Eukaryotic cell explained with its characteristics

len Alfred Ajibola - 04th July, 2023 @ 09:22 AM

Topics in Biology

Difference between plant cell and animal cell Nucleus explained with its structures Nucleus explained with its types and functions Organelles of the cell explained with their characteristics Eukaryotic cell explained with its characteristics Prokaryotic cell explained with its structure Characteristics of prokaryotic cell Concept of cell Cell theory in biology Importance and limitations of ecological pyramid Protists explained with their characteristics Contents of the scrotum: Epididymis, vas deferens, spermatic cord and cremaster muscle Tropical savanna explained with its characteristics Concept of ecological pyramid Hindbrain: Medulla Oblongata and its features Food web explained with examples Biology Scheme of Work, SS1, First Term Biology Scheme of Work, SS1, 2nd Term Biology Scheme of Work, SS1, 3rd Term Male accessory sex organs: Seminal vesicles and bulbourethral glands

Academic Questions in Biology

Please click here to see all Questions and Answers

Male Reproductive System - Len Academy

From the above diagram, which of the organ below isn't a requirement for the male reproductive system?

  • A. Bladder

  • B. Ureter

  • C. Glans Penis

  • D. Testis

  • E. Bulbourethral Gland

  • F. Epididymis

A walnut shaped male accessory sex organ located between the bladder and penis is the _____.

  • A. Ductus Ejaculatorii

  • B. Bulbourethral Gland

  • C. Prostate Gland

  • D. Ductus Deferens

  • E. Seminal Vesicles

  • F. Epididymis

In a food chain, the primary consumers are classified under trophic level  _____.

  • A. Zero

  • B. One

  • C. Two

  • D. Three

  • E. Four

  • F. Five

Cold blooded animals are referred to as _____.

  • A. Homeotherms

  • B. Endotherms

  • C. Poilokitherms

  • D. Ectotherms

  • E. Thermotherms

  • F. None of the above

All reptiles are vertebrates.

  • A. True

  • B. False

_____ cells are responsible for the formation of osteoblasts.

  • A. Osteocytes
  • B. Chondrocytes
  • C. Chondroblasts
  • D. Osteoclasts
  • E. Osteoprogenitor cells
  • F. Osteoblastic

_____ is a bone that constitute the axial skeleton.

  • A. Clavicle
  • B. Scapula
  • C. Patella
  • D. Radius
  • E. Sternum
  • F. Femur

Which of the following is false concerning cartilages and bones?

  • A. Cartilage does not have a direct blood supply while bones have direct blood supply
  • B. The process of ossification replaces a cartilage to bone
  • C. The protein that makes up cartilage is called chondrin while that that makes up bone is called ossein
  • D. Cartilage grows from both ends while bones grow from one of its epiphysis
  • E. They both have living cells within them
  • F. Haversian system is absent in cartilage but present in bones

Eukaryotic Cells:

Eukaryotes or eukaryotic cells are classified under the domain eukaryota. The term 'eukaryota' means 'true nucleus' or 'true kernel'.

Eukaryotic organisms have definite nucleus bounded by a membrane. In addition, eukaryotes have other membrane-bound compartments generally termed as organelles. These include the mitochondria, endoplasmic reticulum, golgi apparatus, chloroplast, lysosomes, and so on. Meanwhile, understand that these organelles have specific functions within the cell. 

Just as our bodily organs have their specific functions, you can think of the term 'organelles' as 'little organs' with their respective specialized function within the cell.

Please read the introduction to cell here.

Note: Cytoskeleton is present in eukaryotes, and this gives the cell its shape.


Eukaryotes are considered by scientists to have emerged on earth over 2 billion years ago. They are believed to have their origin from the archaea (prokaryotes). However, they are generally much larger than a prokaryotic cell. They are also generally present in multicellular organisms like fungi, plants and animals.

It is worthy of note to state that eukaryotic cells are present in some unicellular organisms, especially protists like amoeba, paramecium, euglena, chlamydomonas, protozoans, picozoans and so on.

Please read more on protists here.


Eukaryotic cells typically have a size range from 10 –100 µm (micrometer) in diameter. Interestingly, some may be smaller than the aforementioned size. For instance, the smallest eukaryotes are the picozoans with a size as small as 3 µm. However, multicellular eukaryotes like the blue whale can become so massive in size. In another instance, the coast redwood plant is an eukaryote with a height of about 390 feet (120 meters). Regardless their large size, they still represent a smaller percentage of organisms on earth in comparison to the prokaryotes.

You can read on cell theory here.

When compared with the more abundant prokaryotes, scientists are of the opinion that the collective mass (biomass) of all eukaryotes will be approximately equal to those of the prokaryotes.

Please read on prokaryotic cell here


The diagram below shows an eukaryotic cell (for animals).

Eukaryotic Cell - Len Academy


Characteristics of Eukaryotic Cells

A simple way to explain what eukaryotes really are can be achieved via their characteristics. The features below summaries the eukaryotic cell:

  1. They have a well defined nucleus enclosed within the nuclear membrane.

  2. The nuclear membrane of eukaryotic cell is continuous with the endoplasmic reticulum.

  3. The nucleus contains a single linear DNA (genetic material) present on the chromosomes.
    You can read an introduction to the male reproductive system here.

  4. Histones are present in eukaryotic nucleus. They bind to DNA, control gene activities, and give the chromosomes their shape.

