developmental bio exam 1

nucleus

Houses genomic DNA and where transcription, replication, and ribosome biogenesis

nucleolus

rRNA transcription, processing, and assembly of ribosomal subunits.

ribosomes

translate mRNA transcripts into polypeptide chains. protein synthesis

er

makes, folds, and transports proteins and lipids

rough er

synthesis of membrane proteins, enzymes, and formation of transport vesicles

smooth er

lipid synthesis, detox of liver cells, ca+ storage, carb metabolism in liver cells

golgi apparatus

storage and transport of macromolecules, forms lysosomes

lysosomes

digestion of nutrients, bacteria, and damaged organelles

peroxisomes

detoxify by using h2o2

mitocondria

converts chemical energy of food to atp

cytoskeleton

maintains cell shape and place of organelles

microtubules

facillitate organelle and vesicle transport

actin filaments

control cell shape and function

microtubules

facilitate organelle and vesicle transport

dynein

moves cargo toward cell center, walks across microtubules

kinesin

moves cargo away from cell center, walks across microtubules

microtubule organizing center

Primary cellular site of microtubule nucleation and spatial organization

mitosis

cellular divison that yeilds two identical daughter cells

interphase

G1 (cell growth/metabolism), {S}(DNA synthesis and centrosome duplication), and G2 (preparation for mitosis, error checking).

prophase

cromatin coils into visible chromosomes a, nuclear envelope breaks down, and centrioles move to opposite poles

metaphase

chromatids line up along the equator of the cell, and spindle fibers attach to them

anaphase

chromatids are separated and pulled to opposite poles of the cell

telophase

chromatids uncoil back into chromatin and nuclear envelops reform around chromatin

cytokinesis

cell divides

why are sea urchins considered a model organism that has been used to provide insight into the study of Developmental Biology

produce millions of gametes, easily fertilized, every stage is easily observed, fertillized eggs develop syncrously

what stage is this

interphase

what stage is this

prophase

what stage is this

metaphase

what stage is this

anaphase

what stage is this

telophase

immunocytochemistry

technique used to find proteins or antigens in cells using antibody binding and microscopy

What components make up the cell cytoskeleton?

microtubules, actin filaments, and intermediate filaments

Which protein subunit forms microfillaments, and how are they assembled?

G-actin-ATP monomers undergo nucleation, followed by rapid elongation at the barbed end into (F-actin). ATP hydrolysis follows assembly, leading to treadmilling where monomers add to the barbed end while dissociating from the pointed end.

What protein forms microtubules, and how are they polymerized?

alpha, beta-tubulin dimers bind GTP; GTP-bound dimers self-assemble head-to-tail into linear protofilaments. Typically, 13 protofilaments associate laterally to form a hollow tube

During which phase of the cell cycle do microtubules radiate from the centrosome?

interphase

What is the purpose of using indirect immunocytochemistry in this experiment?

Signal amplification (multiple secondary antibodies bind each primary antibody, yielding significantly higher fluorescence intensity

Which fluorophore is used to visualize microtubules in this experiment?

FITC

What is the funcƟon of the secondary anƟbody conjugated to FITC in this procedure?

Upon excitation at FITC emits green fluorescence allowing spatial localization of microtubule networks

What is the role of Phalloidin-Rhodamine in this experiment?

Phalloidin-Rhodamine directly labels and stabilizes polymerized actin filaments without requiring a primary/secondary antibody complex, emitting bright red

Why is Triton-X-100 used in the procedure?

Triton X-100 is a non-ionic detergent used as a permeabilizing agent.

What is the purpose of using DAPI in this immunocytochemistry procedure?

