VCE Biology Question Thread

[vox nihili]

[copy/paste from notes]

EDIT: suddenly occurred to me that I'm not supposed to spoon-feed, copy-paste removed.

Instead - what is your understanding so far?  Explain what you already know or think, and what specifically you don't get!

ily for this HAHA

Lol we had to cut out tiny chromosomes and arrange them into a karyotype- took like 2 hours the night before and it was worth 1 mark -_-

Cruelest thing they ask you to do, no joke. God it's tedious.

[vox nihili]

I'm currently in the throes of preparing revision lectures for students from disadvantaged backgrounds. We run these each year during the term 3 holidays at Melbourne Uni. More details to come on that, but now I have a question for all of you.

It's reasonable to say that revision lectures are usually pretty hopeless. So how can we improve them for you?

We're obviously working really hard on our own ideas, but frankly, you guys are the VCE students so you'll know 100x better than I will. Hence, I'm asking you

[heids]

ily for this HAHA

Man, when I tutor I'm all good, but on AN I'm like 'meh copy paste is way easier'... whoopsies, always forget that I'm being destructive not helpful
but learning from you though

I'm currently in the throes of preparing revision lectures for students from disadvantaged backgrounds.

Found out about those lectures two days after applications to volunteer closed. -.-
But yeah, giving a lecture at my school hopefully, so I'll be eager to hear from you guys too!

[henmatt]

Yo
I was just wondering, what is the difference between the flanking region of a gene, and an intron?

Cheers

[tashhhaaa]

hey guys,

what is the level of detail that we need to know for each phase of the cell cycle?

[cosine]

I'm currently in the throes of preparing revision lectures for students from disadvantaged backgrounds. We run these each year during the term 3 holidays at Melbourne Uni. More details to come on that, but now I have a question for all of you.

It's reasonable to say that revision lectures are usually pretty hopeless. So how can we improve them for you?

We're obviously working really hard on our own ideas, but frankly, you guys are the VCE students so you'll know 100x better than I will. Hence, I'm asking you

I think a good way to improve them is to provide information in a creative manner, like make it interactive and get students from the lecture to engage etc.. Most lectures go on for hours and honestly they get really boring, and after a certain number of hours, every student is day dreaming - hence, something needs to be engaging, and interesting. I hope it makes sense xD

[cosine]

hey guys,

what is the level of detail that we need to know for each phase of the cell cycle?

Cell cycle is composed of 5 main stages including:

- G1 phase: The cell prepares itself, grows and develops itself in size. There is a checkpoint at the end of this phase known as G0 phase or check point 1. This checkpoint ensures that the cell has appropriately grown in size and if it is ready for the next stage.

- S phase: This is the synthesis phase. The DNA of the cell replicates and hence two identical sister chromatids are present for each chromosome, held together by a centromere. (You should know the steps that occur during DNA replication)

- G2 phase: The cell further grows and develops, and new organelles are produces for the two separate cells after mitosis. There is a check point after this phase known as check point 2, and at this point the DNA replication is being checked, to ensure that all DNA has successfully replicated without any mutations.

- M phase: Mitosis phase is compose of four separate stages: Prophase, Metaphase, Anaphase, Telophase. You should also know what occurs in each of these stages. Note that there is a check point between metaphase and anaphase, to ensure that the mitotic spindle has successfully attached to the centromeres of each chromosomes, so that the sister chromatids can be pulled apart during anaphase.

- Cytokinesis: A cleavage furrow (animals) pushes inwards in the cell and a region of abscission forms, essentially dividing the two identical daughter diploid cells.

Hope that helped, that is all we need to know

[tashhhaaa]

Cell cycle is composed of 5 main stages including:

- G1 phase: The cell prepares itself, grows and develops itself in size. There is a checkpoint at the end of this phase known as G0 phase or check point 1. This checkpoint ensures that the cell has appropriately grown in size and if it is ready for the next stage.

- S phase: This is the synthesis phase. The DNA of the cell replicates and hence two identical sister chromatids are present for each chromosome, held together by a centromere. (You should know the steps that occur during DNA replication)

- G2 phase: The cell further grows and develops, and new organelles are produces for the two separate cells after mitosis. There is a check point after this phase known as check point 2, and at this point the DNA replication is being checked, to ensure that all DNA has successfully replicated without any mutations.

