Class notes Biology (SBIO000)

ANIMAL
DEVELOPMENT
Ms KC MALAKANE

, What you already know…
• How do organisms reproduce themselves?
Asexually – Mitosis
Sexually – Meiosis
• How do sperm cells and egg cells form?
Meiosis
Oogenesis = egg cell
Spermatogenesis = sperm cell
• Why do we use model organisms?
Species chosen due to ease to study in the laboratory

, Figure 12.UN01
INTERPHASE

MITOSIS G1 S
Cytokinesis
Mitosis G2

MITOTIC (M) PHASE




Prophase
Telophase and
Cytokinesis

Prometaphase
Anaphase
Metaphase

, MEIOSIS I
Figure 13.8a




Prophase I Metaphase I Anaphase I Telophase I and
Cytokinesis
Centrosome
(with centriole pair) Sister chromatids
remain attached
Sister Chiasmata Centromere
chromatids (with kinetochore)
Spindle
Metaphase
plate




Cleavage
furrow
Homologous
Homologous Fragments chromosomes
chromosomes of nuclear separate
envelope
Microtubule Each pair of homologous Two haploid
attached to chromosomes separates. cells form; each
kinetochore chromosome
Duplicated homologous Chromosomes line up still consists
chromosomes (red and blue) by homologous pairs. of two sister
pair and exchange segments; chromatids.
2n  6 in this example.