Question

Suppose that the galA gene was regulated by a repressor. Which of the following would be correct? Check all that apply.
1) The repressor for the galA gene would bind to DNA in the presence of galactose.
2) The repressor for the galA gene would not bind to DNA in the presence of galactose.
3)The repressor for the galA gene would bind to DNA in the absence of galactose.
4)The repressor for the galA gene would not bind to DNA in the absence of galactose.

Answer 1

hi welcome to openstudy!! wat does the galA gene code for?

Answer 2

Consider the following genes in a hypothetical bacterium:
galA – encodes an enzyme that is required for cells to digest the sugar galactose
argB – encodes an enzyme that is required for cells to produce the amino acid arginine

Answer 3

What? Is that a second question?

Answer 4

this is the ques from edx course right?

Answer 5

No, I explained what galA and argB is.

Answer 6

I think the correct answers are b and c. Am I correct?

Answer 7

2 and 3 I mean

Answer 8

ohh..ok...so according to wat u said...d gene galA would be transcribed when the bacterium has galactose and needs the energy...and a repressor prevents the expression of gene...so now can u guess wats d answer?

Answer 9

yes u r correct...because both the sentences in a way mean the same....

Answer 10

Thanks, I am so stressed I am not sure for anything any more... :-)

Answer 11

but u r right...just chill out...if u r stressed out just take a small break....

Answer 12

i have the same ques and options in the same sequence on edx.org biology secrets of life course...

Answer 13

Me too! :-)

Answer 14

Do you know how to answer the 2) Part F question?

Answer 15

ahh i forgot...as u r new to this site i would suggest u to take a look at the code of conduct
http://openstudy.com/code-of-conduct

Answer 16

OK thanks!

Answer 17

f the recombinant plasmid is carrying this sequence, drag and drop the first 12 bands to create the pattern expected for the sequencing reactions as outlined above.
are u talking about this ques?

Answer 18

yes

Answer 19

see if the sequence is ACGGTT for eg
then the first band would be observed in the ddATP column because that are first base...then the next band at ddCTP and so on....

Answer 20

What if there is a stop codon after the promoter. Do I start after the stop codon...

Answer 21

The sequence starts after the promoter, right?

Answer 22

yes...because transcription starts after the promoter....see right now transcription is going on..not translation...so u need not worry about the stop codon....because even the stop codon has to be transcribed.

Answer 23

if u reach till the terminator sequence then u have to stop which in this case is not possible because they are asking only the first 12 bases...

Answer 24

That's why I got the other question wrong...

Answer 25

always remember...start transcription immediately after the promoter ends...

Answer 26

Thank you so much!

Answer 27

ur welcome:D

Answer 28

i am done wid those ques...if u get stuck somewer i wud b there to help:D

Answer 29

Thank you!!!!!!!!!!!!!!!!!!! Am sure I will :-)

Answer 30

and ya 1 more thing....make sure u right the band 1 with only 1 base at the bottom of the gel...as it is the smallest fragment it would run greater distance...

Answer 31

???? I did not get that, you mean that I will use the first 12 bases and I will start placing them from bottom to the top?

Answer 32

After the promoter that is.... (the 12 bases after the promoter)...

Answer 33

yes....in the ACGGTT sequence...the 1st band is in the ddATP column right?
so place the band at the bottom then above that next band in the ddCTP column and so on...

Answer 34

yep after the promoter....

Answer 35

Got it!

Answer 36

cool:D

Answer 37

I got it wrong and I do not understand why. I started from bottom to top as you said and I doubled check it...

Answer 38

wait ill send u the screenshot of my ans...i got it correct..

Answer 39

i m soo sorry...i didnt read the ques correctly....i really am very very very sorry
i forgot to mention that they had given the primer and we had to start immediately after the primer...i feel so bad...omg...srry:'(

Answer 40

That's why...

Answer 41

My fault...completely my fault...i feel really very horrible...i wish i could do something...i m very very sorry..:'(

Answer 42

u have d diag in front of u right? lets look at the enzyme aval1

Answer 43

it cuts at 2 sites correct? so how mant fragments would u get? remember thats a circular DNA

Answer 44

3 fragm.

Answer 45

No, 2.

Answer 46

are u sure? imagine that u r cutting a circle at 2 sites....

Answer 47

ahh correct...now they have given the bp distance between the 2 sites so that we can know the size of the fragment....can u tell me the size of smaller fragment?

Answer 48

1200

Answer 49

correct...now this fragment would form a band on the gel...right? this band would be placed in the column of aval1 and should correspond the band in the standards which shows 1200bp or place it in between 2000bp and 1000bp

Answer 50

Got it!! If we were asked to find the numbers I wouldn't have a problem, is the chart that confused me. Thank you once more! Bye for now...!

Answer 51

cool...ur welcome..bye..gn:)

Answer 52

gn

Answer 53

wrong again. I truly do not understand why. not passed.

Answer 54

not your fault I missed a band. so stupid

Answer 55

but i guess u hv 2 submissions there...

Answer 56

no just one. I lost the chance of passing. I am not sure whether I will be able to get the certificate now. average midterm I got 55%

Answer 57

and i feel terrible...sorry..:( just check again i think 1 or 2 of the ques have 2 submissions...maybe u can get the rest 5%

Answer 58

those I got them right from the 1st time :-)

Answer 59

I will ask the edx team to see if I have a chance or not.

Answer 60

yes...try doing that,...:)