Mr Moore Biology Cell Cycle Mitosis Meiosis Chapter
Mr. Moore Biology Cell Cycle: Mitosis & Meiosis Chapter # _______ Pages # _____ 1
Rewind Your Mind n What is the equation for photosynthesis, where does it occur, in whom, why? • Equation: CO 2 + H 2 O + Sunlight = C 6 H 12 O 6 + O 2 • Where: Chloroplasts • Whom: Autotrophs (Plants, Protists and some Bacteria) n What is the difference between Diffusion and Active transport? • Diffusion is Passive transport and does not require ATP (with Concentration Gradient), Active Transport does require ATP (against Concentration Gradient) • Why: To capture solar energy and store it in chemical molecules (Glucose) 2
Year in Progress Scientific Method Cell Cycle and Replication Eukaryotic Organelles Cells (Prokaryotic vs. Eukaryotic) Macromolecules Molecules (H 2 O) Basic Chem. Characteristics Of Life 3
Cell Cycle: Overview Of Cell Cycle w le yc C l l Ce rvie e v O 4
Cell Cycle (FYI) n n In most cases living things grow by producing more cells. On average, the cells of a an adult organism are no larger then those of an infant organism; there are just more of them. In order for the organism to maintain consistency (Homeostasis) between “old” cells and “new” cells an organizational system must be in place. The system that has evolved scientists call the “Cell Cycle”. 5
Cell Reproduction n n 1. 2. 3. Cells are continuously dividing to form new cells. Each time the Cell Cycle is completed, 2 or more new cells are produced. Why are new cells required? : Growth of the organism (Why not just larger cells? ) Replacement of worn-out/ damaged cells Reproduce (Sexually: 2 Parents, Asexually: 1 Parent) 6
Cell Cycle Stages n n G 1 (Gap 1): During this stage the cell carries on “normal” activities and growth. S Phase (Synthesis): During this stage the cell’s DNA is synthesized (Made or Copied). G 2 (Gap 2): During this stage the cell continues its “normal” activities, and minor pre-division preparations. M Phase (Mitosis or Meiosis): During this stage the DNA is distributed evenly to the “Daughter Cells” (New cells being formed). 8
Cell Cycle Diagram 9
Interphase n n n Interphase includes the entire time that the cell needs to prepare for cell division. It is the largest portion of the Cell Cycle Includes all of G 1, S, and G 2 Included Sections of Interphase 10
“M” Phase The M Phase is one of two processes: Mitosis –Somatic Cells, Meiosis –Gametes n Both of these processes are responsible for the Division of the DNA equally to the “New” daughter cells n Mitosis: Division of body cells, has 4 parts n Meiosis: Division of sex cells, has 8 parts n 11
Duration (Time) of Cell Cycle (FYI) n n n Between species (and even between different tissues within the same species) the amount of time needed to complete the Cell Cycle differs. In the Animal Kingdom embryo’s can go threw the entire process in about 20 minutes. In “adults” the process can last about 24 hours. Some cells, even in the animal kingdom (example: nerve cells), never complete a whole Cell Cycle. Why would skin and digestive system cells complete the Cell Cycle more often then other cells? 12
Focus: Human Cells Scientists view our cells in 2 main categories: 1. Somatic Cells: “Body cells” Include everything from your head to your toes with one exception… 2. Gametes: “Sex Cells” Include both the reproductive cells of the male and female Male = sperm, Female = egg n These 2 types of cells differ in a couple interesting ways, including how they complete the Cell Cycle 13
Somatic (Body) Cells n n n Include all of the cells that make up the “formal” body of a human. Each of these cells has the exact same DNA (although each cell may read different portions of that DNA to function). Each Somatic cell has a total of 46 Chromosomes. (It acquired 23 of these chromosomes from one parent, and the other 23 from the other parent) <Mom & Dad> 14
Genetic Material Vocabulary n n n Nucleotides: The monomer of DNA. Smallest unit of the genetic material. Composed of a Phosphate, Sugar (Deoxyribose), and a Nitrogenous base (A, T, C or G) Chromatin: DNA (40%) that has been wrapped around various proteins (60%) to be condensed (Shrunk) inside the cell’s Nucleus. Chromosome: Made up of Chromatin. Each composed of > 140 million nucleotides. Can be seen while the cell is going threw “M Phase”. 15
