Select all of the correct choices look at the statements...

. Select all of the correct choices. Look at the statements about meiosis. Some of the statements are correct, some are false. Select all of the true statements. For human reproductive cells, there is more DNA in cells at the start of meiosis 1 than there is at the start of meiosis 2. Homologous pairs separate before crossing over occurs If a reproductive cell starts with 6 chromosomes in G1, after meiosis 1 has finished, there are 6 replicated chromosomes at the start of meiosis 2 in each new cell If a reproductive cell starts with 6 chromosomes in G1, after meiosis 1 has finished, there are 6 chromatids at the start of meiosis 2 in each new cell If a reproductive cell starts with 6 chromosomes in meiosis 1, in each new cell there are still 6 chromosomes at the end of meiosis 2 If an organism has a 2n value of 6, after meiosis there can be more than 8 different gametes made due to crossing over and independent assortment. Each single crossover event in prophase 1 of meiosis produces 2 recombinant chromosomes. Each single crossover event in prophase 1 of meiosis produces 4 recombinant chromosomes

Transcript

00:01 Let me want to answer this question.

00:01 Let's talk about the process of myosis.

00:03 In general, remember that myosis is going to start with a deployed cell, with a deploy cell, remember that this cell has already moved to the process of interface.

00:13 For example, let's have this cell.

00:15 This is your guessing cell.

00:17 Imagine this is only one pair of chromosomes, okay? after interface that includes the s phase where dna replication of yours, your cell is going to become like this, something like this.

00:30 Your chromosomes have been replicated, but the chromosome number does not change.

00:34 It means this cell is deployed and this cell is also diploid.

00:38 For example, in humans, this cell is going to have 46 chromosomes and this cell is also 46 chromosomes because this is only one chromosome, this is one single chromosome, this is one single chromosome as similar to here.

00:49 This is one chromosome, this is one chromosome and this is another chromosome.

00:53 So during myosis, one way is going to happen is that you're going to move each of this chromosomes to one cell so you're going to have this and the same here okay but remember that during myosis 1 there is going to be a process called crossing over where there is exchange of blocks of genes so for example this chromosome is going to have one piece that comes from this chromosome and this chromosome is going to have one piece that is from this chromosome during myiosis 2 what is going to happen is that you're going to split these chromosomes in the middle like something like this for example if this is one chromosome, they're going to split it like this.

01:39 And one chromatic, because it is one chromatic, it's going to separate from the other chromatic.

01:42 And once they are detached from each other, now each of them is going to become a chromosome.

01:47 So you're going to have here one chromosome, here another chromosome, another chromosome, and here you have another chromosome.

01:58 So remember that this is one different cell, but these cells are going to be, i'm sorry, they're going to be applied.

02:05 It means they are going to have halts the number of chromosomes to the parental cell, and these cells are going to be also applied, but these cells here are called gametes.

02:16 In females are going to be ovum and in males are going to be sperm.

02:21 So this question says, select all of the correct choices.

02:25 Look at the statements about myosis.

02:27 Some of the statements are correct, some are false.

02:29 Select all of the true statements.

02:32 For human reproductive cells, there is more dna in cells at the start of myost.

02:37 Than there is at the start of myosis 2.

02:40 And this statement number one is true.

02:44 Okay, why? well, because, for example, it is talking about humans.

02:48 So that this 2n is 46.

02:54 It means you have 23 pairs of chromosomes.

02:58 Okay, so you have 23 pairs of chromosomes and your chromosomes are replicated.

03:02 When you have this, for example, this chromosome here, this is one chromosome.

03:06 This is one chromosome.

03:10 But here you have two sister chromatids.

03:12 This is one chromatid and this is another chromatid.

03:16 But there are also known as dna molecules.

03:18 So per chromosome you have two dna molecules.

03:20 Okay, this is one dna molecule and this is another dna molecule.

03:31 So you have two dna molecules per chromosome.

03:34 And as here, you have 46 chromosomes, then you're going to have how many dna molecules? if per chromosome you have two dna molecules here, because they are like this with this shape, and then you're going to have 92 dna molecules at the beginning of myosis 1, 92 dna molecules.

03:55 And what about when you start myosis 2? it means here because this is myosis 2.

04:00 Well, here you have divided the number of chromosomes to half.

04:06 It means you have here 23 chromosomes.

04:10 Okay, so if you have 23 chromosomes, then how many molecules are going to have dna molecules? you're going to have 46 dna molecules.

04:21 So particularly you're going to have more dna molecules at the beginning of myiosis 1 than at the beginning of myiosis 2.

04:26 So option or statement number 1 is true.

04:29 Then let's go for a statement number 2 that says homologous pairs separate before causing over occurs.

04:34 In statement number 2 is false.

04:36 Okay.

04:37 Why? well because, well let's say here false.

04:39 Because for example here you're going to have your cell.

04:44 At the beginning of myosis 1 it means during prophets 1, your cells are your chromosomes, your homologous chromosomes, are going to get very close to each other, and they are going to exchange blocks of genes.

04:54 That is called, that is not crossing over.

04:56 After this, these cells are going to align in the middle of the cell during metaphase, they are going to attach to the spindle, and they are going to align in the middle of the cell.

05:05 After this, during anapace, one of myosis 1, these homologous chromosomes are going to separate, and one is going to move towards this pole, and the second one is going to move towards this pole, because the spindle is going to move towards this pole, move each of them to one different pole.

05:23 But this occurs during anaphy, it means after crossing over.

05:27 This question is, or this statement number two says homologous pairs separate before crossing over occurs, and this is false because it occurs after crossing over occurs.

05:38 Then we have the statement number three that says, if a good productive cell starts with six chromosomes in g1, okay, remember that g1 is a process of the interface.

05:49 Here.

05:50 So you're going to have that a two -end number is going to be six.

05:53 Let's change all of this.

05:55 It's going to be six.

05:57 Hence, this is going to be also six.

05:59 And he says, after myiosis one has finished, there are six replicated chromosomes at the start of myosis two in each new cell.

06:07 This option is true.

06:09 Why? well, because remember that you're going to start myiosis one with a deploy number that is six.

06:14 It means you're going to have a total of six chromosomes.

06:17 It means you're going to have three pairs.

06:18 Okay.

06:19 So imagine you have you have a number.