CELLS AND DNA-.pptx FRANK JOSHUA RUHAZWE

UNDERSTAND BASIC CONCEPTS OF CELL & DNA

1. CELLS AND DNA PRESENTER : FRANK JOSHUA RESIDENT GENERAL SURGERY RESIDENT COURSE NAME :FORENSIC MEDICINE KAMPALA INTERNATIONAL UNIVERSITY-UGANDA [email protected] WhatsApp number [phone]/6/2024 FRANK JOSHUA RUHAZWE

2. OUTLINE Cell theory & Definition Classification of Cells Cellular components Cell division Diseases Related with abnormalities in cell division. Reference 2 5/6/2024 FRANK JOSHUA RUHAZWE

3. Cell theory & Definition Definition of Cell A cell is the smallest basic structure and functional unit of an organism. All living things are made up of cells. Cells are the smallest working units of all living things. All cells come from preexisting cells through cell division. 3 5/6/2024 FRANK JOSHUA RUHAZWE

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5. CLASSIFICATION OF CELLS Based on Structure Based on Function Based on Number of Cells in an Organism Based on Cell Wall Based on Mobility Based on Location in an Organism 5 5/6/2024 FRANK JOSHUA RUHAZWE

6. Based on Structure: Prokaryotic Cells: Cells without a true nucleus, lacking membrane-bound organelles. Examples include bacteria and archaea. Eukaryotic Cells: Cells with a true nucleus and membrane-bound organelles. Examples include animal, plant, fungal, and protist cells. 6 5/6/2024 FRANK JOSHUA RUHAZWE

7. Based on Function: Somatic Cells: Also known as body cells, they make up the tissues, organs, and systems of multicellular organisms. They perform various functions depending on their specific type and location. Produced by mitosis Germ Cells: These are specialized cells involved in reproduction. In humans, germ cells are the sperm and egg cells (gametes). Produced by meiosis 7 5/6/2024 FRANK JOSHUA RUHAZWE

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9. Based on Number of Cells in an Organism: Unicellular: Organisms composed of a single cell, such as bacteria, archaea, and some protists . Multicellular : Organisms composed of multiple cells organized into tissues, organs, and organ systems. Examples include plants, animals, and fungi 9 5/6/2024 FRANK JOSHUA RUHAZWE

10. Based on Cell Wall: Cells with Cell Walls: Many prokaryotic cells and plant cells have a cell wall, which provides structural support and protection. Example Animal cell Cells without Cell Walls: cells typically lack a cell wall, though they have other structures like the extracellular matrix Example Protoplast 10 5/6/2024 FRANK JOSHUA RUHAZWE

11. Based on Mobility: Motile Cells: Cells capable of movement. Examples include sperm cells, certain immune cells, and some types of bacteria. Non-motile Cells: Cells that do not exhibit self-directed movement. Examples include most plant cells and many types of animal cells 11 5/6/2024 FRANK JOSHUA RUHAZWE

12. Based on Location in an Organism: Epithelial Cells: Cells that line the surfaces and cavities of the body, providing protection, secretion, and absorption. Nerve Cells (Neurons): Cells that transmit electrical signals throughout the body, allowing for communication and coordination of bodily functions. Muscle Cells: Cells that contract and relax to produce movement. 12 5/6/2024 FRANK JOSHUA RUHAZWE

13. CELLULAR COMPONENTS CELL WALL Outer membrane of cell that controls movement in and out of the cell. Double layer. Most commonly found in plant cells & Animals Supports & protects cells 13 5/6/2024 FRANK JOSHUA RUHAZWE

14. Nucleus Directs cell activities Separated from cytoplasm by nuclear membrane Contains genetic material - DNA Nuclear Membrane Surrounds nucleus Made of two layers Openings allow material to enter and leave nucleus 14 5/6/2024 FRANK JOSHUA RUHAZWE

15. Chromosomes In nucleus Made of DNA Contain instructions for traits & characteristics 15 5/6/2024 FRANK JOSHUA RUHAZWE

16. Cytoplasm Gel-like mixture Surrounded by cell membrane It is composed of water , salts and various organic molecules Responsible for holding components of cells ,storage and support the cell structure. 16 5/6/2024 FRANK JOSHUA RUHAZWE

17. Endoplasmic Reticulum Moves materials around in cell Smooth type: lacks ribosomes and involved in production of lipids. Rough type (pictured): ribosomes embedded in surface .involved in production of proteins 17 5/6/2024 FRANK JOSHUA RUHAZWE