Genetic Material Visual Concept Chromatin DNA Chromosome Nucleotides 16
Chromosomal Vocabulary Prefixes/ Suffixes: Di= 2, -ploid= “genetic material”, Homo= same n Each Somatic (Body) cell is considered to be Diploid means “ 2 Genetic Material” “Each Somatic cell has 2 copies of the same type (not necessarily same thing) of Genetic material” (One copy received from MOM, and one copy received from DAD) n It can also be stated that each Chromosome is composed (made from) of “Homologous Pairs” 17
Chromosome Diagram “Chromosome” “Homologous Pair” ½ from Mom ½ from Dad Each Somatic Cell Chromosome is Diploid! 19
Centromere n n The section where the Chromatids are connected is referred to as the Centromere. This specific section of DNA is extremely important when the cell goes threw division. 20
Karyotype A method scientists use to study the chromosomes of different organisms. n Pairs up all of the Homologous chromosomes to look for oddity as well as certain physical characteristics. n In Humans: 46 chromosomes (23 pairs), can look for sex of fetus, or certain genetic disorders (Example: Downs Syndrome) First 22 pairs called “Autosomes”, 23 rd pair is the sex chromosomes n 21
Example: Karyotype 22
Karyotype Vocabulary Prefix: Mono= 1, Tri= 3 n Typical humans have two of each chromosome (Homologous Pair, each parent gives one) n Mistakes do happen: 1. When only 1 copy of a chromosome. Monosomy 2. When there are 3 copies of a chromosome. Trisomy Example: When an individual has three 21 st (Trisomy) chromosomes it leads to Downs Syndrome 23
Male and Female Karyotype n n n The 23 rd pair of chromosomes in humans are called the “Sex Chromosomes”: In Females the pair is equal in size (full length) and referred to as “XX” In Males the pair is unequal in size (1 full, 1 half) and referred to as “XY” Possible Combinations 24
Review of Chromosomes iew v e R 25
Practice EOC Questions n A cloned plant has a diploid chromosome number of 12. What is the diploid chromosome number of the plant cell that was used to produce the cloned plant? A. 6 B. 12 C. 18 D. 24 n Which genetic abnormality can be identified through karyotyping? A. point mutation B. recessive allele C. extra chromosome D. sex-linked allele 26
Practice EOC Question n A karyotype of a human female shows that she has only one sex chromosome. Which genotype would represent her genetic condition? A. XO B. XXX C. XY D. XYY 27
Rewind Your Mind n What are some of the adaptations in plants that allow them to go threw Photosynthesis? • Chloroplasts, with chlorophyll in them to collect solar energy. • Xylem and Phloem tubes, to move nutrients up and down the stem. n What is the difference in a “somatic” cell and a “gamete”? • Somatic Cells are body cells with 46 chromosomes, Gametes are sex cells. Male sex cells are sperm, female sex cells are eggs. • Stomata, the openings in the bottom of the leaf to allow gas exchange… and Guard cells to determine the size of the opening. 28
Cell Cycle: “M Phase”: Mitosis v s. O i s o w e i v er Mit 29
Preparation for Division In order for each cell to maintain homeostasis, it needs a complete copy of the genetic material (DNA). n Interphase (G 1, S and G 2) is the copying of the DNA and copying organelles phase. n Mitosis is the DIVISION of the DNA into two equal parts, one complete copy for each new cell… n 30
Mitosis Basics n n n “M” phase of the cell cycle Is the division of the DNA between 2 daughter cells Occurs in Somatic (Body) cells for Growth and Repair/ Replace of damaged cells and tissue. Starts with 1 Diploid cell, and ends in 2 Diploid cells that are identical copies of the “Parent” cell (original cell) Has 4 parts: Prophase, Metaphase, Anaphase, Telophase. 31
Prophase n n n The first and longest phase of mitosis. Chromosomes become visible. Centrioles take their positions on opposite sides of the nucleus. Spindle (a microtubule) becomes organized. During prophase, the condensed chromosomes become attached to fibers in the spindle at a point near the centromere of each chromatid. Nucleolus disappears, nuclear membrane breaks down. 32
Prophase Centrioles Spindle Chromosomes Nuclear Membrane 33
