Hi,

Please help me fix grammatical and any other mistakes in my writing.

#1-
So the story begin when a small aerobic prokaryote came in a large prokaryote the large prokaryote ingests it and it turns to a mitochondrion , then a small photosynthetic prokaryote comes the large prokaryote ingests it and it turned to a chloroplast. The life use to consist of 3 large domains archaea, bacteria, and eukaryotes. The evolution of eukaryotic cells happened when an organism lived inside the other and occupies permanently, and evolves over time into what I call a one nation.

#2-
The first thing I would look for to tell whether a cell is a prokaryotic or a eukaryotic is the cell size. Eukaryotes are larger and more complexing than prokaryotic cells. The second thing I would look for is the nucleus if the cell had a nucleus it is a eukaryote. And Prokaryotes do not have a nucleus. Eukaryotic cells have organelles and prokaryotes don’t.
Eukaryotic DNA is bounded between a membrane witch creates a nucleus. DNA in prokaryotes isnt bounded to a nucleus. So in eukaryotes the DNA is housed in a nucleus and prokaryotes lack the membrane-bound nucleus and there DNA is located in a nucleoid region.

#3-
Ribosomes are tiny organelles that the cell needs to make proteins. Proteins and RNA structure the ribosomes and two subunits consists it.
Ribosomes have ribosomal RNA (rRNA). Ribosomal RNA is produced from the nucleolus. DNA gets transcribed into MRNA. MRNA leaves the nucleolus and gets translated into proteins at ribosomes. Ribosomes make proteins from amino acids.

#4-

E. coli bacterium and salmonella are examples of prokaryotic cells.
E. coli are single celled microorganisms. E. coli isn't always bad for our body. They usually live in our intestines to help us digest food. There are bad kinds of E. coli that can poison us. The poisons kind of E. coli can be found in raw meat, and fruit juice that isn’t pasteurized. Salmonella are harmful bacteria's that are passed from the feces of people or animals to other living things. They cause illness and affect the intestines in our body. It can also come from raw meat and eating raw eggs.
To avoid the harm of these bacteria's we should wash our hand when we get out the bathroom. We should avoid eating raw food and eggs.

Go through and make sure that EVERY sentence ends with a period (or other correct end punctuation).

http://grammar.ccc.commnet.edu/grammar/runons.htm

When you have done that, you'll be ready to consider other things.

#1-

So the story begin when a small aerobic prokaryote came in a large prokaryote. The large prokaryote ingests it and it turns to a mitochondrion. A small photosynthetic prokaryote comes the large prokaryote ingests it and it turned to a chloroplast. The life use to consist of 3 large domains archaea, bacteria, and eukaryotes. The evolution of eukaryotic cells happened ;when an organism lived inside the other and occupies permanently, and evolves over time into what I call a one nation.

#2-
The first thing I would look for to tell whether a cell is a prokaryotic or a eukaryotic is the cell size. Eukaryotes are larger and more complexing than prokaryotic cells. The second thing I would look for is the nucleus. If the cell had a nucleus it is a eukaryote. And Prokaryotes do not have a nucleus. Eukaryotic cells have organelles and prokaryotes don’t.
Eukaryotic DNA is bounded between a membrane witch creates a nucleus. DNA in prokaryotes isnt bounded to a nucleus. So in eukaryotes the DNA is housed in a nucleus and prokaryotes lack the membrane-bound nucleus and there DNA is located in a nucleoid region.

#3-
Ribosomes are tiny organelles that the cell needs to make proteins. Proteins and RNA structure the ribosomes and two subunits consists it.
Ribosomes have ribosomal RNA (rRNA). Ribosomal RNA is produced from the nucleolus. DNA gets transcribed into MRNA. MRNA leaves the nucleolus and gets translated into proteins at ribosomes. Ribosomes make proteins from amino acids.

#4-

E. coli bacterium and salmonella are examples of prokaryotic cells.
E. coli are single celled microorganisms. E. coli isn't always bad for our body. They usually live in our intestines to help us digest food. There are bad kinds of E. coli that can poison us. The poisons kind of E. coli can be found in raw meat, and fruit juice that isn’t pasteurized. Salmonella are harmful bacteria's that are passed from the feces of people or animals to other living things. They cause illness and affect the intestines in our body. It can also come from raw meat and eating raw eggs.
To avoid the harm of these bacteria's we should wash our hand when we get out the bathroom. We should avoid eating raw food and eggs.

