Chapter 21: Genes and Development

Question 1

What is genetic equivalence?

Answer 1

-all cells of of an organism contain the same DNA, and thus the same genes
-every cell has the information to make any other cell in the organism

Question 2

What is the evidence of genetic equivalence in plants?

Answer 2

if you remove a branch, stem, or roots from a plant, cells can re-differentiate to reform these parts

Question 3

What is the evidence of genetic equivalence in animals?

Answer 3

ability to clone animals

Question 4

What is differential gene expression?

Answer 4

different cells use the same set of genes in different ways to become specialized

Question 5

What are the 3 stages of cell differentiation?

Answer 5

1. committed
2. determined
3. differentiated

Question 6

Describe the committed stage.

Answer 6

cell follows particular path of specialization; weak + easily reversible

Question 7

Describe the determined stage.

Answer 7

cell is locked into becoming a particular cell type (not yet fully specialized)

Question 8

Describe the differentiated stage.

Answer 8

cell has clear cut identity

Question 9

What causes differential gene expression in the cell?

Answer 9

regulatory transcription factors

Question 10

How does cell division contribute to development of an organism?

Answer 10

• highly controlled location, timing and extent
  
  • mitosis promoting factor
  • cell cycle checkpoints
  • social controls (signaling from other cells)
• signals can induce division, differentiation, movement, shape changes, or cell death

Question 11

What are the mechanisms of cell differentiation?

Answer 11

1. cytoplasmic determinants
2. induction

Question 12

What are cytoplasmic determinants?

Answer 12

• molecules that are asymmetrically located in the cytoplasm of the cell
• causes one cell to divide into 2 dif types

Question 13

What is induction?

Answer 13

• one cell receives a signal that another doesn’t
• causes that cell to differentiate on a different path

Question 14

What is apoptosis?

Answer 14

tightly controlled self destruction (predominant in animals)

Question 15

What are morphogens?

Answer 15

establish anterior posterior axis

Question 16

What are hox genes?

Answer 16

specify body parts that will develop from segments

Question 17

What is pattern formation?

Answer 17

events that determine the spatial organization of cell in an embryo

Question 18

Describe the bicoid gene.

Answer 18

produced at anterior region and diffuses towards posterior (creates concentration gradient)

Question 19

A mutant with no bicoid will have…

Answer 19

two posterior structures (tails)

Question 20

Describe three main aspects of hox genes.

Answer 20

1. encode TFs that trigger development of certain body parts
2. location on the chromosome matches the pattern of expression
3. evolutionarily conserved

Question 21

What are homeotic mutations?

Answer 21

one body part substituted in place of another