L32-43 Test 4 Flashcards
What two capacities are needed for a multi cellular organism to function?
Structural integrity + receive and respond to stimuli = functional units
How do organisms start of simple and become complex?
Gene expression of 4 processes; cell proliferation, specialisation, interactions between cells, movement and migration of cells.
Proteins important for multicellular development:
Cell adhesion and signalling transmembrane proteins;
Gene regulatory proteins
Types of cell anchoring junctions
Cell - cell =adherents (actin and cadherin proteins) and desmosome ( intermediate and cadherin proteins)
Cell - matrix = actin linked ( actin and integrin proteins) and hemidosomes ( intermediate and integrin proteins)
What different dna regulators lead to variation of body plan/ shape / structure
Regulatory proteins - Transcription factors
Non coding regulatory dna - enhancers
How can mutations and developmental errors be useful?
Helps identify pivotal genes and protein production
Large scale screening using mutagenesis and knockout studies
How do differences in protein expression and cell-cell communication manifest into anatomical changes?
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List the germ layers of a fertilised egg
Ectoderm mesoderm endoderm
Is a cells fate decided?
As the 3 regions develop they are more committed to their fate
Describe the two stages of commitment
1- specification - cultured in a neutral environment & differentiate according to its fate. But dif environment = change in fate
2- determination - differentiate according to shape in different environments
What is meant by ‘regionally determined’
Undifferentiated tissue is determined as ‘leg tissue’ but not a specific part - not fully committed
Define induction
One group of cells influence the developmental fate of another
What is inductive interaction
It determines a pattern formation ie what drives cells with the same potential to follow a different path of development
What is the main influence on a cells behaviour?
Environment- determines gene expression
What determines cell fate?
Asymetric division
+(inductive interactions and inductive signals)
HOX genes function
Regulate body plan
what does the wuschel gene do?
maintains meristem in plants
what hormone classes are there in plants?
Auxin, Gibberellins, Cytokinins, Abscisic acid, Ethylene, Bassionsteroids
three phases of plant morphogenesis:
cell differentiation, cell growth, cell division
what two things determine the flowering of a plant?
the environment and specialised growth and differentiation
what is whorl in plants?
different layers of meristem; sepal, petal, stamen, carpel
what controls the pattern of whorl?
selector genes
tissues are composed of what cells?
cells that have common embryonic origin
what is histology the study of?
tissues ( preparation, sectioning, staining, and imaging)
what lines all internal surfaces?
epithelia cells
do epithelia cells have a top and bottom?
yes, they are polarised and have closely associated junctions separated by very little intercellular space
what comprises the ECM
Basel lamina and reticular lamina
list the function of the epithelia tissue
protect, selective barriers, filtration, secretion, absorption, excretion
name the epithelial tissue cell shapes
squamous, cuboidal, columnar, NB
name the epithelial tissue cell layers
simple, pseudostratified, stratified
connective tissue main elements
extracellular matrix, cells
what do all forms of CT (connective tissue) have?
undifferentiated progenitor cells
what are connective tissue derived from?
embryonic mesenchymal cells
what are connective tissue derived from?
embryonic mesenchymal cells
what makes p muscle tissue
myocyes
what are muscle tissues involved in?
generating force - but they have differing characteristics
what are the properties of skeletal muscle?
long cylindrical fibres, range from a few cm to 30 cm , striated , developed from the fusion of 100s of myoblasts, innervated by somatic motor neurones , close to capillary
name the characteristics of smooth muscle cells:
short, central oval nucleus, not striated, large stretch and coil capacity, slower and longer lasting contraction some are autorhythmic - myogenic , two types
what are the two type of smooth muscle cells
visceral and multiunit
how are neighbouring cardiac muscle fibres connected?
by intercalated discs via desmosomes
many – are present to allow the myocardium to contract as one coordinated unit
gap junctions
what does myogenic mean?
signal comes from within the heart to contract
what cell groups are autorythmic in cardiac cells?
pacemaker(san)- under autonomic regulation
conduction system (AVN, bundle of his, bundle branches, purkinje fibres)
what are the two nervous tissue categories?
central nervous system - brain and spinal cord
peripheral nervous system - somatic nervous system & autonomic nervous system
stem cells are:
rare cell types, in a specific niche, that can renew themselves over the lifetime of the organ and produce daughter cells
what is the difference between embryonic SC and adult SC?
embryonic alter the gene expression, adult maintains the SC properties
what are the two essential properties of stem cells?
self renewal and potency
types of stem cells
totipotent, pluripotent, oligopotent, unipotent
do all Basel keratinocytes have potential?
no
what is layer out during embryonic growth with short range signals?
the pattern of organ growth and size
where can stem cells be found?
Basel layer, tips of basal papillae
what there fundamental processes determine organ size?
cell division
cell growth
cell death
these all are part of intercellular programme and extracellular signal molecules that determine mitogens, growth factors, survival factors
when does the vascular process start and what is the next stage?
early embryonic endothelial cell with vasculogenesis and then branches to form angiogenesis
steps are for which process?