  5. They have various organelles with each serving their respective functions.

  6. Eukaryotic cells are larger in size than prokaryotic cells.
    You can read interesting facts for students here.

  7. Organelles in eukaryotes have their own membranes.

  8. Organelles in eukaryotic cells include the mitochondria, golgi apparatus, endoplasmic reticulum, chloroplast, lysosomes, and so on.

  9. The locomotary organelles in eukaryotes are typically flagella and cilia, and these are composed of microtubules.

  10. Cytoskeleton is present in eukaryotes, and this gives the cell its shape.
    Please read on bones of the human skeleton here.

  11. Plants and animals are eukaryotes. In plants, the outermost layer of the cell is bounded by cell wall. This cell wall is made up of cellulose, hemicellulose, proteins and pectin. Also, a plant cell has chloroplast.

  12. Animal cell have cell membrane (plasma membrane or cytoplasmic membrane) as its outermost layer. The cell membrane is composed of lipids and proteins. Chloroplast is absent in animal cell.

  13. Cell division is the basis of reproduction in eukaryotic cell. This can occur via mitosis and meiosis.

Please read the characteristics of prokaryotes here here


Reproduction in eukaryotes can be either asexual or sexual. Asexual reproduction occurs through mitosis while sexual reproduction involves meiosis and fusion of gametes.


Mitosis occurs in plants and animals whenever more cells are needed. For instance, this could be observed during growth and repair of damaged tissues (or organs). Growth in this instance involves an increase in the number of somatic cells, bringing about a resultant increase in size.

Please read key points for students here.

Note: Agamogenesis is often associated with cellular division, and it is a mitotic process. Conversely, amphimixis is associated with meiotic division.

In humans, mitotic division occur in all somatic (body) cells while meiosis occurs only in sex cells.

Mitosis and Meiosis - Len Academy


With regards to meiosis, the DNA is first replicated (DNA replication), after which the parent cell divides into four haploid daughter cells. Understand that these haploid cells are the sex cells, with each containing only one set of chromosomes. This is accompanied by a genetic recombination of chromosomes. As a result of this process, the new cell formed isn't a clone of the parent cell.

You can read on sexual propagation in plants here.

The process of meiosis is seen in the production of spermatozoa and ova in animals, and pollen grains and ovules in plants.

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Russia is home to the largest area of forest in our world with a land mass of 815 million hectares

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The movements of the fingers are controlled by muscles of the palms and forehands

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Pufferfish - Len Academy

Pufferfish contain a toxin called tetrodotoxin. This makes them foul tasting and poisonous to predators. Tetrodotoxin is about 1,200 times more poisonous than cyanide, and there is enough toxin in one pufferfish to kill 30 adult humans. Unfortunately, there isn't any known antidote to this poison.

Interestingly, a delicacy in Japan (called fugu) is made from pufferfish. This meal is very expensive, and must be prepared by trained and licensed chefs. An improper preparation of fugu may lead to the customer's death. Sadly, such deaths are recorded annually

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Robert Wadlow (1918–1940) remains the tallest man ever recorded in the Guinness World Records. He was an American who stood at 8 feet, 11 inches.

An abnormally enlarged pituitary gland had resulted into Robert Wadlow's giant size.

Cockroach is the fastest land animal on six legs

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Notable points in Biology

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An artery is composed of three layers:

  • The outermost layer is termed tunica adventitia (or tunica external). It consist mainly of collagen fibres and connective tissues that anchors the arteries to other nearby tissues.

  • The middle layer is named tunica media. It is made up of smooth muscles and elastic fibres that supports the artery in conveying blood at high pressures.

  • The inner layer is called tunica intima (or tunica internal). It is lined by a smooth tissue called endothelium, and is made up of a fine network of connective tissues.

Please read on the layers of an artery here

All living organisms possess various features in order to survive in their environment. This is the concept of adaptation. As an instance, a fish is able to live in water because it has gills and fins.

Also, a camel is able to survive in the desert because it has large feet to aid walking on sand without sinking. It also has long eyelashes to help protect it from the blowing sand and wind.

Plants are also able to live in different habitats because they have the required adaptive features towards that habitat. For instance:

  • Plants that live in/on water are termed hydrophytes.

  • Plants that live on land with moderate amount of water are termed mesophytes.

  • Plants that live on deserts or arid lands are termed xerophytes.

The point is:

All organisms have various features on them that enables them adapt in their habitat

For a thing to be considered living, it must possess all the basic characteristics of life. These include:

  1. Movement

  2. Respiration

  3. Nutrition

  4. Irritability or Sensitivity

  5. Growth

  6. Excretion

  7. Reproduction

  8. Death

  9. Adaptation

  10. Competition

Please read the explanations on all the basic characteristics of life here

During strenuous exercises like sprinting or running, your body may actually work in the shortage of oxygen. During this time, your body owes oxygen (called oxygen debt) and it must be replenished or repayed after the exercise is stopped. This is why you breathe excess of oxygen after you stopped the exercise.

This is the concept of anaerobic respiration

Food Chain - Len Academy

A food chain is a diagram that shows the relationship between plants and animals within a habitat on the basis of how they rely on each other for food.

Note: Habitat is a place where an organism live. It is of three types:

  • Terrestrial (Land)
  • Aquatic (Water)
  • Arboreal (Treetops)

You can read on food chain here