Flashcards in ILA Deck (21)
what is the process of DNA transcription?
1. topoisomerase unwinds the DNA supercoils
2. DNA helicase breaks H+ bonds and exposes the nucleotides
3. SSBs coat the DNA strands to prevent annealing
4. RNA polymerase binds at TATA promotor region
5. moves in 3' to 5' direction
6. adds one ribonucleotide at a time until stop codon is reached
7. mRNA strand is produced with poly-A tail and 5' cap
what is the process of splicing?
it is the removal of introns to form a fully coding strand
carried out in nucleus by splicosomes
exons are spliced back together
mature mRNA leaves nucleus via nuclear pores
what happens during translation?
1. mRNA binds to a ribosome which has small and large
subunits with an APE section in the large subunit
2. tRNA carries anticodons
3. tRNA binds to the ribosome
4. mRNA moves in a 3’ to 5’ direction and the anticodon
binds to mRNA
5. As each amino acid is bound the mRNA shifts along the
6. At termination codon the ribosome detaches and mRNA is
broken down in the cytosol
what are single nucleotide polymorphisms (SNPs)?
• DNA sequence variation when a single nucleotide (ATCG)
differs between people
• Can result in a different codon which generates a different
protein and thus disease
• E.g. sickle cell anaemia or cystic fibrosis
• Can affect recognition/promoter/termination sequences to change the length of proteins
what are the subunits of haemoglobin?
2 x alpha
2 x beta
what is sickle cell anaemia caused by?
normal haemoglobin - HbA
sickle cell haemoglobin = HbS
affects primary structure
GAG to GTG on 17th nucleotide
(single nucleotide polymorphism)
what is the inheritance of sickle cell anaemia?
if both parents have it = 1/4
what functional changes occur i n sickle cell anaemia?
• Cells don’t live as long
• Lower affinity for oxygen
• Gets stuck in blood vessels
• Overall, leads to reduced delivery of O2 to muscles
what is the primary structure of proteins? What bonds are present?
chain of amino acids
what is the secondary structure of proteins? what bonds are present?
alpha helix, beta pleated sheets
what is the tertiary structure of proteins?
what bonds occur in the tertiary structure of proteins?
van der waals
what is the quaternary structure of proteins?
the overall 3D structure of protein
what is osmolality?
concentration of solution expressed as solute particles per kg
what is osmolarity?
concentration of solution expressed as solute particles per L
what is oncotic pressure?
pressure exerted by plasma proteins on capillary wall
what is osmosis?
the process by which molecules within a solvent pass through a semi permeable membrane from a high concentration to a low concentration
what is the role of the hypothalamus and osmoreceptors in water homeostasis?
• Osmoreceptors within hypothalamus detect when water potential in the blood is low
• Loss of water reduces their volume which triggers stimulation of nerve cells in the hypothalamus
• This triggers ADH to be released from the posterior pituitary
what is the role of the posterior pituitary and vasopressin in water homeostasis?
• Posterior pituitary is stimulated by the hypothalamus
• Action potentials travel down and cause ADH to be released into
the blood stream
• This then acts on the kidneys, resulting in increased fluid
what happens in the kidney during water conservation?
In water conservation
• Urine is diluted as it moves through the loop of Henle
• It is concentrated again in the distal tubules and collecting ducts
• The descending loop is impermeable to sodium chloride and permeable to water
• The ascending loop is permeable to sodium chloride and impermeable to water
• Once dilute urine enters the distal tubules, water is reabsorbed without sodium chloride -> concentrated urine