Basel lamina breaks down -> endothelial cell migrate into internal space -> endothelia cells proliferate -> development of lumen -> vessel is stabilised by pericyte recruitment
angiogenesis
what does vascular endothelial growth factor trigger?
angiogenesis
what does Notch signalling do?
controls which cells become tip/stalk
comapre phototrophic and auxotrophic bacteria
phototrophic is wild type and does not need a special nutritional factor, Auxotrohic has been impaired and can’t grow in a media without x
what are biosynthetic auxotrophs?
require additional nutrients - effect ability to synthesise AA /nucleotide/vitamine
what are catabolic auxotrophs?
lost ability to catabolise carbon source
what are some housekeeping genes of E. coli?
DNA replication, transcription and translation, cell division, glycolysis
compare ts and cs mutants
ts = temperature sensitive
cs = cold sensitive
what are some examples of mutagens?
chemical or physical agents;
nitrous acid, reactive oxygen species, alkylating agents, intercalating agents, uv light.
what’s the difference between DNA transitions vs transversions?
cytosine (pyrimidine) -> guanine (purine) = transversion
adenine (purine) -> guanine (purine) = transitions
what could cause mismatched base pairs?
error in replication, tautamerisation or damage such as deamination
what is an example of a mismatched base pair?
hypoxanthine (from deamination of adenine )
what are the consequences of point mutations?
some are lethal –> not inherited
some have no effect
genes under control of promoter - can effect sequence or regulation of translation
promotor- can effect transcription (but may have no consequence)
non coding - no consequence or effect on promoter or regulatory sequences
3 types of mutations?
silent, missense, nonsence
what is a frameshift mutation?
an insertion or deletion of a nucleotide
missence vs nonsence vs frameshift?
missence = protein may have genotypic of phenotypic change
nonsence and frameshift = usually detrimental with both genotypic and phenotypic changed
deletions?
remove kilobases and lose several genes / single base pair
– framshift mutation - coding or regulation effected
inversion?
flip of kilo base and several genes or be much shorter - can disrupt but could just invert
consequences of tandem repeats?
overproduction of proteins / evolution of proteins
transposons ?
nucleotide sequence that moves its self around - can disrupt genes
compare reversion and suppression mutations:
1 - change back into original sequence , 2- second mutation that results in original phenotype
intergenic suppression?
2nd mutation in Dif gene - surpasses phenotype = nonsence suppression
what is nonsence suppression?
trna mutation reads past the substitution DNA mutation
why are strains with nonsence suppressors sick?
ignore / suppress stop codon = long proteins - incorrect folding
what is phenotype lag?
phenotype not seen for several generations- eg tonB - mutation = no more made but there are copies still present
what is cross feeding?
block in metabolic pathway - metabolites move between bac = dependent on each other
Ames test is a biological asset
use his auxotroph bacteria -> plate one with chemical one withought –> measure reversions to see if chemical is mutagenic
what is an operon?
a group of genes under the control of the same promotor = genes can be regulated together
what are housekeeping genes?
active all the time eg replication and translation
diauxic growth
used consecutively not simultaneously
lac operon
normally off
induced by allolactose (bound to repressor = on)
transduction meaning
genetic exchange mediated by bacteriophages
T2 phage:
single or double stranded DNA or RNA, genome varies, circular or linear
what influences phage ecology?
characteristics of host, population dynamics, long term evolution
explain the mechanism for competence
ComX recreated - > ComP (receptor) sets off reaction of events = gene expression
therefore competence
name the pheromones released for the mechanism for competence
ComX and CSF (ComP = receptor)
types of phage and their characteristics:
T2 - double stranded genome of 160 KBP - kills E. coli(lytic)
Labda phage - double stranded linear 48KBP – interacts with Ecoli, infection lytic or lysogenic
restrictive modification system :
enzymatic cleavage of phage DNA - enzyme = restriction
host DNA - modified by methylation = not effected
Restriction enzymes- bac and archer –> defence
Lysogenic cycle
attachment - incorporation into genome- passed on
lysogen and prophage?
lysogen= strain of bac carrying lysogenic phage
prophage = phage in lysogenic state
how do plasmids copy?
Rolling Circular replication –> nick -> 3’ acts as primer -> old strand now ssDNA –> enters new bacteria –> circularised and ligated –> replication initiated at single stranded origin of replication –> RNA primers starts DNA polymerase off –> ligate
- 2 plasmids
Her strain?
integrated into genome f plasmid is transferred
why do u want to clone ad/or express a gene?
determine nucleotide sequence
analyse its control sequence
identify mutations
investigate the structure and function of the encoded protein
produce large amounts of encoded protein
make “tagged” versions of the product for ease of purification
investigate the intracellular targeting of the gene product
