AP Biology: Cellular Reproduction

Provide the differences between cell reproduction in eukaryotes and prokaryotes.

Eukaryotes: have linear chromosomes, have different means of cellular reproduction. Prokaryotes: only reproduce through fission, have circular DNA.

List the steps of prokaryotic (binary) fission.

First, the circular DNA replicates. Then, the size of the cell increases. Next, 2 copies of DNA separate. Finally, cytokinesis occurs.

List the steps of the most common way eukaryotic cells reproduce.

First, (linear) DNA gets duplicated. Next, the distribution of the DNA (in the form of chromosomes) occurs (mitosis). Finally, cytokinesis splits the two cells apart.

List all the phases of the cell cycle.

Interphase; G1 (G0), S, G2, Prophase, Metaphase, Anaphase, and Telophase.

What is the purpose of winding up DNA into chromosomes?

Chromosomes have evolved to package DNA during cell reproduction.

What form does DNA take throughout the phases?

G1: two strands of chromatin (diploid pair), S-G2: four strands of chromatin (two diploid pairs), Prophase-Metaphase: chromosomes, Anaphase-Telophase: 4 strands of chromatin.

Define kinetochores (spindle fibers).

The cytoskeletal elements responsible for moving the chromosomes during mitosis

Define centrometres.

The middle of a chromosome.

Define chromatids.

One of the two identical halves of a chromosome.v

What occurs in G1?

This is when the cell matures and organelles begin replicating, DNA is in chromatin (the chromatin is dissolved).

What occurs in S?

This is when chromatin replicates (chromatin is dissolved).

What occurs in G2?

The cell prepares for mitosis, spindle fibers begin forming (during S-G2, centrioles duplicate and mitochondria divide).

What occurs in prophase?

Chromatin condenses into chromosomes (early prophase) and becomes moveable (late prophase). The centrosomes are at opposite poles of the cell (early). The spindle fibers connect to the centromeres and the nuclear envelope dissolves (late).

What occurs in metaphase?

The chromosomes line up at the spindle equator.

What occurs in anaphase?

The chromosomes separate at the centromere. Polar microtubules (cytoskeletal elements) stretch the cell longer (first part of cytokinesis).

What occurs in telophase?

The daughter chromosomes are at separate poles. Polar microtubules start to rebuild the nuclear envelope, chromosomes go back to chromatin, and chromosome movement ends.