20. Development

Cytoplasmic determinants __________.

Cells can influence each other's development by a process known as __________.

Instead of developing a head and a tail, an abnormal Drosophila embryo develops two tails. This is most likely due to __________.

Cell differentiation is first observable when __________.

During the process of differentiation, cells __________.

__________ can give rise to any type of cell whereas __________ can give rise to a subset of cell types.

The similarity of the homeobox in many different kinds of organisms is evidence __________.

The highly conserved sequence element present within homeotic genes is called the __________.

What are the two main genetic and cellular mechanisms that underlie differentiation?

Which of the following statements is true?

Which of the following statements is true?

The products of Hox genes __________.

Which of the following occurs when a covalent bond forms? a. Electrons in valence shells are transferred from one atom to another. b. Electrons in valence shells are shared between atoms. c. Partial charges on polar molecules interact. d. Nonpolar molecules are pushed together.by surrounding water molecules.

Which of the following is a valid difference between embryonic stem cells and the stem cells found in adult tissues? a. In laboratory culture, only adult stem cells are immortal. b. In nature, only embryonic stem cells give rise to all the different types of cells in the organism. c. Only adult stem cells can differentiate in culture. d. Embryonic stem cells are generally more difficult to grow in culture than adult stem cells.

A friend is interested in isolating genes that are expressed solely in liver cells but only has access to skin cells. She asks you for advice on whether to start her studies. What will you say?

Scientists have recently developed a process by which a skin cell from a human can be triggered to develop into a human heart muscle cell. This is possible because                   . a. most cells in the human body contain the genetic instructions for making all types of human cells; b. a skin cell is produced when all genes in the cell are expressed; turning off some genes in the cell results in a heart cell; c. scientists can add new genes to old cells to make them take different forms; d. a skin cell expresses only recessive alleles, so it can be triggered to produce dominant heart cell alleles; e. it is easy to mutate the genes in skin cells to produce the alleles required for other cell types

What is the connection between genetic regulatory cascades and the observation that differentiation is a step-by-step process?