BIO/BIOCHEM Flashcards
What is the role of signal sequence ?
Signal sequence : a portion of mRNA that is located in the 5′ region and will signal to the ribosome that translation needs to be continued in the rough endoplasmic reticulum.
What is the nuclear localization signal ?
Nuclear localization signal : is a sequence that tags the protein for it to be transported into the nucleus
What does a mature RNA sequence for a protein located on cell membrane contain ?
mature RNA sequence for a protein that is secreted or that will locate to the cell membrane will contain the SIGNAL SEQUNCCE.
What is the role of calcium during muscle contraction process?
Ca2+ binds to troponin and allows tropomyosin to move, freeing the site of interaction between actin and myosin.
How many fused rings are in steroids ?
4 fused rings (contain 6-6-6-5 fused ring assembly)
What can fix an epileptic issue due to massive firing of neurons in a small area ?
An INCREASE in neuron firing threshold would make it more challenging for a neuron to fire an action potential. This will reduce the frequency of downstream neuron depolarizations, resulting in relief of the symptoms.
Which region of the kidney is glomerular filtrate most concetrated ?
Medullary portion of collecting duct
(last part of tubule where reabsorption of water and salts occur)
What occurs in proximal convoluted tubule ?
portion of tubule where glomerular filtrate First passes through
What is role of collecting duct ?
collecting duct: concentrates filtrate
assuming no denaturation of proteins, what is expected to increase with temperature ?
PROTEIN ACTIVITY (expected to increase with temperature)
How are action potentials stimulated ?
by release of a neurotransmitter that binds to ligand gated channels,
What is the role of Na+/K+ ATPASE during a neuronal action potential ?
aids in The RESTORATION and maintenance of the RESTING POTENTIAL.
This is achieved by moving three Na+ out of the cell for every two K+ ions that are brought into the cell.
What is the function of transcription factors ?
regulate the expression of other genes ( by binding to the promoter or the enhancer of the gene located on the DNA).
How do hydrophobic molecules pass through membrane ?
SIMPLE DIFFUSION
What must occur for regulation of the expression of genes to be possible ?
The downstream target genes must contain DNA REGIONS in their promoter or enhancer, that can interact with transcription factors
What is produced after ATP hydrolysis ?
ADP + Pi (inorganic phosphate)
What are lipid rafts?
lipid rafts: cholesterol rich domains within the membrane
What is the role of microtubules ?
Microtubules: bind to chromosomes at the level of the kinetochore and regulate their migration toward the opposite poles of the cell during anaphase.
What regulates to formation of filtrate in Urinary system ?
The DIFFERENCES IN PRESSURE regulate filtrate formation
what are the main pressures that work in urinary system and how do they work ?
There are three pressures that work together to regulate filtration in the glomerulus:
-glomerular capillary pressure
-capsular hydrostatic pressure
- blood colloid osmotic pressure.
The glomerular capillary pressure will force filtrate from a capillary into Bowman’s capsule; the other two forces promote movement of the filtrate in the opposite direction.
How do enzymes alter the rate of chemical reactions ?
Enzymes :
can alter pH of environment
can co-localize substrates to modify rate of reaction
-alter substrate shape
What is a brief summary of translation ?
Proteins are generated during translation.
In this process, mRNA triplets are read by ribosomes, and tRNA molecules provide the amino acids. Each amino acid is matched to a tRNA molecule carrying a specific anti-codon. A specific amino acid will be added only if it is recognized by its specific codon.
What happens to cells in interphase ?
cells in interphase are NOT actively DIVIDING
What do mature erythrocytes NOT contain ?
Mature erythrocytes do NOT contain DNA since they are enucleated (no nucleus)
What is the role of endothelial cells?
Endothelial cells: cells that are in direct contact with blood and the surrounding matrix so these are the cells that play the most important role in GAS EXCHANGE
What are animal viruses ?
animal viruses are OBLIGATE PARASITES
Animal viruses can only infect animal cells, not bacteria.
How are bacterial chromosomes structured ?
they are CIRCULAR
What is a telomere ? what do they contain ?
telomere refers to a distal end of a chromosome. Telomeres contain non-coding repeats.
How are nucleotides connected in DNA?
Nucleotides are linked to one another by phosphodiester bonds between the sugar base of one nucleotide (thymine) and the phosphate group of the adjacent nucleotide (adenine) (in a way that the 5′ end bears a phosphate, and the 3′ end a hydroxyl group)
What is the role of aldosterone ? What happens in absence of aldosterone ?
aldosterone is responsible for retaining water and sodium in the body (keep levels high in body) and elimination of potassium ions from the body.
