Sister chromatids are: a) the result of crossing over. b) identical molecules of DNA resulting f

Sister chromatids are: a) the result of crossing over. b)...

Key Concepts

Sister Chromatids

Sister chromatids are identical copies of a chromosome that are created during the DNA replication process. They are connected by a centromere and are separated during cell division to ensure that each new cell receives an exact copy of the genetic material.

DNA Replication

DNA replication is the biological process by which a cell duplicates its DNA before it divides. This process produces sister chromatids, ensuring that each daughter cell has a complete set of genetic information.

Homologous Chromosomes

Homologous chromosomes are pairs of chromosomes in a diploid organism, where each chromosome comes from one parent. Although they carry the same types of genes, they are not identical because they may have different alleles, and they participate in recombination during meiosis.

Crossing Over

Crossing over is a process that occurs during prophase I of meiosis, where paired homologous chromosomes exchange segments of genetic material. This mechanism contributes to genetic diversity but is distinct from the formation of sister chromatids.

Mitosis and Meiosis

Mitosis and meiosis are types of cell division. Mitosis results in two genetically identical daughter cells by separating sister chromatids, while meiosis produces gametes with half the number of chromosomes, involving additional processes such as homologous recombination and crossing over.

Transcript

00:02 All right, so on this figure, i'm showing you on the process of mitosis and we discuss what are system chromatid.

00:08 And then we go back to the question.

00:09 So first of all, we are looking at a somatic cell, so it's going through a process called mitosis.

00:18 So you're looking at four different chromosomes inside the cell.

00:22 And then during the asphys of interface, these chromosomes replicate itself.

00:28 Now, as you can see, you have four chromosomes in total.

00:31 But each chromosome actually has two copies.

00:35 So they look like an x shape.

00:36 So obviously this is one copy and this is another copy and they're linked together by a structure called centrumia in the middle.

00:44 So remember the two black dots, meaning there are two chromosomes, but since they are linked together now, they are called sister chromatids.

00:53 All right? so at this point, they are actually linked together.

00:58 Now remember, sister chromatids are identical because there's nothing crossing over or exchange of genetic materials happen.

01:08 So it's just plain replication.

01:11 So on this figure, it shows you after the mitosis actually starts, these four chromosomes line up in the middle of the metaphase plate inside of the cell.

01:23 And then at the enderface, now the centrumia in the middle actually separates.

01:28 Now the two cystochromatite separates.

01:31 As you can see, one moves towards one side and then the other move towards the other side.

01:39 And the two system comma separates into two different chromosomes.

01:41 So temporarily in anina phase, you see eight chromosome inside of one cell.

01:46 And remember again, these two chromosomes that were looking at, they're identical...

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