Now check all verb tenses. All should be in the present, or all should be in the past. Don't mix them up.

#1-

So the story began when a small aerobic prokaryote came in a large prokaryote. The large prokaryote ingests it and it turns to a mitochondrion. A small photosynthetic prokaryote comes the large prokaryote ingests it and it turned to a chloroplast. The life use to consist of 3 large domains archaea, bacteria, and eukaryotes. The evolution of eukaryotic cells happened ;when an organism lived inside the other and occupies permanently, and evolves over time into what I call a one nation.

The verb tenses are still mixed up.

present: ingests, turns, comes, ingests, occupies, evolves, call

past: began, turned, used, happened, lived,

So the story began when a small aerobic prokaryote came in a large prokaryote. The large prokaryote ingested it and it turned to a mitochondrion. A small photosynthetic prokaryote came the large prokaryote ingested it and it turned to a chloroplast. The life used to consist of 3 large domains archaea, bacteria, and eukaryotes. The evolution of eukaryotic cells happened ;when an organism lived inside the other and occupied permanently, and evolved over time into what I called a one nation.

#2The first thing I would look for to tell whether a cell is a prokaryotic or a eukaryotic is the cell size. Eukaryotes are larger and more complexing than prokaryotic cells. The second thing I would look for is the nucleus if the cell has a nucleus it is a eukaryote. And Prokaryotes do not have a nucleus. Eukaryotic cells have organelles and prokaryotes don’t.

Eukaryotic DNA is bounded between a membrane witch creates a nucleus. DNA in prokaryotes isn't bounded to a nucleus. So in eukaryotes the DNA is housed in a nucleus and prokaryotes lack the membrane-bound nucleus and there DNA is located in a nucleoid region.

What is the purpose of the writing? Is this to be formal, or informal? Your used of "I" makes me wonder what the purpose is.

heres the question tell me what you would look for to tell whether a cell was prokaryotic or eukaryotic. Be specific.

#1-

So the story begin(s) when a small aerobic prokaryote came in(to?) a large(er?) prokaryote. The large prokaryote ingests(ingested?) it and it turns (in)to a mitochondrion. A small photosynthetic prokaryote comes (and) the large prokaryote ingests it and it turned (in)to a chloroplast. The life use(d) to consist of 3 large domains (:) archaea, bacteria, and eukarya. The evolution of eukaryotic cells happened when an organism lived inside the other and occupied (it) permanently, and evolves over time into what I call a one nation.
#2-
The first thing I would look for to tell whether a cell is a(drop it) prokaryotic or a(drop it) eukaryotic is the cell size. Eukaryotes are larger and more complex than prokaryotic cells. The second thing I would look for is the nucleus. If the cell had a nucleus it is a eukaryote. And(I'd replace this with the word but) prokaryotes do not have a nucleus. Eukaryotic cells have organelles and prokaryotes don’t.
Eukaryotic DNA is bound between a membrane witch(which. No hard feelings, I keep getting that one wrong too) creates a nucleus. DNA in prokaryotes isn't bounded to a nucleus. So in eukaryotes the DNA is housed in a nucleus and prokaryotes lack the membrane-bound nucleus and their DNA is located in a nucleoid region.
#3-
Ribosomes are tiny organelles that the cell needs to make proteins. Proteins and RNA structure the ribosomes and two subunits consist(itute) it.
Ribosomes have ribosomal RNA (rRNA). Ribosomal RNA is produced from the nucleolus. DNA gets transcribed into mRNA. mRNA leaves the nucleolus and gets translated into proteins at ribosomes. Ribosomes make proteins from amino acids.
#4-

E. coli bacterium and salmonella are examples of prokaryotic cells. E. coli are single celled microorganisms. E. coli isn't always bad for our body. They usually live in our intestines to help us digest food. There are bad kinds of E. coli that can poison us. The poisons kind of E. coli can be found in raw meat, and fruit juice that isn't pasteurized. Salmonella are harmful bacteria that are passed from the feces of people or animals to other living things. They cause illness and affect the intestines in our body. It can also come from eating raw meat and raw eggs.
To avoid the harm of these bacteria we should wash our hand(s) when we get out (of) the bathroom. We should avoid eating raw food and eggs.

Not bad, 9.8 of 10. About 10th grade level, although could pass for 11th once you fix the mistakes that I've pointed out. Great job.