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StupidProdigy

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Re: VCE Biology Question Thread
« Reply #5700 on: August 17, 2015, 11:06:21 am »
0
When is using index fossils better/more appropriate than using radioisotopic dating techniques? And what kind of age range can index fossils cover overall? The argon dating can cover up to 1.3million years right, could fossils older than this be recovered? Thankyou! :)
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heids

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Re: VCE Biology Question Thread
« Reply #5701 on: August 17, 2015, 12:16:56 pm »
+2
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.)
Aspiringdoc is right - G0 is definitely not the name of the checkpoint, rather the 'resting' phase where cells aren't dividing or preparing to divide.  I think when cells 'fail' the checkpoint, they probably go to apoptosis rather than into G0, but my knowledge is shaky here :(

Brief notes proofread then!  Sorry this has turned into a note-making-teaching-session, I'm just obsessed with neat, organised, and most importantly MINIMISED notes :P  Basically, my idea is this: if you say something in 10 words rather than 20 words in 3 different places (60 words), you're much more likely to learn the 10 words' worth of info easily.  Time spent organising and condensing notes is not wasted time (in fact tbh it was my absolutely top study method), as you're sorting it out logically in your head, rethinking and rewriting stuff, and making connections.  First-draft notes will always be a mess, but at some point you need to sort them (not that I expect perfect notes from a year 9 lol!!)

Spoiler
First, comments on notes layout:
> what are they doing with three spaces between sentences/paras!?
> I assume you've got clear bolded/coloured/big headings in whatever you copied it from, they're ESSENTIAL in notes
> could be more concise all through so you're not wading through unnecessary words:
e.g. The process of mitosis is divided into several stages. The main stages are prophase, metaphase, anaphase, and telophase.
--> the stages of mitosis are: prophase, metaphase, anaphase, and telophase.


Sorry, quite messy.. dw, I didn't mean to pull them apart; they really are great notes, and I promise I had noooooo clue about mitosis until year 12!  You're way ahead, this is brilliant! (and you realise you're going to be so bored, or into 2nd year uni med books, by year 12 right??)

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. Yeah, mitosis is division of the NUCLEUS, cytokinesis (which is NOT part of mitosis) is division of the CYTOPLASM, in other words, division of the whole cell.  They're distinct, mitosis is nothing to do with cell division.  Telophase and cytokinesis occur at the same time.

 

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
sorry, can't stand too much unnecessary info in notes :P

 

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. so here, you should condense your two sentences into one; this is the art of note-making, combining information from multiple sources into one smooth, organised source that doesn't repeat itself ever.  You'll have to rearrange one of the sentences to fit important bits of info from the other.  As you gradually develop your notes and add more sources, rigorously combine anything that's similar or says the same thing in different words or places in your document.

 

Metaphase

 

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

 

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) dw, I didn't even know it existed - it's not important

 

Anaphase

 

Chromosomes split (into sister chromatids) and the sister chromatids move to opposite poles of the cell. this is the 'tug of war' - spindle fibres are like the ropes, and the centrioles the 'teams', who are tugging them apart

 

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. Do you totally get what this is saying? Note-taking lesson #2: never ever ever ever ever ever copy and paste - always put everything in your own words, and if you don't get something either research or delete.

Checkpoints
note-taking tip #3: don't have something of a similar type scattered through your notes.  So if you gather every reference to checkpoints and errors throughout your notes, group them under ONE heading in ONE place, to reduce superfluous info and make it more organised and easy to learn!
 

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.

When is using index fossils better/more appropriate than using radioisotopic dating techniques? And what kind of age range can index fossils cover overall? The argon dating can cover up to 1.3million years right, could fossils older than this be recovered? Thankyou! :)
Noooo man, you're reminding me that it's time to relearn all of Unit 4 AOS 2!  Forgotten everything, was hoping people wouldn't get up to this :(
« Last Edit: August 17, 2015, 12:20:04 pm by bangali_lok »
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StupidProdigy

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Re: VCE Biology Question Thread
« Reply #5702 on: August 17, 2015, 12:51:01 pm »
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Alright, back to AOS 1.. :P How do plasmids become cut open by restriction enzymes? because doesn't bacterial dna have methyl caps on it to stop its own restriction enzymes damaging it whilst fighting against viruses and the like? I'm guessing that you use restriction enzymes from other bacteria that are not naturally present in the bacterium of interest to cut open plasmid, since the plasmid would be resistant to its own restriction enzymes yeah? Thankyou
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TheAspiringDoc