Metaphase The second phase of mitosis, often only lasts a few minutes. n Chromosomes line up across the center of the cell. n Microtubules connect the centromere of each chromosome to the poles of the spindle. n 34
Metaphase 35
Anaphase is the third phase of mitosis. n The centromeres that join the sister chromatids separate, becoming individual chromosomes. n Chromosomes continue to separate until they have formed two groups near the poles of the spindle. (Anaphase stops when the chromosomes stop moving!) n 36
Anaphase 37
Telophase n n n Fourth and final stage! Chromosomes begin to unravel again. Nuclear membrane reforms around each cluster of chromosomes. The spindle breaks apart, and the nucleus becomes visible again in each daughter cell. Mitosis is complete…not cell division!! 38
Telophase 39
Cytokinesis n n n As a result of Mitosis 2 nuclei are formed, usually within the cytoplasm of a single cell. All that remains to complete Cell division (After the completion of the M phase of the cycle) is Cytokinesis…the division of the cytoplasm itself. Cytokinesis usually occurs the same time as Telophase. 40
Cytokinesis in Plant & Animal Cells In most animal cells, the cell membrane is drawn inward…pinching in. (Each part contains its own organelles and new nucleus. ) n In plant cells a cell plate forms ½ way between the nuclei…and gradually grows into a separating membrane…the cell wall then begins to appear in the cell plate. n 41
Cytokinesis Pinching in Cell Plate Formation 42
Mitosis: Hand Jive (Demonstration) n n 1. 2. 3. 4. 5. I, P, M, A, T (order of cell cycle) Your hands represent the DNA in the cell(s) Interphase (G 1, S, G 2): Hand clasp Prophase: 2 Fists together Metaphase: Crossed fingers Anaphase: Sandwich hands Telophase/ Cytokinesis: 2 fists apart 43
Cell Cycle Controls The cell cycle can be placed on “permanent” hold in a phase of G 1, called G 0. During this time the cell functions as normal until it is given directions to start the cycle again. n The directions to start the cell cycle are given by several different proteins, most notably the “Cyclin Protein Family”. n 44
Genetic Mutations n n In most humans the Cyclin Protein functions properly, and signals the need to start the Cell Cycle only when a neighboring cell has died, or needs to be replaced (example: Scratch, scrape, Broken bone). However, if a Mutation were to change the instructions (DNA) to stay “on” or “never turn on” it can have devastating effects on the organism. 45
Uncontrolled Cell Growth n Cancer is a disorder where the cells do not respond to the signals that regulate the growth of most cells. As a result, they form masses of cells called tumors that can damage the surrounding tissues. 46
Mitosis Review w ie Rev 47
Practice Problem n If a diploid cell started out with 28 chromosomes and went threw Mitosis, what would the end result be? Mitosis leads to two identical cells that are a copy of the original cell! 2 Diploid cells with 28 chromosomes each!! 28 28 28 48
Practice Problem n What cells go threw Mitosis? Why? • Only Somatic (Body) Cells go threw Mitosis. • Mitosis is the process by which organisms (including Humans) grow as well as repair or replace damaged cells. 49
Practice EOC Problems n Which term best describes the type of cell division in which parent cells produce daughter cells with the same number of chromosomes as the parent cells? A. mitosis B. meiosis C. spermatogenesis D. oogenesis n Before a cell goes through either mitosis or meiosis, which process must be carried out by the DNA in the nucleus? A. replication B. nondisjunction C. transcription D. translation 50
Practice EOC Problems n A cloned plant has a diploid chromosome number of 12. What is the diploid chromosome number of the plant cell that was used to produce the cloned plant? A. 6 B. 12 C. 18 D. 24 51
Rewind Your Mind n What is the difference between Aerobic and Anaerobic Cellular Respiration? • Aerobic Respiration is with Oxygen, Anaerobic Respiration is without oxygen. • The equation for Aerobic respiration is: C 6 H 12 O 6 + O 2 = CO 2 + H 2 O + 38 ATP • Anaerobic only produces 2 ATP n What are the differences between Somatic Cells and Gametes? • Somatic cells are “Body” cells and go threw the process of Mitosis to reproduce. • Gametes are “Sex” cells, sperm in males, eggs in females. Will go threw Meiosis. 52
