development Flashcards
germ lines
cells have different proteins and eventually develop into own type of cell (skin, muscle, bone, etc.)
processes that occur in animal development
controlled cell division, cell specialization, cell heredity, morphogenesis
what is cell specialization?
expression of different genes
what is cell heredity?
once cell starts to express specific genes, all cells formed from that cell will only ever develop into specific cell types
morphogenesis
spatial arrangement of specialized cells
control over cell division
most eukaryote cells do not have the ability to divide.
growth factorsand how it may be produced
these proteins must be present to complete cell cycle.
growth factors may be produced externally or internally to allow cells to pass checkpoints
in eukaryotes what stage are most specialized cells in.
in the 1st part of interphase G1
production of growth factors depends on…
conditions in and around the cell
membrane proteins main functions in development
carry signals, cell recognition.
membrane proteins involved in cell recognition and signalling can intereact with growth factors
cancer results when…
cells dividing too much. proteins producing a signal for cell division without a growth factor (no checkpoints)
example of skin cells with growth factors
divides until surrounded by other cells, if cells are removed, growth factors are produced and cell division occurs
when does cell specialization occur
through the turning off and on (expression) of genes
order of cell specialization
undifferentiated cell———> germ layer——> tissue cells with similar function—–> speicalized cell
3 processes that lead to specialization: chromatin (DNA and histones) packaging
adding methyl (CH3) to histobes causes chromatin to condense preventing transcription
adding acetyl (COH3) causes chromatin to unravel
3 processes that lead to specialization: single gene activation and when this happens
inactivation of X/Y chromosomes
whole chromosome condensed preventing transcription
maternal or paternal chromosomes are deactivated at random
happens when zygote has started to divide. all daughter cells have some chromosome deactivated
results in regions of organism with different alleles expressed (dog with 2 colours)
methylation and cytosine prevents…
and during DNA replication…
methylation and cytosine prevents transcription
methylation states are copied to new DNA strands
2 forms of heredity within organisms
- genetic code
- cell state (contents of cytoplasm and inactivated genes- epigenetic)
what does inactivation genes result in?
cell heredity and increasing levels of specialization
once a cell enters a level of specialization, it cant change into anything else
for gamete production is the inactivation of genes removed?
yes
cell specialization in plants
only regions have cells that divide
these cells can develop into any type of specialized cell because genes have not been inactivated.
(only happens during animal development)
gene expression
in prokaryotes
genes involved in related functions are grouped by operons
regulatory proteins can bind other molecules. this binding affects their ability to attach to the operator region of a gene
operator
binds with regulatory protein, preventing transcription
genes involved in building organic molecules are associated with…
repressible operons.
-gene expression is blocked when the product of the metabolic pathway is present
genes involved in breaking down organic molecules are associated with
inducible operons
ex: lactose operon presence allows for transcription to occur
2 types of feedback control in metabolic activity
feedback inhibition (quick)
gene expression (slow)
- gene expression in eukaryotes
contents of cytoplasm of fertilized egg not equally distributed
after cell division, daughter cells have different proteins and RNA’s resulting them to express different genes
most genes are in an active state
many__________ may be required for transcription to take place.
these_______ intereact with ________ near the gene
regulatory proteins
proteins, DNA
some of the non coding DNA is involved in the…
regulation of gene expression
oncogene
gene that causes cancer
4 processes resulting in oncogene
gene moved (translocated) to a region of the chromosome that is more expressed
gene duplicated producing more cell growth factor
mutations to promotor region, resulting in increased transcription
mutation to gene that make it more effective in promoting cell division
controlling gene expression at the mRNA level
most DNA on chromosomes dont code for amino acids.
some of the non-coding DNA is used to make microRNA’s
some microRNA’s bind with mRNA, degrading it or block its trabslation.
