Definitions Flashcards

Question

gamate

Answer 1

a specialized reproductive cell through which sexually reproducing parents pass chromosomes to their offspring (a sperm or an egg

Answer 2

the complete DNA sequence of an individual organism

Answer 3

a series of rapid biotic cell divisions following fertilization in many early embryos - it divides the embryo without increasing its mass

Answer 4

a cleavage-stage cell resulting from mitosis

Answer 5

a fertilized egg with a diploid chromosomal complement in its zygote nucleus generated by fusion of the haploid male and female pronuclei

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vertebrate embryo of 16-64 cells - proceeds the blastula/ blastocyst stage

Answer 7

a process involving movement of the blastomer of the embryo relative to one another resulting in the formation of three germ layers of the embryo | hey buddy

Answer 8

a stage of the embryo following gastrulation that contains the three germs layers that will interact to GENERATE THE ORGANS OF THE BODY

Answer 9

DNA sequence that controls the efficiency and rate of transcription from a specific promoter

Answer 10

the process by which one cell population influences the development of neighbouring cells via interactions at close range

Answer 11

the ability of cells or tissue to respond to a specific inductive signal

Answer 12

substances that, by their differing concentrations differently specify cell fates

Answer 13

a state in which a cells developmental fate has become restricted even though it is not yet displaying overt changes in cellular biochem and function, it is more limited to what it will become but won't necessarily look different - two stages of commitment: 1. specification 2. determination

Answer 14

first stage of commitment of cell or tissue fate during which the cell or tissue is capable of differentiating autonomously (by itself) when placed in a neutral environment with respect to the developmental pathway - at this stage cell commitment can still be reversed

Answer 15

- predominates in most invertebrates -

Answer 16

- predominates in vertebrates - is the process by which cells achieve their respective fates through interactions with other cells - cleavage divisions are variable and fate assignment is flexible - massive cell rearrangements and migrations precede or accompany specification - known as regulative development: if a blastomere is lost the embryo can compensate

Answer 17

- mostly in insects - the interaction of nuclei and transcription factors which eventually result in cell specification, take place in a common cytoplasm

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the second and IRREVERSIBLE stage of cell or tissue commitment in which it is capable of differentiating autonomously even when placed into a non-neutral (such as when transplanted into another region of the embryo)

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- greek holos = complete - a cell division (cleavage) pattern in the embryo in which the entire egg is divided into smaller cells - frogs and mammals

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- greek meros = part - the cell division (cleavage) pattern in zygotes containing large amounts of yolk where only a portion of the cytoplasm is cleaved.

Answer 21

folding of a sheet (epithelium) of cells (like the indention of a soft rubber ball when it's poked) - type of cell movement during gastrulation (step 1)

Answer 22

inward movement of an expanding outer layer so that it spreads over the internal surface of the remaining external cells - type of cell movement during gastrulation (step 2)

Answer 23

migration of individual cells from the surface to the embryos interior. - individual cells become mesenchymal (separate from one another) and migrate independently - epithelial to mesenchyme transitions (EMT) - type of cell movement during gastrulation (step 3)

Answer 24

splitting one cellular sheet into two more or less parallel sheets. - results in the formation of a new (additional) epithelial sheet of cells - type of cell movement during gastrulation (step 4)

Answer 25

movement of epithelial sheets (usually ectodermal cells) spreading as a unit (rather than individually) to enclose deeper layers of the embryo. - can occur by cells dividing, changing shape or by several layers of cells intercalating into fewer layers (all three mechanisms usually used at same time)

Answer 26

the primitive gut of sea urchin blastula - formed by invagination of the vegetal plate into the blasteocel

Answer 27

a phenomena wherein cells intercalate to narrow the tissue and at the same time move it forward (think of traffic on a highway where several lanes merge into one) - basically the archenteron becomes a long thin tube - this involves cell shape change and cell migration - cells become thinner and intercalated

Answer 28

animals which the blastopore will become the anus - "mouth second"

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animal which the blastopore will become the mouth - "mouth 1st"

