Ask a Question
  
  
  
Top Posters
Since Sunday
21
15
7
7
6
6
6
5
5
5
5
5
New Topic  
wrote...
Posts: 55
In a sexual life cycle, fertilization represents the fusion of gametes, combining two haploid genomes (from the maternal and paternal parents) to form a diploid zygote. In order to maintain the correct number of chromosomes in the diploid generation, it is essential that only a single sperm fuse with each egg. Polyspermy, the fusion of two or more sperm with a single egg, results in an incorrect number of chromosomes in the zygote and is almost always lethal.

In animals, polyspermy is prevented by a number of mechanisms. Using fertilization of sea urchin eggs as a model for vertebrate and mammalian systems, Rick Steinhardt, Gerald Shatten, and their colleagues examined the role that changes in cytoplasmic Ca2+ concentration play in preventing polyspermy.

Part A - Experimental technique: Tracking cytoplasmic Ca2+ distribution after a sperm enters the egg
Based on what they knew about the fertilization envelope (a protective layer that forms around the egg when a sperm fuses with it), Steinhardt, Shatten, and their colleagues hypothesized that changes in the distribution of Ca2+ ions in sea urchin eggs are involved in the formation of the fertilization envelope.
In sea urchin eggs (as in most eukaryotic cells) the concentration of Ca2+ ions is much higher in the endoplasmic reticulum (ER) than in the cytoplasm. To see how cytoplasmic Ca2+ concentration changes in the egg during fertilization, the researchers injected a Ca2+-specific fluorescent dye into the cytoplasm of unfertilized eggs. After adding sperm to the eggs, they observed the eggs with a fluorescence microscope.
The following images show the changes in fluorescence that occurred after a single sperm entered the egg. The fluorescence of the dye increased with increasing cytoplasmic Ca2+ concentration. The green color indicates the region of the cell with the highest fluorescence at that point in time.

Sort the labeled regions of the fertilized egg above based on the status of the ER Ca2+ channels and Ca2+ pumps in that region.
Attached file
Thumbnail(s):
You must login or register to gain access to this attachment.
Read 26792 times
5 Replies
Replies
wrote...
Staff Member
Educator
See if this attachment helps. Look up the word 'urchin'.
Attached file
(5654.82 KB)
You must login or register to gain access to this attachment.
jasinte,  michelleroddd,  jacquelinetremb,  vans,  Roy1,  Lemoncchik,  PHILLisCHILL,  Strange9,  desbestiny,  bio_man,  nanea,  mcobbs24,  Nissy,  adri07,  raiistars,  kelang65,  dianacaswell,  Anna1997,  tigerclaws776,  farcoco,  cbrown22,  Antray,  tamiareed,  ashleyymcc,  steve11adams,  poop111,  sdfgfad,  firetrojan94
Mastering in Nutritional Biology
Tralalalala Slight Smile
wrote...
Thankssss!!  Slight Smile
wrote...
Thanks!
wrote...
Staff Member
Educator
Did any of you guys get the actual answer?
dimplepatel2013,  brianadramirez,  uLucas,  lrisley48,  afrd13,  mdislam,  Andreaux,  churchxiii
Mastering in Nutritional Biology
Tralalalala Slight Smile
Answer verified by a subject expert
wrote...
Posts: 21
Edited: 4 years ago, mosesmazon
Sign in or Sign up in seconds to unlock everything on Biology Forums.
Part A - Experimental technique: Tracking cytoplasmic Ca2+ distribution after a sperm enters the egg.
Sort the labeled regions of the fertilized egg above based on the status of the ER Ca2+ channels and Ca2+ pumps in that region.
1st Box - A,C,F
2nd Box - B,E,H
3rd Box - D,G

Part B - Experimental results: Cytoplasmic Ca2+ concentration and the fertilization envelope.
Drag the labels to the appropriate targets to indicate the sequence of events occurring between fusion of the sperm and egg and formation of the fertilization envelope.
2.) Cortical granules fuse with egg plasma membrane.
3.) Sperm-binding receptors on egg plasma membrane are degraded.
4.) Vitelline layer is released from egg plama membrane.
5.) Perivitelline space expands due to osmotic water movement.

Part C - Experimental prediction: The effect of Ca2+ channel blockers on formation of the fertilization envelope.
Drag the labels (yes or no) to predict whether or not the following events can occur under control conditions and experimental conditions.
Control - yes,yes,yes,no
Experimental - yes,no,no,yes
This verified answer contains over 230 words and 1 attached file(s).
Source Mastering Biology
Attached file
Thumbnail(s):
You must login or register to gain access to this attachment.
paigevdupuis,  agester,  chads108,  hasina277,  taner194,  cocacolaman140,  lovely7296,  padre,  bruhman,  binglehop,  shuang37,  Rahpoo,  bio_man,  epitomeofbeauty,  deniseshanexo,  uLucas,  calculus_please,  taylordposey,  Crys_gross,  Keepchucking12,  Amethyst_Dreams
WHATSACOMINAGO
Related Topics
New Topic      
This topic is not open for further replies. Only administrators and moderators can reply. If you'd like to contribute to this topic, start a new thread and make reference to this one. Otherwise, contact a moderator for more options.
Explore
Post your homework questions and get free online help from our incredible volunteers.
Learn More
Improve Grades
Help Others
Save Time
Accessible 24/7
  114 People Browsing
 134 Signed Up Today
Related Images
 136
 72
 20
Your Opinion
Which of the following is the best resource to supplement your studies:
Votes: 43

Previous poll results: Where do you get your textbooks?