Lecture 22 chapter 22

Question 1

Developmental Genetics

Answer 1

study of the regulatory processes that control of cell growth, differentiation and morphogenesis, which is the process that gives rise to tissues, organs, and anatomy.

• the study of cell fate, cell determination and differentiation

Question 2

Totipotent cell

Answer 2

ability of a single cell to divide and produce ALL of the differentiated cells in an organism
- only in the morula (16 cell)

Question 3

determination

Answer 3

a cell becomes committed to a particular cell fate (unipotentcy)

Question 4

Pluripotent

Answer 4

embryonic stem cells originate as inner mass cells within a blastocyst
- can become any tissue in the body EXCLUDING a placenta

Question 5

multipotency

Answer 5

ability for cells to differentiate

-ex. stem cells

Question 6

oligopotent

Answer 6

cells with the ability to give rise to only the cells of its lineage

Question 7

Maternal origin

Answer 7

determination of anterior-posterior and dorsal-ventral axes of the embryo are initiated by mRNA from the mother

Question 8

Morphogen

Answer 8

a protein that affects the developmental fate of the surrounding region through a concentration gradient

Question 9

dorsal gene

Answer 9

determination of the dorsal-ventral axis

Question 10

Bicoid gene, nanos gene, hunchback gene

Answer 10

determination of the anterior-posterior axis

Question 11

segmentation genes

Answer 11

control the differentiation of the embryo into individual segments

Question 12

Gap genes

Answer 12

broad region gap differentiation

- hunchback

Question 13

Pair-rule genes

Answer 13

affect alternate segments

Question 14

segment-polarity genes

Answer 14

development of individual segments

- affect the polarity of segments

Question 15

Homeotic Genes in Drosophila

Answer 15

identity of segments

Question 16

Homeobox genes in other organisms

Answer 16

genes encoding DNA binding proteins

- these proteins usually play a regulatory rule

Question 17

Hox genes

Answer 17

encode transcription factors that help determine the identity of body regions
- Identity of individual segments

Question 18

Apoptosis

Answer 18

controlled, programmed cell death

Question 19

Necrosis

Answer 19

injured cells dying in an uncontrolled manner

Question 20

Scientists have cloned some animals by injecting a nucleus from an early embryo into an enucleated egg cell. Does this outcome demonstrate that genetic material is not lost during development? Why or why not?

Answer 20

No, it does not prove that genetic material is not lost during development, because differentiation has not yet taken place in an early embryo. The early embryo would likely still contain all its genes and could therefore giver rise to a complete animal. The use of specialized cells, such as a cell from an undder, does not prove that genes are not lost during development because if they were lost there would be no cloned animal

Question 21

High concentration of which protein stimulates the development of anterior structures?

a. dorsal
b. toll
c. bicoid
d. Nanos

Answer 21

c. bicoid

Question 22

The correct sequence in which the segmentation genes act is:

a. segment-polarity genes _> gap genes -> pair rule genes
b. gap genes -> pair-rule genes -> segment-polarity genes
c. segment-polarity genes -> pair-rule genes -> gap genes
d. gap genes -> segment-polarity genes -> pair-rule genes

Answer 22

b. gap genes -> pair-rule genes -> segment-polarity genes

Question 23

Mutations in homeotic genes often cause?

a. the deletion of segments
b. the absence of structures
c. too many segments
d. structures to appear in the wrong place

Answer 23

d. structures to appear in the wrong place

Question 24

What types of flower structures would you expect to see in whorls 1 through 4 of a mutant plant that failed to produce both class A and class B gene products?

a. Carpels, stamens, stamens, carpels,
b. sepals, sepals, carpels, carpels,
c. sepals, sepals, sepals, sepals
d. carpels, carpels, carpels, carpels

Answer 24

d. carpels, carpels, carpels, carpels

Question 25

How does death from apoptosis differ from necrosis?

Answer 25

apoptosis is controlled programmed cell death
- DNA degraded,, nucleus and cytoplasm shrink, and the cell is phagocytized without leakage of cellular contents

necrosis is messy, and due to injury or lysing of cells
- cell swells and bursts causing an inflammatory response

Question 26

How does somatic recombination differ from alternative splicing of RNA?

Answer 26

somatic recombination takes place though the rearrangement of DNA segments, so each lymphocyte has a different sequence of nucleotides in its DNA.

Alternative splicing takes place through the rearrangement of RNA sequences in pre-mRNA; there is no change in the DNa that encodes the pre-mRNA.

The generation of antibody diversity requires both the somatic recombination of DNA sequences and the alternative splicing of the pre-mRNA sequences

Question 27

What are some properties of Hox genes

Answer 27

• their protein product is a Transcription factor
• contain DNA sequence known as the Homeobox which when expressed can bind DNA
• in many animals, the organization of the Hox genes of the chromosome is physically the same as the order of their expression along the anterior-posterior axis of the developing animal

Question 28

How many families of Hox genes do humans have?

Answer 28

4
HOXA on chromosome 7
HOXB on chromosome 17
HOXC on chromosome 12 
HOXD on chromosome 2

Question 29

Who identified and classified 15 genes of key importance in determine the body plan and the formation of body segments of the fruit fly D. melanogaster. They were awarded the Nobel prize in physiology or medicine in 1995

Answer 29

Ed. Lewis Christiane Nusslein-Volhard, and Eric F. Wieschaus

Question 30

in order to clone an animal what needs to be reestablished?

Answer 30

Totipotence