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-yolk free cytoplasm found at the animal pole (clear island of no yolk) -aka cytoplasmic cap -where meroblastic divisions occur, leading blastodisc to turn into blastoderm -after fertilization, wave of ca cause contraction of actin cytoskeleton which moves the region to animal Summary: Small region at the animal pole of the telolecithal eggs of fish and chicks, containing the yolk-free cytoplasm where cleavage can occur and that gives rise to the embryo. -after cortical granule reaction, the chorion (vitelline envelope) lifts from the surface of the egg (makes fertilization envelope) -cytoplasmic streaming due to actin myosin contractions (fromwave of ca) causes NON YOLKY CYTOPLASM at animal hemisphere

Answer 31

an egg in which the yolk is unevenly distributed, with most of the yolk concentrated at one pole of the egg,(vegetal pole), while the other pole, the animal pole, contains less yolk and more cytoplasm.

Answer 32

-a distinct cell layer of early blastoderm layer between the blastodisc (non yolk part that divides mesoblastic divisions, specificlly the deeo cells) and the yolky layer -occur during mid blastula transition. (cleavage 10) -nuclei of yolksynticial layer comes from the margin cells of blastoderm -induce mesoderm

Answer 33

-found in early blastoderm stage -outermost cell layer of blastoderm -during epiboly, these cells spread over the yolk -deep cells intercalate with these superficial cells to form this during gastrulation -eventually joins to yolk synticial layer

Answer 34

-cells located between the enveloping layer (EVL) and the yolk synticial layer -cell layer in early blastoderm

Answer 35

happens halfway in epiboly thickening thorughout the margin part of Epibolizing blastoderm is called the germ ring germ ring has two layers 1) epiblast 2) Hypoblast Epiblast is the syperficial layer, upper layers of cells

Answer 36

inner layer of the germ ring -internalizing vells at blastoderm margin also forms this

Answer 37

-intercalation of the epiblast and the hypoblast on the dorsal side (forms this shield) -thickening on the dorsal side (accumulation of cells on one part of germ ring) -homologous to drosal lip of amphibians -epiboly pauses while this shield forms -once blastoderm margin covers entire egg, the shield converges anteriorly forming precursor to notochord and precordal plate (like blastopore lip in xeno) Important for: dorsal ventral axis -can convert lateral and ventral mesoderm (blood and connective tissue) into dorsal mesoderm (notochord and somites) -can cause ectoderm to become neural rather than epiderm

Answer 38

-mitochondrial cloud -associated with maternal mrna locatlization -visible in early stages of growth

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-special type of chromosome found in growing oocytes -transform into lampbruhs form during diplotene stage of meiosis -come about since zebrafish are highly transcriptionally active during growth phase

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-hole in vitelline envelope that sperm gies through during fertilization -comes about since one follicle cell v(what secretes the envelope) is in contact with the envelope

Answer 41

amniotes/mammals

Answer 42

-unique for mammalian cleavage -mediated by e cadherin -occur at 8 cell stage -blastomeres become tightly oacked because they changed adhesive properties (more e cadherin make them bind more) -cell cell junctions are formed inner cells have gap junctions which allow small molecules to move between them outter cells have tight juctions, which prevent inner cells with exchanging things with outside environment

Answer 43

occurs in 16 cell morula (goes from 8 cell to 16) -small group of internal cells that will produce the embryo

Answer 44

in the 16 cell morula -the large group of external cells (external to the inner cell mass) -these cells will become the trophectoderm -these cells do not contribute to formation of actual embryo but form the CHORION (outer layerthat surrounds embryo, which ensd up forming placenta) they are the external cells that also bind the embryo to the uterus (task to make these is important for mammal development so that it can stick to the uterine wall (not elsewhere) once at uterine wall, these have L-selectin on surface of cells to bind to endometrium sulfated polysaccharides of the uterine

Answer 45

-this differentiation is the first differentiation event of mammalian embryogenesis

Answer 46

Cavitation: A process whereby the trophoblast cells secrete fluid into the morula to create a blastocoel. The membranes of trophoblast cells pump Na+ ions into the central cavity, which draws in water osmotically, thus creating and enlarging the blastocoel. As the blastocoel forms through cavitation, the ICM becomes positioned on one side of the trophoblast cells – this type of blastula is known as a blastocyst.

