Lab 12: Mitosis and Cell Division

Flashcards covering key concepts, definitions, and processes related to mitosis and cell division.

Mitosis

The division of the nucleus in eukaryotic cells, resulting in two genetically identical daughter nuclei.

Cytokinesis

The division of the cytoplasm that typically follows mitosis, forming two separate daughter cells.

End result of mitotic cell division

Two genetically identical daughter cells with the same number of chromosomes as the parent (2n).

Importance of mitosis

For growth, repair, replacement of dead cells, and development in multicellular organisms.

Erythropoiesis

The production of red blood cells (~2 million/sec), driven by mitosis in the red bone marrow.

Cell cycle phases

Interphase (G1, S, G2), Mitosis (M), and Cytokinesis.

G1 phase

The cell grows and performs normal metabolic functions.

S phase

DNA replication; each chromosome is duplicated, forming sister chromatids.

G2 phase

The cell prepares for division by synthesizing organelles and spindle components.

Ploidy

The number of sets of chromosomes in a cell (e.g., haploid = 1n, diploid = 2n).

Chromosomes in diploid human cell

46 (2n = 46).

Sister chromatids

Identical DNA copies joined at the centromere, formed after DNA replication.

Centromere

The region where sister chromatids are joined and where spindle fibers attach.

Counting chromosomes in mitosis

By counting centromeres, not chromatids.

Features of prophase

Chromatin condenses into visible chromosomes, centrosomes separate, spindle fibers form, nucleoli disappear.

Features of prometaphase

Nuclear envelope breaks down, chromosomes attach to spindle via kinetochores.

Metaphase

Chromosomes align at the metaphase plate (middle of the cell); each attached to both spindle poles.

Anaphase

Centromeres divide, sister chromatids (now daughter chromosomes) move to opposite poles.

Telophase

Chromosomes de-condense, nuclear membranes reform, nucleoli reappear, spindle disassembles.

Cytokinesis in plants vs. animals

Plants form a cell plate; animals form a cleavage furrow.

Plant cell plate formation

Golgi-derived vesicles carrying cell wall materials fuse at the cell center.

Centrioles in plant cells

No, they organize spindle fibers without centrioles.

Structure unique to animal cell division

The cleavage furrow formed by actin microfilaments.

Visible regions in root tip slide

Root cap, zone of multiplication, zone of elongation, and zone of differentiation.

Location of mitosis in root tips

In the zone of multiplication (meristematic region).

Magnification to observe mitotic stages in plants

400x and optionally 1000x with oil immersion.

Specimens to view mitosis in animals

Whitefish blastula or roundworm uterus.

Mitotic index

% of cells undergoing mitosis = (mitotic cells / total cells) × 100.

Blastula and mitosis study

Rapid cell division occurs during early embryonic development.

Role of microtubules in mitosis

Form spindle fibers that move chromosomes by attaching to kinetochores.

Chromosome number and species complexity

Because genetic content and regulation, not just chromosome count, determines complexity.