exam 9 Flashcards
model organisms
species that are easy to raise in the lab and use in experiments
differentiation
the process by which cells become specialized in structure and function
morphogenesis
the physical processes that give an organism its shape
the development of the form of an organism and its structures
cytoplasmic determinants
maternal substances in the egg that influence the course of early development
induction
most influential are the signals communicated to an embryonic cell from other embryonic cells in the vicinity, including contact with cell-surface molecules on neighboring cells and binding of growth factors secreted by neighboring cells
such signals cause changes in the target cells, a process called induction
determination
refers to the unseen events that lead to the observable differentiation of a cell
tissue specific proteins
proteins found only in a specific cell type and give the cell its characteristic structure and function`
apoptosis
“programmed cell death”
occurs in cells of the mature organism that are infected, damaged, or have reached the end of their functional life span
pattern formation
development of a spatial organization in which the tissues and organs of an organism are all in their characteristic places
positional information
molecular cues that control pattern information
provided by cytoplasmic determinants and inductive signals
nurse cells & follicle cells
supply the egg with nutrients, mRNAs, and other substances needed for development, and make the egg shell
homeotic genes
genes that control pattern formation in the late embryo, larva, and adult
embryonic lethals
mutations affecting a process as fundamental as segmentation would surely be embryonic lethals, mutations with phenotypes causing death at the embryonic or larval stage
maternal effect gene
gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardlesss of the offspring’s own genotype
egg-polarity gene
another word for maternal effect gene:
gene that, when mutant in the mother, results in a mutant phenotype in the offspring, regardlesss of the offspring’s own genotype
bicoid
an embryo whose mother has 2 muant alleles of the bicoid gene lacks the front half of its body and has posterior structures at both ends
bicoid gene is essential for setting up the anterior end of the embryo
morphogens
substances that establish an embryo’s axes and other features of its form
totipotent
a cell with the potential to “dedifferentiate” and then give rise to all the specialized cell types of the organism
stem cell
relatively unspecialized cell that can both reproduce itself indefinitley and, under appropriate conditions, differentiate into specialiszed cells of one or more types
pluripotent
capable of differentiating into many cell types
CC
the first cloned cat
the two cats are not identical due to random X chromosome inactivation
oncogenes
cancer causing genes
proto-oncogenes
code for proteins that stimulate normal cell growth and division
Genetic changes that convert proto-oncogenes into oncogenes
movement of DNA within the genome
amplification of a proto-oncogene
point mutations in a control element or in the proto-oncogene itself
tumor-suppressor genes (+functions+
encode proteins that help prevent uncontrolled cell growth
- repair damaged DNA
- control the adhesion of cells
- inhibit the cell cycle
ras gene
codes for the ras protein, a G protein that relays a signal from a growth factor receptor on the plasma membrane to a cascade of protein kinases. the cellular response at the end of the pathway is the synthesis of a protein that stimulates the cell cycle
this process would not operate unless triggered by the appropriate growth factor
p53 gene
the protein it encodes for is a specific transcription factor that promotes the synthesis of cell cycle-inhibiting proteins
a mutation that knocks out the p53 gene, can lead to cancer
BRCA1 and BRCA2
mutations in the BRCA1 gene were associated with increasing suscpetability to breast cancer
mutations in that gene or the related BRCA2 gene are found in at least half of inherited breast cancers, and tests using DNA sequencing can detect these mutations
virus
infections particle consisting of little more than genes packaged in a protein coat
classification of viruses
their genomes may consist of
- double stranded DNA
- single stranded DNA
- double stranded RNA
- single stranded RNA
capsid
protein shell enclosing the viral genome
depending on the type of virus, the capsid may be rod-shaped, polyhedral, or more complex in shape
capsids are built from a large number of protein subunits called capsomeres
Tobacco mosaic virus
has a helical capsid wiht the overall shape of a rigid rod
adenoviruses
have an icosahedral capsid with a glycoprotein spike at each vertex
influenza virus
have eight different RNA molecules, each wrapped in a helical capsid, and an outer envelope studded with glycoprotein spikes
Bacteriophage
has a complex capsid consistign of an icosahedral head and a tail apparatus
