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DNA is unwound by DNA helicase. This exposes the two strands of DNA, through the breaking of hydrogen bonds. This allows for complementary RNA nucleotides to join to one of the two strands - i.e. they are...

any three from: no cell wall in animal cells/ (cellulose) cell wall in plant cell centrioles present in animal cell, not in present in plant cell (permanent) vacuole in plant cell, lack of (permanent) vac...

H+ ions and electrons released from NADH and FADH2,on to the inner mitochondrial membrane. electrons enter electron transport chain, and energy released from transfer of electrons is used to pump H+ ions ...

A nerve impulse in the sarcoplasmic reticulum causes calcium ions to move out of it into the muscle cells where it binds to tropmyosin/troponin causing it to move and reveal the actin filament. The myosin...

The cell membrane consists of a double layer of phospholipids, with proteins floating in it. Phospholipids are a type of molecule with a phosphate head, and fatty tails, which form a double layer around t...