Lecture 2: Cell cycle and mitosis; Embryogenesis and Animal Development (Campbell 12.1-12.2)

Flashcards covering embryogenesis, the cell cycle, and mitosis concepts from the lecture notes.

What are the three cellular processes guiding embryogenesis?

Cell division (mitosis), cell differentiation, and morphogenesis.

What is the role of mitosis in the animal life cycle?

To produce genetically identical diploid somatic cells for growth, development, and tissue maintenance while preserving chromosome number.

In a diploid cell with 2n chromosomes, what is the chromosome and chromatid status during G1?

There are 2n chromosomes, each consisting of a single chromatid.

What happens to chromosomes during S phase of the cell cycle?

DNA replication occurs; chromosomes exist as two sister chromatids per chromosome (still 2n overall).

What is the chromosome status during G2 phase?

2n chromosomes, each with two sister chromatids; centrosomes replicate.

List the stages of mitosis in order.

Prophase, Prometaphase, Metaphase, Anaphase, Telophase, followed by Cytokinesis.

What occurs during Prophase?

Chromosomes condense; centrosomes move to poles; mitotic spindle forms; nucleolus disappears.

What occurs during Prometaphase?

Nuclear envelope breaks down; spindle microtubules attach to kinetochores.

What occurs during Metaphase?

Chromosomes align on the metaphase plate between the two poles.

What occurs during Anaphase?

Sister chromatids separate and are pulled to opposite poles; cell elongates due to nonkinetochore microtubules.

What occurs during Telophase and Cytokinesis?

Nuclear membranes form around two sets of chromosomes; cytoplasm splits to form two daughter cells.

What are the two main types of microtubules in the mitotic spindle and their roles?

Kinetochore microtubules attach to chromosomes and move them; nonkinetochore microtubules push poles apart to elongate the cell.

What is embryogenesis?

Development of a functional embryo from a single-celled zygote.

Name the main stages from zygote to organogenesis.

Fertilization → Cleavage → Blastula → Gastrulation → Organogenesis.

In a diploid spider mite cell with 2n=4, how many chromosomes are present before and after DNA replication?

Before replication: 4 chromosomes; after replication: 4 chromosomes but 8 chromatids (each chromosome has two sister chromatids).

What is a metaphase plate?

An imaginary plane at the cell equator where chromosomes align during metaphase.

During anaphase, what happens to centromeres and sister chromatids?

Centromeres split and sister chromatids separate, moving to opposite poles.

What is the function of kinetochores?

Protein structures at the centromeres where kinetochore microtubules attach to move chromosomes.

What drives cytokinesis in animal cells?

A contractile actin ring forms a cleavage furrow that pinches the cell membrane to split the cell.

What is the order of the eukaryotic cell cycle phases?

G1 → S → G2 → M.

What does 2n vs n denote?

2n = diploid, n = haploid.