Chronology of Death Trivia Quiz

Answer: Apoptosis

While it may sound terrible that so many of your cells are undergoing this process every day, apoptosis is highly regulated and is a natural part of the life cycle of a cell. It is often contrasted with necrosis, the death of a cell due to distress or injury. The process of blebbing creates protrusions on the cell membrane that can be observed with an optical microscope. As the cell undergoes apoptosis the cell membrane may split and form several completely separate compartments. DNA fragmentation occurs when enzymes known as endonucleases cleave (chop) the DNA into small pieces.

Of the incorrect answers, mitosis is a type of cell division in which the the nucleus of the parent cell is split and copied into two identical daughter nuclei which then govern their own cells. Synthesis is a general word that means the production of a molecule (or indeed a more complex structure) and is generally associated with DNA.

Answer: Autophagy

The word 'autophagy' is used to describe a variety of situations in cell biology. While full cell death can occur as result of autophagy, it is also used to refer to the process by which the cell destroys and recycles only some parts of the cell to allow them to be reused. In fact, it is often debated whether or not full cell death from autophagy is deliberate, or whether or not the cell is actually attempting to prevent cell death and self-digests in an attempt to save itself (a sad way to go indeed!). The Nobel Prize was awarded to Yoshinori Ohsumi in 2016 for his work with autophagy in yeast cells. He has been awarded many other awards throughout his career, notably the Breakthrough Prize in Life Science in 2017.

Meiosis is a type of cell division in which the DNA (in the form of chromosomes) is not replicated and thus the daughter cells only have half as much genetic material as the parent cell. This is the process by which gametes (sex cells) are produced. Transcription is the reading of DNA and the subsequent creation of RNA, the first step in protein synthesis.

Answer: Lysosome

Lysosomes are membrane-bound organelles, meaning that though they are inside the cell, they form separate compartments in which they can maintain an artificially high concentration of desired molecules. The inside of a lysosome has a pH of around 4.5-5, the ideal conditions for enzymes that function via hydrolysis. They can break down almost all biomolecules, including sugars, lipids and peptides. They were discovered in 1949 by the Belgian scientist Christian de Duve, for which he eventually won the Nobel Prize in Physiology or Medicine in 1974.

All three of the incorrect answers are also organelles that can be found inside a cell. The nucleus is the home of the genetic material of a cell, typically stored in chromosomes. Mitochondria are often referred to as the 'powerhouse' of the cell as they generate the chemical energy source ATP. Chloroplasts are the location of photosynthesis in plants and algae and are not found in animal cells.

Answer: Ubiquitin

The name 'ubiquitin' comes from the word 'ubiquitous', and is so called as it has been found in almost all eukaryotic (cells that have a nucleus) organisms that have been studied. It is a relatively small protein as is thus highly suitable for the 'tagging' of other proteins, a process in which the ubiquitin becomes attached to the target protein. While ubiquitination is often thought to be a signal to other proteins in the cell that the tagged protein should be taken to the proteasome and destroyed, it has been shown that it can serve other functions such as altering the protein's location within the cell and preventing the protein from binding other molecules.

RuBisCO is an enzyme involved in photosynthesis and is often cited as the most abundant protein on Earth. Amyloid beta is a protein that is most commonly discussed in association with Alzheimer's disease, as plaques of amyloid beta have been shown to be linked with the progression of the disease. Cytochrome C is also a common protein, found in mitochondria and essential in the electron transport chain.

Answer: Streptococcus

The word 'streptococcus' comes from the Greek 'streptos' meaning 'twisted chain' and 'kokkos' meaning 'berry'. The second part of the word indicates that they are spherical in shape, while the first means that they tend to divide along a single axis to form a chain. This is in contrast with staphylococcus, which can divide in any direction and are thus commonly observed in a structure reminiscent of a bunch grapes. Types of streptococcus are implicated in conjunctivitis, pneumonia, meningitis, and strep throat.

Amoxicillin is an antibiotic that is similar to penicillin, and is thus never given to those that are allergic to penicillin. It is used to treat a variety of bacterial infections, notably those in the middle ear. Metronidazole is active against both bacteria and protozoa and is commonly used to treat endocarditis. Doxycycline is used to combat acne, chlamydia and Lyme disease.

Answer: Viruses

Bacteriophages are some of the most successful infectious agents on Earth and are found almost anywhere that bacteria can be found. One estimate of their prevalence in sea water suggested that there were almost one billion phages per millilitre. The general structure of the phage is an outer coat comprised of a variety of proteins, encasing the genetic material (that may be either DNA or RNA). Typically, a protein on the head of the phage will be optimised to allow it to penetrate the exterior of a bacterium, wherein it releases it's genetic material and begins to replicate.

Answer: Rabbits

The disease caused by the myxoma virus is myxomatosis, a particularly unpleasant disease that primarily affects rabbits. The effects of the disease are numerous and vary between different species of rabbit, but can include the formation of skin tumours, a loss of appetite and fever. A rabbit that has contracted myxomatosis will typically die within fourteen days.

Despite the unfriendly effects of the disease, it has been used to control the population of rabbits in several areas worldwide. One prominent example of this is in Australia, where the population of rabbits was reduced from 600 million to 100 million in the two years between 1950 and 1952.

Answer: Bees

Nosema apis is one of a collection of different infectious agents within the genus nosema. This classification of nosema in the tree of life has proved a challenging problem for taxonomists. It is classified as a 'microsporidian', a single-celled parasite capable of forming spores. These parasites were originally thought to be protists but have now been shown to be more similar to fungi, hence their classification as fungi. Other scientists view them as a sister group to the fungi, with both sharing a single common ancestor.

Nosema is capable of bringing down an entire hive. Once a bee is infected, that bee will struggle to break down pollen and thus fail to gain energy. The disease is passed from one bee to another via faeces and can thus easily spread across the hive. It is common for bees to fly out to collect pollen and then be weakened by the disease to the point that they are not able to return to the hive. The spread of the spores can be inhibited with the antibiotic fumagillin.

Answer: Telomeres

The human genome contains around 3 billion base pairs of DNA, all stored within 23 pairs of chromosomes. Not all of the DNA in the genome is 'useful', that is to say that not all of it codes for some protein that serves a biochemical function. There is some 'noncoding' DNA that occupies the space between useful parts of the genome, allowing us to denote genes that carry out specific functions. When the entire genome is copied, it is common for some of the base pairs nearest the end to be missed out or lost.

Telomeres are sections of noncoding DNA found at the end of each chromosome in a cell to ensure that when the DNA is copied, part of the telomere can be sacrificed as opposed to the useful coding DNA in the rest of the chromosome. As humans age the average length of a telomere shortens, from around 11,000 base pairs at birth to 4,000 base pairs in old age.

Answer: Henrietta Lacks

After having divided a certain number of times, cells typically undergo a process known as 'senescence' in which they exit the cell cycle and cease to divide any more. However, some cells (often cancer cells) manage to escape senescence and are thus able to continue dividing ad infinitum without loss of function. This is incredibly useful for researchers as it means that if you want to do an experiment with living cells, you don't have to buy fresh cells (known as 'primary' cells), you can just buy a frozen stock of a given cell line and continue to grow (culture) them in your laboratory.

The cell line known today as HeLa was taken from Henrietta Lacks, a cervical cancer patient, in 1951. The descendants of the original cells donated by Henrietta are still widely used in research to this day and many people thank her for her contribution to science. One of the first uses of the HeLa cell line was in the development of a vaccine for polio in 1954.