18. Ribosomes Each cell contains thousands Make proteins Found on Endoplasmic reticulum & floating freely in cytoplasm. Read information encoded on m-RNA and use it to assemble amino acids into proteins. 18 5/6/2024 FRANK JOSHUA RUHAZWE

19. Mitochondria Produces energy through chemical reactions – breaking down fats & carbohydrates Controls level of water and other materials in cell Recycles and decomposes proteins, fats, and carbohydrates 19 5/6/2024 FRANK JOSHUA RUHAZWE

20. Golgi Bodies Protein 'packaging plant' Move materials within the cell Move materials out of the cell 20 5/6/2024 FRANK JOSHUA RUHAZWE

21. Lysosome Digestive 'plant' for proteins, fats, and carbohydrates Transports undigested material to cell membrane for removal 21 5/6/2024 FRANK JOSHUA RUHAZWE

22. Vacuoles Membrane-bound sacs for storage, digestion, and waste removal Contains water solution Help plants maintain shape 22 5/6/2024 FRANK JOSHUA RUHAZWE

23. Chloroplast Usually found in plant cells Contains green chlorophyll Where photosynthesis takes place 23 5/6/2024 FRANK JOSHUA RUHAZWE

24. DNA stands for deoxyribose nucleic acid This chemical substance is present in the nucleus of all cells in all living organisms DNA controls all the chemical changes which take place in cells DNA 24 5/6/2024 FRANK JOSHUA RUHAZWE

25. DNA is a very large molecule made up of a long chain of sub-units The sub-units are called nucleotides Each nucleotide is made up of A sugar called deoxyribose A phosphate group - PO 4 An organic base DNA molecule 25 5/6/2024 FRANK JOSHUA RUHAZWE

26. Ribose is a sugar, like glucose, but with only five carbon atoms in its molecule Deoxyribose is almost the same but lacks one oxygen atom at position 2. Ribose & deoxyribose 26 5/6/2024 FRANK JOSHUA RUHAZWE

27. The most common organic bases are Adenine (A) Thymine (T) Cytosine (C) Guanine (G) The bases 27 PURINE –Adenine and Guanine,have two- Carbon Nitrogenous ring bases PYRIMIDINES – Cytocine and Thyamine have one Carbon N itrogenous base ring 5/6/2024 FRANK JOSHUA RUHAZWE

28. The deoxyribose, the phosphate and one of the bases adenine deoxyribose PO 4 Combine to form a nucleotide Nucleotides 28 5/6/2024 FRANK JOSHUA RUHAZWE

29. A molecule of DNA is formed by millions of nucleotides joined together in a long chain PO 4 PO 4 PO 4 PO 4 sugar-phosphate backbone + bases Joined nucleotides 29 5/6/2024 FRANK JOSHUA RUHAZWE

30. In fact, the DNA usually consists of a double strand of nucleotides The sugar-phosphate chains are on the outside and the strands are held together by chemical bonds between the bases 30 5/6/2024 FRANK JOSHUA RUHAZWE

31. PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 2-stranded DNA 31 5/6/2024 FRANK JOSHUA RUHAZWE

32. The bases always pair up in the same way Adenine forms a bond with Thymine and Cytosine bonds with Guanine Bonding 1 Adenine Thymine Cytosine Guanine 32 5/6/2024 FRANK JOSHUA RUHAZWE

33. PO 4 PO 4 PO 4 thymine PO 4 PO 4 PO 4 PO 4 adenine cytosine PO 4 guanine Bonding 2 33 5/6/2024 FRANK JOSHUA RUHAZWE

34. PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 Pairing up 34 5/6/2024 FRANK JOSHUA RUHAZWE

35. The paired strands are coiled into a spiral called A DOUBLE HELIX 35 5/6/2024 FRANK JOSHUA RUHAZWE

36. sugar-phosphate chain bases THE DOUBLE HELIX 36 5/6/2024 FRANK JOSHUA RUHAZWE

37. A DIY model of part of a DNA molecule 37 5/6/2024 FRANK JOSHUA RUHAZWE

38. Before a cell divides, the DNA strands unwind and separate Each strand makes a new partner by adding the appropriate nucleotides The result is that there are now two double-stranded DNA molecules in the nucleus So that when the cell divides, each nucleus contains identical DNA This process is called replication Replication 38 5/6/2024 FRANK JOSHUA RUHAZWE

39. PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 The strands separate 39 5/6/2024 FRANK JOSHUA RUHAZWE

40. PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 PO 4 Each strand builds up its partner by adding the appropriate nucleotides 40 5/6/2024 FRANK JOSHUA RUHAZWE

