Top answers

Name 2 forms of epigenetic modification, and explain the effect they have on the genotype.

Acetylation: addition of an acetyl group to a histone molecule. Forces DNA strands apart, allowing easier access for RNA polymerase for transcription. Therefore increases expression of target gene(s) due to ...
NG
Answered by Nick G. • Biology tutor
3054 Views

Describe the chemical composition of phospholipids and how they form cell membranes? (10 marks)

Phospholipids are amphipathic molecules i.e. they have a hydrophilic (“water-loving”), polar head end, and a hydrophobic (“water-fearing”), nonpolar tail end (1 mark). The major phospholipids in most animal ...
AB
Answered by Akash B. • Biology tutor
7626 Views

Describe how DNA is well-adapted to being a molecule for conserved information storage

DNA is a long, large molecule, which allows a lot of information to be stored within in. It has a sugar-phosphate backbone, which protects it from physical and chemical damage as the phospho-diester linkages...
JE
Answered by Juliet E. • Biology tutor
5448 Views

Describe how ACh transmits nerve impulses across Cholinergic Synapse

1.AP arrives at the presynaptic neurone2.AP stimulates voltage gated Ca ion channels to open3.Increased permeability of Ca ion channels causes synaptic vesicles to fuse with presynaptic membrane4. Exocytosis...
NA
Answered by Natasha A. • Biology tutor
3404 Views

Explain how skeletal muscle contracts.

There are several simple steps that occur each time a skeletal muscle contracts which follow the sliding filament model. Firstly a nerve impulse travels down a motor neuron releasing neurotransmitter acetylc...
YG
Answered by Yuval G. • Biology tutor
7956 Views