of overlapping cells. Figure 12.18 B 25 µm Control of Cell Division • Cancer cells: no density-dependent inhibition or anchorage dependence. • Do not respond normally to the body’s control mechanisms and form tumors. • Loss of the cell cycle controls.

  27. Control of Cell Division • Malignant tumors invade surrounding tissues and can metastasize, exporting cancer cells to other parts of the body where they may form secondary tumors.

  28. Cancer Risk Factors Quiz • http://www.webmd.com/cancer/rm-quiz-cancer-myths-facts

  29. Lab Objectives • To list the phases of the cell cycle in the order in which they occur. • To list the phases of the M-phase of the cell cycle (Mitosis) and explain what happens during each. • To illustrate/draw what happens during each phase of Mitosis. • To identify the role of cell structures during cell division (centrioles, chromatin, chromosomes, nucleus). • To learn the importance of cell division for organisms (asexual reproduction, growth, repair).

  30. Mitosis in Allium Root Interphase Prophase Metaphase

  31. Mitosis in Allium Root Anaphase Telophase

  32. Prophase Interphase Metaphase Telophase Anaphase

  33. Allium Lab- Mitosis • X = the area just behind the root cap • Y = the area behind region X (fewer cells, fewer nuclei visible) Y X

  34. Bellwork 5/6 The illustration below represents a cell that is entering mitosis. • Identify one function of mitosis. The cell shown in the illustration has recently completed the synthesis phase (S phase) of the cell cycle and is in prophase of mitosis. 2. What happened in this cell during the S phase in preparation for division? Describe the evidence that supports your answer. 3. In your Student Answer Booklet, draw the end products that will be formed when this cell completes mitosis.

  35. Agenda 5/6- Mitotic Cell Division • Bellwork • Discuss lab, start lab report • Review for Monday’s test

  36. Agenda 5/9- Sexual vs. Asexual Reproduction • Cell Cycle, Mitosis, and DNA Replication Test • New information: Sexual vs. Asexual Reproduction • Video- Life’s Greatest Miracle • HW- • Due Tues: Lab Report • Due Wed: Vocabulary (on next slide)

  37. HW- vocabulary- use book or internet to define these terms (max 7 words per definition, in your OWN WORDS) and draw a picture for each. • Homologous chromosomes • Tetrad • Crossing over • Trait • Gene • Allele • Hybrid • Homozygous • Heterozygous • Phenotype • Genotype • Probability

  38. Eukaryotic Cell Division • Mitosis- normal cell division • Parent cell divides into two identical daughter cells (diploid = 2n) • n = number of types of chromosomes • Meiosis- cell division resulting in reproductive cells (gametes) • Parent cell divides into 4 daughter cells, each with half the number of chromosomes (haploid = 1n)

  39. Mitosis • 2 diploid daughter cells formed, just like parent cell (two of each chromosome) • Preceded by interphase (G1, S, G2 phase) • Mitosis: • Prophase • Metaphase • Anaphase • Telophase

  40. Figure 10-5 Prophase Interphase Cytokinesis Metaphase Telophase Anaphase

  41. Why don’t you look exactly like your parents or siblings? • A different form of cell division: Meiosis! • Sexual reproduction increases genetic variation in a population, which increases a species’ ability to adapt to changes in their environment.

  42. Sexual Reproduction • Male gamete (sperm) and female gamete (egg) are haploid (1n) • Fertilization occurs when an egg and a sperm fuse to form a zygote (2n). • Meiosis is the form of cell division that results in gametes.

  43. Meiosisoccurs in somatic (body) cells to produce reproductive cells (gametes) • 4 haploid daughter cells formed (only one of each chromosome) • Preceded by interphase and DNA replication • Two Divisions: • Meiosis I • Meiosis II

  44. Bellwork 5/10

  45. Agenda 5/10- Sexual vs Asexual Reproduction • Bellwork • New Information: Sexual vs. Asexual Reproduction • Video- finish and discuss • HW- vocabulary

  46. Why Sex? The Evolution of Sexual Reproduction Sexual Reproduction • offspring are a combination of parents • introduces variety in population Asexual Reproduction • offspring are identical to parents • little variety in population • binary fission, budding

More Related