问题 问答题 简答题

称取25mg蛋白酶粉配制成25ml酶溶液,从中取出0.1ml酶液,以酪蛋白为底物,用Folin-酚比色法测定酶活力,得知每小时产生1500μg酪氨酸。另取2ml酶液,测得蛋白氮为0.2mg,若以每分种产生lμg酪氨酸的酶量为1个活力单位计算,求出:①每m1酶液中所含蛋白质量及活力单位;②比活力;③l克酶制剂的总蛋白及总活力。

答案

参考答案:

提示:①蛋白质与氮的换算系数为6.25,因此2ml为0.2mgN,1ml为0.1mg×6.25。

0.1ml酶液每小时产生1500酪氨酸,则1ml每分钟产生15000/60=250单位

②0.625mg含有250单位,则1mg含有250/0.625=400

③25mg蛋白粉配成25ml酶液,1ml中含有0.625mg蛋白质,则1mg蛋白酶粉含有0.625mg蛋白质,1000mg蛋白酶粉含有625mg蛋白质,1g含有0.625g蛋白质。

填空题
阅读理解

阅读并选择最佳选项。(共5小题;每小题1分,计5分)

请阅读下面的短文,并从下列各题所给的A、B、C、D三个选项中,选择最佳选项。

Alex,Nicole and Vickie are friends.They live in the same neighborhood.They want to make some money to buy Christmas presents.

“We need to print out fliers(传单)and pass them around to all the houses,”says Nicole.Alex’s dad helps them print out fliers.The three friends go to all the houses and put a flier in everyone’s mailbox.

“It’s winter,”says Vickie.“There is lots of snow on the ground.Maybe people will need us to sweep the snow for them.”

First,Mrs.Jones hires the children to sweep the snow from her driveway(车道).She says,“I have twin baby girls.I am much too busy to sweep the snow myself.”

Then,Mrs.Smith calls them.She says,“I am very old,and the snow is much too heavy for me to move.”

Then,Mr.Lee visits them.He says,“My garden is much too big to sweep all by myself.Can you help me?”

The children work very hard sweeping the snow.It is cold,but they also have great fun.They make 30 dollars in all.Now they can buy nice Christmas presents for their friends and families.

小题1:Whose idea is it to make money by sweeping the snow?

A.Alex’s

B.Nicole’s.

C.Vickie’s.

D.Alex’s Dad’s.小题2:How does Alex’s dad help?

A.He gives them some money.

B.He helps them sweep the snow.

C.He prints some fliers for them.

D.He puts the fliers in mailboxes.小题3:What does the word“hire”mean in Chinese?

A.出租

B.雇佣

C.命令

D.欺骗小题4:Why does Mr. Lee ask the children for help?

A.He is too busy with his babies.

B.He is too old to sweep snow.

C.His garden is much too big.

D.He wants to help the children.小题5:The passage is mainly about ________.

A.helping others

B.making money

C.spending holiday

D.buying presents