bios 224 midterm usask

SUBSCRIBE

bios 224 midterm usask

• metazoa

–Answer all animals

2. PARAZOA

–Answer (sponges) lack defined tissues and organs

• closest relative of choanoflagelletes
• shapes are adaptes to maximize the efficiency of water flow

-communicate through Ca++

• diestive is intracellular through phagocytosis

3. EUMETAZOA

–Answer species with differentiated tissues

• choanoflagellates

–Answer first evidence of multicellular communication, form intercellu- lar space between the cell

• evolution

–Answer shaped genotypes and physiology; cause of diversity.

• fertilization

–Answer the action or process of fertilizing an egg, female animal, or plant, involving the fusion of male and female gametes to form a zygote.

• zygote

–Answer a diploid cell resulting from the fusion of two haploid gametes (blas- tomeres); a fertilized ovum. 1 / 3

SUBSCRIBE

• biphasic

–Answer during cleavage, blastomere growth is biphasic.each division results in smaller cells alternating between meiotic phase and DNA phase synthesis phase (no growth stages)

• what stage do blastomeres become polarized

–Answer when the cells have divided into eight cells

• the animal pole

–Answer small rapidly dividing cells gives rise to surface structures and the anteror end of the embryo

• vegetel pole

–Answer slowly dividing cells gives rise to internal structures(gut and posterior embryo) -Differentiates the extraembryonic membranes that protect and nourish the devel- oping embryo (placenta, chorion)

• morula

–Answer a compact mass of cells formed once the zygote has divided into 16-32 blastomeres

• morula expresses desosomes

–Answer

–Answer tight and gap junctions bind cells together an outer sigle layer of epilethal cells separating the embryo from its environment Impermeabilize the mass of cells and create a space in between

• 2 main events that occur on the blastomere membrane at the morula stage 2 / 3

SUBSCRIBE

–Answer compaction expression

• compaction

–Answer the 8 cells embryo express cell adhesion molocules that join cells together making a barrier that impermeabalize the blastomeres surface and control the para cellular transport

• expression

–Answer Na+/K+ ATPase pump Na+ on one side of the embrane morula accumulate fluids starting at a cavition in the embryo

• blastula

–Answer The hollow ball of cells marking the end stage of cleavage during early embryonic development

• blastocoel

–Answer space into which cells will migrate to for, the digestive tract and other structures of the embryo

• blastomeres become deferentially distributed into

–Answer trophoblast –Answer provides nu- trients to the embryo, and develops into a large part of the placenta Inner cell mass(after gastrulation –Answer trophectoderm(contiguos with the ectoderm)) –Answer cells that will form the embryo, first cells to differentiate from the fertilized egg, and form the outer layer of the blastocyst

• gastrulation
• / 3