41. CELL DIVISION Cell division happens when a parent cell divides into two or more cells called daughter cells. Cell division usually occurs as part of a larger cell cycle . In eukaryotes, there are two distinct types of cell division: Mitosis Meiosis. 41 5/6/2024 FRANK JOSHUA RUHAZWE

42. MITOSIS Mitosis:  The process cells use to make exact replicas of themselves. Mitosis is observed in almost all the body’s cells, including eyes, skin, hair, and muscle cells. It involves Interphase Prophase Metaphase Anaphase Telophase Cytokinesis Interphase (Planning & Preparation) During interphase, the cell is not actively dividing, but it’s  getting ready for mitosis 42 5/6/2024 FRANK JOSHUA RUHAZWE

43. Prophase Chromatin condenses into visible chromosomes, consisting of two sister chromatids held together by a centromere. The nuclear envelope breaks down, and spindle fibers begin to form . M etaphase : The spindle fibers attach to the centromeres of the chromosomes. Chromosomes line up along the metaphase plate, and each chromosome is attached to spindle fibers from opposite poles of the cell. 43 5/6/2024 FRANK JOSHUA RUHAZWE

44. Anaphase (Building Walls): Anaphase is the stage where the chromosomes, which were aligned in the middle of the cell during metaphase, are pulled apart to opposite ends . This separation is like how workers move materials for building walls . Telophase (Almost Two Buildings): Chromatids arrive at opposite poles and decondense into chromatin. Nuclear envelopes reform around the separated chromatin, and the spindle fibers disassemble . The construction is nearly complete, with structures gathering at each end of the site. 44 5/6/2024 FRANK JOSHUA RUHAZWE

45. Cytokinesis (Two Buildings) The final step is like officially splitting the construction site into two . Each side gets its own workers, tools, and materials, resulting in two complete buildings – or in mitosis, two new cells. 45 5/6/2024 FRANK JOSHUA RUHAZWE

46. MEIOSIS Meiosis is a specialized type of cell division that occurs in sexually reproducing organisms. It involves two consecutive divisions, resulting in the production of four haploid daughter cells , each containing half the number of chromosomes as the parent cell . Meiosis is essential for the formation of gametes (sperm and egg cells ). Stages/Phases of Meiosis Meiosis is composed of two rounds of cell division, namely Meiosis I and Meiosis II. Each round of division contains a period of karyokinesis (nuclear division) and cytokinesis (cytoplasmic division). 46 5/6/2024 FRANK JOSHUA RUHAZWE

47. MEIOSIS 1 47 5/6/2024 FRANK JOSHUA RUHAZWE

48. MEIOSIS II 48 5/6/2024 FRANK JOSHUA RUHAZWE

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50. Diseases Related with abnormalities in cell division. Cancer : Cancer is one of the most well-known diseases resulting from abnormal cell division. It occurs when cells undergo uncontrolled proliferation, often due to mutations in genes that regulate cell growth and division. Mutations can disrupt the normal checkpoints that regulate the cell cycle, leading to the formation of Malignant tumors Errors in cell division can lead to cancer . For example, translocations , deletions , and duplications of chromosomes or chromosomal segments can contribute to the development of certain types of leukemia, lymphoma, and solid tumors. 50 5/6/2024 FRANK JOSHUA RUHAZWE

51. Down Syndrome Down syndrome, also known as trisomy 21, is a genetic disorder caused by the presence of an extra copy of chromosome 21. This additional chromosome typically arises from a mistake during cell division in the egg or sperm cells prior to fertilization. Individuals with Down syndrome often have characteristic physical features and may experience cognitive impairment and other health issues. 51 5/6/2024 FRANK JOSHUA RUHAZWE

52. Turner Syndrome: Turner syndrome is a genetic disorder that affects females and is characterized by the absence or partial absence of one of the X chromosomes. This condition typically results from errors during cell division in either the egg or sperm cells . Individuals with Turner syndrome may have short stature, heart defects, infertility, and other health problems. 52 5/6/2024 FRANK JOSHUA RUHAZWE

53. Mitotic Errors and Birth Defects: E rrors during mitosis can result in birth defects and developmental disorders . A bnormal cell division during embryonic development can lead to structural abnormalities in organs and tissues. . N eural tube defects ( e.g., spina bifida ) Limb malformations Congenital heart defects. 53 5/6/2024 FRANK JOSHUA RUHAZWE

54. THANKS !!! 54 5/6/2024 FRANK JOSHUA RUHAZWE