- M phase: Mitosis phase is compose of four separate stages: Prophase, Metaphase, Anaphase, Telophase. You should also know what occurs in each of these stages. Note that there is a check point between metaphase and anaphase, to ensure that the mitotic spindle has successfully attached to the centromeres of each chromosomes, so that the sister chromatids can be pulled apart during anaphase.

- Cytokinesis: A cleavage furrow (animals) pushes inwards in the cell and a region of abscission forms, essentially dividing the two identical daughter diploid cells.

Hope that helped, that is all we need to know

thank you so much!

[cosine]

Does pure breeding just mean the organism is simply homozygous for the trait ?

[Rishi97]

Does pure breeding just mean the organism is simply homozygous for the trait ?

Yup

[cosine]

Few questions about a practice exam I am doing:

1. Do we need to know anything about reverse transcriptase?
2. Do we need to know about plant responses such as phototropism etc?
3. Are we required to know specific autoimmune diseases?

Many thanks

[cosine]

I know that memory B cells are stored in the spleen and detect the foreign pathogen/antigen the next time it reinvades, but upon the detection, do these cells produce antibodies or are they proliferated into more memory B cells and plasma cells? Cheers.

[grannysmith]

I know that memory B cells are stored in the spleen and detect the foreign pathogen/antigen the next time it reinvades, but upon the detection, do these cells produce antibodies or are they proliferated into more memory B cells and plasma cells? Cheers.

They proliferate and differentiate again. There's a faster and greater response because there are a greater number of B (memory) cells upon the 2nd exposure. This also explains why every subsequent exposure to a specific antigen elicits a faster response - there are more and more specific memory B cells which detect and respond.

Few questions about a practice exam I am doing:

1. Do we need to know anything about reverse transcriptase?
2. Do we need to know about plant responses such as phototropism etc?
3. Are we required to know specific autoimmune diseases?

Many thanks

Yes, no, no.

[cosine]

They proliferate and differentiate again. There's a faster and greater response because there are a greater number of B (memory) cells upon the 2nd exposure. This also explains why every subsequent exposure to a specific antigen elicits a faster response - there are more and more specific memory B cells which detect and respond.
Yes, no, no.

So could you say that memory B cells are technically only just B cells upon the second detection of the antigen? (as they differentiate into memory and plasma B cells?)

Thank you man

[TheAspiringDoc]

Cell cycle is composed of 5 main stages including:

- G1 phase: The cell prepares itself, grows and develops itself in size. There is a checkpoint at the end of this phase known as G0 phase or check point 1. This checkpoint ensures that the cell has appropriately grown in size and if it is ready for the next stage.

- S phase: This is the synthesis phase. The DNA of the cell replicates and hence two identical sister chromatids are present for each chromosome, held together by a centromere. (You should know the steps that occur during DNA replication)

- G2 phase: The cell further grows and develops, and new organelles are produces for the two separate cells after mitosis. There is a check point after this phase known as check point 2, and at this point the DNA replication is being checked, to ensure that all DNA has successfully replicated without any mutations.

- M phase: Mitosis phase is compose of four separate stages: Prophase, Metaphase, Anaphase, Telophase. You should also know what occurs in each of these stages. Note that there is a check point between metaphase and anaphase, to ensure that the mitotic spindle has successfully attached to the centromeres of each chromosomes, so that the sister chromatids can be pulled apart during anaphase.

- Cytokinesis: A cleavage furrow (animals) pushes inwards in the cell and a region of abscission forms, essentially dividing the two identical daughter diploid cells.

Hope that helped, that is all we need to know

Great overview cosine!
Just thought I'd raise a point that I'm not sure about.

You said that the checkpoint at the end of G1 is known as G0 phase - I thought that cells that are not in the process of dividing are in the G0 phase, which occurs directly after M phase, and hence not after G1 (which is like the alternative pathway after M phase if the cell wants to divide again.)

Also, since my notes contain a bit more info on the phases of mitosis (some of which is verbatim copied from what you just wrote - sorry  ), I thought I might as well add them for anyone who is interested and so that they get proofread ()

Spoiler

The Cell Cycle

 

The cell cycle is the series of events that take place in a cell leading to its division and duplication (replication) that produces two daughter cells.

