Biology

Characteristics of prokaryotic cell

len Alfred Ajibola - 04th July, 2023 @ 09:21 AM

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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



Characteristics of Prokaryotes:

  1. They do not have a definite nucleus.

  2. They lack a nuclear membrane.
    Please read the introduction to prokaryotic cell here.

  3. The DNA is located on a single chromosome.

  4. They can have non-chromosomal DNA which are not utilized in sexual reproduction.

  5. The cytoplasm is composed mainly of cytosol, ribosomes, inclusions, cytoskeleton, enzymes and salts.
    Please read on eukaryotic cell explained with its characteristics.

  6. Mitochondria, golgi apparatus and lysosomes are absent.

  7. Adhesive hairlike structures called pili (pilus) may be present, and these can be used to initiate harmful activities on a host cell. It is shown in the image below:

    Prokaryotic Cell - Len Academy

  8. Sexual pili may be present, and are utilized in reproduction.
    You can attempt Len Academy questions in biology here.

  9. The locomotory structure typical to the prokaryote is a whiplike structure called flagella. The flagella are made of up the protein flagellin.

  10. Histone proteins are absent in prokaryotic chromosomes.

  11. The cell wall is made up of peptidoglycan (or murein), which is a polymer of sugars and amino acids.
    You can read on monosaccharides and disaccharides here.

  12. The plasma membrane is semipermeable, allowing certain substances to enter and exit the cell.

  13. Reproduction can be sexual or asexual.
    You can read asexual reproduction in plants here.

Asexual reproduction in prokaryotes occur through a process termed binary fission, while sexual reproduction occurs through gene recombination, (that is: conjugation, transformation and transduction).

 

Binary fission is a process whereby the reproducing cell (preferably called the parent cell) divides into two identical organisms. To achieve this, the DNA first makes an exact copy of itself which it attaches to the cell membrane. This process initiates an increase in the cell's size, thus making it move inwards. As this happen, a new cell wall encloses each DNA, giving rise to the daughter cells with an identical DNA. This is shown in the image below.

Binary fission in Bacteria - Len Academy

Through the process of binary fission, two identical cells are formed. Binary fission in prokaryotes can go on and on, leading to the formation of millions of new identical cells.

Please read on the concept of cell here.

 

Gene recombination is a method of sexual reproduction in prokaryotes. It involves a process whereby genes from one bacteria are transferred into the genome of another. This process can occur in a variety of ways. They include:

  1. Conjugation: Genes are exchanged between two prokaryotes through their respective sex pilus. This is shown in the image below:

    Conjugation in Bacteria - Len Academy
    Check out interesting facts for students here.


  2. Transformation: The bacteria cell takes up DNA from its surroundings and incorporates it into their DNA. This leads to the formation of a new cell. Transformation in bacteria is shown below:

    Transformation in Bacteria - Len Academy
    Please read on cell theory here.


  3. Transduction: DNA is transfered into a bacteria cell through a bacteriophage.

    Transduction in Bacteria - Len Academy

    The term 'bacteriophage' refers to viruses that initiates the transfer of genetic materials into the bacteria cell.
    You can read keypoints in biology here.

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Amazing facts in Biology

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

Giant Squid - Len Academy

Giant squid lives deep in the ocean and they have the largest eyes in the world

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

Platypus - Len Academy

Platypus (sometimes referred to as the duck-billed platypus) is an egg-laying, semiaquatic mammal found in eastern Australia. It has no stomach and as such, its food goes from the mouth through the esophagus and directly to their intestines.

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

Wombat - Len Academy ​​​​​​

Wombats are the only animal with a cube-shaped poo. They can stack up these cube-shaped poo, marking their territory with it

Robert Waldow - Len Academy

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

Laughing ape - Len Academy

Like humans, all apes laugh when tickled

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An ostrich's eye is bigger than its brain


Notable points in Biology

Layers of an Artery - Len Academy

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