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Cell and functions

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A cell is the smallest unit of life. Cells are often called the "building blocks of life". The study of cells is called cell biology.

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Cell and functions

  1. 1. Cell Cell: The cell is the basic structural and functional unit of all known living organisms. It is the smallest unit of life.
  2. 2. Conversion Quotation Amount International Quotation 1 Lac 100,000.00 100 Thousands 10 Lacs 1,000,000.00 1 Million 1 Crore 10,000,000.00 10 Million 10 Crores 100,000,000.00 100 Million 100 Crores 1,000,000,000.00 1 Billion 100,000 Crores 1,000,000,000,000.00 1 trillion Human cell No. 37.2 trillion 3 crore72 lac crores (372 00000 crores)
  3. 3. Chromosomes •Usually in the form of chromatin •Contains genetic information •Composed of DNA •Thicken for cellular division •Set number per species (i.e. 23 pairs for human) Different Functions of a Cell
  4. 4. Nuclear membrane • Surrounds nucleus • Composed of two layers • Numerous openings for nuclear traffic
  5. 5. Nucleolus • Spherical shape • Visible when cell is not dividing • Contains RNA for protein manufacture
  6. 6. Centrioles • Paired cylindrical organelles near nucleus • Composed of nine tubes, each with three tubules • Involved in cellular division • Lie at right angles to each other
  7. 7. Chloroplasts • A plastid usually found in plant cells • Contain green chlorophyll where photosynthesis takes place
  8. 8. Cytoskeleton • Composed of microtubules • Supports cell and provides shape • Aids movement of materials in and out of cells
  9. 9. Endoplasmic reticulum • Tubular network fused to nuclear membrane • Goes through cytoplasm onto cell membrane • Stores, separates, and serves as cell's transport system • Smooth type: lacks ribosomes • Rough type (pictured): ribosomes embedded in surface
  10. 10. Golgi apparatus • Protein 'packaging plant' • A membrane structure found near nucleus • Composed of numerous layers forming a sac
  11. 11. Lysosome • Digestive 'plant' for proteins, lipids, and carbohydrates • Transports undigested material to cell membrane for removal • Vary in shape depending on process being carried out • Cell breaks down if lysosome explodes
  12. 12. Mitochondria • Second largest organelle with unique genetic structure • Double-layered outer membrane with inner folds called cristae • Energy-producing chemical reactions take place on cristae • Controls level of water and other materials in cell • Recycles and decomposes proteins, fats, and carbohydrates, and forms
  13. 13. Ribosomes • Each cell contains thousands • Miniature 'protein factories' • Composes 25% of cell's mass • Stationary type: embedded in rough endoplasmic reticulum • Mobile type: injects proteins directly into cytoplasm
  14. 14. Vacuoles • Membrane-bound sacs for storage, digestion, and waste removal • Contains water solution • Contractile vacuoles for water removal (in unicellular organisms)
  15. 15. Cell wall • Most commonly found in plant cells • Controls turgity • Extracellular structure surrounding plasma membrane • Primary cell wall: extremely elastic • Secondary cell wall: forms around primary cell wall after growth is complete
  16. 16. Plasma membrane • Outer membrane of cell that controls cellular traffic • Contains proteins (left, gray) that span through the membrane and allow passage of materials • Proteins are surrounded by a phospholipid bi- layer.
  17. 17. Difference between a plant and animal cell chart Structure Animal cell Plant cell Nucleus Present Present Cilia Present It is very rare Shape Round (irregular shape) Rectangular (fixed shape) Chloroplast Animal cells don't have chloroplasts Plant cells have chloroplasts because they make their own food Cytoplasm Present Present Ribosomes Present Present Mitochondria Present Present Vacuole One or more small vacuoles (much smaller than plant cells). One, large central vacuole taking up 90% of cell volume. Plastids Absent Present Golgi Apparatus Present Present Cell wall Absent Present Plasma Membrane only cell membrane cell wall and a cell membrane Flagella May be found in some cells May be found in some cells Lysosomes Lysosomes occur in cytoplasm. Lysosomes usually not evident.
