Marianna Bevova

Marianna Bevova

I am a researcher at the European Research Institute for the Biology of Ageing, University of Groningen. I am interested in genetics of human diseases and ageing.

Location Groningen, The Netherlands


  • Dear Alastair,

    DNA is a double-stranded molecule.The two strands are complementary. “Watson” and “Crick” are the labelling of DNA strands. One of the strand is “Crick” (also forward, or plus strand) and another is “Watson” (also reverse, or minus strand). For more detailed description of the DNA strands you can read for example: ...

  • Dear Kathy, Andrew, Michael!

    This is not the most easy course to follow, but I truly hope you enjoy it. Please post questions in the case something is unclear. Your fellow learners and educational team will definitely try to help. Don’t be disappointed if you haven’t grasp all small details. Conceptual understanding is much more important. Moreover,...

  • Dear Maro,

    This is indeed a single-stranded binding proteins. They are binding to the single-stranded DNA during replication and preventing opened DNA to reform a double helix.

  • Dear Sandra, you will learn more about DNA damage from Victor Guryev during Week 3.

  • Dear Maro and Stephanie, maybe these links will help to better understand the material: and

  • Thank you!

  • Thank you, Danielle!

  • Great to hear that, Leah! Thank you.

  • Dear John, there is also a growing glossary at the end of each week.

  • Dear Sandra, stochastic means random. Something that we can't predict precisely.

  • Dear Sindy,

    Photoreactivation is indeed a DNA repair mechanism. Photoreactivating enzyme can repair UV induced DNA damage by utilizing the energy of visible light. This mechanism is widespread in nature but is not universal. It is present in plants, bacteria, animals. However in placental mammals, including humans this mechanisms is no longer active. Other...

  • You are very welcome!

  • Dear Mark,

    Here is a link to review describing animal models of ageing research. I hope this will answer your questions. Indeed, you will learn more about the model systems to study ageing in the following weeks.

  • Dear Naganathan,

    Most of the mutations occur during replication (copying) of DNA when cells divide. So even with minimal physical activity or environmental stress mistakes accumulate in cell DNA with age.

  • Dear Cindy,

    considerable research is devoted to study the mechanisms of DNA repair.
    In 2015 Nobel Prize in Chemistry has been awarded to Tomas Lindahl, Paul Modrich and Aziz Sancar for their “Mechanistic studies of DNA repair”

  • Dear Salvatore,

    your explanation is a very nice one and it is correct that almost all cells in our body do contain their own copy of the DNA. Indeed not all genes are active in every cell. Only genes that are needed for functioning of this particular cell in this period are active. However DNA is a molecule, a primary source of the instructions used in the...

  • Dear David,

    you will learn more about calorie restriction from Cor Calkhoven in Week 5.

    You second question is more difficult to answer as we don’t yet know what is the exact hierarchy of the hallmarks of ageing. Genomic instability, the shorterning of telomeres, epigenetic alterations and loss of proteostasis are considered to be so called primary...

  • Dear Jo-Ann,

    It is a very good question. The protein folding can indeed go wrong. The good news is that we have a “protein quality control” system. The misfolded proteins are normally degraded and recycled by lysosomes and proteasomes. However, during ageing there is a decline is the performance of this system and misfolded proteins can be missed. This may...

  • Dear all, thank you so much for your nice comments! I'll pass them to the whole team.

    I personally have truly enjoyed being with you during this six weeks. It was great to read your comments and discussion and to see your enthusiasm and devotion. Especially for some of you without a prior background in genetics/molecular biology it was not an easy course...

  • We will read it :) Thank you so much Bianca. This is so rewarding to read it! I'll pass your "thank you" to the whole team. Stay healthy!

  • Dear Dorothy - hopefully this review will help:

  • Dear Harrie - wish you a quick recovery and hope to see you back here! Of course it is not a problem to lag behind, the course will be open even after week 6th. Just go with your own pace.

  • There is a very nice (however very dense) review from Carlos Lopez-Otin et al., The Hallmarks of Ageing published in Cell on June 6, 2013 (

    They proposed 9 candidate hallmarks of aging that are “generally considered to contribute to the ageing process and together determine the aging...

  • Dear Robert,
    I am glad to hear you are sad ( sounds a bit strange :) that the course is coming to an end. I hope this means that you enjoyed this course. There is so much more to learn and explore in the field of ageing! So don't stop! and although ERIBA doesn't have a news letter ( yet), but the web site contains planty if information about latest news and...

