Question

A¬espectrometria¬de¬massas,¬utilizada¬para¬a¬identificação¬das¬ proteínas¬no¬estudo¬apresentado¬no¬texto,¬é¬uma¬técnica¬que¬ permite¬ determinar¬ com¬ precisão¬ a¬ massa¬ molecular¬ de¬ moléculas¬ carregadas.¬ A¬ determinação¬ da¬ massa¬ exata¬ da¬ molécula¬é¬feita¬a¬partir¬do¬conhecimento¬da¬sua¬carga¬e¬da¬ razão¬ massa/carga¬ (m/z),¬ parâmetro¬ que¬ influencia¬ no¬ movimento¬das¬espécies,¬permitindo¬sua¬determinação.¬Caso¬ a¬ carga¬ das¬ moléculas¬ seja¬ unitária,¬ a¬ razão¬ m/z¬ é¬ numericamente¬igual¬à¬massa¬da¬espécie¬a¬ser¬identificada.¬ Caso¬ a¬ carga¬ seja¬ 2,¬ a¬ razão¬ m/z¬ detectada¬ é¬ metade¬ da¬ massa¬da¬molécula.¬ A¬ imagem¬ a¬ seguir¬ representa,¬ na¬ forma¬ de¬ um¬ gráfico,¬ o¬ resultado¬de¬uma¬análise¬por¬espectrometria¬de¬massas¬de¬ uma¬amostra¬pura¬contendo¬apenas¬uma¬espécie¬intacta¬com¬ fórmula¬ molecular¬ [C44H69NO12Ca]2+¬ e¬ massa¬ exata,¬ considerando¬ os¬ isótopos¬ mais¬ abundantes,¬ de¬¬ 843,444¬g/mol,¬detectada¬como¬m/z¬421,722.¬

Figura da questão (imagem do caderno de prova)

¬ ¬ A¬presença¬de¬outros¬sinais¬além¬do¬sinal¬de¬m/z¬421,722,¬ mesmo¬em¬uma¬amostra¬pura¬não¬contendo¬nenhuma¬outra¬ espécie¬além¬do¬[C44H69NO12Ca]2+,¬deve-se¬ ¬

Accepted Answer

A) ¬à¬presença¬de¬outros¬isótopos¬menos¬abundantes¬e¬mais¬ pesados¬de¬átomos¬presentes¬na¬molécula.¬

Answer

B) ¬às¬ espécies¬ com¬ cargas¬ unitárias¬ que¬ possuem¬ massa¬ maior.¬

Answer

C) ¬à¬ presença¬ de¬ outros¬ isótopos¬ mais¬ abundantes¬ e¬ mais¬ pesados¬de¬átomos¬presentes¬na¬molécula.¬

Answer

D) ¬à¬carga¬do¬cálcio,¬que¬faz¬com¬que¬a¬espécie¬detectada¬ tenha¬mais¬de¬uma¬massa¬molecular.¬

Answer

E) ¬à¬presença¬de¬outros¬isótopos¬menos¬abundantes¬e¬mais¬ leves¬de¬átomos¬presentes¬na¬molécula.¬ Texto para as questões de 68 a 70 ¬ Think¬for¬a¬minute¬about¬the¬  little¬bumps¬on¬your¬tongue.¬You¬ probably¬saw¬a¬diagram¬of¬those¬ taste¬bud¬arrangements¬once¬in¬ a¬ biology¬ textbook¬ —¬ sweet¬ sensors¬at¬the¬tip,¬salty¬on¬either¬ side,¬sour¬behind¬them,¬bitter¬in¬ the¬back.¬ But¬ the¬ idea¬ that¬ specific¬ tastes¬ are¬ confined¬ to¬ certain¬ areas¬of¬the¬tongue¬is¬a¬myth¬that¬ “persists¬ in¬ the¬ collective¬ consciousness,¬despite¬decades¬ of¬ research¬ debunking¬ it”,¬ according¬ to¬ a¬ review¬ published¬ this¬ month¬ in¬ The¬ New¬ England¬Journal¬of¬Medicine.¬Also¬wrong:¬the¬notion¬that¬taste¬ is¬limited¬to¬the¬mouth.¬ The¬old¬diagram,¬which¬has¬been¬used¬in¬many¬textbooks¬ over¬the¬years,¬originated¬in¬a¬study¬published¬by¬David¬Hanig,¬ a¬ German¬ scientist,¬ in¬ 1901.¬ But¬ the¬ scientist¬ was¬ not¬ suggesting¬that¬various¬tastes¬are¬segregated¬on¬the¬tongue.¬ He¬ was¬ actually¬ measuring¬ the¬ sensitivity¬ of¬ different¬ areas,¬ said¬ Paul¬ Breslin,¬ a¬ researcher¬ at¬ Monell¬ Chemical¬ Senses¬ Center¬ in¬ Philadelphia.¬ “What¬ he¬ found¬ was¬ that¬ you¬ could¬ detect¬things¬at¬a¬lower¬concentration¬in¬one¬part¬relative¬to¬ another,”¬Dr.¬Breslin¬said.¬The¬tip¬of¬the¬tongue,¬for¬example,¬is¬ dense¬with¬sweet¬sensors¬but¬contains¬the¬others¬as¬well.¬ The¬ map’s¬ mistakes¬ are¬ easy¬ to¬ confirm.¬ If¬ you¬ place¬ a¬ lemon¬wedge¬at¬the¬tip¬of¬your¬tongue,¬it¬will¬taste¬sour,¬and¬if¬ you¬put¬a¬bit¬of¬honey¬toward¬the¬side,¬it¬will¬be¬sweet.¬ The¬perception¬of¬taste¬is¬a¬remarkably¬complex¬process,¬ starting¬from¬that¬first¬encounter¬with¬the¬tongue.¬Taste¬cells¬ have¬ a¬ variety¬ of¬ sensors¬ that¬ signal¬ the¬ brain¬ when¬ they¬ encounter¬nutrients¬or¬toxins.¬For¬some¬tastes,¬tiny¬pores¬in¬cell¬ membranes¬let¬taste¬chemicals¬in.¬ Such¬taste¬receptors¬aren’t¬limited¬to¬the¬tongue;¬they¬are¬ also¬found¬in¬the¬gastrointestinal¬tract,¬liver,¬pancreas,¬fat¬cells,¬ brain,¬muscle¬cells,¬thyroid¬and¬lungs.¬We¬don’t¬generally¬think¬ of¬these¬organs¬as¬tasting¬anything,¬but¬they¬use¬the¬receptors¬ to¬pick¬up¬the¬presence¬of¬various¬molecules¬and¬metabolize¬ them,¬ said¬ Diego¬ Bohórquez,¬ a¬ self-described¬ gut-brain¬ neuroscientist¬at¬Duke¬University.¬For¬example,¬when¬the¬gut¬ notices¬sugar¬in¬food,¬it¬tells¬the¬brain¬to¬alert¬other¬organs¬to¬ get¬ready¬for¬digestion.¬ New¬York¬Times.¬May¬29,¬2024.¬Adaptado.¬ ¬

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