June 2011 Flashcards
How do chemical mediators reach the cells they affect
Spread via diffusion
Explain how the relationship between oestrogen and LH is an example of positive feedback
MORE oestrogen produces MORE LH
Explain how extra progesterone prevents ovulation
Inhibits secretion of FSH and LH
LH stimulates ovulation
Explain why plants that are grown from seeds are very variable in their yield
Meiosis
Crossing over
Random fertilisation
Explain the advantage of growing plants from tissue culture rather than seeds
Will all be genetically identical
All plants will have desired characteristics
Explain how an animal’s body temperature affects it’s oxygen consumption
Increase temperature
Increase metabolism
More energy
Oxygen consumption linked to respiration
Describe how transcriptional factors are important in the synthesis of particular proteins
Bind to DNA/gene
Stimulate transcription
Suggest why siRNA may be useful in treating some diseases
Some diseases mutations
siRNA stop product of this gene
How is hydrolysis important in the formation of new proteins
Hydrolysis breaks protein
Explain how condensation is important in the formation of new proteins
Condensation involved in protein synthesis
Describe how hormones are different from chemical mediators in the cells they affect
Hormones have widespread effect
How is mRNA structure different from tRNA
mRNA doesn’t have hydrogen bonds
mRNA is longer
Why are the percentage of bases in the middle of the chromosome different from the end part
Different genes
Have different base sequence
Explain how acetylcholine contributes to a synapse being unidirectional
Released in pre-synapse
Diffuses from high conc. To low conc.
Binds to receptors in post-synapse side
