the paper 3 bio that could Flashcards
Describe the sliding muscle filament theory
Action potential travels into muscle via T tubules, Ca2+ released
Ca2+ Bind to tropomyosin molecules, casuing them to move
Myosin gets exposed and attaches to actin, myosin actin cross bridge formed
ATP gets hydrolysed, detaches from myosin head and sarcomeres shorted
When nervous stimulation stops Ca2+ get actively transported to sarcoplasmic reticulum using energy from ATP hydrolysis
Tropomyosin blocks the actin filament from binding, muscle contractions stop
How is insulin secreted?
At rest in B cells, K+ channels are open (negative resting potential)
When glucose concentration rises, glucose diffuses into cell and gets phosphorylated (Causes K+ channel to close and Ca2+ to open)
Ca2+ causes insulin vesicle to be destroyed, insulin binds to insulin receptor and glycogenesis occurs
How does glucagon work?
Glucagon gets released from alpha cells to increase glucose levels back to its optimum, binds to its receptors, increases levels of cAMP, glycogenesis and gluconeogenesis occurs
Diabetes type 1 and 2
Type 1: Autoimmune system attacks the Beta cells (Fixed by insulin injections)
Type 2: Not enough insulin gets produced
The heart
SAN sends out regular waves of electrical activity to the left and right atrial walls (causes contraction)
Electrical waves passed to AVN, then to bundle of His
Bundle of His splits Purkynge tissue, causes contraction of left and right ventricle
How does genetic engineering work?
Transferring DNA fragments from one organism or species to another
How are DNA fragments created
Restriction endonucleases cut at recognition sites near desired gene
mRNA of desired gene converted to cDNA with reverse transcriptase
Double stranded DNA gets synthesised by DNA polymerase
Gene then gets synthesised by a gene machine, determined by the primary protein structure
Advantages and disadvantages of In situ conservation
Advantages:
Conserves species without habitat removal
Ecosystem integrity maintained
Cheaper than Ex situ
Protects biodiversity
Disadvantages:
Too much genetic diversity has been lost to allow species to adapt
Wildlife reserves may be damaged by ecotourism
Advantages and disadvantages of Ex-situ conservation
Advantages:
Protects organisms from predation and poaching
Helps attract funding and awareness
Artificial insemination used to maximise reproductive success
Disadvantages:
Limited genetic diversity
Difficult to provide a suitable environment
Many animals may be unable to be reintroduced to wild
Property of water thats good
High specific heat capacity
Cohesive
Surface tension
Good solvent
Good transport medium
Semiconservative replication
DNA helicase breaks H bonds between the two strands
Free complementary nucleotides pair to exposed strands
DNA polymerase join the nucleotides and zip it back up
