Cell Trivia

Random interesting facts about cells

Dominance of Prokaryotic Cells

• Prokaryotic cells have been on earth twice as long as eukaryotic cells and are WAY more common on earth than eukaryotic cells.
• For every cell in the human body, there are about 10 bacterial cells. So only about 10% of the cells in our body are our own human, eukaryotic cells.
• Prokaryotic cells can go through an entire life cycle and divide in about 10 to 20 minutes.

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Mitochondria

• Though we usually draw our models with 1, 2, or 3 mitochondria in a cell, cells that use a lot of energy may have around 2000 of them
• In addition to producing energy that cells can use, mitochondria also have an ability to produce heat. The mitochondrial membrane uses facilitated diffusion to let certain ions in, and the ion flow releases potential energy as heat. This is one way that warm-blooded animals maintain body temperature.

Mitochondria

• 1 in 100 people with diabetes have it due to a mutation in mitochondrial DNA. These people are also deaf. Since the disease is caused by mitochondrial DNA, it is only inherited maternally.
• Exercise scientists work with personal trainers to help athletes increase both the number and size of mitochondria in their muscles.

Nucleus

• Most eukaryotic cells have one nucleus, though some have none and some have several. Cells with multiple nuclei can be formed when multiple cells unite, or when nuclei divide without the cell dividing.
• While the origin of most organelles can be explained with widely-accepted theories, biologists argue about the origin of the nucleus. Several hypotheses exist, including one that says the nucleus was a cell that evolved a second, outer membrane (which became the plasma membrane.)
• Most molecules that move into or out of the nucleus have to be actively transported by proteins called importins and exportins

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Red blood cells

• Eukaryotic, but have almost no organelles (just a membrane and hemoglobin
• In mammals, mature red blood cells have no nucleus (other vertebrates have nuclei in their RBC’s)
• Since they have no genetic material or ribosomes, they can’t be targeted by viruses!
• Adult humans have about 25,000,000,000,000 red blood cells (25 trillion)
• That is one-fourth of the cells in the human body

Giardia

• A single-celled eukaryotic organism that infects the intestines of some animals.
• First described by French zoologist Alfred Mathieu Giard
• Giardia cells have no mitochondria and 2 nuclei, and each nucleus has 4 associated flagella that giardia uses to swim. In dry conditions, giardia can form a protective cyst that encases it inside a protein-carbohydrate wall
• causes an unpleasant intestinal disease called giardiasis, which is also known as “beaver fever.” The diseases is transmitted through contaminated water or through the fecal-oral route, and in rural areas of NY the feces of beavers is though to play a large role in contaminating water supplies

Apoptosis

• Cells of multicellular organisms are capable of destroying themselves in a highly-controlled, programmed manner called apoptosis
• This happens in a human to about 50,000,000,000 cells every day (50 billion). That’s about one out of every 2000 cells.
• Apoptosis is beneficial to the organism, because it prevents harmful mutations or cancer cells from multiplying, and it can stop the invasion of viruses.
• Plants can do something similar, but the presence of cell walls and lack of an immune system make it harder.

Eukaryotic Cell Life Spans

• Most eukaryotic cells live for a few days
• Human egg cells live in a prolonged rest phase that lasts several years, from before birth until ovulation after puberty
• Cells in the pancreas can live and function normally for a whole year

Cell counts

Cell size extremes

• Some fungi produce single-cell filaments that grow underground and can be hundreds of meters long.
• Nerve cells have projections called axons that can be very long. A human axon can easily be 3 feet long, but it will be much thinner than a hair.
• Mycoplasma gallicepticum, a bacteria living in the bladders and genitals of primates, is thought to be the smallest known organism (thus the smallest cell). It is less than 1/10^th the size of a red blood cell
• most bacteria have not been studied, so this is hard to know for sure
• many bacteria “downsize” during times of low nutrient availability.

Cell sizes

X-Chromosome

7 μme

Mitochondrion

4 μme

E. Coli

(prokaryotic cell)

3 μme

Lysosome

1 μme

Cell sizes

Salt Grain: 500 μm

Mitochondria�4 μm�Baker’s Yeast�

Cell sizes

Red Blood Cell�4 μm�Baker’s Yeast