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Growth and Development (B5)

Growth and Development (B5). B5.1 How does an organism produce new cells?. DNA has a double helix structure. The cell cycle. Cell cycle: the main processes Cell growth during which The number of organelles increase

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Growth and Development (B5)

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  1. Growth and Development (B5) B5.1 How does an organism produce new cells?

  2. DNA has a double helix structure

  3. The cell cycle • Cell cycle: the main processes • Cell growth during which • The number of organelles increase • The chromosomes are copied when the two strands of each DNA molecule separate and new strands form alongside them • Mitosis during which • Copies of the chromosomes separate • The cell divides

  4. Cell growth during which • The number of organelles increase • The chromosomes are copied when the two strands • of each DNA molecule separate and new strands form • alongside them

  5. 2. Mitosis during which • Copies of the chromosomes separate • The cell divides • Cell Division by Mitosis: this produces two new cells identical to each other and to the parent cell

  6. There are two types of cell division: M_______ M_______ How does an organism produce new cells? Mitosis Meiosis

  7. Meiosis • A type of cell division that produces gametes • It is important in meiosis that the cells produced only contain half the chromosome number of the parent cell. • A zygote contains a set of chromosomes from each parent

  8. Meiosis Gametes Zygote

  9. Questions • Cell growth • Mitosis • What happens in the normal cell cycle? • What happens during cell growth? • Number of organelles increase • Chromosomes are copied by separating DNA strands and forming new strands • What happens during Mitosis? • Copies of the chromosomes separate • The cell divides

  10. More questions • In which organs do cells divide by Meiosis? • Ovaries and Testes • How many chromosomes are in the gamete if the parent cell has 46? • 23 • How many chromosomes does the zygote have? Where are they from? • 46 • A set from each gamete. (from each parent)

  11. Growth and Development (B5) B5.2 How do genes control growth and development within the cell?

  12. DNA - the genetic code • The genetic code is in the cell nucleus BUT proteins are produced in the cell cytoplasm Nucleus Cytoplasm

  13. Genes do not leave the nucleus but a copy of the gene is produced to carry the genetic code to the cytoplasm In the nucleus Travels to the cytoplasm In the cytoplasm

  14. Both strands of DNA are made up of four different bases. The bases always pair up in the same way A -T C - G

  15. In mRNA U (not T) The Genetic Code The order of the bases in a gene is the code for building up amino acids in the correct order to make a particular protein Chromosome made of DNA mRNA copy of gene Protein made of amino acids

  16. How many different bases are in DNA? How is the order of the amino acids in proteins determined? Where are proteins made in cells? In the cytoplasm In the nucleus of every cell Questions How does the code get into the cytoplasm? A copy of the gene carries the code (RNA) Where is the genetic code found? Four different bases, always pairing the same way The order of bases in a gene is the code

  17. Growth and Development (B5) B5.3 How do new organisms develop from a single cell?

  18. Early embryos The zygote divides by mitosis to form an embryo In a human embryo, up to the eight cell stage, all the cells are identical and could produce any sort of cell required by the organism (embryonic stem cells) After this point the cells become specialised and form different types of tissue. Some of the genes are switched off.

  19. Specialised Cells After this point the cells become specialised and form different types of tissue • Although body cells in an organism contain the same genes, many genes in a particular cell are not active because it only produces the specific proteins it needs

  20. Gene switches • Gene for insulin is on in the pancreas but off in the kidney • Gene for ADH is on in the pituitary gland but off in the salivary gland One cell type becomes many! gametes zygote mitosis Specialised cell types in tissues

  21. Cloning • In carefully controlled conditions of mammalian cloning, it is possible to reactivate inactive genes in the nucleus of a body cell to form cells of all tissue types. • Adult and embryonic stem cells have the potential to produce cells needed to replace damaged tissues.

  22. Plants from from single cells • New cells in plants specialise into cells of roots, leaves or flowers.

  23. Unlike animal cells some plant cells remain unspecialised and can develop into any type of plant cell. These unspecialised cells allow the production of clones of plants with desirable features, from cuttings.

  24. Plant meristems • Plant meristems divide to produce cells that result in increased height, length of roots and girth of the plant.

