Biology chap 7

• Cell growth - has 2 parts
• Interphase and Division phase
• In interphase is also known as Prepratory phase
• Interphase- cell size increases
• interphase- cell organelles increases
• interphase -cytoplasm increases
• interphase genetic materials duplicates
• genetic material is DNA
• In division phase, 2 parts are included
• division phase- division of nucleus
• DIvision phase - division of cytoplasm
• interphase and division phase repeats in a cyclic manner it is known as cell cycle
• what is cell cycle?

  interphase and division phase repeats in a cyclic manner
• Mitosis - helps in growth of the body
• IN mitosis, p1 and p2 which are they?

  Karyokinesis and Cytokinesis
• division of nuclues is karyokinesis
• division of cytoplasm is cytokinesis
• how many phases in karyokinesis?

  4
• what is prophase?

  • first phase of karyokinesis
• Changes happening in prophase?

  • chromatin reticulum resolves to form chromosomes
  • chromosome number duplicate
  • nucleus and nuclear membrane disappears
  • spindle fibres are formed
• which phase?

  prophase

  
• explain metaphase changes happening in cell?

  1. chromosomes comes to the centre of the cells
  2. spindle fibres get attached to the centromere
  3. metaphase 2nd phase of karyokinesis
• identify this phase?

  metaphase

  
• 3rd phase of karyokinesis

  is Anaphase
• explain changes happening in anaphase?

  1. chromatids broken into half and goes into opposite poles
  2. daughter chromosomes are formed
• which phase is this. whats is happening?

  anaphase. Chromatids broken and going to poles

  
• Last phase of karyokinesis is telophase
• Explain changes happening in telophase? (2)


  1. formation of daughter nuclei
  2. two daughter nuclei are formed
  3. chromosomes in each nuclei changes into chromatin reticulum
• identify phase. how did this happen?

  telophase. 2 daughter nuclei were formed and changed into chromatin reticulum.

  
• As centrosomes are absent in plant cells, spindle fibres are formed without centrioles
• cell division only completes after division of cytoplasm
• cytokynesis in animal cell?

  1. the plasma membrane invaginates at the centre of the cell
  2. daughter cellas are formed
• cytokynesis in plaant cell?

  1. small vesicles are formed between the daughter nuclei
  2. small vesicles join together to form cell plates
  3. the cell plate extends to both sides and joins with the plasma membrane
• characterestics of mitosis?

  there will be no change in the chromosome number
• disruption in controlled mitosis leads to cancer
• disruption in controlled mitosis leads to cancer how?

  excessive cell division and its proliferation happens when mitosis is disrupted. this leads to cancer
• different stages of growth?

  1. zygote
  2. embryo
  3. foetus
  4. infancy
  5. childhood
  6. adolescence
  7. old age
• adolescence period is between 10 to 19 years o age
• the growth of an individual is complete by the beginning of twenties
• what are the characteristics of old age?

  1. rate of cell division decreases
  2. availability of oxygen to cells decreases
  3. deterioration of cells increases
  4. muscles shrink
  5. production of energy decreases
  6. efficiency of sense organs decreases