Thus, in the absence of aldosterone, the levels of potassium will increase.
Explain the negative feedback that occurs for ACTH?
Release of ACTH from the pituitary is regulated by negative feedback. In normal conditions, high levels of circulating glucose and other stressors activate the production of corticotropin-releasing hormone (CRH) from the hypothalamus.
CRH will stimulate the pituitary gland to release ACTH which will trigger cortisol release from the adrenal cortex.
Finally, the presence of high levels of circulating cortisol will inhibit CRH secretion (negative feedback) thus closing the loop.
What occurs in patient with Addison’s Disease ?
Addison’s disease: the circulating levels of ACTH will be higher than normal because the factor that triggers the inhibition of CRH production, high cortisol levels, is absent or low.
How does high levels of glucocorticoids affect muscles ?
High levels of circulating glucocorticoids will increase protein degradation in various tissues, muscles included.
A direct consequence of protein degradation in muscles is muscle weakness.
What happens if insulin stimulates first step of glycolytic pathway ?
This will result in a decrease of the cellular concentration of glucose. To compensate for the low cellular glucose concentration, glucose uptake is increased.
How can brain still get nourishment in diabetic patient ?
brain has glucose transporters that aer insulin independent
What is the function of end-membrane system?
The endomembrane system: is the portion of the cells that is in charge of modifying proteins that will be secreted.
(Thus, it is most likely that insulin cleavage will occur in the endomembrane system)
What is myoglobin ?
Myoglobin : the substance that holds oxygen in MUSCLES and ORGANs
What controls heart rate ?
Brain stem
What controls muscle coordination ?
cerebellum
What controls appetite ?
hypothalamus
What is extremely sensitive to timing of mRNA turnover?
coordination of cell differentiation during development is extremely sensitive to the timing of mRNA turnover.
What is the best way to incorporate antisense gene into cells of an individual ?
infect an embryo with a virus that carries the antisense gene.
The appropriate virus could become incorporated into the genome of the embryonic cells, thus causing all cells derived from these embryonic cells to contain the antisense gene.
How would an antisense molecule line up with an mRNA sequence ?
When the RNA molecules hybridize, the antisense molecule would line up in an ANTIPARALLEL fashion with the sense molecule, meaning its 3′ end would line up with the 5′ end of its complement.
How does inflation of lungs occur?
Inflation of lungs in mammals is accomplished by NEGATIVE pressure pumping action.
Because the lung stays in contact with the thoracic wall as it enlarges due to contraction of the diaphragm and the external intercostal muscles, a pressure that is lower than atmospheric pressure (negative pressure) is generated within the alveolar sacs
What is transduction ?
Transduction: is the process whereby genes are transferred by a virus
What is transformation ?
transformation: bacteria take up DNA from their surroundings.
What occurs in conjugation ?
Conjugation : production of a special pilus (sex pilus) by one bacterium and transfer through it of DNA to another bacterium.
It requires special genes for the pilus and these are usually present on a plasmid (called F fertility)
What is the most effective method of increasing total amount of water lost through skin?
raising the environmental temperature since it would cause a person to perspire, releasing water to the environment where it can evaporate and cool down the body.
Where would you expect to find ice in a frozen body of freeze-tolerant frog?
You would expect to find ice in the extracellular fluid – ex: blood plasma and lymph
Does the sodium pump DIRECTLY cause action potentials along neurons ?
NO, because action potentials result in an increased permeability of plasma membrane to sodium (leading to depolarization) hence NOT direct
Where is sodium pump most active (body structure)
LOOP OF HENLE
Na+ is reabsorbed from the filtrate moving through the nephron.
What bonds holds DNA backbone
Phosphodiester bonds
What kind of bond is formed by DNA backbone ?
The DNA backbone is formed by phosphodiester linkage between deoxyribonucleotide molecules.
What does structure of pyrimidine look like ?
What does structure of purine look like
differentiate between structures of purines and pyrimidines
Purines have 2 rings
Pyrimidines : have 1 ring
Differentiate between purines and pyrimidines ?
Purines: 2 rings
pyrimidines 1 ring
What kind of side chains are seen in cysteine
Cysteine has SULFYHYDRYL groups (that can form disulfide bridges)
Where does the electron transport chain occur ? How do the complexes in ETC function?
Mitochondrial Inner membrane
the complexes function in a chain (the reactions by complex are Coupled together )
What is the function of Endoplasmic Reticulum ?
endoplasmic reticulum is responsible for the synthesis and transport of various organic molecules, including carbohydrates, lipids, and proteins.
What is function of Golgi apparatus ?
Golgi apparatus: packaging proteins into vesicles for their transport to their proper location