Lecture 22 chapter 22 Flashcards
Developmental Genetics
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
Totipotent cell
ability of a single cell to divide and produce ALL of the differentiated cells in an organism
- only in the morula (16 cell)
determination
a cell becomes committed to a particular cell fate (unipotentcy)
Pluripotent
embryonic stem cells originate as inner mass cells within a blastocyst
- can become any tissue in the body EXCLUDING a placenta
multipotency
ability for cells to differentiate
-ex. stem cells
oligopotent
cells with the ability to give rise to only the cells of its lineage
Maternal origin
determination of anterior-posterior and dorsal-ventral axes of the embryo are initiated by mRNA from the mother
Morphogen
a protein that affects the developmental fate of the surrounding region through a concentration gradient
dorsal gene
determination of the dorsal-ventral axis
Bicoid gene, nanos gene, hunchback gene
determination of the anterior-posterior axis
segmentation genes
control the differentiation of the embryo into individual segments
Gap genes
broad region gap differentiation
- hunchback
Pair-rule genes
affect alternate segments
segment-polarity genes
development of individual segments
- affect the polarity of segments
Homeotic Genes in Drosophila
identity of segments
Homeobox genes in other organisms
genes encoding DNA binding proteins
- these proteins usually play a regulatory rule
Hox genes
encode transcription factors that help determine the identity of body regions
- Identity of individual segments
Apoptosis
controlled, programmed cell death
Necrosis
injured cells dying in an uncontrolled manner
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?
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
High concentration of which protein stimulates the development of anterior structures?
a. dorsal
b. toll
c. bicoid
d. Nanos
c. bicoid
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
b. gap genes -> pair-rule genes -> segment-polarity genes
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
d. structures to appear in the wrong place
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
d. carpels, carpels, carpels, carpels
How does death from apoptosis differ from necrosis?
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
How does somatic recombination differ from alternative splicing of RNA?
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
What are some properties of Hox genes
- 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
How many families of Hox genes do humans have?
4 HOXA on chromosome 7 HOXB on chromosome 17 HOXC on chromosome 12 HOXD on chromosome 2
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
Ed. Lewis Christiane Nusslein-Volhard, and Eric F. Wieschaus
in order to clone an animal what needs to be reestablished?
Totipotence
