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So we know that DNA contains the code that makes you, you ..... But how is it that we all have DNA for the same stuff - eyes, ears etc - but we don't get the same eyes, ears etc?
Step 1 : Lets look at how DNA is stored within our cells - each cell of ours has about 2 meters of DNA in it - if it wasn't stored carefully, life as we know it would be an even more tangled mess than it sometimes is.
So how is it done ..... (Learn)
Step 1 : How did you do - not too tangled any more? Finish the questions on chromosomes and chromatids (or knot) (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
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Step 2 : So DNA codes for proteins and proteins make us - a chunk of DNA that codes for a particular protein = a B - but our genes can be different eg eye colour = a different "trait" - blue, green, brown etc. interestingly regardless of the trait type - the same genes are found in the same places on your chromosomes..... = locus (loci - plural)
Have a look and see (Learn)
Mission 2 : Who can roll their tongues? or not - ho did that happen. Read and answer the questions on Genes, Loci and Alleles. (Learn)
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Yes = now its time for your next Step/Video clip/Challenge/Mission.
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Step 3 : So we all have tongues - yes? (speak up if you don't) Are they all the same?
So why is it that some can roll their tongue and some can't - why is there no half tongue rollers amongst us?
Luckily we are all a little bit different = variation - but what is variation, what types are there where does it come from?
Here are some reminders from the past (Yr 10 and 11) (Learn)
Mission 3 : Read and complete the work on variation (Learn)
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Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Step 4 : Variation comes from the type of reproduction we humans do - must be a good reason for that ..... review what you learned about reproduction types back in Yr 10. (Learn)
Mission 4 : Now complete the work on reviewing the 2 types of reproduction - sexual and asexual. (Learn)
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Yes = now its time for your next Step/Video clip/Challenge/Mission.
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Step 5 : We've learn't about alleles = the different versions of genes that we can have - that causes some of the variation we see.
The only other way to get variation is to get new genes - the only way to get new genes is to change the DNA. This is called a mutation and it is NOTHING like what happens in the movies.
To understand the real happenings of mutations in us, watch the next clips - make sure you understand about the 3 different types of mutation. (Learn)
Mission 5 : Are you a mutant?
Read and complete the work on "Mutation as a Cause of Variation" and "Types of Mutations" (Learn)
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Yes = now its time for your next Step/Video clip/Challenge/Mission.
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Step 6(a) : We humans are the product of Sexual Reproduction ..... We also should know that we have 46 chromosomes in each of our cells - But if our parents have 46 chromosomes too, how do we only end up with 46? Mum (46) + Dad (46) = Us (46). How come we don't end up with 92?
When you look in the mirror you can see bits of your parents in you = you are a blend of both of your biological parents. Somehow we only end up with half of each parents DNA.
In sexual reproduction our bodies make special cells called gametes - each gamete only has 23 chromosomes. So when the male gamete (sperm) meets the female gamete (egg). 23 + 23 =46.
We met cell division before = Mitosis - but this time we don't end up with an exact copy of the original cell.
The special cell division process that does this is called Meiosis. It not only halves the chromosome number, but it also mixes up the genetic material to lead to more variation.
Watch as Meiosis is explained to you - pay attention to how the chromosome number gets halved and how variation happens. (Learn)
Step 6(b) : So how many ways exactly does Meiosis cause variation .... 1. Independent assortment. (Learn)
Step 6(c) : So how many ways exactly does Meiosis cause variation .... 2. Crossing Over. (Learn)
Step 6(d) : So how many ways exactly does Meiosis cause variation .... 3. Segregation (Learn)
Step 6(e) : So how many ways exactly does Meiosis cause variation .... 4. Random Fertilization (Learn)
Mission 6 : This is a mega mission - so go back and rewind/replay as you need to as you work your way through the "Meiosis as a cause of Variation" sections in your workbook. (Learn)
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Yes = now its time for your next Step/Video clip/Challenge/Mission.
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Recap : Mitosis vs Meiosis = here a pair of clips that will help compare and contrast what happens in both these different forms of cell division. (Learn)
Mission 7 : At the end of this section of your workbook you'll find (maybe) a puzzle page or two, a review planning page then a practice copy of the end of topic test. Complete these pages plus don't forget the definition page found at the start of the topic = you'll be ready for the test. (Learn)
Done that? = Share with your teacher.
Yes = now its time for your next Step/Video clip/Challenge/Mission.
No = go back and complete the Step/Video clip/Challenge/Mission please.
Sources of Genetic Variation review questions - you should have completed these by now = we'll go over the answers together. This should give you an idea of where you are at with your understanding of Sources of Genetic Variation = let you know what you need to do the get ready for the practice exam at the end of the whole section on Genetic variation and Change.
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