Block 4 Review Flashcards
The ectoderm is the precursor for what structures?
nervous system and epidermis
The precursor of gut, lung, and liver is the what?
endoderm
The precursor of muscles and connective tissue is the what?
mesoderm
What part of the DNA provides instructions for producing a multicellular animal?
non-coding regulatory DNA
DNA contains regulatory elements that serve as binding sites for what?
gene regulatory proteins
In most organisms, coding sequences in DNA are ___
similar
What type of DNA sequences provide uniqueness to organism?
non-coding sequences
Cells make developmental decisions long before they show any outward signs of ____
differentiation
cells that are fated to develop into a specialized cell type despite changes in environment are called ____
determined
cells that can change rapidly due to alterations in environment are called ____ _____
completely undetermined
cells that have some attributes of a particular cell type but can change with environment are called ____
committed
Most important environmental cues are signals from where?
neighboring cells
Define inductive signaling
induction of a different developmental program in select cells in a homogeneous group leading to altered character
Few cells closest to the source take on induced character. Why?
signal is limited in time and space
What are the two types of signals in inductive signaling?
short range: cell-cell contacts
long range: substances that can diffuse through the extracellular medium
A long range inductive signal that imposes a pattern on a field of cells is called what?
a morphogen
morphogens exert graded effects by forming ___ of different concentrations
gradients
Each concentration of morphogen can direct the target cells into a different ____ pathway
developmental
What are morphogen gradients formed by? (2 things)
localized production of an inducer; localized production of an inhibitor
A positive feedback system stars off ___ and ___
homogenous and symmetrical
true or false?
The environment of a positive feedback system imposes weak asymmetry
true
Positive feedback involving intracellular signals also make cells ___
polarized
Broken asymmetry is “___ or ___” phenomenon
all or nothing
true or false?
postive feedback is irreversible
true
Asymmetry is generated by ___ feedback
postive
What is phase 1 of neural development?
different cell types develop independently at different locations in embryo according to local program and are unconnected (genesis of neurons)
What is phase 2 of neural development?
axons and dendrites grow out along specific routes setting up a provisional but orderly network of connections between various parts of the system (outgrowth of axons and dendrites)
What is phase 3 of neural development?
continues into adult life, connections are adjusted and refined through interactions with distant regions via electric signals (refinement of synaptic connections)
Tip of axon/dendrite has an irregular, spiky enlargement called what?
growth cone
Growth cone crawls through surrounding tissue, trailing the axon or dendrite behind. One of the growth cones starts migrating fast and develops __-____ proteins which form an ___
axon-specific; axon
growth cone behavior is dictated by its ___ machinery?
cytoskeletal
growth cones throw out ___ and ___
filopodia and lamelopodia
Monomeric GTPases __ and ___ control the assembly/disassembly of actin filaments, which control movement of growth cone
Rho and Rac
growth coins exploit two major cues to find their way. What are they?
extracellular matrix environment; chemotactic factors
Netrin, Slit, and Semaphorin are examples of what?
chemotactic factors
netrin is attractant; slit and semaphorin are repellents
axonal growth cone reach target cells, halt, communicate and make ___ with target cells
synapses
What regulates which growth cones synapse and where?
signals from target tissue
Target cell produces limited amount of ____ factors needed for survival
neurotrophic
Activity dependent synaptic remodeling depends on what?
electrical activity and synaptic signaling
“Neurons that ___ together, ___ together”
fire; wire
Name layer of skin:
made of epithelial cells; forms the outer covering of skin; creates water barrier; continuously repaired and renewed
epidermis
name layer of skin:
second layer; rich in collagen; provides toughness
dermis
name layer of skin:
fatty subcutaneous layer
hypodermis
Starting from the outermost cell layer, name all of the cell layers/types
squame flaking off; keratinized squames; granular cell layer; prickle cell layers; basal cell layer; basal lamina; connective tissue of dermis
epidermis is a stratified layer made of ___
keratinocytes
the basal cell layer is attached to what?
basal lamina
Prickle cells have numerous desmosomes that attach tufts of ___ filaments
keratin
granular cells are sealed together to form what?
waterproof barrier
granule cell layer forms a boundary between inner metabolically active strata and outer dead epidermis. true or false?
true
true or false?
outermost layer is called squame, flattened dead cells densely packed with keratin but with no organelles
true
are basal cells dividing cells?
yes
time for birth of cell in basal layer to shedding from surface is how long?
