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How is cytoskeleton formed
Fibres built from protein monomers that are polymerised into long strands or meshes but forming various structures inside the cells for different roles
Function of the cytoskeleton
Maintaining cell shape, protecting the cell, enable motion, intracellular transport, cell division
Microfilaments
Smallest of fibres
made from actin
monomers are globular (G-) actin when polymerised into filament, two parallel strands wind into helix to form F-actin
can form bundles and tlthough flexible as strands can take various more brittle structure
Intermediate fibres
10nM in diameter
made of vimentin or ctokeratins
strength functions in and out of the cell
keratin proteins form into intermediate filaments
vimentin coulds and forma a tetrameric complex that forms sheets
Microtubules
25nM in diameter
built from tubular dimers that are then stacked into a strong hollow fibre of 13 vertical protofilaments
Track for vesicles moved by motor proteins, form the spindle during mitosis, hold organelles into place, structural component of flagella and cilia
Regulation of microtubules
Regulation by the centrosome and radiate out from this organelle
has direction and plus and minus ends
Large Internal cell motility
change of cell shape by the remodelling of actin and tubulin
Subtle internal cell motility
moves inside the cell, motor proteins carry vesicles or slide microtubules or actin filaments
External cell motility
Special organelles such as cilia and flagella
Cilia and Flagella Structure
built using a special arrangement of microtubules (9+2)
the outer pairs are connected by dyne motor proteins
Dynein proteins function
slide one pair of doublets against the other when energy is provided
Structure of DNA and RNA
ribose sugar
phosphoric acid
nitrogenous base
Difference between DNA and RNA
OH on carbon 2 in RNA and just H on carbon 2 in DNA
Charge of phosphoric acid
negative at pH 7
Bases of DNA
adenine and guanine
cytosine and thymine
Bases of RNA
Adenine and guanine
cytosine and uracil
Purines
Adenine and guanine
Pyrimidines
Cytosine and thymine
Direction of DNA and RNA
5’ to 3’ and is governed by ribose sugar
What is attached to carbon 1 on DNA and RNA
Nitrogenous base
What is attached to carbon 2 in DNA and RNA
OH in RNA and H in DNA
What is attached to carbon 5 in DNA and RNA
Phosphate
What is attached to carbon 3 in DNA and RNA
Phosphate from the next nucleotide