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Re: VCE Biology Question Thread
« Reply #5703 on: August 17, 2015, 04:52:09 pm »
+1
Thanks for the feedback Bangali :)
Yeah, sorry, they actually look really nicely formatted on my computer, it's just that when I copied and pasted from word all the fonts and sizes and colours and spaces were removed/changed..
My thoughts on the repetitiveness of my notes is that I'll learn better if I keep reading the same thing over and over again, just slightly differently worded each time. But I'll definitely take your advice on.
Also, I'd kinda been writing my notes in the same sort of manner that I'd respond to a question in an exam - elaborately.
And when you said telophase and cytokinesis occur at the same time, are you saying that .. well.. they occur at the same time? LOL, sorry, it's just that the way I've seen it taught everywhere is that mitosis happens, then cytokinesis follows.
Oh, and with the cell cycle checkpoints and how I kept referring to them, my thought process was that if I spaced them throughout the other headings, then I'd develop more of an understanding as how they are all interconnected.
Thanks again!!  ;D

heids

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Re: VCE Biology Question Thread
« Reply #5704 on: August 17, 2015, 05:14:10 pm »
+3
@SP, hope someone else can answer, as I'm ignorant here (lol hanging round this site makes me feel so dumb :P).  FYI, this is beyond what you need to know, but not discouraging you from researching.

Thanks for the feedback Bangali :)
Yeah, sorry, they actually look really nicely formatted on my computer, it's just that when I copied and pasted from word all the fonts and sizes and colours and spaces were removed/changed..
My thoughts on the repetitiveness of my notes is that I'll learn better if I keep reading the same thing over and over again, just slightly differently worded each time. But I'll definitely take your advice on.
Also, I'd kinda been writing my notes in the same sort of manner that I'd respond to a question in an exam - elaborately.
And when you said telophase and cytokinesis occur at the same time, are you saying that .. well.. they occur at the same time? LOL, sorry, it's just that the way I've seen it taught everywhere is that mitosis happens, then cytokinesis follows.
Oh, and with the cell cycle checkpoints and how I kept referring to them, my thought process was that if I spaced them throughout the other headings, then I'd develop more of an understanding as how they are all interconnected.
Thanks again!!  ;D
I'm pretty sure that telophase and cytokinesis start happening at the same time - the cell starts dividing as the chromosomes reach opposite ends and nuclear membranes start forming.

I figured that about the formatting, just wanted to check :P

I totally get your logic, but making concise/repetitionless has two massive benefits, TRUST ME:

well a trifle off-topic

1. Highlights exactly what you need to know.
One page of notes looks way easier to learn than 3-5, and it shows exactly what you need to know about each topic rather than it being scattered everywhere.  If you have one sentence to be familiar with, rather than three slightly different ones, it's easier.  And when you step through exactly what you need to know in your head, it's all clearly organised and 'filed' rather than being 'everywhere'.  Eliminating unnecessary words points out exactly what you need to know so you can learn that without wasting your time filtering the useless stuff that gets in the way.  It also helps you easily find whatever info you want.
If you want to keep rereading something, how about you just read the one sheet again and again? :P

2. Makes you synthesise information.
The process of deciding on one ultimate wording and switching sentence orders is insanely valuable because it forces you to digest the information and think about exactly what's going on.  Copy-paste is useless, as it doesn't acknowledge what the words are saying and the overlap between info and how it all fits together.
Similarly, organising your notes to put similar things together actually makes you think about the links between things better.
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TheAspiringDoc

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Re: VCE Biology Question Thread
« Reply #5705 on: August 17, 2015, 05:20:47 pm »
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@SP, hope someone else can answer, as I'm ignorant here (lol hanging round this site makes me feel so dumb :P).  FYI, this is beyond what you need to know, but not discouraging you from researching.
I'm pretty sure that telophase and cytokinesis start happening at the same time - the cell starts dividing as the chromosomes reach opposite ends and nuclear membranes start forming.

I figured that about the formatting, just wanted to check :P

I totally get your logic, but making concise/repetitionless has two massive benefits, TRUST ME:

well a trifle off-topic

1. Highlights exactly what you need to know.
One page of notes looks way easier to learn than 3-5, and it shows exactly what you need to know about each topic rather than it being scattered everywhere.  If you have one sentence to be familiar with, rather than three slightly different ones, it's easier.  And when you step through exactly what you need to know in your head, it's all clearly organised and 'filed' rather than being 'everywhere'.  Eliminating unnecessary words points out exactly what you need to know so you can learn that without wasting your time filtering the useless stuff that gets in the way.  It also helps you easily find whatever info you want.
If you want to keep rereading something, how about you just read the one sheet again and again? :P