DAPI emits blue light enabling visual identification and spatial mapping of cell nuclei and condensed mitotic chromosomes.

zygote

single cell embryo when sperm fertilizes egg

blastula

structure formed after early cell divisions of zygote with a hollow sphere of cells

gastrula

where embryo has begun to form 3 germ layers

pluetus stage larva

echinoderm larvae charachterized by larval form

prism stage larva

the embryo assumes a pyramidal/prism shape, and the digestive tract differentiates into mouth, esophagus, stomach, and intestine.

cleavage

Rapid mitotic divisions of the early embryo without intervening cell growth,

archeteron

primitive gut

isolecithal

small amt of yolk evenly distributed in oocyte

holoblastic cleavage

where egg is divided into separate cells

blastomere

An individual cell produced by cleavage divisions of a fertilized egg.

blastocoel

The fluid-filled central cavity enclosed within the blastula wall.

Perivitelline Membrane

The hardened extracellular matrix formed around the egg immediately following fertilization, serving as a mechanical barrier against polyspermy.

fertilization envelope

The elevated protective layer that detaches from the vitelline envelope via cortical granule exocytosis upon sperm entrance.

ectoderm

Outermost germ layer; gives rise to the epidermis, nervous system, neural crest, and sensory organs

endoderm

Innermost germ layer; forms the epithelial lining of the gastrointestinal tract, respiratory tract, liver and pancreas

Notochord

flexible rod derived from axial mesoderm; provides structural support and secretes signaling factors

Dorsal Lip of Blastopore

initiates gastrulation movements and secretes BMP antagonists to induce neural tissue fate

cleavage furrow

groove formed during cytokinesis

blastocoel

fluid filled cavity inside blastula

blastopore

Entry site created by cell invagination during gastrulation

Fast response to prevent Polyspermy

Transient electrical depolarization of the egg plasma membrane. Sperm binding triggers an influx of Na+ ions, shifting membrane potential from -70 mV to +20 mv within seconds, preventing additional sperm fusion

slow response to polyspermy

Intracellular $\text{Ca}^{2+}$ release triggers exocytosis of cortical granules into the perivitelline space, lifting and hardening the vitelline membrane into a fertilization envelope.

blastula

Spherical multicellular embryo stage enclosing a blastocoel cavity

gastrula

after blastula formation of 3 germ layers

animal axis

low yolk density, and rapid cleavage rate; forms ectodermal tissues.

vegetal axis

dense yolk granules; undergoes slower cleavage, giving rise to endodermal and mesodermal lineages.

dorsal axis

back side

ventral side

front side

oocyte

Female germ cell

epiboly

gastrulation where a sheet of cells spreads and thins out to cover underlying cell layers.

invagination

Localized inward folding of a sheet of blastomeres into the blastocoel

ingression

Migration of individual blastomere cells from an epithelial surface layer into the blastocoel interior cavity

involution

nward rolling of an expanding outer cell layer over the rim of an outer pore/lip into the internal cavity

Radial Holoblastic Cleavage

Cleavage pattern where division planes are perpendicular or parallel to the polar axis,

During GastrulaƟon, what are the three germ layers and what do they eventually develop into

ectoderm endoderm and mesoderm

what type of cleavage occurs in sea urchins

radial holoblastic cleavage

Explain how injecƟng a ripe sea urchin causes it to release mature sperm or unferƟlized
eggs.

induces systemic depolarization of visceral smooth muscle and nerve networks, stimulating gonadal contraction and release of mature sperm

Describe the changes of a developing Sea Urchin embryo that has been incubated for 24 hours in lithium chloride

archeteron evaginated outward, projecting a pouch, ectodermal layer is missing

Describe the changes of a developing Sea Urchin embryo that has been incubated 24
hours in sodium thiocyanate

embryo remains hollow sphere, doent undergo gastrulation, outer surface covered in cilia, no archeteron

exogastrulaƟon

archenteron invaginates outward away from the blastocoel

Endogenous Normal Expression Domain of $Wnt8$

establishing the primary endomesodermal signaling center.

How does treatment with 60 mM LiCl beginning at the 2-cell stage affect the normal
paƩern of Wnt8 expression aŌer 24 hours?

wnt8 becomes ubiquitously expanded throughout the entire embryo after 24 hours