Animal Development Lecture

Question 1

Zoology definition

Answer 1

Study of living things

Question 2

All animals have these features (7)

Answer 2

Eukaryotic,
multi-cellular,
heterotrophic,
mobility,
sensory/nervous system,
extracellular matrix,
cell-cell signaling

Question 3

Most common method of discovering ancestry now

Answer 3

Gene sequencing

Question 4

Emergent properties

Answer 4

Descendants having new properties their ancestors did not

Question 5

Indirect vs Direct development (2)

Answer 5

Indirect: Having a larval stage that undergoes metamorphosis to become an adult
Direct: Being born as a small adult that then grows larger without metamorphosis

Question 6

Gamete vs Zygote ploidy

Answer 6

Haploid and Diploid, respectively

Question 7

Spermatogenesis - What process is it? Yields? (6)

Answer 7

Production and maturation of sperm in the testis. It is
1 Spermatogonium –>
1 Primary spermatocyte –>
2 Secondary Spermatocyte –>
4 Spermatids –>
4 haploid spermatozoa

Question 8

Meiosis

Answer 8

Making 4 haploid reproductive cells from 1 diploid spermatocyte or oocyte that are varied genetically, introducing genetic variability into the zygote.

Question 9

Oogenesis (7)

Answer 9

Production and maturation of ova in the ovary.
Cytoplasm is favored in the ovum and unfavored in the 3 polar bodies.
Genetic partitioning is still equal amongst the polar bodies and ovum.
Oogonium –>
Primary oocyte –>
secondary oocyte + polar body –>
ovum + 3 polar bodies.

Question 10

Function of forming a zygote (4)

Answer 10

Restoration of diploid # chromosomes,
Recombination of maternal and paternal genes,
activates the egg to begin development,
sperm contributes a centriole

Question 11

Fertilization initial process (6)

Answer 11

Sperm comes near the surface of the ovum.
The acrosome of the sperm releases digestive enzymes.
The acrosome and ovum membranes fuse.
The sperm enters the ovum’s membrane.
Nuclei fuse to become a diploid zygote.
Blocks to polyspermy occur.

Question 12

Polyspermy and why is it bad? (2)

Answer 12

When more than one sperm penetrates the egg during fertilization.
Polyspermy is bad because excess male genetic material complicates embryonic development and results in death of the zygote.

Question 13

Slow block to polyspermy

Answer 13

The space between the vitelline envelope and plasma membrane of the egg fill with a hard substance, forming a mechanical barrier that prevents sperm from entering the egg. This forms the fertilization membrane.

Question 14

Fast block to polyspermy

Answer 14

Change in electric potential energy of the plasma membrane is done within a few seconds after the first sperm binds to the nucleus of the egg. This shifts from a negative to a positive charge. Sperm cannot fuse to membranes with a positive charge, so polyspermy is avoided this way.

Question 15

Embryonic cells are called (cells that have been cleaved)

Answer 15

Blastomeres

Question 16

Cleavage pattern depends on

Answer 16

How much yolk is present, phylogeny (genetics)

Question 17

Isolecithal, Mesolecithal, Telolecithal eggs

Answer 17

Small amount of yolk that is evenly distributed,
moderate amount of yolk that is concentrated at the vegetal pole,
large amount of yolk, concentrated at the vegetal pole

Question 18

A-V axis

Answer 18

Animal pole is north, Vegetal pole is south

Question 19

Holoblastic cleavage

Answer 19

Cleavage that occurs through the entire egg, occurs in iso/mesolecithal eggs

Question 20

Yolk - consequences of yolk?

Answer 20

A substance that nourishes the embryo but impedes cleavage, leading to cleavage being slowed down or not occurring at all. As cleavage continues, the site where there is no yolk will be cleaved at a far greater rate than the yolky side of the egg, leading to that portion of the egg having more blastomeres. Gastrulation can occur around the mass of vegetal yolk that remains uncleaved. This occurs in frogs.

