Bio paper 2 Flashcards
(52 cards)
why does converting pyruvate to lactate allow for the continued production of ATP by anaerobic respiration?
Allows NAD to be reformed.
Means that glycolysis can continue
role of glucagon in gluconeogenesis
Attaches to receptors on target cells and activated enzymes.
Glycerol converted into glucose.
How does increasing a cell’s sensitivity to insulin lower blood glucose conc.?
More insulin binds to receptors on plasma membrane of target cells.
Increases the rate of glucose uptake by channel proteins.
How does inhibiting adenylate cyclase help lower blood glucose conc.?
Less ATP is converted into cAMP
Less protein kinase enzyme activated due to less cAMP
Less glycogen can be converted into glucose
Steroid hormones are hydrophobic.
Explain why steroid hormones can rapidly enter a cell by passing through its
cell-surface membrane.
They are lipid soluble so they can diffuse through the phospholipid bilayer.
Alport syndrome (AS) is an inherited disorder that affects kidney glomeruli of both men and women. Affected individuals have proteinuria (high quantities of protein in their urine).
Suggest how AS could cause proteinuria.
Damages basement proteins
Proteins can pass into glomerular filtrate.
Microinjection of DNA into fertilised egg cells is a frequent method of producing transgenic fish. However, the insertion of the transferred gene into nuclear DNA may be delayed. Consequently, the offspring of transgenic fish may not possess the desired characteristic.
Suggest and explain how delayed insertion of the GH gene could produce offspring of transgenic fish without the desired characteristic.
Cell division has occurred before gene added
Cells producing the gametes do not receive the gene
how can black bears can hibernate for up to 7 months without food or water?
Use fat stores in respiration
Less food store is required due to lower respiration
Gluconeogenesis occurs
Why does adding a respiratory inhibitor change resting potential of a neurone from -70mV to 0mV?
Less ATP produced due to less respiration
Therefore, less active transport
So electrochemical gradient isn’t maintained
Why are bacteria able to use human DNA to produce human proteins?
- Genetic code is universal
- Mechanism of transcription is universal
- Mechanism of translation is universal
Roles of ATP in muscle contractions
- Break actinomyosin bridges
- Bend the myosin heads (powerstroke)
- So actin filaments are moved
- For active transport of Ca2+ ions into the sacroplasmic reticulum
Describe how ultrafiltration occurs
- Glomerulus has a high hydrostatic pressure
- Forces water and glucose out through small pores in the capillary endothelium and through the capillary basement membrane.
- Basement membrane acts as a filter
- Leads to renal capsule
Describe the role of Ca2+ ions and ATP in the contraction of a myofibril
- Ca2+ ions diffuse into myofibrils from the sacroplasmic reticulum
- The Ca2+ ions cause tropmyosin to move exposing myosin binding sites on actin allowing myosin to bind to actin forming crossbridges
- Hydrolysis of ATP on myosin head causes myosin to bend and this pulls the actin filament over the myosin head
- Binding of a new ATP to the myosin head causes the myosin to detach from the actin
During vigorous exercise pH of skeletal muscle falls.
Why does this lead to a reduction in the ability of Ca2+ to stimulate muscle contractions?
- Lower pH means Ca2+ receptors change shape
- Fewer Ca2+ ions bind to tropomyosin so fewer tropomyosin molecules move meaning that fewer binding sites on the actin are exposed
- Fewer crossbridges can form
Role of glycogen granules in skeletal muscle
- Store of glucose
- Allows for more respiration to provide ATP
How does the heart contract
- SAN initiates a WOD across both atria causing them contract (atrial systole)
- AVN releases 2nd WOD
- Layer of fibrous, non-conducting tissue delays the impuslse allowing all the blood to leave the atria and fill the ventricles and valves to close.
- WOD from AVN travels down septum via bundle of His.
- Branches into Purkinje fibres in walls of ventricles.
- Causes heart to contract apex upwards forcing blood out of the heart.
role of receptors and nervous system in increasing heart rate during exercise
- More carbon dioxide produced as more respiration meaning that there will be more acidic conditions.
- Chemoreceptors detect this pH decrease.
- More impulses are sent to the cardiac centre in the medulla so more impulses are sent to the SAN via the sympathetic nervous system
OR
- Exercise cause blood pressure to increase
- Baroreceptors detect this pressure increase
- More impulses ate sent to the cardiac centre in the medulla so more impulses are sent to the SAN via the parasympathetic nervous system
Why can an increase in biomass be taken as a measurement of net primary productivity?
Biomass represents the dry mass of carbon
Represents the gross primary production - respiration losses
NPP = GPP - R
How can transcription factors be used to reprogramme cells to form iPS cells?
Transcription factors bind to promoter regions
Stimulates RNA polymerase
Where is rubisco found?
Stroma of chloroplast
How can alterations to tumour surpressor genes lead to development of tumours?
There is a mutation in the tumour surpressor gene
Increased methylation of tumour surpressor genes
Transcription of tumour surpressor genes is prevented meaning cell division is uncontrollable
Why are log scales used?
Very large range
Absorption of sodium and chloride ions from filtrate produced in nephrons is inhibited.
How does this increase the volume of urine produced?
The water potential of the filtrate decreases
Less water is reabsorbed from the filtrate by osmosis at the collecting duct
Enzymes in the insertion of a DNA fragment into plasmids
Restriction endonuclease:
- Cuts the DNA fragment and the plasmid at the same specific gene to produce complementary sticky ends
DNA ligase:
- Joins the DNA fragment and plasmid by their complementary sticky ends
