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Cellular Control (Body Plan Development (Homeobox Gene Sequences (sequence…
Cellular Control
Body Plan Development
Homeobox Gene Sequences
sequence of 180 base pairs found in genes that help regulate patterns of anatomical development in animals, fungi and plants
They code for a 60 amino acids within a chain, called the homeodomain sequence, in a protein
The proteins created are transcription factors, binding to DNA and controlling gene expression
They are highly conserved (has remained in descendant species throughout evolutionary history), and are very similar in many species
The proteins have a HTH shape, which recognises and attaches to the enhancer region (TAAT) of a gene to be transcribed
Hox Genes
subset of homeobox genes involved in formation of anatomical features in correct locations of body plan, only found in animals
They regulate development of embryos along the anterior-posterior axis. Clusters of hox genes are found in each separate body part
They encode for homeodomain proteins which control mitosis, apoptosis, cell migration and regulate the cell cycle
They are very similar across different classes of animals and can be swapped while still functioning properly
Apoptosis
Sequence
- Enzymes break down cytoskeleton
- Cytoplasm becomes dense with tightly packed organelles
- Cell surface membrane changes and small protrusions called blebs form
4.Chromatin condensed, nuclear envelope breaks and DNA slips into fragments
- The cell breaks into vesicles which are ingested by phagocytes
Control
Genes that regulate cell cycle and apoptosis can respond to stimuli from cells and externally (e.g. stress)
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Development
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If not enough apoptosis occurs, tumours form
If too much apoptosis occurs, cell loss and degeneration happens
During limb development, apoptosis causes digits to separate
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