26. Developmental Genetics

Question 1

the area of genetics concerned with the roles genes play in orchestrating the changes that occur during development.

Answer 1

Developmental Genetics

Question 2

the spatial arrangement of different regions of the body. At the cellular level, it is due to the cells’ arrangement and specialization.

Answer 2

Body Pattern

Question 3

signals in the form of chemical substances and other environmental cues that enable a cell to deduce its position relative to other cells.

Answer 3

Positional Information

Question 4

a molecule that conveys positional information and promotes developmental changes.

Answer 4

Morphogen

Question 5

(1) the effects of an inducer in increasing the transcription of a gene; (2) the process by which a cell or group of cells governs the developmental fate of neighboring cells.

Answer 5

Induction

Question 6

the binding of the surfaces of cells to each other or of the surface of a cell to the extracellular matrix.

Answer 6

Cell Adhesion

Question 7

a molecule (e.g., protein or carbohydrate) that acts as a surface receptor and plays a role in cell adhesion.

Answer 7

Cell Adhesion Molecule (CAMs)

Question 8

a gene that functions in governing the developmental fate of a particular region of the body.

Answer 8

Homeotic Gene

Question 9

an animal that has an anteroposterior axis with left-right symmetry.

Answer 9

Bilaterian

Question 10

the process in which a cell or region of an organism adopts a particular fate that will be realized later in development.

Answer 10

Determination

Question 11

transient subdivisions that occur in the Drosophila embryo prior to the formation of segments.

Answer 11

Parasegments

Question 12

morphologically discrete body subdivisions that develop in the embryo of a species such as Drosophila.

Answer 12

Segments

Question 13

an early stage of animal and plant development resulting in an embryo with organized tissue layers and a body plan.

Answer 13

Embryogenesis

Question 14

in animals, the axis that runs from the head (anterior) to the tail or base of the spine or abdomen (posterior).

Answer 14

Anteroposterior Axis

Question 15

in animals, the axis from the upper side of the back (e.g., the spine in humans) to the opposite side (e.g., the stomach in humans).

Answer 15

Dorsoventral Axis

Question 16

in bilaterians, the axis that determines left-right symmetry.

Answer 16

Left-Right Axis

Question 17

in animals, an axis for designating positions on limbs in which the part of the limb attached to the trunk is proximal, whereas the end of the limb is distal.

Answer 17

Proximodistal Axis

Question 18

in animals, a gene whose encoded product is involved in the development of body segments.

Answer 18

Segmentation Gene

Question 19

a gene that is expressed after fertilization.

Answer 19

Zygotic Gene

Question 20

the morphological features that a cell or group of cells will ultimately adopt.

Answer 20

Cell Fate

Question 21

an adjective that was originally coined to describe mutants in which one body part is replaced by another.

Answer 21

Homeotic

Question 22

a mutation that changes a gene product so that it gains a new or abnormal function.

Answer 22

Gain-of-Function Mutation

Question 23

a change in a genetic sequence that creates a loss-of-function allele.

Answer 23

Loss-of-Function Mutation

Question 24

a 180-bp consensus sequence found in homeotic genes.

Answer 24

Homeobox

Question 25

the protein domain encoded by the homeobox and promotes the binding of the protein to the major groove of DNA.

Answer 25

Homeodomain

Question 26

an illustration of the cell division patterns and the fates of any cell’s descendants.

Answer 26

Cell Lineage Diagram

Question 27

a series of cells that are derived from a particular cell by cell division.

Answer 27

Cell Lineage

Question 28

a mutation that alters the timing of expression of a gene and thereby alters the outcomes of cell fates of particular cell lineages.

Answer 28

Heterochronic Mutation

Question 29

describes attributes that are the result of homology. In the case of genes, this term describes two genes that are derived from the same ancestral gene.

Answer 29

Homologous

Question 30

homologous genes in different species that were derived from the same ancestral gene.

Answer 30

Orthologs

Question 31

a group of several homeotic genes located in a particular chromosomal region in vertebrates.

Answer 31

Hox Complex

Question 32

an experimental strategy in which researchers first identify the wild-type gene using cloning methods. The next step is to make a mutant version of the wild-type gene, introduce it into an organism, and see how the mutant gene affects the phenotype of the organism.

Answer 32

Reverse Genetics

Question 33

in the case of diploid species, the condition in which both copies of a gene have been altered to an inactive form.

Answer 33

Gene Knockout

Question 34

the traditional method of genetics research, in which mutant alleles are first identified by their effect on phenotype and then identified at the molecular level.

Answer 34

Forward Genetics

Question 35

a cell that is destined to differentiate into a specific cell type.

Answer 35

Determined Cell

Question 36

a cell that has become a specialized type of cell within a multicellular organism.

Answer 36

Differentiated Cell

Question 37

a domain found in transcription factors that enables them to dimerize and bind to DNA.

Answer 37

Basic Helix-Loop-Helix (bHLH) Domain

Question 38

a type of transcription factor involved in muscle-cell differentiation.

Answer 38

Myogenic bHLH Protein