In cells with a nucleus, as in eukaryotic cells, the cell cycle can be divided into three periods: interphase, the mitotic (M) phase, and cytokinesis.

 

Interphase

The cell grows, accumulating nutrients needed for mitosis, preparing it for cell division and duplicating its DNA. G1, synthesis and G2 are all parts of interphase.

 

Mitotic Phase

The cell splits itself into two distinct daughter cells. NOT QUITE SURE IF THIS IS RIGHT ANYMORE (isn’t that in cytokinesis, which is mitosis but maybe part of the M phase??)  Chromosomes in the cell nucleus are separated into two identical sets of chromosomes, each with its own nucleus.

 

Cytokinesis

The physical process of cell division in which the cytoplasm of a parental cell splits and forms two daughter cells.

 

To ensure proper division of the cell, there are control mechanisms known as cell cycle checkpoints.

 

The Phases of the Cell Cycle

 

Gap 1 (G1)

Cells increase in size in Gap 1. The G1 checkpoint control mechanism ensures that everything is ready for DNA synthesis.

 

Synthesis (S)

DNA replication occurs during this phase, and hence two identical sister chromatids are present for each chromosome, held together by a centromere.

 

Gap 2 (G2)

During the gap between DNA synthesis and mitosis, the cell will continue to grow and new organelles are produced for the two separate cells after mitosis. The G2 checkpoint control mechanism ensures that everything is ready to enter the M (mitosis) phase and divide.

 

Mitosis (M)

Cell growth stops at this stage and cellular energy is focused on the orderly division into two daughter cells or two daughter nuclei? . A checkpoint in the middle of mitosis (the Metaphase Checkpoint) ensures that the cell is ready to complete cell division.

 

More on Mitosis

 

Mitosis is a part of the cell cycle process by which chromosomes in a cell’s nucleus are separated into two identical sets of chromosomes, each in its own nucleus.

 

The process of mitosis is divided into several stages. The main stages are prophase, metaphase, anaphase, and telophase.

 

During mitosis, the chromosomes, which have already duplicated, condense and attach to fibers that pull one copy of each chromosome to opposite sides of the cell. The result is two genetically identical daughter nuclei. The cell may then divide by cytokinesis to produce two daughter cells.

 

Errors can occur during mitosis. One such error is multipolar mitosis, in which the wrong amounts of daughter cells are produced. Other errors during mitosis can induce apoptosis (programmed cell death) or cause mutations. Certain types of cancer can arise from such mutations.

 

The Phases of Mitosis

 

Prophase

 

The cell prepares to divide by tightly condensing its chromosomes and initiating mitotic spindle formation.

 

a.k.a.

 

The complex of DNA and proteins contained in the nucleus, known as chromatin, condenses.

 

Metaphase

 

The cell’s chromosomes align themselves in the middle (or ‘equator’) of the cell through a type of cellular “tug of war”.

 

There is a checkpoint between metaphase and anaphase, to ensure that the mitotic spindle has successfully attached to the centromeres of each chromosome, so that sister chromatids can be pulled apart during anaphase.

 

Unsure about the above (metaphase checkpoint)

 

Anaphase

 

Chromosomes split (into sister chromatids) and the sister chromatids move to opposite poles of the cell.

 

Telophase



[]poiuhjg/,.The sister chromatids reach opposite poles and the small nuclear vesicles in the cell begin to reform around the group of chromosomes at each end.

 

Cell Cycle Control

 

Regulation of the cell cycle involves processes crucial to the survival of a cell, including the detection and repair of genetic damage as well as the prevention of uncontrolled cell division. The molecular events that control the cell cycle are ordered and directional; that is, each process occurs in a sequential fashion and it is impossible to "reverse" the cycle.

Checkpoints

 

Cell cycle checkpoints are used by the cell to monitor and regulate the progress of the cell cycle. Checkpoints prevent cell cycle progression at specific points, allowing verification of necessary phase processes and repair of DNA damage. The cell cannot proceed to the next phase until checkpoint requirements have been met.

 

There are several checkpoints to ensure that damaged or incomplete DNA is not passed on to daughter cells. Three main checkpoints exist: the G1/S checkpoint, the G2/M checkpoint and the metaphase (mitotic) checkpoint.

 

p53 plays an important role in triggering the control mechanisms at both G1/S and G2/M checkpoints.

Sorry, quite messy..