Cell Cycle: “M Phase”: Meiosis ew ervi v O is s Meio 53
Asexual Reproduction n Almost every Kingdom (including Animal) have some species that go threw Asexual Reproduction (One Parent). Asexual Reproduction would be similar to “Mitosis” Mitosis in that each “infant” would only have 1 parent, and be an identical copy of that individual. Examples include: Budding, and Binary Fission. Example: “Hydra” 54
Sexual Reproduction n Most Plants and Animals primarily go threw “Sexual Reproduction” (Genetic Information from 2 parents). Benefit to “Sexual Reproduction” is Genetic Variability: Each member of that species is slightly different. If a change in the environment were to occur, there is a greater likelihood that some individuals would survive. The process that organisms use to allow Sexual Reproduction is “Meiosis”. Meiosis 55
? Numbers Problem? n n (FYI) A Human somatic cell has 46 chromosomes. If sexual reproduction was to occur without any special preparation, the infant would receive 46 chromosomes from Mom and 46 chromosomes from Dad. 92 chromosomes is Too Much genetic material and the infant would die… Meiosis is a way to reduce the number of chromosomes (half) in special cells (gametes) so that their number of can maintain constant (homeostasis) from one generation to the next! 56
Meiosis Basics n n n “M” phase of the Sexual Cell Cycle Is the division of the DNA between 4 daughter cells Occurs in Gametes (sex) cells for sexual reproduction. Ensures constant chromosomal numbers from generation to generation. Starts with 1 Diploid cell, and ends in 4 Haploid cells (Monoploid Cells) that are different from the “Parent” cell Has 8 parts: Prophase I, Metaphase I, Anaphase I, Telophase I, Prophase II, Metaphase II, Anaphase II, Telophase II. 57
Mitosis vs. Meiosis Comparison Mitosis Meiosis Cell Type: Somatic Gamete Start With: 1 Diploid Cell End With: 2 Diploid Cells 4 Haploid Cells Purpose: Growth/ Repair Sexual Reproduction One Two # of Divisions: Example: 1 Cell, 46 (2 n) End: 2 Cells, 46 (2 n) 4 Cells, 23 (n) 58
Diploid vs. Haploid (Monoploid) As we discussed in “Mitosis”, Somatic cells are Diploid (2 n): Meaning that each cell has 2 copies of each chromosome… 1 from mom and 1 from dad. n In “Meiosis” the body makes Gamete cells (Sex Cell) that are Haploid (n). n Prefix: Hap- = one, Mono- = one Haploid Cells have only one copy of the genetic code, so that when 2 Gametes (n) join the original number (2 n) can be restored. n 59
Meiosis at a “Glance” n n Divided into 2 main sections: Meiosis I, and Meiosis II. During Meiosis I, unlike in Mitosis, the Homologous Chromosomes align together instead of separately. Meiosis II is: “The exact same process as Mitosis!” Whether Mitosis or Meiosis, the DNA is copied in the “S Phase” of the Cell Cycle. Mitosis only divides this information once, but Meiosis divides the information a second time!! 60
Visual Comparison MITOSIS MEIOSIS “S” Phase First Division Second Division 61
Stages of Meiosis Prophase I (4 n) after “S Phase” Metaphase I (4 n) 62
Stages of Meiosis Anaphase I Telophase I (4 n) (2 n) 63
Stages of Meiosis Prophase II (2 n) Metaphase II (2 n) 64
Stages of Meiosis Draw Chromatids Separating! Anaphase II (2 n) Telophase II (n) 65
are u q S sis nce o i Me Da 66
Genetic Variability n n n 1. 2. The purpose of Sexual Reproduction (and therefore Meiosis) is for Genetic Variability. Those differences in the members of the species comes from the fact that they are a mixture of both parents (Mom & Dad). Besides just some chromosomes from each parent, there are even further mixtures caused by: Independent Assortment Crossing over 67
Independent Assortment Blue = Dad n n Independent Assortment: The fact that not all of Mom’s (or Dad’s) chromosomes have to move together into a newly formed gamete. Ex. You can have 10 of your dad’s chromosomes in your gamete, and 13 of your mother’s (Or any combination) as long as it totals 23 (haploid) Somatic: (2 n) = 4, Gametes: (n) = 2 Pink = Mom Somatic Cell Gametes 68
Crossing Over n n Crossing Over: During Metaphase I (of Meiosis), homologous chromosomes become so close to each other, that they sometimes transfer information between chromosomes. This can lead to even greater variation between the gametes formed by that individual. 69