  25. If the hormonal conditions in their environment are changed, unspecialised plant cells can develop into a range of other tissues (egxylem and phloem) or organs (eg leaves, roots, flowers)

  26. Cut stems from a plant can develop roots in the presence of plant hormones (auxins) and grow into a complete plant which is a clone of the parent

  27. Phototropism • Phototropism is the plant’s response to light. It increases the plant’s chance of survival • Light causes auxin to move to the opposite side of the shoot tip. The cells on the side with more auxin grow bigger.

  28. REVISE Check your knowledge

  29. Growth and Development (B5) B5.1 How does an organism produce new cells?

  30. double helix DNA has a ____________ structure

  31. The Cell Cycle • Cell cycle: the main processes • Cell growth during which - ______________________________ ___________________________ when the two strands of each DNA molecule separate and new strands form alongside them • Mitosis during which • ____________________________ • ____________________________ • - The number of organellesincrease - The chromosomes are copied Copies of the chromosomes separate The cell divides

  32. Cell growth during which • _______________________________ • ____________________________ when the two strands of each DNA molecule separate and new strands form alongside them • The number of organelles increase The chromosomes are copied

  33. 2. Mitosis during which ____________________________ _______________________ • Copies of the chromosomes separate • The cell divides • Cell Division by Mitosis: this produces ____ new cells identical to each other and to the parent cell two

  34. There are two types of cell division: M_______ M_______ How does an organism produce new cells? Mitosis Meiosis

  35. Meiosis • A type of cell division that produces • It is important in meiosis that the cells produced only contain the chromosome number of the parent cell. • A contains a set of chromosomes from each parent gametes half zygote

  36. Meiosis Gametes Zygote

  37. Questions • Cell growth • Mitosis • What happens in the normal cell cycle? • What happens during cell growth? • Number of organelles increase • Chromosomes are copied by separating DNA strands and forming new strands • What happens during Mitosis? • Copies of the chromosomes separate • The cell divides

  38. More questions • In which organs do cells divide by Meiosis? • Ovaries and Testes • How many chromosomes are in the gamete if the parent cell has 46? • 23 • How many chromosomes does the zygote have? Where are they from? • 46 • A set from each gamete. (from each parent)

  39. Growth and Development (B5) B5.2 How do genes control growth and development within the cell?

  40. DNA - the genetic code cell nucleus • The genetic code is in the ________ BUT proteins are produced in the cell __________. cytoplasm Nucleus Cytoplasm

  41. copy of the gene Genes do not leave the nucleus but a _______________ is produced to carry the genetic code to the cytoplasm In the nucleus Travels to the cytoplasm In the cytoplasm

  42. four Both strands of DNA are made up of ____ different bases. The bases always pair up _______________ A - ? C - ? in the same way T G

  43. In mRNA __ (not T) The Genetic Code order of the bases The _____________________ in a gene is the code for building up amino acids in the correct order to make a particular ________. protein Chromosome made of ____ DNA mRNA ____ __________ copy of gene U Protein made of __________. amino acids

  44. How many different bases are in DNA? How is the order of the amino acids in proteins determined? Where are proteins made in cells? In the cytoplasm In the nucleus of every cell Questions How does the code get into the cytoplasm? A copy of the gene carries the code (RNA) Where is the genetic code found? Four different bases, always pairing the same way The order of bases in a gene is the code

  45. Growth and Development (B5) B5.3 How do new organisms develop from a single cell?

  46. Early embryos The zygote divides by ________ to form an embryo mitosis In a human embryo, up to the _____ _____ stage, all the cells are identical and could produce any sort of cell required by the organism (embryonic stem cells) eight cell After this point the cells become __________ and form different types of _________. specialised tissue

  47. SpecialisedCells After this point the cells become ________ and form different types of ________. specialised • Although body cells in an organism contain the same genes, many genes in a particular cell are _________ because it only produces the specific _________ it needs tissue not active proteins

  48. Gene switches • Gene for insulin is on in the _________ but off in the kidney • Gene for ADH is on in the ____________ but off in the salivary gland One cell type becomes many! gametes pancreas zygote mitosis Specialised cell types in tissues pituitary gland

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