  • Dear Nicola,

    as Gerald correctly answered - the meaning of the oligoclonal is - derived from a few clones. Another terms to describe the amount of clones contributing - "polyclonal", wich means -derived from many clones and "monoclonal"—derived from one clone.

    And indeed you are right - random is a synonym of stochastic. We could have used random...It...

  • nice one - "go slow and eat lettuce" :))

  • Dear Gillian,
    I hope that will help:

  • Dear Svetlana,
    you are right about Telomeres. However the question 2 is formulated as: "Which of the following statements about chromatids is NOT correct?" So exactly the statement: "The two chromatids of the mitotic chromosome are held together by a telomere." is not correct one.

  • Dear Harrie,
    thank you for mentioning this!
    The link should be fixed now.

  • Dear Angela,

    Concerning your question about the difference between pluripotent and multipotent stem cells.

    Based on proliferation capacity all stem cells may be divided into three major groups: totipotent, pluripotent and multipotent ones. Totipotent stem cells have a capacity to differentiate in any cell type in a body plus the extraembryonic or...

  • Dear Jan,

    omnipotent stem cells or totipotent ones are the cell that can form all cell types in a body, plus the extraembryonic, or placental, cells.
    The cells that are produced from the fusion of an egg and sperm cell and the first several divisions of the fertilized egg are totipotent. These are the only totipotent (omnipotent) cells. After several...

  • Dear Ann,
    K15 or Keratin 15 is used as a stem cell marker in skin (epidermal stem cell marker).

    Sorry to hear that you have found the test depressing. Some questions are maybe indeed too difficult but I hope it won't discourage you from continuing the course.

    If you find the course interesting and you are learning new things and concepts from this...

  • Dear MaryKaren, de novo mutations that fathers contribute to their offspring are not only on Y chromosome. These mutations can occur anywhere in the genome. Please also see my reply on similar question in this step from the 16th of May (below).

  • Dear Svetlana, vast majority of all mutations occur are neutral. Only small proportion of mutations may have negative or positive effect.

  • yes, actually each of us have mutations. Each child is born with estimated 40-60 new mutations in the genome. Vast majority of those will not have consequences for our health. During our lifetime many mutations occur in somatic cells. Some of these somatic mutations may lead for example to cancer.

  • Dear Karen, you are right that the effect of the paternal age on the amount of mutations is because of the total number of the cell divisions in male germ line.

    It has been estimated that the male germ line has undergo around 160 genome replications in 20 year old male and in 40 years old male the number of replications increasing till around 610 (study of...

  • Dear Terri Ann, very sorry to hear that.
    Are you referring to the question 2 - What is centromere? The correct answer is indeed "This is the part of the chromosome where the two sister chromatids are linked". Was it the formulation of the answer that was not clear?
    This test is indeed not an exam. The only purpose of these pre-lecture quizes is to improve...

  • Dear Martha, William and Dorothy - great that you are following the course!! If you have time you can read an additional literature provided in the links to pre-quizzes. That may help to understand the following lectures.

  • Dear Hugh, this question is difficult to answer. There are aways cells in our body that can not anymore perform their functions. If our body function properly - most of these cells would be replaced with the new ones. With age this ability of our organism is going down.

    Dear Veronica - healthy lifestyle will help. Smoking for example has been shown to be...

  • Dear Mitzy,
    I assume you are referring to somatic and germline mutations. This classification is applicable for multicellular organisms. In humans we call mutation somatic if it is occurs in the somatic cells- that are all cells in the body except of germ cells. Germ cells are egg and sperm. Mutations that occur in egg and sperm are called germline...

  • Of course Jacqueline, I absolutely agree with it. Of course we can't do experiments in humans, please don't get me wrong.

  • Glad to hear it became more clear!

  • Dear Maxim,

    a lot of researchers indeed trying to identify reliable biomarkers of ageing. You will hear about some examples of biomarkers during this course.

    However the "problem" with studying humans (apart from all ethical issues) is that we all have different genetic background, different lifestyle and habits. We eat different food every day, the...

  • Dear Peter,
    one addition- there are some exceptions from the Central Dogma. The unidirectional flow of information is a bit simplification. We currently know that non-coding RNA exist in cells (meaning that RNA is not translated into a protein). Another example is that in some viruses (retroviruses) reverse transcription occurs. This is the transfer of...

