This is part of a series of videos that you can use to review for the upcoming AP Bio exam.
You can think of it as a guided FRQ, but i'm also going to use it as an opportunity to help
you review some aspects of cell division. I'd say more but it would ruin the fun. Let's start.
This diagram shows the amount of DNA in a dividing eukaryotic cell and its daughter cells over time.
Two questions: 1) What kind of cell division must be occurring? 2) Connect what's happening
in each numbered phase to an event that occurs during cell division. I'm Mr W. I'm the creator of
Learn-Biology.com, the AP Bio learning website. I'm also the creator of BIOMANIA, the AP Bio
exam preparation app. Pause the video, answer the question yourself, then hit "play" to see my explanation.
The diagram you were looking at was about a cell that's undergoing meiosis.
Meiosis is cell division that reduces a cell's chromosome number from diploid (with two
chromosome sets) to haploid (with one chromosome set). Here's the connection between the opening
diagram and what happens during meiosis. At roman numeral I on the left we have the DNA level in
a cell that's about to undergo meiosis. That cell would be a germ cell. In an animal you'd find these
germ cells in the testes of a male or in the ovary of a female. Before that germ cell divides
it replicates its DNA. That results in a cell with twice the amount of DNA, represented by
roman numeral III. Those X-shaped structures in the second cell on the right are doubled
chromosomes consisting of two sister chromatids. Meiosis consists of two cell divisions. During
Meiosis I the cell divides and homologous pairs of chromosomes are pulled apart. Homologous pairs?
Homologous pairs are the matching chromosomes inherited from the mother and the father.
That first cell division creates two haploid daughter cells, but each daughter cell has
doubled chromosomes consisting of those two sister chromatids. The amount of DNA in each daughter
cell is indicated by roman numeral IV. Next each daughter cell divides. That's step 3 on the right
and roman numeral V on the left. As the daughter cell divides, the sister chromatids separate. The
result is 4 haploid daughter cells. You can see those on the far right of the diagram.
on the right side. The amount of DNA in these cells is now half that of the germ cell that started the
process shown at roman numeral VI. I've written a song about meiosis that explains the whole thing.
Here's a short excerpt. Meiosis makes eggs and sperm, it's the same in the robin as
it is in the worm, makes haploid gametes with recombination, meiosis creates variation!
Another meiotic variety creator is metaphase one with homologues at the equator, 'cause how each
pair lines up is random and independent... I suggest you watch the rest of the song.
The link is below. It'll teach you all the phases and everything that happens. And then do two more
things. First, download the BIOMANIA AP bio app. It has hundreds of multiple choice questions
flashcards and FRQs that will get you ready for the AP bio exam. In fact the question we
just discussed comes from one of the FRQ on my app. Think about how well you'd do on the AP exam
if you knew the answers to all those questions. It's for iPhone. it's for Android. The download
is free. An in-app purchase, just $6.99 unlocks all the content. Second, subscribe to my website
Learn-biology.com. Don't forget the dash. For $29.95 you get access to an entire interactive
biology course with tutorials teaching you all of the AP biology content you need to know, You
also get great AP biology exam materials, and you won't believe how much you'll learn. Please leave
me comments telling me what questions you have. If you do that soon i might have time to make a
video with the answer before the AP Bio exam. Also like the video and tell your friends about it.
BIOMANIA, learn-biology.com. For AP BIO review they're the bomb. Interaction's going to help
you learn, and get you that 4 or 5 you want to earn. I'll see you at the next video! Thank you so much!
Meiosis makes eggs the sperm. It's the same in the robin as it is in the worm, makes
haploid gametes, with recombination, meiosis creates variation! another meiotic variety creator is
metaphase one with homologues at the equator because how each pair lines up is random and independent