Lecture 16 - Meiosis

What is a karyotype?

It is a picture of all of the chromosomes inside of a nucleus. Goes from longest to shortest chromosome, then the last are sex chromosomes.

What is the difference between diploid and haploid?

Diploid represents TWO COPIES of the exact same unique chromosome (like chromosome pairs), while haploid represents the number of distinct types of chromsomes present.

What is a cell’s ploidy?

Ploidy represents the number of each type of chromosome present.

All cells first divide through mitosis to make a lot of cells—even ones that will go through meiosis. How do certain cells know if they’re going to become gametes?

They will receieve hormonal signals or tags onto the cells, making them change their pathway and develop into gametes via meiosis.

How are primordial germ cells made?

They are made after fertilization and the maturation of the zygote into an embryo.

PGCs (primordial germ cells) are specialized diploid cells that are set aside in early development, eventually going through meiosis themselves to produce haploid gametes. But until they go through meiosis, like at puberty, they will be dividing mitotically. Females are on day 1!

ALL OTHER CELLS IN AN EMBRYO will go through mitosis, remaining diploid.

JUst finished the 10/30 lecture