mcb 3219 final (exams 1 and 2 material)

What is the vitelline envelope?

A species-specific egg surface layer that sperm must recognize and bind to

What is chemotaxis in fertilization?

Attraction of sperm to egg via chemicals like resact

What triggers the acrosome reaction?

Contact between sperm and egg

What happens during the acrosome reaction?

Calcium influx triggers exocytosis and release of bindin to penetrate egg layers

What is bindin?

A protein that mediates sperm binding to the egg

What is polyspermy?

Fertilization of an egg by multiple sperm

What is the fast block to polyspermy?

Membrane depolarization due to Na+ influx and K+/Cl- changes

What is the slow block to polyspermy?

Calcium wave triggers cortical granule exocytosis forming fertilization envelope

What do cortical granules do?

Release enzymes that modify sperm receptors to prevent further binding

Is calcium necessary for cortical granule release?

Yes

What happens if RNA synthesis is inhibited after fertilization?

Proteins can still be made from maternal mRNA stores

What is cleavage?

Rapid mitotic divisions after fertilization

What is holoblastic cleavage?

Complete cleavage (e.g.

What is meroblastic cleavage?

Incomplete cleavage (e.g.

What determines cleavage type?

Yolk distribution

What is MBT (midblastula transition)?

Point where zygotic transcription begins and cell cycle slows

What triggers MBT?

Nucleocytoplasmic ratio

What is fate mapping?

Tracking what cells become using markers

Difference between fate and potency?

Fate = what a cell normally becomes; potency = what it could become

What is determination?

When a cell is committed to a specific fate regardless of environment

What are cytoplasmic determinants?

Localized factors that influence cell fate

What is genomic equivalence?

All cells contain the same genome but express different genes

What experiment showed genomic equivalence?

Nuclear transplantation (Gurdon frog cloning)

What is gene amplification?

Replication of specific genes (e.g.

What are nucleolar organizers?

Chromosomal regions that produce rRNA

What techniques measure protein abundance?

Western blot

What technique measures RNA levels?

RT-PCR

What are maternal effect genes?

Genes where mother's genotype determines offspring phenotype

What is bicoid?

Anterior morphogen in Drosophila

What is nanos?

Posterior morphogen that inhibits hunchback

What is a morphogen?

A molecule forming a gradient that determines cell fate

What are gap genes?

Define large embryonic regions

What are pair-rule genes?

Define parasegments (even-skipped

What is even-skipped?

Expressed in odd parasegments

What is cortical rotation?

Movement of cytoplasm after fertilization establishing dorsal side

What is the Nieuwkoop center?

Region that induces dorsal structures

What is β-catenin’s role?

Establishes dorsal axis

What happens without β-catenin?

Embryo becomes ventralized

What pathway regulates β-catenin?

Wnt signaling pathway

What does GSK-3 do?

Degrades β-catenin (ventral side)

What is the Spemann organizer?

Region that induces a secondary body axis

What does the organizer form?

Notochord and prechordal plate

What are the three germ layers?

Ectoderm

What does ectoderm form?

Skin and nervous system

What does mesoderm form?

Muscle

What does endoderm form?

GI tract

What induces mesoderm formation?

Signals from vegetal cells

What molecules inhibit BMP4?

Chordin

What does BMP4 do?

Promotes epidermis

What is neural induction?

Conversion of ectoderm into neural tissue

What structure induces neural tissue?

Notochord

What is neurulation?

Formation of neural tube

What causes spina bifida?

Failure of posterior neural tube closure

What causes anencephaly?

Failure of anterior neural tube closure

What does Shh do?

Ventralizes neural tube

What does BMP do in neural tube?

Dorsalizes neural tube

What are Hox genes?

Genes that determine anterior-posterior identity

What is posterior dominance?

Posterior genes suppress anterior genes

What is an anterior transformation?

Posterior segment takes on anterior identity

What is a posterior transformation?

Anterior segment takes on posterior identity

What are somites?

Segments forming axial skeleton and muscle

What do somites become?

Dermis

What is dermomyotome?

Forms dermis and muscle

What is sclerotome?

Forms axial skeleton

What is syndetome?

Forms tendons

What is MyoD?

Master regulator of muscle differentiation

What is Myf5?

Muscle determination factor

What happens if MyoD and Myf5 are knocked out?

No muscle forms

What is myogenin?

Involved in muscle differentiation

What is desmin?

Marker for skeletal muscle

What is 5-azacytidine?

Demethylating agent that activates gene expression

What is clonal analysis?

Testing if cells are determined by observing colony types

What indicates determination in clonal analysis?

Colonies of one cell type

What indicates multipotency?

Mixed cell types in colonies

mammals and sea urchin cleavage

holoblastic, isolecithal

amphibian cleavage

holoblastic and mesolecithal

fish, reptiles, birds cleavage

meroblastic and telolecithal

insect cleavage

meroblastic and centrolecithal