Biology Unit 4 Questions Megathread

[WhoTookMyUsername]

against a dominant trait. Remember selection only acts on phenotype.
So complete selection against a dominant trait will ensure NO dominant alleles are left in the gene pool, while complete selection against a recessive trait will still see SOME heterozygous people (at least for a few generations)

[generalkorn12]

Would anyone be able to briefly summarise the steps involved in DNA Replication? I'm having trouble knowing where exactly Ligase, Helicase and Polymerase fit in to the picture.

[nooshnoosh95]

Would anyone be able to briefly summarise the steps involved in DNA Replication? I'm having trouble knowing where exactly Ligase, Helicase and Polymerase fit in to the picture.

so these are the notes from my teacher on DNA replication:

1.unwinding of the DNA molecule-->helicase separates the two strands of DNA and 'unzip' the at the point of opening called the replication fork
2. making new DNA strands--> DNA polymerase(III) extends the primer by adding nucleotides in the 5' to 3' direction, DNA ligase joins okazaki fragments of the lagging strand
3. rewinding the DNA molecule--> each new daughter DNA double helix is made up of one parental (old) strand and one new strand (semiconservative)
...thats it put simply

[WhoTookMyUsername]

anyone able to answer my above questions

[WhoTookMyUsername]

In addition to the above questions ()
My teacher took off half a mark because we wrote 1/2 chance instead of 50% chance... of inheriting a disorder
i wrote both and he still took a half mark off.
Is 1/2 wrong?

[pi]

In addition to the above questions ()
My teacher took off half a mark because we wrote 1/2 chance instead of 50% chance... of inheriting a disorder
i wrote both and he still took a half mark off.
Is 1/2 wrong?

Bio is a bit like further at the VCE level, fractions are too complicated. Just do percentages Whilst 1/2 isn't wrong, it is not the norm.

[lexitu]

It is 1/1 (100%) fine and you should definitely argue that. We use fractions predominantly in uni and on the exam percentages, fractions and ratios in the form of 1:1 etc. will all be accepted.

[scar]

Hi Bazza 16.  I think I can answer someof your questions.

-1) Is there a start transcription signal equivalent of the stop transcription signal (aattaa or something ? )

It varies but they are often called TATTA boxes.   http://www.dnai.org  has a really good explanation of all this in their DNA analysis section.


0) in a person with robertsonian translocation that results in 1 14 chromosome 1 14/21 chromosome and 1 21. Chromosome what are the possible gametes?
Is it:

14
14 + 14/21
21+ 14/21
21
14 + 21
?
( I ask this beuase I have not seen 14 + 14/21 anywhere

The 14/21 pairs up with the normal 14 so the gamete must have one or the other.  The 21 is independently assorted and could go either way.

In other words    (14 and 21)       and (14/21 and ....)
or                         (14/21 and 21) and (14 and ...)

[Drunk]

Is there a difference between germ line cells and gametes?

[jane1234]

Is there a difference between germ line cells and gametes?

Yep. Germ line cells give rise to gametes, i.e. they are the diploid cells that undergo meiosis to form the haploid cell, also known as the gamete. So a germ line cell is the "parent" of 4 gametes.

[Kaille]

If there was reproductive isolation (ie blue birds refused to mate with red birds) in a population that lived in the same area , would this confer sympatric speciation (formation of two or more descendant species from a single ancestor all occuping the same geographical location)?

[jadeee]

Is there a difference between germ line cells and gametes?

Yep. Germ line cells give rise to gametes, i.e. they are the diploid cells that undergo meiosis to form the haploid cell, also known as the gamete. So a germ line cell is the "parent" of 4 gametes.

Teachers at my school don't distinguish between germline cells and gametes - they say that germline cells include gametes and the "parent" cells that give rise to them? Is this true?

Also, if a question asks me to name the part of DNA that doesn't code for proteins, am I incorrect in saying the upstream/spacer region as opposed to introns?

[Russ]

All gametes are germline cells. Not all germline cells are gametes. So you can mark the distinction if you want, but the  terms are used fairly interchangeable. I certainly use them fairly loosely and I don't think it's really going to be an assessment point.

I would just say "non coding regions/DNA" since that's the catch-all term, but yes upstream of the start codon is also not translated and downstream of the stop codon are not translated either (within the transcription reading frame).

[jadeee]

ah ok, thanks.

In a replicated chromosome - X - are there 2 DNA molecules and 2 chromatids?

[Drunk]

Is it true that all organelles are inherited from the mother? Or am I just completely wrong?