The enzyme reverse transciptase is critical for?

[littlelady]

4. The enzyme reverse transciptase is critical for?

A. converting the RNA genome of a virus into the DNA form of the host cell.
B. converting the RNA genome of a bacterium into the doble stranded RNA form.
C. replacig the uracil with the thymine in DNA strands.
D. replacing the broken phosphodiester bonds formed after viral attack in the host cell genome.
E. all of the above

5. Which of the following processes are part of gene expression?

A. replication of DNA to make a copy
B. DNA transcribed to RNA
c. RNA translated to make protein
D. a and b
E. b and c

6. How was the defecct in cystic fibrosis discovered?

A. Researchers searched for a gene ain a chromosomal region likely to included the defective gene
B. Researchers used mouse models to identify a human gene
C. researchers discovered the protein and proved it was missing in humans with cystic fibrosis
D. all of the above
E. none of the above

 

[Kushal]

1. oxygen actually has 2 lone pairs in the water molecule; it uses 2 out of its 6 outermost electrons in bonding with hydrogen, leaving the 4 electrons, i.e. 2 lone pairs. i think you're right about the 4 h-bonds. 2 h-bonds due to the two lone pairs and 2 h-bonds due to the two hydrogen atoms having the high partial positive charge.

3. right, all three of them

5. gene expression has to do with proteins. c should be the right answer.

i'm not so sure about 2. and i don't know about 4 and 6.

 

[littlelady]

thanks Kushal,

I have one more question to ask u

which of the following accurately lists the proper for these cells compentets in increasing size??
A. protein, proton, ribosome, mitochondira, bacteria......
: B. proton, protein, mitochondria, ribosome, bacteria
C. proton, protein, ribosome, mtochondria, bacteria
D. protein, proton, ribosome, mitochondria, bacteria
E. proton, protein, bacteria, ribosome, mitochondira


I think the answer is E because Bacteria is Prokaryotes...it's before Eukaryotes...what do u think?

 

[iansmith]

Think about it.

E states that a bacteria is smaller than a ribosome

What is a ribosome and what is the purpose of a ribosome?

 

[littlelady]

iansmith,

ribosome is used for protein synthesis. But bacteria = prokaryotes...ribosome and mitochondria are eukaryotes. I think E is the right anwer.

 

[bomba923]

Hint: Bacteria contain ribosomes.

What should that tell you about their relative sizes?

 

[littlelady]

Dear Bomba, Kushal, and Ismith,

I have another question

The most important buffering system for maintain proper blood PH is

A. charge on the amino acid
B. the bicarbonate buffer system of Co2, carbonic acid and bicarbonate
C. Phosphate groups of serum phosphorproteins
D. all of the above

First, I picked B because Co2 + H2o = H2C03 PKA = 6.1

BUT when i think about phosphate H2po4- = H+ + hpo4- PKA 7.2 intracellus PH is around 7.4 so equal amounts of acid / base...therefore, this one work too


Amino acid contain many Co2 and NH3 groups. Several group have PKA close to 7.4...so this could maintain PROPER BLOOD PH, too.

Am i right?? so the answer is ALL OF THE ABOVE?

 

[Kushal]

ribosomes are really tiny structures, about 20-30 nm. protons are even smaller of course. proteins are in between them.

bacteria is an organism. it should be larger!

to help you out, protons are smallest. proteins are molecules, they 'consist' of protons. ribosomes are organelles which consist of molecules(rRNA). mitochondria are also organelles but much larger(there's an endosymbiont theory saying that mitochondria as well as chloroplasts, were prokaryotes) and finally you bacteria whioch are organisms after all.

sorry i don't know the answer for the above question; I've not done it yet...ooopss

 

[bomba923]

Dear Bomba, Kushal, and Ismith,

I have another question

The most important buffering system for maintain proper blood PH is

A. charge on the amino acid
B. the bicarbonate buffer system of Co2, carbonic acid and bicarbonate
C. Phosphate groups of serum phosphorproteins
D. all of the above

First, I picked B because Co2 + H2o = H2C03 PKA = 6.1

BUT when i think about phosphate H2po4- = H+ + hpo4- PKA 7.2 intracellus PH is around 7.4 so equal amounts of acid / base...therefore, this one work too


Amino acid contain many Co2 and NH3 groups. Several group have PKA close to 7.4...so this could maintain PROPER BLOOD PH, too.

Am i right?? so the answer is ALL OF THE ABOVE?