  18. 18. THE EVOLUTION OF THE CELL Some of the oldest cells on Earth are single-cell organisms called bacteria. Fossil records indicate that mounds of bacteria once covered young Earth. Some began making their own food using carbon dioxide in the atmosphere and energy they harvested from the sun. This process (called photosynthesis) produced enough oxygen to change Earth's atmosphere. Soon afterward, new oxygen-breathing life forms came onto the scene. With a population of increasingly diverse bacterial life, the stage was set for some amazing things to happen. Bacteria are single-celled organisms with a circular DNA molecule and no organelles.
  19. 19. There is compelling evidence that mitochondria and chloroplasts were once primitive bacterial cells. This evidence is described in the endosymbiotic theory. How did this theory get its name? Symbiosis occurs when two different species benefit from living and working together. When one organism actually lives inside the other it's called end symbiosis. The endosymbiotic theory describes how a large host cell and ingested bacteria could easily become dependent on one another for survival, resulting in a permanent relationship. Over millions of years of evolution, mitochondria and chloroplasts have become more specialized and today they cannot live outside the cell.
  20. 20. In everyday speech, people use the word theory to mean an opinion or speculation not necessarily based on facts. But in the field of science, a theory is a well established explanation based on extensive experimentation and observation. Scientific theories are developed and verified by the scientific community and are generally accepted as fact. Mitochondria and chloroplasts have striking similarities to bacteria cells. They have their own DNA, which is separate from the DNA found in the nucleus of the cell. And both organelles use their DNA to produce many proteins and enzymes required for their function. A double membrane surrounds both mitochondria and chloroplasts, further evidence that each was ingested by a primitive host. The two organelles also reproduce like bacteria, replicating their own DNA and directing their own division.
  21. 21. Mitochondrial DNA (mtDNA) has a unique pattern of inheritance. It is passed down directly from mother to child, and it accumulates changes much more slowly than other types of DNA. Because of its unique characteristics, mtDNA has provided important clues about evolutionary history. For example, differences in mtDNA are examined to estimate how closely related one species is to another. Analysis of mitochondrial DNA from people around the world has revealed many clues about ancient human migration patterns.
  22. 22. Conditions on Earth 4 billion years ago were very different than they are today. The atmosphere lacked oxygen, and an ozone layer did not yet protect Earth from harmful radiation. Heavy rains, lightening and volcanic activity were common. Yet the earliest cells originated in this extreme environment. Today, a group of single-celled organisms called archaeabacteria, or archaea, still thrive in extreme habitats
  23. 23. Summary of the Phases of Mitosis
  24. 24. Interphase • Chromosomes are not visible because they are uncoiled
  25. 25. Prophase • The chromosomes coil. • The nuclear membrane disintegrates. • Spindle fibers (microtubules) form. • The drawing shows a cell with 8 chromosomes. Each chromosome has 2 chromatids for a total of 16 chromatids.
  26. 26. Metaphase • The chromosomes become aligned. • The drawing shows a cell with 8 chromosomes. Each chromosome has 2 chromatids for a total of 16 chromatids.
  27. 27. Anaphase • The chromatids separate the number of chromosomes doubles. • The drawing shows a cell with 16 chromosomes. Each chromosome has 1 chromatid for a total of 16 chromatids.
  28. 28. Telophase • The cell divides into two. • The chromosomes uncoil. • The nucleus reforms. • The spindle apparataus disassembles. • The drawing shows a cell with 16 chromosomes. Each chromosome has 1 chromatid for a total of 16 chromatids.
  29. 29. G1 Interphase • The chromosomes have one chromatid. • The drawing shows two cells. Each cell has 8 chromosomes. Each chromosome has 1 chromatid for a total of 8 chromatids per cell.
  30. 30. G2 Interphase • The chromosomes have two chromatids each. • The drawing shows two cells. Each cell has 8 chromosomes. Each chromosome has 2 chromatids for a total of 16 chromatids per cell.
  31. 31. Summary of the Phases of Meiosis
  32. 32. Prophase I • Homologous chromosomes become paired. • Crossing-over occurs between homologous chromosomes. Crossing over:-
  33. 33. Metaphase I Homologous pairs become aligned in the center of the cell. The random alignment pattern is called independent assortment. For example, a cell with 2N = 6 chromosomes could have any of the alignment patterns shown at the left..
  34. 34. Anaphase I • Homologous chromosomes separate.
