IB Biology : Chemical Signaling

calcium ions can move in and out of the cell through the...

calcium pump

identify receptors that are present on the outer side of the target cells

cell surface receptors

what does the chemical N-acyl homoserin lactone trigger in Vibrio fischeri?

bioluminescence

what type of hormone is insulin?

peptide hormone

what type of amino acids are found in transmembrane receptors?

found on either side of the cell membrane - hydrophilic

spanning the cell membrane - hydrophobic

identify the role of a ligand in initiating signal transduction pathways by receptors

it binds to the extracellular domain of the receptor

identify the correct order of events in a signal transduction pathway

I. secondary messengers active protein kinase

II. receptor gets activated

III. ligand binds to the receptor

IV. protein kinases phosphorylates other proteins

V. gene expression is regulated

III, II, I, IV, and V

identify which of the following is the first step in the mechanism of action of epinephrine (adrenaline) receptors

conformational change in the GPCR

identify which of the following best describes positive feedback in cell signalling pathways

a mechanism that amplifies the signal and increases the response

identify which type of receptor is associated with positive feedback in cell signaling pathways

I. intracellular receptors

II. transmembrane receptors with tyrosine kinase activity

III. transmembrane receptors with G-protein coupling

II and III only

identify which of the following is an example of negative feedback in cell signalling pathways

insulin signaling in response to high blood glucose levels

ADH (antidiuretic hormone) is produced in the pituitary gland and targets the collecting duct of the kidney. how does it reach the target tissue?

travel through the blood

what effect does progesterone have on target cells in the endometrium?

inhibits proliferation of endometrial cells

in the context of a feedback loop, what is the function of oestradiol?

stimulating hormone production

which of the following best describes quorum sensing in bacteria?

a process by which bacteria regulate their gene expression and behavior in response to the density of their population

what is the role of quorum sensing in the regulation of bioluminescence in the bacterium Vibrio fischeri?

the bacteria emit light only when their population density reaches a critical threshold

what initiates quorum sensing?

reaching a certain population density

which of the following is true about DNA replication?

DNA replication happens during the S phase of the cell cycle

which of the following best describes the role of transmembrane receptors with tyrosine kinase activity in insulin signalling?

they bind to insulin, causing phosphorylation of tyrosine inside the cell

which of the following signaling chemicals is involved in the regulation of immune responses?

cytokines

which of the following describes how intracellular receptors affect gene expression?

hormones enable the complex to bind to specific DNA sequences, stimulating gene transcription, by binding to a site on the receptor and initiating its activation

which is the second messenger in the epinephrine reaction?

cAMP

what is the consequence of the opening of ion channels in response to the binding of acetylcholine to its receptor?

depolarization of the membrane potential

neonicotinoids are compounds that used to be widely used on farms as effective insecticides. it appeared they were easily absorbed by plants and were present in pollen and nectar, killing honey bees. scientists discovered that neonicotinoids affect the cholinergic synapses in the nervous system of insects, causing their paralysis and death. how do neonicotinoids affect the synapses?

they block postsynaptic acetylcholine receptors so synaptic transmission is prevented

what distinguishes peptide hormones from steroid hormones?

peptide hormones act through second messengers

identify which of the following hormones uses an intracellular receptor to affect gene expression

progesterone

which of the following are steroid hormones?

I. oestrogen

II. cortisol

III. insulin

I and II only

what is the correct order of events in the initiation of signal transduction pathways by receptors?

I. binding of the signaling chemical to the receptor

II. activation of downstream signaling molecules

III. internalization of the receptor-ligand complex

IV. conformational change in the receptor protein

I, II, III and IV

which ion will enter the cell through the ion channel opened by the binding of acetylcholine to its receptor?

sodium (Na+)

when neurotransmitters bind to a receptor on the post synaptic neuron causing Na+ ion channels to open. what function are they carrying out?

the ligand or neurotransmitter is acting as a signaling molecule

what is a ligand?

a signaling chemical that binds to a specific receptor

which of the following is not a function of G protein receptors?

maintaining cellular respiration