(4pts) Drugs, medicines, and poisons often work by acting on endogenous proteins. They do this by looking similar to a signal molecule and binding to the endogenous protein. Look up these four examples to fill in this chart. Drug, medicine, or poison Looks similar to this endogenous molecule: Binds to this endogenous protein/receptor: Muscarine Acetylcholine muscarinic receptors Prozac Serotonin serotonin transporter protein Ketamine NMDA NMDA receptor Tamoxifen estrogen estrogen receptor

Drug, medicine, or poison: Muscarine; Looks similar to this endogenous molecule: Acetylcholine; Binds to this endogenous protein/receptor: muscarinic receptors

Drug, medicine, or poison: Tamoxifen; Looks similar to this endogenous molecule: estrogen; Binds to this endogenous protein/receptor: estrogen receptor

Drug, medicine, or poison: Prozac; Looks similar to this endogenous molecule: Serotonin; Binds to this endogenous protein/receptor: serotonin transporter protein

Drug, medicine, or poison: Ketamine; Looks similar to this endogenous molecule: NMDA; Binds to this endogenous protein/receptor: NMDA receptor

Explanation:

Muscarine is a poisonous natural product found in certain mushrooms. It is similar to acetylcholine and competes with acetylcholine at its receptor binding sites.Signs of muscarine poisoning include salivation, lacrimation, vomiting, diarrhea, abdominal pain, bradycardia, etc.

Tamoxifen is a selective estrogen receptor modulator. It is similar to estrogen and acts by inhibiting the effects of estrogen in the breast tissue. It is used to prevent and treat breast cancer in men and women.

Prozac is an antidepressant which belongs to th class known as selective serotonin reuptake inhibitors. It looks similar to serotonin and inhibits its action by competing with serotonin for its binding site. It is used for the treatment of depression disorders.

Ketamine is an NMDA (N-Methyl-D-aspartate) receptor antagonist. NMDA receptor antagonists are a class of drugs that work by inhibiting the action of the NMDA receptor. They are commonly used as anesthetics for animals and humans to induce a state of anesthesia known as dissociative anesthesia.

step 1 ammonium can be absorbed by plants, but some is converted into nitrates which are better for plants to absorb. this is called nitrification. 2. step 2 the deer eats the plants and uses the nitrogen-containing proteins for cell growth. 3. step 3 bacteria in the soil conduct nitrogen fixation to convert nitrogen gas from the atmosphere into ammonium. 4. step 4 some of the nitrates are absorbed back into plants, but denitrification breaks down the nitrates into nitrogen gas released back into the atmosphere. 5. step 5 nitrogen is found in the urine, which gets broken down into ammonium through the process of ammonification. 6. step 6 plants absorb the ammonium and begin assimilation, the process to add the nitrogen to protein.

step 1: initiation

initiation is the beginning of transcription. it occurs when the enzyme rna polymerase binds to a region of a gene called the promoter. this signals the dna to unwind so the enzyme can ‘‘read’’ the bases in one of the dna strands. the enzyme is now ready to make a strand of mrna with a complementary sequence of bases.

step 2: elongation

elongation is the addition of nucleotides to the mrna strand. rna polymerase reads the unwound dna strand and builds the mrna molecule, using complementary base pairs. there is a brief time during this process when the newly formed rna is bound to the unwound dna. during this process, an adenine (a) in the dna binds to an uracil (u) in the rna.

step 3: termination

termination is the ending of transcription, and occurs when rna polymerase crosses a stop (termination) sequence in the gene. the mrna strand is complete, and it detaches from dna.