  • Dear all,
    total DNA in a nucleus (all chromosomes) form nuclear genome, additionally there in DNA in mitochondria and it forms mitochondrial genome. Nuclear genome is much larger with around 26,000 genes, and circular mitochondrial genome contains only 37 genes. Nuclear genome plus mitochondrial genome form the full genome of a cell and contains all of the...

  • Dear Carla, there are links to the glossaries in the weekly introductions. And now you also know that the glossary will come at the end of each week.

  • Dear Rob, each chromosome contains part of the nuclear genome.

  • Dear Martin, sorry to hear that! Maybe it is internet speed problem? Have you tried to download the videos and then watch them?

  • Dear Gerald, life expectancy at the age of 60 is the average number of years that a person at that age can be expected to live. This number is widely used for comparison of life expectancy. For example to compare the difference between countries or as it is mentioned in this lecture- to look at the trend across the years. The life expectancy at the age of 60...

  • You are absolutely right Abraham and you will hear more about other changes in cell with age during this course.

  • Dear James, thank you for your comment. These numbers are years and not percentages. As Fiona explained the graph that follows immediately after shows the proportion of population over 60 years. But the point of the sentence before is an increase in life expectancy at the age of 60. That means that for example in 1992 a man was expected to live 16.6 additional...

  • :)

  • Dear Christopher, yes, the glossaries are available as PDFs. Just look for them under "downloads" below "mark as complete" button.

  • Nice to see you again, Penny! I indeed remember you from the previous run. I hope you will enjoy the course.

  • Dear Julie, very sorry to hear that. If you are interested- you may read this article, hopefully the topic will become more clear:

  • Dear Hanan, the selection is towards the best fitness and successful reproduction of an individual. We are talking in the case of humans of a time period till ~45 y.o. This is a period of time that is under selective pressure in humans. The period after ~45 y.o. (of course not sharp) is in the “selection shadow”. That means for example that during evolution...

  • Thank you for a nice words Marian and thank you for your feedback about the quizzes!

  • Dear John, enjoy your holidays! The course will remain open after the official six weeks, so you'll have enought time to finish it.

  • Dear David, I hope it was a an expression of a positive surprise :) and I hope you will find the time to write the assay. It is really helpfull to pull together a lot of knowledge you have from this course and to think about the concepts.

  • Dear Brad, great to hear that you enjoyed writing the assay! In order to submit it you need to copy/paste the content of your essay to the box in the assay step (6.8).

  • Dear Nargis, it is 2.5%. So the subtitles and transcript are correct.

  • Thank you, Kim!

  • Thank you so much for your nice words Craig!

  • Dear all, here is an interesting reading from the last issue of Science journal on ageing in different species -

  • Dear Edith,
    in this course we have pre-lecture quizzes before each lecture series. With exactly the same purpose you mentioned. These pre-quizzes contain the links to videos or articles with background information to understand the following lectures. It is of course an extra time to watch and read these links but it hopefully of help for people without...

  • Dear Christy,
    The question is indeed - how do cells differentiate between a chromosome end from a DNA break? The answer is telomeres. The concept of a telomere came way back in the 1930s from work by Hermann Muller and Barbara McClintock. Their work suggested that some special structure, which Muller called a telomere, was important to protect chromosome...

  • Dear Doug, mistakes occur as well during sequencing. Different platforms are making different % of mistakes. For example the sequencer HiSeq2500 that we use at ERIBA makes up to 1% of mistakes during incorporation of the new bases (sequencing by synthesis). This problem is partly resolved by sequencing many copies of the same DNA fragment. If we are looking...

  • Dear Otto, it is indeed "bind"or 'attached". In this particular case it is referring to the binding of the DNA labelled probe to the DNA sequence of interest.

  • Dear Frank- at the beginning of each week in the description under the weekly introduction there is a link. You can also print or download the glossary and use is while watching the lectures.

  • Dear Ian, sorry to hear that. It works for me, I just checked. Did you try "standard" downloading?

  • Dear Bill, there is a link to the glossary at the beginning of each week.

  • Dear Alison, a cell line is a population of cells descended from a single cell. It can be of a different origin. For example human, mouse cell lines are used a lot in research.

  • and another type of "nanobiorobots" to correct the genome mutations in each and every cell :)

  • Dear Susan, we will go back to all the concepts mentioned during the first week in weeks to follow. I hope at the end of the course things become more clear and you will have a general picture of the ageing processes in our cells.

  • Dear all, I'll try to clarify. In general - most of the mutations are benign. They have no concequenses for the organism. In this course we are talking about two types of mutations - germline mutations and somatic mutations. The first ones are the one that may be passed to the next generation. The somatic mutations are occur in the somatic cells and are not...

