b2 cell division

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  • Created by: Avaaa
  • Created on: 20-03-17 20:11
how many pairs of chromosomes are there in the nucllues
• In the nucleus of a typical human body cell there are 23 pairs of chromosomes.
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=what do we get
• We inherit one set of 23 chromosomes from each of our parents
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what is a gene
• A gene is a small section of DNA. • Each gene codes for a particular combination of amino acids which make a specific protein. • These proteins determine our characteristics. • Some characteristics are controlled by a single gene
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what is a chromosome
. • Chromosomes are made from a large molecule called DNA (deoxyribose nucleic acid).
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2 main roles of DNA
1. It can replicate prior to cell division (mitosis or meiosis). 2. Its code is used to synthesise proteins
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BODY CELLS DIVIDE BY
mitosis (MI TOE SIS LOL TOE)
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WHAT HAPPENS WITH MITOSIS
When a body cell divides by mitosis: ■ copies of the genetic material are made ■ then the cell divides once to form two genetically identical body cells. as the nucleus is split in two which results in two genetically identical nuceli.
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when does meiosis occur
during growth or to produce replacement cells.
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whats produced by mitosis
• The cells of the offspring produced by asexual reproduction are produced by mitosis from the parental cells. • They contain the same genes as the parents.
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body cells have two sets of chromosomes but sex cells only have...
gametes have one set of chromosomes
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which cells divide to form gametes
Cells in reproductive organs – testes and ovaries in humans – divide to form gametes.
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what happens when a cell divides to form gametes
) When a cell divides to form gametes: ■ copies of the genetic information are made ■ then the cell divides twice to form four gametes, each with a single set of chromosomes.
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what happens when gametes join at fertilisation
a single body cell with new pairs of chromosomes is formed. A new individual then develops by this cell repeatedly dividing by mitosis.
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what are the cells of the offspring prouduced by aexual respirition produced by
mitois from the parental cells
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and what do they contain
the same alleles as the parents
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asexual reproduction leads to
little variation as • Organisms that reproduce asexually create new individuals by mitosis. • They are genetically identical to the parent. • They may develop differently due to differences in their environment
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sexual reproduction leads to alot more variation because
Meiosis ensures that all gametes contain the same genes, but have a different selection of alleles. • Also, it is random which sperm fertilises which egg. • Therefore all individuals (except for identical twins) produced sexually are genetically di
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when do animal cells differentiate
at an early stage
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what about plant cells
many plant cells retain the ability to differentiate throughout life.
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what are stemm cells
undifferentiated cells that are able to differentiate into specialized cell types. that perform a specific function.
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where are they from
) Cells from human embryos and adult bone marrow, called stem cells, can be made to differentiate into many different types of cells, eg nerve cells.---EMBRYOS ADULT BONE MARROW UMBILICAL CHORDS
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what do human stem cells have the ability to do
Human stem cells have the ability to develop into any kind of human cell.
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what does treatment w stem cells do
) Treatment with stem cells may be able to help conditions such as paralysis.
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why do perople sometimes disagree w stem cels from embryos
• They feel that all embryos have got the potential to become a baby, and that they should not be used in this way. it could be seen as killing a potentiall life. But there are very few stem cells in an adult so ...
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what do they do w stem cells
• There is currently a lot of research involving the use of stem cells to treat various diseases and injuries.
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Other cards in this set

Card 2

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=what do we get

Back

• We inherit one set of 23 chromosomes from each of our parents

Card 3

Front

what is a gene

Back

Preview of the front of card 3

Card 4

Front

what is a chromosome

Back

Preview of the front of card 4

Card 5

Front

2 main roles of DNA

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