Answer 47

Cavitation forms the enlarging of the blastocoel... as it forms, the inner cell mass gets positioned on one side of the trypoblast cells, Cthis type of blastula is known as blastocyst zona pellucida preents the blastocyst from sticking to tube wall (not uterine), eventually the blastocyst releases proteases to digest this and hatches from the zona pellucida, allowing it to bind to the uterine wall

Answer 48

cells of inner mass form two layers, another name for this inner cell mass is bilaminar germ disc this is one, seperates into two parts: 1) Embryonic epiblast: forms embryo proper 2)cells that line amniotic cavity: aminotic fluid fills here

Answer 49

Second part of inner mass cell (bilaminar germ disc) delaminate to form a layer facing the blastocoel

Answer 50

inner mass cells derives 2 layers... epiblast and hypoblast these two together are the bilaminar germ disc (once the inner mass cells form into these two, both of them together is no longer called hte inner mass cell but called this)

Answer 51

a part of the epiblast (whic is a part of the bilaminar germ disc)... this is the part that turns in to the embryo (embryo proper) theother part of the epiblast turns into amniptic cavity

Answer 52

other part of the bilaminar germ disc, this is the part that fills with amniotic fluid that is a shock absorber and prevents dehydration

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-original tryphoblasts form a layer called this -originally adheres to endrometrium layer

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-cells that are able to grow by nuclear division without cytokinesis form this -furthers progression of embryo into uterine wall by digesting uterine tissue -original tryphoblast cells turn into this thing

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Cytrotrophoblasts secrete paracrine factors that attract maternal blood vessels, and maternal vasucular tissue is DISPLACED by trophoblasts... forming this

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Ammonites/chicks

Answer 57

vertebrates who's embryos form an amnion

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"water sac" - a membrane enclosing and protecting the embryo and its surroundings amnionic fluid - water sac provides protection from desiccation and mechanical shock

Answer 59

essential for gas exchange

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stores waste and helps mediates exchange

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- occurs in bird eggs - cleavage only occurs in the blastodisc and doesn't extend into the yolk - blastodisc: a small amount of cytoplasm sitting atop a large yolk

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a 1-cell thick transparent layer of deep cells from the centre of the blastoderm which shedded and died

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upper layer of area pellucida (forms part of the area pellucida)

Answer 64

a space that sits between the blastoderm and the yolk

Answer 65

surrounds the area pellucida and is the peripheral ring that does not shed deep cells - its opaque

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in-between thin layer of cells

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delaminate (divided) area pellucida cells which are primary hypoblasts/polyinvagination islands - forms hypoblast - found beneath epiblast

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the pushing of the hypoblast islands anterior due to deep yolky cells of posterior margin migrates anterior beneath the epiblast

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a crescent shaped cluster of cells beneath the epiblast at the posterior margin

Answer 70

signalling center that plays key role in the formation of primative streak and hypoblast

Answer 71

the first morphological sign of gastrulation in amniotes that first arises from a local thickening of the epiblast at Koller's sickle - defines AP axis of avian embryo - goes from posterior to anterior -

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the depression formed within the primitive streak where migrating cells pass into the deep layers of the embryo

Answer 73

a funnel shaped depression anterior end of the primitive streak - the frog organizer and the fish shield

Answer 74

ectoderm : neuraltion and neural tube neuralation: formation of the cns and the formation of neural tube from the neural plate

Answer 75

region of dorsal ectoderm so specified to become neural ectoderm Low levels of BMP caues it to be this High levels of BMP cause it to be epidermins Intermediate levels: cause ectoderm to be neural crest cells

Answer 76

neural plates folds into a tube in a process called neuralation -precursor of the CNS