  • Cor Calkhoven will tell more about calorie restriction at Week 5 of this course.

  • Dear Edith, thank you very much for the nice words!

    You will hear more about stem cells in the coming weeks! I hope your question will be answered then.

    1. Concerning you question about the germ cells. A new individual don't start with a 'blank state". Mutations accumulate in germ line as well. An older fathers, for example, are contributing more...

  • Dear John, all educators/tutors have their function written after their family names (like me for example :). Additionally we are scanning the commments of other people and add/correct if nesessary. I have noticed yesterday that several course participants who are not educators make very nice and to the point comments! It is great to see!

  • Dear Alison, for example Hydra does not age as a result of high levels of cell proliferation and regenerative capacity.

  • Dear Pathiyil Ravi Shankar, the end -ase is rather indicator of an enzyme, independent of the function. For example- polymerase-is an enzyme that synthesizes long chains or polymers of nucleic acids; Kinase - is an enzyme that catalyzes the transfer of phosphate groups.

  • Let me add that the neutral mutations (the ones that have no pronounced effect on fitness) that are not under selective preassure are a subject of so called genetic drift. That means that such alleles may by chance change their frequencies in population - become frequent or vanish completely....

  • Dear Ellie,

    Thank you for your comment.
    It is indeed probably not the most easiest assignment. However you don’t need to be afraid to step into it. We did cover these topics in the lectures. Important to mention - these are the topics that are currently under very active investigation. That means that there are no correct or incorrect answers. You can...

  • Dear Johanna, indeed there are more to cover in the field of research on ageing than we have done at this course. It is difficult to cover it all in 6 weeks. We briefly mentioned mitochondria in Week 1 but did not go into further details. It is an important topic to study in connection with ageing. Here are for example some links to articles which you can...

  • Dear Peter, here is the reference - Studying chromosome instability in the mouse. 2008, F. Foijer et al., Biochimica et Biophysica Acta 1786:73–82., and the direct link to the article is -

  • Sorry to hear that. I just checked and I can see the video. Another option is to download the video and then watch it. You can find the download option at the lower right corner of the video.

  • Dear Michael, Jeanne. There is currently still no clear cut answer to your question. Indeed more women compare to men develop Alzheimer’s disease. This is partly because women tend to live longer and the risk of developing Alzheimer’s disease increases with age. But some studies suggest that there can be other reasons why women are more often affected....

  • Dear Helen, very sorry to hear that. I have added a pdf version of this table. You can find it at the end of the text under "Downloads".

  • Thank you David! You are correct, I have changed it in the pdf file.

  • However the vast majority of the Alzheimer disease cases are sporadic ones. The sporadic form characterized by modest familial aggregation and the age of onset is usually after 60 years old. These form is a so called complex disease. That means that a disease is caused by an interplay between genes (several ones) and environment. In this case genetic...

  • Dear Grazyna,
    Unfortunately I can’t answer your personal question.

    In general: There are two main forms of Alzheimer disease. These are so called familial or early onset form and a “sporadic” or late-onset form. Familial forms, or early onset ones (age of onset is usually before 60) represent minority of Alzheimer disease cases. These forms have a...

  • Dear Richard, I just checked and it works for me. Can you please check if you have subtitles on (right lower corner of the video screen).

  • Dear Quang Vu - a great proposal! There are already many studies doing exactly this! For example a LifeLines cohort in the Netherlands. You can read more about this cohort here:

  • Dear Thomas, about the 'designed babies' - I would like to remind that the majority of the phenotypes in humans are of complex (it is a term in genetics) nature. This means that in contrast to monogenic trait (like cystic fibrosis, for example) that are caused by mutations in a single gene, the complex trait is an interplay between genes (not one, but...

  • Dear Della, each cell contains the whole genome. You are completely right- there can be one single cell with translocations, etc. Most of the studies until now have been done on multiple cells, so we could only study the common changes in the genomes of many cells together. With the newly developed technique of single cell sequencing we can now see what kind...

  • Dear all,
    Don’t get disappointed by the test results. The tests are for your own control and I think it is very good decision to concentrate on the concepts! These are the most crucial parts. You can return to details later.

  • Dear Donals, a very good question!

    1. It is a common practice to use Sanger method of sequencing as an independent method to confirm the results obtained with Next Generation Sequencing technique.
    Sanger sequence is still often less error prone than NGS, so if particular mutations need to be confirmed (after screening the whole genome for them using NGS...