VCAA question

[Snorlax]

I'm really confused about this question that I recently saw on the 2010 past paper.
http://www.vcaa.vic.edu.au/Documents/exams/biology/2010biology2-w.pdf
Q3, of Multiple choice.
Could someone go through this?

You can obviously reduce the options to either A or D, but why is the correct answer D?

[psyxwar]

Mitochondrial DNA is inherited maternally.

[Stick]

Mitochondrial DNA is always inherited from the mother.

EDIT: beaten XD

[Snorlax]

waitwut?
This is the first time i'v heard of this. Is this in our course?

[psyxwar]

Probably, it certainly is assumed knowledge if VCAA expected you to know it. It's in the textbook I use (NOB) at least.

[Snorlax]

Really?
What topic were you introduced to this in?

[pi]

This is definitely in the course.

It occurs because during fertilisation, only the genetic material (the 'pronucleus') of the sperm really enter the egg, the tail and the mitochondria (yes, sperm have mitochondria which they use to move with along with other factors) are degenerated. This means that the zygote only has mitochondria from the ovum, which we know is from the mother Hence, all mtDNA is from the mother!

[Snorlax]

I'm honestly so confused right now
I'll have a look through my textbook/teachers sometime this week. damn.

[simpak]

Which part is confusing you?  The only part you need to know is that mtDNA is inherited from the mother, which you know now.  No need to go back through the textbook

[Snorlax]

But now it seems like I might be lacking a lot more detail in my studies!
Like to me, knowing mtDNA is inherited maternally is quite specific, and not sure if I'm confident in the other aspects too...If that made any sense
So far in the course, mtDNA hasn't been covered in my class into specifics - such as it being inherited from the mother, so I'v either missed it, or it's been skipped. idunno. I'll ask my teacher

P.S
Found another question about mtDNA in the 2008 paper. Shows the relative importance

Thanks guys.

[simpak]

The only other thing you might like to know about mtDNA is that it can be used to date old evolutionary relationships.

[Snorlax]

Yeh, I saw that briefly in a handout.


I'v got another question I don't understand about restriction enzymes.
http://www.vcaa.vic.edu.au/Documents/exams/biology/2008biol2-w.pdf
Multiple choice, Q20, I don't understand.
I guess I don't understand the concept of the restriction enzymes and the cuts.

[swagsxcboi]

Yeh, I saw that briefly in a handout.


I'v got another question I don't understand about restriction enzymes.
http://www.vcaa.vic.edu.au/Documents/exams/biology/2008biol2-w.pdf
Multiple choice, Q20, I don't understand.
I guess I don't understand the concept of the restriction enzymes and the cuts.

The answer is C
Restriction enzymes may be found within bacteria and they act as a defence mechanism, digesting viral DNA or RNA at a specific nucleotide sequence. EcoR1 = obtained from E.Coli bacteria
A restriction enzyme will 'digest' (cut) the phosphodiester bonds that form the phosphate-sugar backbone of DNA. As a result, the hydrogen bonds (weak) between the bases will also be broken.
Since we know that EcoR1 will only digest that DNA fragment at cutting site Q, we know that the smaller fragment will be 3 kb long.
We also know that BamH1 will only digest that DNA fragment at cutting site P, and that means the smaller fragment will be 2 kb long.
With this knowledge, we know that if both enzymes are added, the DNA fragment will be digested into 3 pieces. The total length of the DNA strand is 10kb. Thus, 2kb, 3kb and 5kb.

[vox nihili]

I'm honestly so confused right now
I'll have a look through my textbook/teachers sometime this week. damn.

Pi's answer was really good. When a sperm and egg come together, the tail drops off. The head is the only thing that goes in. There are no mitochondria in the head (all the mitochondria are in the tale), therefore, none of the dad's mitochondria get in the zygote. Therefore, the mitochondria all come from mum. Thus the mtDNA all comes from mum.

[simpak]

nonsense come to think of it, I wouldn't worry too much if your teacher hasn't mentioned mtDNA yet - it will probably be covered during evolution because it ties in with the dating thing I said before.  But now you are well equipped to go forth either way.