BIO Ch19

What can be said about the zygote of an animal embryo as it undergoes many cell divisions during the process of cleavage?

After many cell divisions, the embryo will be about the same size as the zygote.

A zygote is a fertilized egg formed by an egg and a sperm. The zygote undergoes many mitotic events as it develops into a solid ball of cells (ie, blastomeres) called a blastula. What changes occur in this early cleavage?

During the initial stages of cleavage, there is a tremendous increase in the number of cells coupled with a decrease in the size of the cells composing the developing organism.

In contrast to the cell cycle of adult somatic cells, the dividing cells of an early embryo lack which cell cycle stage(s)?

G1 and G2

Which genes are expressed in Drosophila after pattern formation along the A/P axis has been successfully established?

Homeotic genes

Egg cells were combined with this cell type to form the cloned sheep named Dolly.

Mammary cells

Plants have special groups of self-renewing cells called

Meristems

Caenorhabditis elegans is an organism with exactly 959 somatic cells. This organism is a(n)

Nematode

Scientists attempted for many years to conduct nuclear transplants but failed. However, geneticists had success in cloning a sheep. They were successful because they:

Picked a cell very early in development.

In the mid-1990s, a sheep (Dolly) was successfully cloned using Somatic Cell Nuclear Transfer. In this technique

The nucleus of an egg was removed and the egg was fused with a body cell.

In mammals, stem cells are capable of producing particular differentiated cell types as well as more stem cells. Classify the different types of cells into the appropriate category based on the degree to which they have become determined.

Unipotent: Sperm stem cells Multipotent: Cells making different blood call types Pluripotent: Embryonic stem cells (ES cells), inner cell mass of a blastocyst Totipotent: The zygote, cells making the embryo and extraembryonic membranes

What can be said about animal and vegetal poles?

When animal pole cells are cultured with vegetal pole cells, some of the animal pole cells become mesoderm.

Is it theoretically possible to generate an entire animal from one somatic cell nucleus?

Yes, because a somatic nucleus contains all the genetic information present in the zygote.