1 month
Stem cells provide an indefinite supply of fresh ___ cells to epidermis
differentiated
The following are characteristics of what:
not terminally differentiated; can divide without limit; undergo slow division; when divide, give rise to 1 cell with stem cell characteristics and the other with the ability to be differentiated
stem cells
True or false?
stem cells are not tissue specific
false, they are
to maintain a steady pool of stem cell production, precisely ___% of daughter cells must remain as stem cells
50
Explain divisional asymmetry
asymmetric division may create 2 cells, one with stem cell characteristics and another with factors that give it the ability to differentiate
Explain environmental asymmetry
division makes 2 identical cells but environmental may influence/alter 1 cell
true or false?
in regards to regulation of epidermal stem cells, contact with basal lamina controls numbers of stem cells
true
loss of contact with basal lamina triggers what?
terminal differentiation
proliferative potential directly correlates with expression of what? (helps mediate adhesion to basal lamina)
B1 subunit of integrin
Mixed with stem cells are other cells that divide frequently. what are these cells called?
transit amplifying cells
True or false?
transit amplifying cells can divide an unlimited amount of times
false; duh. that would be cancer. divide for a limited number of times
The free surfaces of cilia on olfactory receptors have ___ receptor proteins
odorant
what type of receptors are olfactory receptors?
G protein coupled
Odorant receptor genes:
___ in a dog
___ in humans
1000; 350
Each neuron expresses only one gene, enabling the cell to respond to only one what?
class of odorant
____ features of the odorant recognized by the receptor
structural
The activation of the G protein that is coupled with the olfactory receptor leads to an influx of sodium and calcium into the the cell which generates what?
action potential that is sent to brain
what are the relay stations in the brain called?
glomeruli
where are glomeruli located?
olfactory bulbs - one on each side of the brain
how many glomeruli are in one bulb in a mouse brain
1800
individual olfactory neurons survive for how long?
only a month
Regeneration of olfactory receptor cells is one of the only few instances of adult ____
neurogenesis
Epidermal cells: A matrix of ___ and ___ made into a sheet lined with a thin membrane of silicone on the outside can form an artificial matrix
collagen and glycosaminoglycan
___ and ____ ___ from patient’s tissue migrate towards artificial skin and reform the connective tissue underneath
fibroblasts; blood capillaries
What are the two places in the brain where stem cells are prevalent?
ventricles: migrate to olfactory bulb
hippocampus: involved in learning and memory
cultures established from dissociated brain tissue show ____ which are clusters of neural stem cells
neruorspheres
neurospheres produce both ___ and ___ cells
neurons and glial cells
neural stem cells grafted into adult brain have remarkable ability to adjust their ___ and ___ to match their location
behavior and function
grafted cells produce neurons that connect with host neurons and give rise to ____ that secrete ___ ____
glial cells; myelin sheath
Retinoid acid causes stem cells to develop into what?
adipocyte, neuron, or smooth muscle cell
IL-3 and IL-1 cause stem cell to develop into what?
macrophage
fibroblast growth factor causes stem cell to develop into what?
astrocytes and oligodendrocytes
The ability of a cell to give rise to all cells of an organism, including embryonic and extra embryonic tissues is called what?
totipotency
The ability of a cell to give rise to all cells of the embryo and subsequently adult tissues is called what?
pluripotency
The ability of a cell to give rise to different types of a given lineage is called what?
multipotency example: blood stem cells can become red or white
Founder stem cells define the size of large final structures. If the adult organ needs to be renewed, founder stem cells can divide as stem cells giving rise to one daughter stem cell and a set of cells that have a set number of what?
transit amplifying divisions
The immortal stand hypothesis ensures integrity of the genome because the template is never lost. true or false?
true
Embryonic stem cells are derived from the ___ stage of embryo
blastocyst
embryonic stem cells give rise to disorganized growths called ____
teratomas
what are some limitations of embryonic stem cell usage?
tissue rejection; genetic instability
IPS : inducing pluripotent stem cells involves what?
supplying transcription factors to a somatic cell to trick it into thinking its a stem cell
Describe somatic cell nuclear transfer
Take an egg cell and remove nucleus. Fuse it with a somatic cell. Stimulate cell division - blastocyst forms with DNA from somatic cell. Extract inner cell mass and now you have cultured pluripotent embryonic stem cells
a pro erythroblast contains a large ___ but loses it completely when it differentiates into a mature RBC
nucleus
bone marrow has capacity to become multiple tissues. true or false
true
Mesenchymal stem cells and adipose tissue are in bone marrow. What do they differentiate into?
not blood like hematopoietic stem cells.
MSC can become other types of tissue
