Egg Cells

[des-esseintes]

Hello, I am a new poster here.

 

My chemistry teacher made a strange announcement last lesson. He said that the egg cell is the largest cell. I can agree. But he also said that a single egg is made up of a single cell! One egg of a hen = One egg cell! Is this true? I'm no biology expert, but I'm quite sure egg cells multiply and create eggs. Anyway, how can you fit a chicken inside one cell?

 

Please confirm my suspicion so I can nail him

[admiral_ju00]

it starts as 1 cell but then it spilts into more and more.

the hen egg at the point you're refering to is multicelled and differenciated.

 

here's a quick rundown

http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/page3.html

[Dave]

Hello' date=' I am a new poster here.

 

My chemistry teacher made a strange announcement last lesson. He said that the egg cell is the largest cell. I can agree. But he also said that a single egg is made up of a single cell! One egg of a hen = One egg cell! Is this true? I'm no biology expert, but I'm quite sure egg cells multiply and create eggs. Anyway, how can you fit a chicken inside one cell?

 

Please confirm my suspicion so I can nail him [/quote']

 

It's probably because he's a chemistry teacher

[YT2095]

just out of curiostity, does that also apply to Human unfertilised eggs?

[admiral_ju00]

just out of curiostity, does that also apply to Human unfertilised eggs?

 

what?

 

this:

I'm quite sure egg cells multiply and create eggs.

 

eggs don't create eggs, they divide/multiply if and when they are fertilized by the sperm. if not, it remains 1 celled 'till it's ejected at that special 1 week a month thing.

 

but i absolutely agree with dave in that this teacher was severly wrong because he's a chemist not a biologist.

[YT2095]

so a human egg if unfertilised is a single cell? that was what I meant. and if that`s correct, how does a human one differ from an unfertilised chicken egg? (other than the obvious! LOL)

[blike]

Seems as if an unfertilized ostrich egg is the largest single cell! (google told me)

[YT2095]

I was gunna say, with the exception of maybe a dinosaur egg (no idea if they`re huge or not though, but looking at a chicken and it`s egg, I imagine they might be) the Ostrich would be the biggest

that leaves me with yet another maybe Nieve question, in Biology I was taught about cells (plant and animal) and although I`m sure I`ve forgotten alot, don`t they have Mitochondria and endoplasmic reticulums (I love that word) Lysosomes and all that other stuff in them too ?

[Dave]

Seems as if an unfertilized ostrich egg is the largest single cell! (google told me)

 

I suppose it would make sense it being the largest egg and all. But then again quite a few things in nature aren't completely logical so it would have hardly surprised me if it was the smallest

[felinlasv]

that leaves me with yet another maybe Nieve question, in Biology I was taught about cells (plant and animal) and although I`m sure I`ve forgotten alot, don`t they have Mitochondria and endoplasmic reticulums (I love that word) Lysosomes and all that other stuff in them too ?

 

Yes indeed, most plantcells do have mitochondria (ATP-production), endoplasmatic reticulum (mainly used for transporting stuff true the cell), lysosomes (contain enzymes to break down lipids) and a whole lot more..

[YT2095]

do eggs contain all this too then, considering they are a "Cell" also?

[Skye]

Eggs are single cells. Human eggs are about 0.1 mm across. Birds eggs are obviously much larger, most of that is cytoplasm. The yolk is part of the cytoplasm, stores of fat and protein and stuff, the egg white is mainly a fluid store I think. Human eggs are much smaller because they don't need all these stores.

 

In order to make these very large cells, the large stores are produced outside the cell. an individual cell just can't produce it all fast enough. In humans, by 'nurse cells' which are similar to eggs but basically are just there to help. I think most of the stuff for bird eggs is made in the liver.

 

Eggs contain everything an animal cell needs though. In some cases, insects mainly I think, they produce extra copies of certain genes, like for ribosomes, so they are able to produce lots of protein during their growth and after fertilisation. Indeed, it's essential that eggs contain everything, as sperm just basically bring DNA to the party.

[YT2095]

so where would the cell Mitochondria be in a chicken egg?

[Skye]

I haven't actually read it but...they'd have to be located throughout the egg in order to provide energy to utilise the stores of molecules.

[Bryn]

try centrifuging an egg to get some mitochondria from it.

[Ms. DNA]

so where would the cell Mitochondria be in a chicken egg?

 

According to the website below, the yolk is actually an enlarged egg cell, so the mitochondria would have to be there.

 

http://waynesword.palomar.edu/lmexer1.htm

[YT2095]

nice link, Thnx

[des-esseintes]

I'm quite confused. Is the chicken egg a single cell or not? How can the chicken foetus grow out of an egg cell, while living inside an egg cell? Doesn't every foetus start from a single multiplying egg cell? Or is this only with mammals?

 

Does anyone have a link to a site with the growth of a chicken egg. Thank you.

[Bryn]

For a rather large number of cell divisions the feotus does not grow in size, it just splits the existing cytoplasm in two. The same undoubtedly happens for the chickens. So the egg can be an egg cell, and it divides and differentiates into tissues but doesn't grow. Infact it can't grow as it has no external food source, only what's already in the egg, that why there is so much food and protein in an egg.

[Glider]

No, a chicken egg is not a single cell. The oocyte is the single cell. The oocyte in a chicken egg is located on the membrane surrounding the yolk sac. If you break open a fertilized chicken egg, you can see the zygote resting on the yolk sac, and blood vessels extending from it. forming a network around the yolk from which it draws nutrients for growth. The egg is just a 'life-support' capsule for the embryo.The fillaments projecting from each end of the yolk sac attach to each end of the shell and act as shock absorbers, keeping the yolk more or less central in the mass of albumin (egg-white). The yolk provides the nutrients for growth and the white provides the water and some protein.

[Tesseract]

No, a chicken egg is not a single cell. The oocyte is the single cell. The oocyte in a chicken egg is located on the membrane surrounding the yolk sac. If you break open a fertilized chicken egg, you can see the zygote resting on the yolk sac, and blood vessels extending from it. forming a network around the yolk from which it draws nutrients for growth. The egg is just a 'life-support' capsule for the embryo.The fillaments projecting from each end of the yolk sac attach to each end of the shell and act as shock absorbers, keeping the yolk more or less central in the mass of albumin (egg-white). The yolk provides the nutrients for growth and the white provides the water and some protein.

 

Did you learn this at medical school???

[Bryn]

Ah, so how big is the egg cell in a chicken egg?

[Glider]

Did you learn this at medical school???

No. Basic biology in secondary school, when I was about 14.

 

Ah, so how big is the egg cell in a chicken egg?

About 0.1mm dia. as far as I recall.

[hierarch]

Off this thread, I am wondering why a hen lay some unfertilized eggs? It seem wasteful for the hen to generate its offspring.

[Bryn]

Well presumably the egg can't be fertilized until it is fully grown, as in human egg cells. So the egg is grown, then you don't let the chicken bonk anyone, and so the egg can't be fertilised.

 

It could also be because humans have bred them that way over thousands of years, those that don't lay unfertilised eggs either get eaten for sunday lunch or don't get the protection of humans and so have a disadvantage.