AFF Lab Reproduction and Development

asexual

... involves no fusion of sperm and a secondary oocyte but usually requires mitosis followed by cytokinesis

sexual

... involves meiosis to make gametes

gametes

... is a specialized haploid cell that must fuse sperm and secondary oocyte together to form a diploid zygote

easier, no need for mate, high production number

asexual reproduction advantages

minimum genetic variation

asexual reproduction disadvantage

genetic variation

sexual reproduction advantage

complex processes of sperm and egg and the necessity for anatomical and behavioral features to bring gametes together

sexual reproduction disadvantages

binary fission, budding, fragmentation, regeneration

methods of asexual reproduction

binary fission

a parent cell mitotically divides into 2 cells of equal size

euglena and sea anemones

binary fission organisms

budding

a new individual grows out from the body of the parent organism and either splits from the parent or stays attached to form large colonies

yeast, flat worms

budding organisms

fragmentation

the body breaks into several pieces and each piece develops into a new individual

sponges, jelly fish

fragmentation organisms

regeneration

an injury occurs and two or more individuals are formed as a result

starfish

regeneration organism

activated and deactivated at certain times

the developmental program is encoded in the genetic material, but no one yet understands exactly how certain genes are...

gametogenesis

haploid gametes are formed by potential parents

fertilization

the gametes fuse to form the diploid zygote which is thus activated to perform metabolic reactions and start dividing

parthenogenesis

egg development in some animals can be brought about by mechanisms other than sperm entry

temperature change, increase in ca+, gamete is diploid so fertilization is not needed

examples of parthenogenesis

haploid parthenogenesis

used to determine sex in ants, bees, and wasps as fertilized eggs are diploid and result in females; unfertilized eggs are haploid and result in males

cleavage/blastulation

rapid cell division with little or no protein synthesis, so there is no increase in size of the egg mass

progressively smaller cells

cleavage/blastulation results in... with each division

specific tissues and organs

the three germ layers formed in gastrulation will subdivide into masses of cells that will become...

organogenesis

the very early formation of various organs in the embryo

morphogenesis

organogenesis involves localized... that may cause cells in an area to fold, split, condense and move

neuralation

the formation of the neural tube that is the basis for the nervous system

differentiation and rapid growth of the embryo

Organogenesis is followed by further...

environment the animal lives, the location of embryonic development, and the stages in the life cycle of the species.

the physical characteristics of an egg are related to the...

moist environment

animals that live in aqueous habitats release their secondary oocytes into the...

coordinated signals and behavioral modifications

The resulting external fertilization of animals in aqueous environments depends upon...

gelatinous coats... amounts of yolk

These eggs of animals in aqueous environments generally have... that protect the egg from physical and bacterial injury and varying... to supply the embryo with sufficient nutrients until hatching

their survival is lower

animals that live in aqueous environments generally produce numerous zygotes since...

oviduct

in land animals internal fertilization typically takes place in the...

cooperative behavior and complicated copulatory structures

the internal fertilization in land animals requires... for delivery of sperm in close proximity to the secondary oocytes and for storage and transport of eggs

delivery of sperm close to the secondary oocyte and for storage and transport of eggs

the internal fertilization in land animals requires cooperative behavior and complicated copulatory structures for...

protection against physical injury and desiccation

land animals that release their

eggs for development outside the mother have eggs covered by harder shells that provide...

exchange oxygen and carbon dioxide with the environment, have enough energy and raw materials to develop to an advanced stage, and have a way of disposing of nitrogenous wastes

The embryo of land animals that release their eggs must...

4 extraembryonic membranes

inside the eggs of land animals that are released... grow out from the embryo and surround it

gas exchange, waste storage and nutrient procurement

the 4 extraembryonic membranes of the eggs of land animals function in...

no outer shells or jely coats

the land animals that carry the developing embryo inside the female's uterus contains...

surround the embryo and also form the placenta

When the egg implants in the uterus, the extraembryonic membranes...

placenta

a highly vascularized organ that brings extraembryonic capillaries close to the female's capillaries where nutrients and wastes are exchanged

increased parental care and greater protection

the land organisms generally produce fewer zygotes that have higher survival rates due to...

oviparous

organisms lay eggs outside the female's body where the young wil hatch

amphibians, birds, fish, insects, and reptiles

oviparous examples

viviparous

organisms give birth to live young that have been nourished in the uterus by blood via the placenta

viviparous example

mammals

ovoviviparous

organisms incorporate both mechanisms by retaining fertilized eggs in the oviduct where the embryos are nourished by egg yolk, then after hatching within the uterus, the young are then delivered alive

sharks and snakes

ovoviviparous examples

the animal hemisphere and vegetal hemisphere

the secondary oocyte in amphibians consists of...

