Chapter 7 part 1 Flashcards
Urge and Urge and Urge, always the procreant urge of the world. Out of the dimness opposite equals advance, always substance and increase, always sex, always distinction
Walt Whitman
Fertiliation is not a moment or an event but a process of carefully orchestrated and coordinated events, including the contact and fusion of gametes, the fusion of pronuclei, and the activation of development. It is a process whereby two cells, each at the verge of _______ to create a new organism that will have numerous cell types and organs. It is just the beginning of a series of cell-cell interactions that characterize animal development
verge of death, unite
_______: The fusion of two sex cells to form a new genetically unique individual
fertilization
Fertilization accomplishes two major goals:
1) sexual recombination
2) reproduction
_______: combines genetic information from both parents in a new way
sexual recombination
_______: creates a new organism
reproduction
Fertilization proceeds through 4 major events:
1) _______ and recognition between sperm
2) _______ of sperm entry into oocyte
3) _______of genetic material contributed by sperm and egg
4) _______ of metabolism within the egg to begin development
1) contact
- ensures that only one species is involved
2) regulation
- ensures only 1 sperm is allowed in
3) fusion
4) activation
Sperm are produced through the modification of a germ-line cell:
1) virtually all _______ is lost
2) _______ condenses into a very compact form
3) a single ______ is produced
1) cytoplasm
2) nucleus
3) flagella
What are the 3 regions of a sperm?
1) head region
2) midpiece
3) tail
Head region:
Acrosomal vesicle sac of enzymes that digest _______ and _______
proteins and sugars
In the head region, the nucleus is _______ and _______, surrounded by very little cytoplasm
compact
haploid
Midpiece:
_______ organize and orient microtubules of the Axoneme
centriole
Midpiece:
_______: central core of microtubules in flagella
axoneme
Midpiece:
Multiple _______ are arranged in rings around the axoneme and surrounded by a tough sheath
mitochondria
Tail:
single _______ to provide movement. Whips _______ and _______
flagellum
- eukaryotic flagella whip back and forth
What is the difference between egg and oocyte?
- egg is gamete capable of binding sperm
- oocyte is developing egg that isnt ready for fertilization
Unlike sperm, eggs accumulate large volumes of _______
cytoplasm
Eggs contain:
1) _______ nutritive and energy supply
2) _______, which allow large burst of protein synthesis immediately following fertilization
3) _______ which provide early instructions for egg development, thousands of _______ stored in some species
4) _______ direct early differentiation, often sequestered in different regions of cytoplasm
5) _______ act as UV filters, DNA repair enzymes, antibodies, distasteful compounds
1) proteins
2) ribosomes and tRNA’s
3) mRNA’s
4) morphogenic factors
5) protective chemicals
Depending on the species, the egg may or may not have completed _______ prior to sperm entry
meiosis II
_______ finished all stages prior to sperm entry, while _______ egg remains in metaphase of meiosis II until sperm entry, then meiosis completes just prior to fusion of male and female pronuclei
Sea urchin
Human
_______ regulates ion and substance flow into/out of egg
cell (plasma) membrane
_______ fibrous extracellular mat outside of membrane that is rich in glycoproteins
vitelline envelop
- zona pellucida in mammals
_______ cells: remnants of ovarian follicle cells that nuture and protect the egg following release from ovary inner layer
cumulus
- corona radiata
_______: outside of vitelline envelop, rich in glycoproteins also involved in attracting and activating sperm
Egg jelly layer (jelly coat)
_______: thin layer of gel-like cytoplasm immediately inside cell membrane
cortex
The egg cortex contains high concentrations of _______ that polymerize to form _______ that may aid sperm entry
actin
microvilli
The egg cortex contains thousands of _______, which is analogous to acrosomal vesicle of sperm
cortical granules
Cortical granules of egg are derived from _______
Golgi
Cortical granules contain _______ enzymes, adhesive _______, _______, and _______ protein
proteolytic
glycoproteins
mucopolysaccharides
hyalin
The 5 major steps to egg and sperm recognition:
1) _______ of the sperm to the egg
2) _______ of the sperm acrosomal vesicle
3) _______ of the sperm to the extracellular matrix of the egg
4) _______ of the sperm through this extracellular matrix
5) _______ of the egg and sperm membranes
1) chemoattraction
2) exocytosis
3) binding
4) passage
5) fusion
Sperm swimming towards soluble chemicals released by the egg is an example of _______
chemotaxis
_______: 14-aa peptide in sea urchins, which does not attract sperm from other species
Resact
Describe the process of sperm attraction to the egg via Resact (4)
1) Resact binds to receptor Guanylyl cyclase (RGC) on sperm
2) RGC converts GTP to cGMP
3) cGMP opens up Ca2+ channel
4) Ca2+ enters, providing directional cue for sperm
Along with its attraction characteristic, Resact also functions as a _______, by stimulating mitochondrial production of ATP and the dynein ATPase required for flagella movement
sperm-activating peptide
The acrosomal reaction is initiated by contact with species-specific _______ within the egg jelly, which also acts as a barrier to prevent interspecific fertilization
sulfated-polysaccharides
Describe the process (part 1) of releasing the contents of the acrosomal vesicle (3)
1) Activation of Ca2+ channels (Ca into cell)
2) Activation of Na+/H+ antiporters (Na+ into, H+ out)
3) Activation of Phospholipase (produces IP3)
During the acrosomal reaction, the increase of intracellular Ca2+ triggers the fusion of the _______ membrane with the _______ membrane releasing its proteolytic enzymes onto the surface of the egg
acrosomal vesicle
sperm cell
The acrosomal process is a rigid structure created by the polymerization of _______ into actin microfilaments
globular actin
The increase in Ca2+ activates _______, a GTP-binding protein that mediates the polymerization of actin
RhoB
- helps create the acrosomal process
- activated when GTP is bound
The acrosomal process is covered with _______, a large species-specific protein
bindin
Sperm binding does not occur all over the egg, but appears to be limited to sites containing large numbers of bindin receptors. In sea urchins the protein is _______
EBR1
- thought to be
What are the 3 sperm-egg specificity mechanisms in sea urchins?
1) resact (chemoattractant)
2) sulfated-polysaccharide (starts acrosomal RXN, found in jelly)
3) bindin receptor (EBR1)