Sexual Life Cycle Vocabulary 1. 2. 3. 4. 5. fertilization- the joining of male (sperm) and female (egg) gametes together zygote- cell formed from process of fertilization cleavage- rapid cell division (mitosis) immediately after fertilization Embryo- Early stages of life (in humans while still in womb) differentiation/ specialization- generic cells becoming specialized (to do a certain job in the body) 70
Sexual Life Cycle 71
Nondisjunction of Chromosomes n Sometimes mistakes happen in the splitting of the chromosomes. If they fail to separate properly during either Anaphase I or Anaphase II it is called Nondisjunction 72
Down Syndrome n n Down Syndrome is an example of a disease that is caused by Nondisjunction. In this disease, the 21 st chromosome (in either the mother or father) did not separate properly, giving the child an extra chromosome. Above: a Karyotype of someone with Downs Syndrome. Left: A picture of a young man with Down Syndrome 73
Practice Problem n A diploid cell with 24 chromosomes starts the process of Meiosis. What will the end product be? n Meiosis ends with 4 cells that are haploid (1/2 the genetic information) 24 12 End: 4 cells with 12 chromosomes each 12 12 12 74
Practice Problem n Given this information determine which example is showing Mitosis, and which is showing Meiosis? • Example X: Meiosis • Example Y: Mitosis 75
Practice EOC Problems n Plant cells that are specialized for cell division are most likely found in what part of a plant? A. root tips B. leaf epidermis C. stem epidermis D. vascular tissue n What process produces many variations in phenotypes? A. independent assortment B. asexual reproduction C. regeneration D. cloning 76
Practice EOC Problems n What advantage do sexually reproducing organisms have over asexually reproducing organisms? A. genetic variation B. genetic stability C. increased fertilization rate D. increased reproductive rate n A cloned plant has a diploid chromosome number of 12. What is the diploid chromosome number of the plant cell that was used to produce the cloned plant? A. 6 B. 12 C. 18 D. 24 77
Practice EOC Problem This diagram shows a diploid cell with two pairs of homologous chromosomes: s S t T n Due to independent assortment, what is the possible genetic make-up of gametes produced by this organism? A. Ss. Tt B. Ss, Tt C. S, s, T, t D. ST, St, s. T, st 78
Practice EOC Problems Which process is an example of asexual reproduction? A. An amoeba divides in half to form two amoebas. B. A bee transfers pollen from one flower to another. C. A female fish deposits eggs on a rock, then a male fish releases sperm on them. D. Earthworms exchange sperm. n n Which genetic abnormality can be identified through karyotyping? A. point mutation B. recessive allele C. extra chromosome D. sex-linked allele 79
Practice EOC Problems n Sexual reproduction provides for what to occur? A. cloning B. budding C. genetic stability D. genetic variation n Which would most likely favor species survival in changing environmental conditions? A. genetic recombination B. energy involvement in gamete production C. length of life cycle D. number of offspring produced 80
Practice EOC Problem n Which term best describes the type of cell division in which parent cells produce daughter cells with the same number of chromosomes as the parent cells? A. mitosis B. meiosis C. spermatogenesis D. oogenesis 81
Practice EOC Problems n What is the primary cause of variation in the offspring of sexually reproducing organisms? A. cytoplasmic division B. environmental changes C. mutation D. recombination of alleles n Before a cell goes through either mitosis or meiosis, which process must be carried out by the DNA in the nucleus? A. replication B. nondisjunction C. transcription D. translation 82
Practice EOC Problem n A plant nursery only grew one type of tomato plant. All of their tomato plants died from the same disease. What was most likely true of the tomato plant population? A. They had a lot of resistance to disease. B. They had a few plants that were resistant to the disease. C. They had too much variation in their genes. D. They had little variation in their genes. 83
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