VCE Biology Question Thread

[cosine]

Is there any type of variation that can occur in meiosis 2? Independent assortment and crossing both happen in meiosis 1 yeah? Thanks

I would say the lining up of the chromosomes, and which sister chromatid is separated to which cell, causes a big variation xD

[BakedDwarf]

Hey guys, what exactly do we need to know about gene regulation? The study design states: "the concept of gene regulation (the switching on and off of genes by factors expressed by regulator genes and environmental factors)"

The information below is all I honestly know about gene regulation; if I got anything wrong, or if I'm missing info, please tell me.

Gene regulation is the regulation of the extent to which a gene is expressed in a cell; genes may be switched on/off:

- depending upon its function and the specialised function of the cell (we don’t want to produce
 enzymes where or when the substrate is not present)

- to conserve energy as protein synthesis (gene expression) requires energy

- for the differentiation of cells with specialised functions

Regulator gene is a gene that switches structural genes ‘on’ and ‘off’ by coding for a repressor protein that may bind to the operator and hence block transcription; the operator is a region of DNA situated around a promoter that interacts with a specific repressor

Anyone... please?

[StupidProdigy]

I thought this question should of said taq polymerase rather than dna polymerase? Isn't it taq that is used in pcr? Thankya

[cosine]

I thought this question should of said taq polymerase rather than dna polymerase? Isn't it taq that is used in pcr? Thankya

taq polymerase is a type of DNA polymerase

[wobblywobbly]

taq polymerase is a type of DNA polymerase

More specifically, it comes from the organism Thermus aquaticus which is where it gets its name from. It's still DNA Polymerase. It's kind of like those weirdly named restriction enzymes, that are named after the organism from where it came from.

[cosine]

More specifically, it comes from the organism Thermus aquaticus which is where it gets its name from. It's still DNA Polymerase. It's kind of like those weirdly named restriction enzymes, that are named after the organism from where it came from.

Thats correct
Just a bit of more information, it actually comes from bacteria that thrive in hot temperatures, as you know, when PCR is taking place, taq polymerase is added during the last step of extension, where the temperature of the sample would be relatively high, hence the activity of taq polymerase will be optimum. (This is why human DNA polymerase is not used, as the enzyme will denature in those temperatures).

[Biology24123]

My class is completing a SAC at GTAC this Monday and I was just wondering if anyone could give me some insight into what takes place there, as my teacher hasnt been to clear. Thanks

I just did it today. Basically you do a gel electrophoresis and you also do an experiment with fruit flies

[mahler004]

Thats correct
Just a bit of more information, it actually comes from bacteria that thrive in hot temperatures, as you know, when PCR is taking place, taq polymerase is added during the last step of extension, where the temperature of the sample would be relatively high, hence the activity of taq polymerase will be optimum. (This is why human DNA polymerase is not used, as the enzyme will denature in those temperatures).

Interestingly, the early development of PCR used a non heat-stable polymerase (from E. Coli). They had the replace the enzyme after every cycle (expensive, time consuming, far from ideal.) It took a few years for the use of Taq polymerase to be adopted - PCR became a much simpler procedure where you just mix a few reagents and press 'go' on the thermocycler (or even completely automate it.)

The paper which describes this process is one of the most cited in history (17800 citations.)

Kary Mullis - the man who is credited with the invention of PCR is completely nuts. Quite a character. His Nobel lecture is worth a read.

[vox nihili]

Interestingly, the early development of PCR used a non heat-stable polymerase (from E. Coli). They had the replace the enzyme after every cycle (expensive, time consuming, far from ideal.) It took a few years for the use of Taq polymerase to be adopted - PCR became a much simpler procedure where you just mix a few reagents and press 'go' on the thermocycler (or even completely automate it.)

The paper which describes this process is one of the most cited in history (17800 citations.)

Kary Mullis - the man who is credited with the invention of PCR is completely nuts. Quite a character. His Nobel lecture is worth a read.

So easy in fact, that we did some PCR just yesterday. It's actually pretty underwhelming when you do it, as I'm sure mahler004 will attest too as well. The machines are kind of cool though.

[Rumena]

Heyy!!
I have the Genetics Crossings sac soon and i just wanted to ask if anyone has done theirs yet? And i they have would they be able to tell me what i should focus more on?!! Thanks!

[Sine]

Heyy!!
I have the Genetics Crossings sac soon and i just wanted to ask if anyone has done theirs yet? And i they have would they be able to tell me what i should focus more on?!! Thanks!

Personally I am yet to do this SAC, make sure that you have got all the terminology under your belt as most questions are filled with it and if you don't understand it some of the relatively easy marks will be unavailable.

Where is everyone in the course and their exam preparation?

I am yet to complete any VCAA practice exams, but on company papers I am sometimes getting 0-1/2(0 to 1 out of 2)marks on problem solving questions closer to the end of the exam paper, I have found that company papers get increasingly difficult through the paper. Are VCAA exams like this or do the have a constant level of difficulty throughout? 

[paper-back]

How do you describe and define independent gene assortment and allele segregation?
Don't they essentially both occur at the same time?

[paper-back]

Heyy!!
I have the Genetics Crossings sac soon and i just wanted to ask if anyone has done theirs yet? And i they have would they be able to tell me what i should focus more on?!! Thanks!

We did it last week. We didn't have much terminology questions in our SAC and the majority of it was just asking us to construct mono-hybrid, di-hybrid crosses and predict phenotype/genotypes of offspring
Of course SAC's vary from school to school, so be vigilant of the questions that you may come across in spite of what I said

[em pren]

Hey guys would anyone happen to know where to find the chapter review answers for the Nature Of Biology Textbook 

[paper-back]

How do you describe and define independent gene assortment and allele segregation?
Don't they essentially both occur at the same time?

Is this correct?

Independent gene assortment occurs as homologues align on meta-phase plate in random orientations and independently of the orientation of other homologous pairs, this results in the gametes inheriting random combinations of alleles for different genes

Crossing over occurs when independent gene assortment cannot occur as genes are located on the same chromosome. Crossing over effectively increases the variation in the gametes as it instead allows for an exchange of alleles during the synapse phase hence allowing for different combination of alleles to be inherited by the gametes

Allele segregation just refer's to the fact that gametes will inherit one allele for a particular gene due to the separation of sister chromatids during the second meiotic division