  35. 35. Prophase II Metaphase II
  36. 36. Anaphase II Telophase II Daughter Cells
  37. 37. See DNA • https://www.youtube.com/watch?v=o_- 6JXLYS-k
  38. 38. HUMAN HEART
  40. 40. WHAT IS A HEART? • Your heart is really a muscle. It's located a little to the left of the middle of your chest, and it's about the size of your fist. There are lots of muscles all over your body — in your arms, in your legs, in your back, even in your behind. But the heart muscle is special because of what it does. The heart sends blood around your body. The blood provides your body with the oxygen and nutrients it needs. It also carries away waste. Your heart is sort of like a pump, or two pumps in one. The right side of your heart receives blood from the body and pumps it to the lungs. The left side of the heart does the exact opposite: It receives blood from the lungs and pumps it out to the body.
  41. 41. Facts About Human Body • 1. Your heart beats about 35 million times in a year. During an average lifetime, the human heart will beat more than 2.5 billion times. • 2. Your body has about 5.6 liters (6 quarts) of blood. This 5.6 liters of blood circulates through the body three times every minute. In one day, the blood travels a total of 19,000 km (12,000 miles)- that's four times the distance across the U.S. from coast to coast. • 3. The heart pumps about 1 million barrels of blood during an average lifetime - that's enough to fill more than 3 super tankers.
  42. 42. • 4. If all arteries, veins, and capillaries of the human circulatory system were laid end to end, the total length would be 60,000 miles, or 100,000 km. That's nearly two and a half times around the Earth! • 5. Even though its thickness averages just 2mm, your skin gets an eighth of all your blood supply. • 6. The skull looks as though it is a single bone. In fact, it is made up of 22 separate bones, cemented together along rigid joints called sutures.
  43. 43. • 7. If a human adult's digestive tract were stretched out, it would be 6 to 9  m (20 to 30 ft) long. • 8. Red blood cells may live for about four months circulating throughout  the body, feeding the 60 trillion other body cells. Red blood cells make  approximately 250,000 round trips of the body before returning to the  bone marrow, where they were born, to die. • 9. Human hair grows about 1/4 inch (about 6 millimeters) every month  and keeps on growing for up to 6 years. The hair then falls out and  another grows in its place. • 10. The average healthy mouth produces about 600 milliliters of saliva  each day. That's enough to fill a 12-ounce soda bottle. • 11. The fastest nerve cells are carrying messages along their axons at an  amazing 130 yards per second (268 mph). •  
  44. 44. Human Nervous System 
  45. 45. DNA Vs RNA
  46. 46. DNA FACTS…1 • DNA or deoxyribonucleic acid codes for your genetic make-up. There are  lots of facts about DNA, but here are 10 that are particularly interesting,  important, or fun. • 1.Even though it codes for all the information that makes up an organism,  DNA is built using only four building blocks, the nucleotides adenine,  guanine, thymine, and cytosine. • 2.Every human being shares 99% of their DNA with every other human. • 3.If you put all the DNA molecules in your body end to end, the DNA would reach from the Earth to the Sun and back over 600 times (100 trillion times six feet divided by 92 million miles). • 4.A parent and child share 99.5% of the same DNA. • 5.You have 98% of your DNA in common with a chimpanzee. • 6.If you could type 60 words per minute, eight hours a day, it would take  approximately 50 years to type the human genome.
  47. 47. DNA FACTS ..2 7.DNA is a fragile molecule. About a thousand times a day, something  happens to it to cause errors. This could include errors during  transcription, damage from ultraviolet light, or any of a host of other  activities. There are many repair mechanisms, but some damage isn't  repaired. This means you carry mutations! Some of the mutations cause  no harm, a few are helpful, while others can cause diseases, such as  cancer. 8.Scientists at Cambridge University believe humans have DNA in common  with the mud worm and that it is the closest invertebrate genetic relative  to us. In other words, you have more in common, genetically speaking,  with a mud worm than you do with a spider or octopus or cockroach. 9. Humans and cabbage share about 40-50% common DNA. 10.Friedrich Miescher discovered DNA in 1869, although scientists did not  understand DNA was the genetic material in cells until 1943. Prior to that  time, it was widely believed that proteins stored genetic information.