contains melanin granules

the animal hemisphere/pole is dark grey or brown since it...

yellow

the vegetal hemisphere/pole lacks melanin granules; this yolk- filed portion is...

absorbs water and swells

when the secondary oocytes of amphibians are released into water, the gelatinous covering that was produced by the oviduct...

vitelline membrane

Sperm have to eat away at the ... before one sperm can penetrate the secondary oocyte and fertilize it

the vegetal hemisphere

once fertilization has occurred, the cell rotates in such a way that the heavier portion of the cell (...) is downward

zygote

once fertilization has occurred, the one cell stage is called the...

grey crescent

An indication that fertilization has occurred is the appearance of a light grey area called the... between the vegetal and animal poles

pinching of the plasma membrane at the penetration site

the grey crescent forms on the side opposite to sperm penetration because there is a ... and this exposes the lighter grey cells on the other side

cleavage furrow

the beginning of the first cleavage is marked by the appearance of a..., which is a groove on the animal pole of the zygote and gradually extends toward the opposite side dividing it into two cells

4 cell stage

the next cleavage occurs at right angles to the first and produces the...

polar/vertical divisions

since the first and second divisions extend from pole to pole, they are termed...

horizontal/equatorial

the third cleavage is termed... because the cleavage furrow forms between the poles perpendicular to the first two divisions

amount of yolk in the vegetal pole

the third cleavage is nearer the animal pole because of the...

smaller

since the third cleavage is closer to the animal pole, the four cells at the animal pole are... than the four cells at the vegetal pole

morula

further divisions occur and at the 32-cell stage a... is formed, a solid ball of cells.

blastocoel

as the cells continue to divide, a fluid-filled space called the... forms inside

polarity

because the yolk is localized in one hemisphere in frogs, the unequal division during cleavage results in... with the blastocoel nearer the animal pole.

blastula

formation of this hollow ball called the... is the termination of cleavage

gastrulation

a morphogenetic process involving the rearrangement of cells to form a three- layered embryo with a primitive gut

motility, shape, and cellular adhesion

during gastrulation, there are changes in cell...

exterior to interior

in gastrulation, the cells move from the... by altering adhesion abilities and cell shape

invagination

a pushing forward that occurs in gastrulation at the dorsal lip

dorsal lip

an area of the grey crescent that is under the blastocoel

blastopore

as the cells continue to move inward, an opening called the... forms below the dorsal lip

yolk plug

invagination continues laterally and then ventrally forming a structure called the..., which is the blastopore as a complete circle with the dorsal, lateral, and ventral lips

involution

is the rolling of cells over the edge of the lips into the interior

gastrocoel

the cells that participate in involution cells will move away from the blastopore and form another cavity called the...

endoderm and mesoderm

the cells that form the gastrocoel will also organize as two embryonic germ layers known as the...

archenteron

the gastrocoel enlarges inward, the cells surrounding it organize as endoderm. at this point the cavity is called the...

primitive gut

the archenteron will eventually become the...

collapse

the enlarging archenteron causes the blastocoel to... and is visible as a thin clear space

coelom... anus

the blastocoel wil become the... (body cavity that holds viscera) and the blastopore becomes the...

mesoderm

middle germ layer arises from those cells that invaginate at the ventral and lateral margins of the blastopore

skeletal, muscular, urogenetial, cardiovascular, lymphatic

mesoderm gives rise to these systems:

peritoneum, dermis of the integument, and notochord

mesoderm also gives rise to the...

ectoderm

outermost germ layer arises from a spreading and thinning of remaining exterior animal pole cells that enclose the embryo that divides into two types

neural ectoderm and cutaneous ectoderm

the two types that the ectoderm divides into

brain and spinal cord

neural ectoderm becomes the...

epidermal structures, sensory receptors in the epidermis, sweat glands, and the cornea and lens of the eye

cutaneous ectoderm gives rise to...

complete closure of the blastopore

the end of gastrulation is marked by the...

neural plate

while the archenteron is forming, the neural ectoderm on the dorsal side of the embryo begins to thicken and form the...

neural groove... neural fold/lip

the central area of the neural plate gradually becomes depressed to form the... while the lateral edges of the plate thicken to form the...

neural tube

the neural folds eventually meet and fuse to form the...

brain... spinal cord

the anterior region of the neural tube becomes the... while the rest becomes the central canal of the...

dorsal

an examination of the embryo in cross section shows that the nervous system develops... to the notochord

notochord

derived from dorsal mesoderm and is a flexible rod that occurs during development of chordates

intervertebral discs

In humans the notochord becomes the centrum of...

somites

the structures that are arranged serially on both sides of the notochord