2. Makes you synthesise information.
The process of deciding on one ultimate wording and switching sentence orders is insanely valuable because it forces you to digest the information and think about exactly what's going on.  Copy-paste is useless, as it doesn't acknowledge what the words are saying and the overlap between info and how it all fits together.
Similarly, organising your notes to put similar things together actually makes you think about the links between things better.
Okay, thanks.
I'm horrible with condensing my notes - I've written 55 pages off of a 5 pages syllabus and I'm not even done  :-[
On an unrelated, and probably in the wrong forum, side note, does anyone have any opinions about the AN biology units 3&4 trial SACs and examinations book (as in, would I be able to work through it and learn more or less all of the content by next year, despite not really  knowing much at all about biology yet?)
Gracias.

cosine

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Re: VCE Biology Question Thread
« Reply #5706 on: August 17, 2015, 05:39:43 pm »
+1
Alright, back to AOS 1.. :P How do plasmids become cut open by restriction enzymes? because doesn't bacterial dna have methyl caps on it to stop its own restriction enzymes damaging it whilst fighting against viruses and the like? I'm guessing that you use restriction enzymes from other bacteria that are not naturally present in the bacterium of interest to cut open plasmid, since the plasmid would be resistant to its own restriction enzymes yeah? Thankyou

Restriction enzymes recognise specific DNA sequences located on the DNA molecule (plasmids in this case). When this recognition site has been identified, the enzyme cuts the specific sequence. I am assuming that a different restriction enzyme, that recognises a different sequence is placed into bacterias and that cuts out the plasmid, so that the desired gene can be joined on to the plasmid using DNA ligase. I think you are thinking too deep into it, but you are definitely right, good question xD
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Biology24123

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Re: VCE Biology Question Thread
« Reply #5707 on: August 17, 2015, 05:45:45 pm »
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Do macrophages have receptors to determine self from non self? If not, how do they "know" to engulf a pathogen

tashhhaaa

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Re: VCE Biology Question Thread
« Reply #5708 on: August 17, 2015, 05:51:47 pm »
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heyyy

if the diploid number of something is 16, how many chromosomes and chromatids would you have after the S phase?

Simple I know but I'm getting confused (not about the arithmetic though lol)

heids

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Re: VCE Biology Question Thread
« Reply #5709 on: August 17, 2015, 05:51:59 pm »
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Do macrophages have receptors to determine self from non self? If not, how do they "know" to engulf a pathogen
Yup, they do - the difference is that they're not specific, so while they have receptors that can tell something is bad, they don't know what sort of bad it is, they just eat it up regardless.

heyyy

if the diploid number of something is 16, how many chromosomes and chromatids would you have after the S phase?

Simple I know but I'm getting confused (not about the arithmetic though lol)
Diploid = 16
Thus normal cell has 16 chromosomes (2x8)
In S phase, each chromosome replicates to make two identical copies joined at centromere, so two chromatids.
So 16 chromosomes, 32 chromatids.
« Last Edit: August 17, 2015, 05:54:16 pm by bangali_lok »
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BakedDwarf

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Re: VCE Biology Question Thread
« Reply #5710 on: August 17, 2015, 05:53:25 pm »
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heyyy

if the diploid number of something is 16, how many chromosomes and chromatids would you have after the S phase?

Simple I know but I'm getting confused (not about the arithmetic though lol)

16 chromosomes, 32 chromatids (do you need an explanation?)

tashhhaaa

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Re: VCE Biology Question Thread
« Reply #5711 on: August 17, 2015, 05:54:07 pm »
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16 chromosomes, 32 chromatids (do you need an explanation?)

if you feel like it, ty!

BakedDwarf

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Re: VCE Biology Question Thread
« Reply #5712 on: August 17, 2015, 06:01:08 pm »
+4
if you feel like it, ty!

The left chromosome is before the S phase (DNA replication). You can see that it is composed of only 1 DNA molecule.

The right chromosome is after the S phase. You can see that it is composed of 2 DNA molecules (2 chromatids).

Hence, that is why the chromosome number remains the same after the S phase, but each chromosome now has 2 DNA molecules instead of 1.

tashhhaaa

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Re: VCE Biology Question Thread
« Reply #5713 on: August 17, 2015, 06:13:48 pm »
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The left chromosome is before the S phase (DNA replication). You can see that it is composed of only 1 DNA molecule.

The right chromosome is after the S phase. You can see that it is composed of 2 DNA molecules (2 chromatids).

Hence, that is why the chromosome number remains the same after the S phase, but each chromosome now has 2 DNA molecules instead of 1.

thank you!

Biology24123

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Re: VCE Biology Question Thread
« Reply #5714 on: August 17, 2015, 06:18:30 pm »
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Yup, they do - the difference is that they're not specific, so while they have receptors that can tell something is bad, they don't know what sort of bad it is, they just eat it up regardless.

Right. So if their self receptor doesn't bind, they will engulf the pathogen