Hint: Which of the choices would you expect to find in concentrations
significant enough--in blood--to potentially buffer its pH?

 

[littlelady]

Bomba,

Blood is around 7.4. But all of the PKA from A, B, and C are closed to 74...is it ALL OF THE ABOVE??

 

[bomba923]

Bomba,

Blood is around 7.4. But all of the PKA from A, B, and C are closed to 74...is it ALL OF THE ABOVE??

There is a difference between
"what is the most important (physiological) buffering system for blood pH"
and
"what can be used (artificially) to buffer a solution containing some blood"

 

[littlelady]

Bomba,

I think the answer is all of the above. But when i read the question again..he asked " MOST IMPORTANT BUFFERING SYSTEM " then i think it's only Bicarbonate..blood is extracelluar has PKA around 6.1 that close to Blood PH...on the other hand, phosphate is only for intracelluar.

amino and phosphate groupalso help to maintain blood PH too but not all amino acid has PKA around 7.4...Also, amino and phosphate are minor not MAJOR to help maintain PH...then i go with BICARBONATE is my final answer :)

 

[bomba923]

Bomba,

I think the answer is all of the above. But when i read the question again..he asked " MOST IMPORTANT BUFFERING SYSTEM " then i think it's only Bicarbonate..blood is extracelluar has PKA around 6.1 that close to Blood PH...on the other hand, phosphate is only for intracelluar.

amino and phosphate groupalso help to maintain blood PH too but not all amino acid has PKA around 7.4...Also, amino and phosphate are minor not MAJOR to help maintain PH...then i go with BICARBONATE is my final answer :)

Yes, B is correct :)

Actually, this goes back to my second hint:
>Which of the choices would you expect to find in concentrations
significant enough--in blood--to potentially buffer its pH?

You mentioned that blood is an extracellular fluid. Amino acids are generally stored and used inside of cells, and so are phosphoproteins (which are not related to blood buffering in any reasonably direct way).

 

[littlelady]

Bomba,

Thank you!



cAN SOMEONE help me to check my PH cal please :)




1. The pH of .55M aqueous solution of hypobromous acid, HBrO, at 25celcius is 4.45. What is the vale of Ka for HBrO?

HBr0 + h20 = H30+ + BRO-

Ph= - log (H+)
4.48 = -log (H+)
H+ = .00003

Ka = (.00003) ( .00003) / (.55 - .00003)
Ka = 2.0 x 10^-9


2. The Ka of hydrofluoric acid (HF) at 25 celcius is 6.8 x 10^-4. What is the pH of .35M aqueous solution of HF?

6.8 x 10^-4 = (x)(x) / (.35-x)
X = .015091

Ph= -log (H+)
ph = -log (.015091)
pH = 1.81

3. What is the final pH when 100 mL HCL is added to 900 mL of water?

(.5m / 1L ) ( 1L / 1000 ml ) (1000 Ml / 1 ) = .05 mol of HCL

Ka is not given..i went online and found ka for HCL is 1 x 10 ^6

1x 10^ 6 = (x)(x) / (.05-x)
X = .o5

ph = - log (h+)
Ph = - log (.05)
PH = 1.3

 

[bomba923]

First two are correct :)
(except for a few minor errors in significant figures)

*For the last one, you may assume that HCl dissociates
completely in aqueous solution; hence pH=1

 

[littlelady]

Bomba923,

What is the final pH when 100 ML of .5M HCL is added to 900 mL of water?

A. 1.3
B. 5.0
C. 13.0
D. .5
D. none of the above

I didn't see pH = 1 ...is it None of the above?? :( hihihi

I didn't see

 

[bomba923]

Bomba923,

What is the final pH when 100 ML of .5M HCL is added to 900 mL of water?

A. 1.3
B. 5.0
C. 13.0
D. .5
D. none of the above

I didn't see pH = 1 ...is it None of the above?? :( hihihi

I didn't see

The first time you posted this question (your previous post), you did NOT state the concentration of your 100ml HCl solution. Well, so to speak, I assumed that you were dealing with 1M HCl solution; thus, dilution with 900mL of water would yield 0.1M HCl solution, which clearly has
pH = 1

But, now that you write out the question more fully--i.e., assigning, in fact, a 0.5M concentration to your 100mL HCl solution--then dilution with 900mL of water would yield 0.05M HCl solution, which clearly has pH = 1.3

So, yes, the answer is "A"

 

[littlelady]

Thank you :) problem solved :) yeehaaa :)