Question 21

Meroblastic cleavage

Answer 21

Occurs in telolecithal eggs (think chicken eggs), all cleavage occurs at the animal pole of the egg and the yolk remains undivided. This can evolve independently in deuterostomes and protostomes

Question 22

Telolecithal eggs will produce young that …

Answer 22

Hatch at a later developmental stage

Question 23

Three main differences between mitosis and meiosis

Answer 23

ploidy of product (diploid vs haploid),
somatic vs reproductive cell development,
Clone of parent cell vs Genetically variant relative to parent cell

Question 24

Direct development occurs because the egg…

Answer 24

Has lots of yolk, young that hatch a later developmental stage

Question 25

Spiral vs Radial cleavage

Answer 25

perpendicular/parallel is radial, oblique (45 degrees to A-V axis) is spiral

Question 26

Consequence of spiral cleavage

Answer 26

Cells are divided unequally at an oblique angle, leading blastomeres to have differences in cytoplasm

Question 27

Alternative means of providing nutrients to developing young?

Answer 27

The placenta provides nutrients to the developing young

Question 28

Rotational cleavage

Answer 28

An evolution of radial cleavage where there is holoblastic radial cleavage occurring; however, the cleavages are occurring perpendicular relative to each other.

Question 29

Blastula

Answer 29

End of cleavage produces a blastula with a blastocoel cavity

Question 30

Blastocoel

Answer 30

The inner cavity of the blastula/gastrula

Question 31

Gastrula is formed by... and is...

Answer 31

Gastrulation, where the blastopore invaginates the gastrula and forms the archenteron. Formation of the mesoderm and coelom occur as well.

Question 32

Blastopore

Answer 32

First hole of the gastrula

Question 33

Archenteron

Answer 33

Deep to the blastopore, which becomes the gut

Question 34

Mesoderm (3)

Answer 34

Formed by enterocoely or schizocoely. Becomes the muscles, reproductive organs, peritoneum (lining of coelem), skeleton

Question 35

Complete gut

Answer 35

Where the archenteron goes clear to the other side, forming a single gut tube.

Question 36

Ectoderm

Answer 36

outer layer of cells of the gastrula, becomes surface of the body epithelial tissue and nervous system

Question 37

Endoderm

Answer 37

inner layer of cells of the gastrula - forms epithelial tissue lining of the gut tube

Question 38

Germ layer

Answer 38

Two or three basic layers that give rise to the various organs and tissues that arise in the multicellular animal

Question 39

Diploblastic vs Triploblastic

Answer 39

Ectoderm/endoderm formation vs Ectoderm/endoderm & mesoderm formation

Question 40

4 traits of protostome

Answer 40

Spiral cleavage, Schizocoely, Mosaic embryo, Blastopore becomes the mouth, anus forms secondarily

Question 41

4 traits of deuterostome

Answer 41

Radial cleavage, enterocoely, regulative embryo, blastopore becomes the anus, mouth forms secondarily

Question 42

Why are sponges unique?

Answer 42

They do not gastrulate, so they do not have germ layers.

Question 43

Schizocoely

Answer 43

Mesoderm cells arise from the lip of the gastrula to the mesodermal site then rapidly divide to form the mesoderm.

Question 44

Enterocoely

Answer 44

Archenteron cells form a mesodermal pouch while the ectoderm gives this process space, and the mesodermal pouches pinch off into a mesoderm with a coelom.

Question 45

Coelom (2)

Answer 45

Deep to the mesoderm, forms the body cavity

Question 46

Are coeloms different between Schizocoely and Enterocoely?

Answer 46

No, they are functionally identical. The way they are formed is an inherited and explains evolutionary relationships.

Question 47

Regulative vs Mosaic development

Answer 47

Regulative blastomeres can be broken apart and evolve independently. Regulative relies on interactions with neighboring cells. Mosaic blastomeres require all blastomeres to participate in development of the embryo or the development will be terminated.