  48. 48. OROGIN OF SPECIES After traveling on the HMS Beagle for five years (1831-1836) collecting biological samples and fossils, Charles Darwin returned home to England to proceed with the monumental task of cataloguing and reporting on his findings, and if that was not enough he also began work on his "hobby" which was developing his theory about natural selection. On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle of Life was first published 150 years ago on 24 November 1859 after more than 20 years of work. His work has become the basis for modern evolutionary science and this book is simply one of the most influential publications in history.
  49. 49. The evolution of crops Domesticated vs. cultivated crops: •A domesticated crop (animal or plant) has been genetically altered from their wild state and brought into a man’s home. •A cultivated crop has been tended for a field through tilling, seedbed preparation, weeding, pruning, watering, fertilizing, etc.
  50. 50. Symbiotic relationship: •A fully domesticated plant cannot survive without the aid of man, but only a minute fraction of the human population could survive without cultivated plants. •Crops and man are mutually dependent. Recent history: •From time of colonization of the Americas until the mid-1800s, little formal breeding. •From 1800-1900s, beginning of the “corn show era”. •From 1900s to present, open-pollinated populations to hybrid.
  51. 51. Crop Center of Origin Chromosome Wheat Near East and  Ethiopian Highlands 2n=42 Rice Asia 2n=24 Maize North America 2n=20 Millets West Africa 2n=18 Sugarcane New Guinea & North  India 2n=80, 126 Cotton Africa 2n=52 Potato South America 2n=42 Center of Origin
  52. 52. Pollination Pollination: Pollination is the process by which pollen is transferred in  the  reproduction  of  plants,  thereby  enabling  fertilization  and  sexual  reproduction. Two types of Pollination 1.Self-Pollination & 2.Cross-Pollination Self-Pollination: Some plant do not need outside help to transfer the pollen grains. They are able to pollinate themselves. Pollen is transferred from the anther to the stigma of the same flower or to the stigma of another flower of same plant. Cross-Pollination: In most plants, transfer of pollens occurs through cross-pollination. In this process, the pollen from one flower is transferred to the stigma of another flower on a different plant of the same kind.
  53. 53. Self pollination Crops Cross pollination Crops Oat =2n=42 Millet = 2n=18 Lettuce =2n=18 Onions = 2n=16 Wheat = 2n=42 Corn =2n=20 Rice =2n=24 Carrot =2n=18 Tomato =2n=24 Rye=2n=14 Self pollinated crops and cross pollinated crops with their chromosome numbers
  54. 54. The sexual process of reproduction Plant reproduction:  Plant  reproduction  is  the  production  of  new  individuals or offspring in plants, which can be accomplished by sexual  or asexual means. Sexual reproduction produces offspring by the fusion  of gametes, resulting in offspring genetically different from the parent  or parents. Animals  typically  produce  male  gametes  called  sperm,  and  female  gametes called eggs and ova, following immediately after meiosis, with  the  gametes  produced  directly  by  meiosis.  Plants  on  the  other  hand  have mitosis occurring in spores, which are produced by meiosis. The  spores  germinate  into  the  gametophyte  phase.  The  gametophytes  of  different groups of plants vary in size; angiosperms have as few as three  cells  in  pollen,  and  mosses  and  other  so  called  primitive  plants  may  have  several  million  cells.  Plants  have  an  alternation  of  generations  where the sporophyte phase is succeeded by the gametophyte phase.  The  sporophyte  phase  produces  spores  within  the  sporangium  by 
  55. 55. Flowering plants Flowers are the sexual organs of flowering plants. Flowering plants are the dominant plant form on land and they reproduce by sexual and asexual means. Often their most distinguishing feature is their reproductive organs, commonly called flowers. The anther produces male gametophytes, the sperm is produced in pollen grains, which attach to the stigma on top of a carpel, in which the female gametophytes (inside ovules) are located. After the pollen tube grows through the carpel's style, the sex cell nuclei from the pollen grain migrate into the ovule to fertilize the egg cell and endosperm nuclei within the female gametophyte in a process termed double fertilization. The resulting zygote develops into an embryo, while the triploid endosperm (one sperm cell plus two female cells) and female tissues of the ovule give rise to the surrounding tissues in the developing seed. The ovary, which produced the female gametophyte(s), then grows into a fruit, which surrounds the seed(s). Plants may either self-pollinate or cross-pollinate. Non flowering plants like ferns, moss and liverworts use other means of sexual reproduction.