1 / 1 pts

Below is the DNA sequence of the template strand of one essential gene for forming endospores in bacteria.

  • The function of this gene is to help bacteria produce endospores in response to nutrient deprivation
  • Because the gene is very long (over 400bp!), I am only showing the beginning and the end separated by “…”

 

Endospore Gene

3'-  TCC TCC TAC  TGA  CTG … ACG TAC ATC-5'

 

DNA strand 1(Template strand)

 

 

DNA strand 2 (Non-template strand)

 

Remember that DNA is double-stranded. Here I am showing you one strand of the DNA. Pretend that you are DNA polymerase and you are replicating the DNA strand 1.

 

What is the complementary DNA strand (e.g. strand 2) based off the sequence? Please pay attention to the direction of DNA (e.g. 5' and 3' ends)

  
  
  
  
 
IncorrectQuestion 2
0 / 1 pts

Now look at this process visually. On the image of the DNA being replicated below, I've added part of the sequence of DNA strand 1 (the top strand).

DNA rep q2.png

Based on our practice last week and the image above,  what direction is the newly synthesized DNA strand being made?  (another way to phrase this is what direction is DNA polymerase moving to copy the strand on top)?

 

You need to remember the direction DNA polymerase reads the template vs the direction it synthesizes thew new strand.

  
  
 
IncorrectQuestion 3
0 / 1 pts

When some bacteria are under nutrient stress (e.g. the nutrients in its environment have run out), they can form endospores as you learned in lab.

Only bacteria that have endospore-genes can form endospores (it's like a bacterial superpower). Genes involved in endospore production, are only used (or "turned on") when bacteria need them. This idea that genes are expressed ("turned on" or used to make proteins) when needed is also known as differential gene expression.

The first step to turning on a gene is to copy the instructions into an mRNA. This process is called transcription.

Below, please transcribe this endospore gene into an mRNA. In order to do this, please consider:

  • Which DNA strand will you copy/transcribe? (The template/coding or the non-template/non-coding strand?)
  • What is the directionality of your mRNA (remember 5' to 3' ends)? Hint: RNA is synthesized with the same rules as DNA that we reviewed last week.

 

Endospore Gene to mRNA

3'-  TCC TCC TAC  TGA  CTG … ACG TAC ATC-5'

 

Template

 

 [you figured this out in Q1]

Non-template

 

Please select the correct mRNA sequence below

mRNA

  
  
  
  
 

Please review the following videos (pick 1 at minimum)

Text option (if you prefer text, but I would highly recommend still watching 1 video because watching the process happen is better than static pictures):

You should know/take notes on the following:

  • What is the sequence of DNA where transcription begins? (In other words, transcription has to start somewhere, what is this region called?)
  • What is the enzyme that performs transcription?
 
Question 4
1 / 1 pts
Where does transcription start?
  
  
  
  
  
 
Question 5
1 / 1 pts
What enzyme makes mRNA?
  
  
  
  
 

Okay, now on to translation!

Once we get an mRNA, we need to use that photocopy to translate it into (make) a protein. This process is translation.

Please use the mRNA you made previously as the recipe or "code" to make the endospore protein.

Notes:

 
Question 6
1 / 1 pts
Where does translation start?
  
  
  
  
 
Question 7
1 / 1 pts
Which of the following actually polymerizes (synthesizes) the protein? In other words, which makes the covalent peptide bonds between amino acid monomers?
  
  
  
 
Question 8
1 / 1 pts
Which brings in each individual amino acid monomer and is key to "decoding" the mRNA?
  
  
  
  
  
 
Question 9
1 / 1 pts

Which is the correct amino acid sequence of the endospore protein you made?

  
  
  
  
  
 

Transcription & translation look a bit different in prokaryotes vs eukaryotes.

In this videoLinks to an external site., review the big picture differences between the two.

 

 
Question 10
1 / 1 pts

Based on what you learned, think carefully about our example.

 

Does our endospore mRNA from this activity have a 5'-cap?

  
  
 

Optional!

Craving a bit more detail? Love biology?

Here are a few extra videos (for fun). I don't go into this level of detail in our micro class (because of time), but some students actually understand content better when they get a bit deeper. If that's you, or you just like this stuff, here's some more detailed bits: