Cells and cell processes
- Created by: Nadia
- Created on: 05-01-13 18:11
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- cells and cell processes
- was first suggested by german scientists Schwann and Schleiden but has been developed since
- microbes include bacteria, viruses, fungi and unicellular algae
- bacterial/ yeast cells differ in various ways from typical animal/plant cells
- bacteria reproduce asexually by splitting in two
- bacteria may have been the earliest forms of life
- yeast reproduces asexually by budding
- bacteria reproduce asexually by splitting in two
- viruses have simple structures and can only reproduce inside host cell
- bacterial/ yeast cells differ in various ways from typical animal/plant cells
- animal +plant cells share certain features- nucleus, cytoplas, cell membrane but plants have cell wall, vacuole + chloroplasts
- chemical reactions in cells are controlled by enzymes (biological catalysts)
- shape of an enzyme allows it to join with its substrate
- each enzyme has optimum pH and temp.
- boiling denatures most enzymes by changing their molecular shape
- biological washing powders contain digestive enzymes to help break down stains+allows lower washing temps.
- proteins are made up of a chain of amino acid molecules, folded to form a specific shape
- DNA is made of 2 long chains of alternating sugar/ phosphate molecules connected by bases.
- structure twisted into double helix
- there are 4 bases (A,C,G,T) the order of the bases controls the order of amino acids together to form proteins
- cell division by mitosis enables organism to grow, replace, repair cells
- in mitosis, the num. of chromosomes remains constant + daughter cells are genetically identical to mother cell
- cell division by meiosis forms gametes
- the number of chromosomes is halved, daughter cells not identical
- mitosis produces 2 daughter cells + meiosis produces 4 cells
- cell division by mitosis enables organism to grow, replace, repair cells
- in mitosis, the num. of chromosomes remains constant + daughter cells are genetically identical to mother cell
- cell division by mitosis enables organism to grow, replace, repair cells
- plants+ animals have different patterns of growth
- animals grow to a certain size, plants grow their whole life
- plants have a spreading, branched form +animals have compact form
- mature tissues have lost the ability to differentiate into different forms
- certain cells are still capable e.g. bone marrow
- human stem cells can replace damaged tissue+be basis of treatments
- human stem cells can be obtained from embryos/ umbilical cord
- plants have stem cells in their shoot/ root tips
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