Chapter 17: Cell Division Flashcards

1
Q

Why do cells need to divide?

A

So that organisms can grow and replace worn out or damaged cells

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2
Q

What are the two types of cell division?

A

Mitosis and Meiosis

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3
Q

What happens in Mitosis?

A
  • Two cells are formed
  • They both have the same number & type of chromasomes as the original cell
  • Mitosis forms all cells in the body except the sexy cells
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4
Q

Descibe the stages in Mitosis…

A
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5
Q

What happens in meiosis?

A
  • When cells divide by meiosis, four cells are formed.
  • These only have half the number of chromosomes of the original cells
  • Meiosis forms sex cells
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6
Q

Describe the stages of meiosis…

A
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7
Q

Why do cells need to be replaced?

A
  • Skin lose thousands of cells everything we touch something….= millions cells every day
  • Cells are scraped off lining of the gut as food passes along
  • Cells in our spleen destroy worn out red blood cells at a rate of 100,000,000,000 a day…dats a lot.
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8
Q

What is genetic variation?

A

Cells formed by meiosis dont all have the same combination of alleles…there is genetic variation in the cells.

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9
Q

Describe the similarities and differences btn Mitosis and Meiosis…

A
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10
Q

Why do the offspring from sexual reproduction vary genetically?

A
  • Because of the huge variation in the sex cells (a ‘low’ estimate of c8.5m different type of sex cells
  • Because of the random way in which fertilisation takes place
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11
Q

What’s the difference between:

Identical twins or Monosyygotic twins and

Fraternal twins?

A

Identical twins or Monosyygotic twins: genetically identical…formed from the same zygote

Fraternal twins: non-identical twosm form from different zygote

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12
Q

Asexual reproduction or cloning

A

…where there is no fusion in the cells

offspring that are genetically identical to parent and each other

asexual reproduction common in plants and some animals

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13
Q

What role do environmental factors play?

A

they can significantly influence the growth and development of plants and animals

plants: level of light, water, minerals; carbon dioxide all influence growth

for humans, different physical, social environments can influence the physical and mental development of people…see identical twins who for some reasons grow apart

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