B5

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B5

• Growth Development

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All living things are made up of cells.
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Animal and Plant Cells
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What else do we have to add?
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Specialised cells

• cells in multicellular organisms can be
  specialised to do particular jobs

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Tissues and Organs

• groups of specialised cells are called tissues
  and groups of tissues form organs

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Organisation

• Cells
• Tissues
• Organs
• Organ systems
• Organism

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Plant Organs Tissues
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Zygotes

• a zygote is a fertilised egg
• It has a set of chromosomes from each parent

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Embryo

• a fertilised egg cell (zygote) divides by mitosis
  to form an embryo

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Embryonic Stem Cells

• 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,
• (unspecialised cells or
• embryonic stem cells)
• after this point, the cells become specialised
  and form different types of tissue

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Adult Stem cells

• Adult stem cells remain unspecialised and can
  become many, but not all, types of cell required
  by the organism

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Mitosis

• Cell division by mitosis
• produces two new cells
• identical to each other and
• to the parent cell

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DNA
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Cell Cycle

• Cell Growth
• numbers of organelles increase
• 2. the chromosomes are copied
• when the two strands of each
• DNA molecule separate and new
• strands form alongside them

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Mitosis

• Mitosis
• copies of the chromosomes
• separate
• 2. the nucleus divides

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Meiosis (Makes Eggs In Ovaries, Sperm In S?)

• meiosis is a type of cell division that produces
  gametes 2
• egg sperm
• In meiosis, it is important
• that the cells produced
• only contain half the
• chromosome number
• of the parent cell
• why?
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  1 1 1 1

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DNA

• DNA has a double helix structure
• http//www.statedclearly.com/what-is-dna/

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Base Pairs

• both strands of the DNA molecule are made up of
  four different bases, which always pair up in the
  same way A T, C G

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Making Proteins

• the order of bases in a gene is the code for
  building up amino acids in the correct order to
  make a particular protein.

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Genes code for Proteins

• The genetic code is in the nucleus but proteins
  are produced in the cell cytoplasm
• The genes (DNA) cannot leave the nucleus
• So how does it happen?

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A problem.

• You want to bake a chocolate cake
• The recipe is in a cook book in the library
• Its a reference book you cant take it out of
  the library
• Solution
• Bring all the ingredients to
• the library and bake the
• cake there!

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Protein synthesis

• Genes dont leave the
• nucleus but.
• a copy of the gene is
• produced to carry the
• genetic code to the
• cytoplasm

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Switching genes off

• 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

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Stem cells

• adult stem cells and embryonic stem cells have
  the potential to produce cells needed to replace
  damaged tissues

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Ethics

• ethical decisions need to be taken when using
  embryonic stem cells
• this work is subject to Government regulation

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Switching genes on again

• 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

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Plant Growth

• Unlike animals, most plants continue to grow
  throughout their lives
• Plant meristems divide by mitosis to produce
  cells that are unspecialised

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Cuttings

• These unspecialised new cells can specialise into
  cells of xylem, phloem, roots, leaves or flowers
  
• these unspecialised cells
• can be used to produce
• clones
• of a plant with desirable
• features, from cuttings

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Auxins

• 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

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Phototropism

• understand how phototropism increases the plants
  chance of survival
• phototropism in terms of the effect of light on
  the distribution of auxin in a shoot tip.

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