Answer 77

Primary: FORMS FROM EPITHELIUM -invagination and rolling up of a sheet of cells that seperate as a tube from the overlying epithelium Steps: 1) FOlding of neural plate 2) elevation of plate 3)Convergence of folds: making the neural groove 4)Closure of neural groove to make the neural tube Three products of primary neuralation: 1) Epidermis 2) neural tube 3) neural crest cells Presence of N cadherin instead of E cadherin drive cell adhesion needed for neural tube closure and seperation of neural cells from epidermis Secondary: FORMS FROM MESENCHYME building a new neural epithelium from mesenchymal cell condensation and subsequent cavitation. (note: mesenchyme to epithelial transition) -more common in tail Both can occur in the same animal, complete neural tube forms when both are combined look at pic o slide6

Answer 78

Neural crest cells: become many cell types including the PNS and melanocytes intermediate levels of BMP cause ectoderm to be this -form where the neural tube and epidermis meet in primary neuralation -sometimes called fourth germ layer Cranial neural crest cells: bone plus neurons, glial etc Trunk neural crest cells: no bones but has rest

Answer 79

Function: MOTOR COORDINATION

Answer 80

Failure to close the posterior neural tube results in this Failure to close the neural tube is a problem... open ends of the neural tube are reffered to as anterior and posterior neuropores... What helps prevent: Follate vitamins (B9: folic acid) Not understood well but there is a folate binding protein expressed on dorsalmost area of neural tube at time of fusion Found this out cause follate receptors in mouse cause more likely neural tube failure to close posterior end in mouse Foods can also cause disruption to the follate receptors ie fungal contaminants ( act. as a teratogen) the mycotoxin is called fumonisin

Answer 81

early:Snail2 transcription factor down-regulates cadherin-6B, a cadherin enriched in premigratory neural crest cells. Early cells follow a ventral pathway through the anterior part of each sclerotome (chunks of mesoderm that will eventually form vertebral cartilage); they will become sensory and sympathetic neurons, adrenomedullary cells and Schwann cells. Late:Late cells follow a dorsolateral pathway to become melanocytes

Answer 82

pigment cells

Answer 83

- develops from the dorsal most region of mesoderm - chordamesoderm forms it

Answer 84

- forms the somites which will form the axial skeleton (vertebrae, ribs), all skeletal muscle and the dorsal dermis, tendons, joints and dorsal aortic cells - somatic mesoderm

Answer 85

segmental block or ball of mesoderm formed for paraxial mesoderm adjacent to notochord - forms most but not all the axial skeleton (vertebrae, ribs), all skeletal muscle, and the dorsal dermis, tendons, joints, and dorsal aortic cells - gives rise dermomyotome and sclerotome

Answer 86

- derived from somite forming the late somites dermatome which forms the dermis and myotome which forms the skeletal muscle

Answer 87

- the second the derivative from from somite forming the late somites syndetome which makes the tendons and sclerotome which forms the vertebral body (bones and cartilage, ribs, dorsal aorta cells

Answer 88

a circular bulge that will form a further limb - formed by the proliferation of mesenchyme cells from the somatic layer of the limb field lateral plate mesoderm (the limb skeleton precursor cells) and form the somites (the limb muscle precursor cells)

Answer 89

underlying mesoderm - Wnt/Fgf10 found here

Answer 90

- found along the distal margin of the wing bud (the boundary between dorsal and ventral) - critical signalling centre for limb development - induced by mesoderm cells secreting Fgf10 - maintained through positive feedback loops after established where Wnt/Fgf8 is signalling in the ectoderm and Wnt/Fgf10 is signalling in the underlying mesoderm - maintains the underlying mesoderm in a plastic proliferative state – enabling elongation of the limb in proximal/distal axis - maintains expression of molecules responsible for the anterior-posterior limb axis (thumb to pinkie - interacts with proteins that specify anterior/posterior as well as dorsal ventra

Answer 91

- signals from the limb bulb that signal development of the limb along the anterior-posterior axis - Sonic Hedgehog (Shh)