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Class 3-cell division & mito


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cell devision and mitosis

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Class 3-cell division & mito

  1. 1. Cell Cycle • The process of cell growth and division in eukaryotes is called cell cycle. • This cycle is divided into phases based on what is happening in the cell at a given time. • A cell grows during the G1 phase. During the phase there is chemical checkpoint that controls whether the divide, delay division or enter the division stage. When conditions in the cell are right, the G1 checkpoint will be passed and the cell will enter the synthesis(S) phase. • During the S phase DNA replication occurs so that future cells will each have a complete set of genetic instructions in the DNA.
  2. 2. Cell Cycle • After DNA replication is complete cells enter the G2 phase, where they continue to grow and prepare for cell division. At a checkpoint in this phase the success of DNA replication is assessed; if all is well the cell enter the mitosis (M) phase. • During the M phase, a complex series of events moves the DNA so that a complete set of genetic instructions will be sent to each daughter cell. The process of mitosis is assessed at a checkpoint during the M phase. • Once this checkpoint is passed, the cell will complete the mitosis as well begin the cytokinesis(C) phase. Part or all of the C phase overlaps with the later part of mitosis, so it is not a distinctly separate phase. • During the C phase the cytoplasm of the cell is divided and two daughter cell are created from the original cell. When this process is finished the daughter cell enter the G1 phase, and the cell cycle is complete.
  3. 3. Chromosome • Chromosome, microscopic structure within cells that carries the molecule deoxyribonucleic acid (DNA)—the hereditary material that influences the development and characteristics of each organism. • A human body cell usually contains 46 chromosomes arranged in 23 pairs.
  4. 4. Through research and the development of staining techniques in the 1950's, scientists were for the first time able to view the human chromosome. Although they appear disorganised within the cell, scientists have been able to identify them and so have numbered them from 1-22 in order of size.
  5. 5. Eukaryotic Chromosomes • Located in the nucleus • Each chromosome consists of a single molecule of DNA and its associated proteins The DNA and protein complex found in eukaryotic chromosomes is called chromatin 1/3 DNA and 2/3 protein •Complex interactions between proteins and nucleic acids in the chromosomes regulate gene and chromosomal function
  6. 6. Cell division All complex organisms originated from a single fertilised egg. Every cell in your body started here, through cell division the numbers are increased Cell then specialise and change into their various roles
  7. 7. Mitosis and Meiosis • Mitosis: -division of somatic (body) cells • Meiosis -division of gametes (sex cells)
  8. 8. Mitosis • Mitosis is the process by which new body cell are produced for: – Growth – Replacing damaged or old cells. This is a complex process requiring different stages
  9. 9. Mitosis • All daughter cells contain the same genetic information from the original parent cell from which it was copied. • Every different type cell in your body contains the same genes, but only some act to make the cells specialise – e.g. into nerve or muscle tissue.
  10. 10. Mitosis • Interphase • Prophase • Metaphase • Anaphase • Telophase
  11. 11. Interphase Interesting things happen! 1. Cell preparing to divide 2. Genetic material doubles •
  12. 12. Prophase Chromosome pair up! 1. Chromosomes thicken and shorten -become visible -2 chromatids joined by a centromere 2. Centrioles move to the opposite sides of the nucleus 3. Nucleolus disappears 4. Nuclear membrane disintegrate •
  13. 13. Metaphase Chromosomes meet in the middle! 1. Chromosomes arrange at equator of cell 2. Become attached to spindle fibres by centromeres 3. Homologous chromosomes do not associate •
  14. 14. Anaphase Chromosomes get pulled apart 1. Spindle fibres contract pulling chromatids to the opposite poles of the cell •
  15. 15. Telophase • 1. 2. 3. 4. 5. Now there are two! Chromosomes uncoil Spindle fibres disintegrate Centrioles replicate Nucleur membrane forms Cell divides
  16. 16. Meiosis • 4 daughter cells produced • Each daughter cell has half the chromosomes of the parent • 2 sets of cell division involved
  17. 17. Mitochondria Mitochondria are membrane-enclosed organells distributed through the cytosol of most eukaryotic cells. Their main function is the conversion of the potential energy of food molecules into ATP. Every type of cell has a different amount of mitochondria. There are more mitochondria in cells that have to perform lots of work, for example- your leg muscle cells, heart muscle cells etc. Other cells need less energy to do their work and have less mitochondria.
  18. 18. Mitochondria • Double membrane with shelf-like cristae • Matrix: Substance located in space formed by inner membrane. • Provide most of the cell’s ATP via aerobic cellular respiration • Mitochondrial enzymes catalyze series of oxidation reactions that provide about 95% of cell’s energy supply • Each mitochondrion has a DNA molecule, allowing it to produce its own enzymes and replicate copies of itself. structure
  19. 19. The Mighty Mitochondrion! Powerhouse of the Cell ATP
  20. 20. Mitochondria 1) 2) 3) 4) 5) TCA cycle Fatty acid oxidation Amino acid oxidation Gluconeogenesis Synthesis of organelle protein
  21. 21. Proteins Amino acids Outer Membrane: Freely permeable to small molecules and ions Inner Membrane: impermeable to most small molecules and ions, including H+ Contains: •Respiratory electron carriers (complexes IIV) •ATP Synthase •Other membrane transporters Fats Sugars Glycerol Glycolysis Glucose Glyceraldehyde-3- NH3 Matrix Contains: •Pyruvate dehydrogenase complex •Citric acid cycle enzyme •Fatty acid β-oxidation enzymes •Amino acid oxidation enzymes •DNA •Ribosomes •Many other enzymes •ATP, ADP, Pi, Mg+2, Ca+2, K+ •Many Soluble metabolic intermediates Carbohydrates P Pyruvate Acetyl CoA Citric acid cycle Oxidative phosphorylation Fatty acids
  22. 22. Electron shuttles span membrane CYTOSOL 2 NADH Glycolysis Glucose 2 Pyruvate MITOCHONDRIO N 2 NADH or 2 FADH2 6 NADH 2 NADH 2 Acetyl CoA + 2 ATP Citric acid cycle + 2 ATP Maximum per glucose: 2 FADH2 Oxidative phosphorylation: electron transport and chemiosmosis + about 32 or 34 ATP About 36 or 38 ATP Rodney-464 page
  23. 23. Chloroplast • Largest organelles of plants and algae • Vary in size and shape • Function: Photosynthesis • Inner membrane system – Grana • thylakoids – Stroma • Calvin cycle • sugar synthesis • Genome • Has its own protein synthesizing enzymes Converts light energy to chemical energy (sugars)
  24. 24. Chloroplasts
  25. 25. Chloroplast Granum Stroma Outer membrane Inner membrane Thylakoid lumen Do not post photos on Internet Thylakoid membrane 1 µm
  26. 26. CO2 H2O Light NADP+ ADP + P i Light Reactions Calvin Cycle ATP NADPH Chloroplast O2 [CH2O] (sugar)
  27. 27. Mitochondria Chloroplast Aerobic respiration Mitochondria (all eukaryotic cells) Photosynthesis Chloroplasts (some plant and algal cells) Light CO2 Glucose + O2 ATP CO2 + Respiration H2O H2O + ATP O2 + Glucose Photosynthesis
  28. 28. Chloroplasts 1) Photosynthesis 2) Fatty acid synthesis 3) Complex lipid synthesis 4) Synthesis of some amino acids 5) Synthesis of organelle protein 6) Calvin cycle 7) Light reaction 8) Reduction of nitrate and sulphate 9) Part of photorespiration