Cell and Development Biology

Lectures

The grown-up and more developed (sorry I had to) version of IA BOC, IB Cell and Developmental Biology similarly focuses on various cellular processes and structures, but with a much greater focus on developmental biology. Development enjoyers will be pleased to know that whereas IA BOC was limited to a few basic developmental concepts in Easter, IB CDB covers invertebrate development for 2 weeks of Lent and plant, vertebrate, and mammalian development for the entirety of Easter. Many topics covered in CDB are familiar, such as DNA replication, gene expression, and cytoskeleton dynamics, but are covered in greater detail compared to IA BOC. Furthermore, CDB is a nice complement to IB Biochemistry, with several overlapping topics that are examined from the cellular point of view, allowing for content from one course to be incorporated into the other during the exams.

Lectures start 10am on Tuesdays, Thursdays, and rather annoyingly, Saturdays. The lecture blocks are nicely organised, with a focus on specific organelles during each term. A nice bonus is a little “breather week” in week 5 of Michaelmas where you have no lectures for… 1 day. It ain’t much, but it’s better than nothing!

Michaelmas:

• Molecular Biology of the Cell Nucleus: The very first block of the subject covers everything about the nucleus of the cell. The first lecture covers the structure and function of DNA and histones, while the next lecture deals with organisation of the nuclear matrix. The final 3 lectures deal with chromosome replication, the dynamics of nucleosomes during chromosome replication, and nuclear import and export.
• Genes, Gene Expression, and Cell Decisions: Here, the ins and outs of transcription are covered for both prokaryotes and eukaryotes. The various transcription regulation methods employed by eukaryotes is a key focus here. 1 lecture is also dedicated to the concept of epigenetics, with a discussion of how epigenetics can regulate gene expression at the transcriptional level. The final two lectures focus on the lac and lambda phages and the gene expression mechanisms behind the decision to enter the lytic cycle or the lysogenic cycle.
• Genetic Systems of Prokaryotes: This lecture block focuses on prokaryotes, starting with an introduction to the structure, function, and organisation of the prokaryotic nucleoid. Comparisons between structural proteins of the eukaryotic chromosome and similar proteins in prokaryotes are discussed. Further in the block, the concept of supercoiling is introduced. Following the lectures on nucleoid structure, the regulation of both transcription and DNA replication in bacteria are discussed, with focus on the Trp operon and different types of plasmid replication. The block concludes with the flexibility of bacterial genomes, discussing insertion sequences, transposons, and bacterial conjugation, with these processes linked to the proliferation of antibiotic resistance.
• Genome Function and Evolution: This lecture block explores the complexities of eukaryotic genomes, with a particular focus on various strategies of genome sequencing and the pros and cons of each strategy. Single Nuclear Polymorphisms and GWAS are expanded upon further in later lectures, while DNA repeats such as microsatellites minisatellites as well as eukaryotic transposons are discussed. The final lecture in the block discusses modern techniques of genetic engineering such as CRISPR/Cas9, the generation of transgenic organisms, and induced pluripotent stem cells. A key theme in this block is the various biochemical and genetic methods used in exploring genomes over the years.
• Yeast as a Model Organism: This lecture series delves into yeasts and how they are useful for genetic studies. Topics covered in IA such as various genetic crosses will make an appearance here, together with some new stuff such as the use of yeast in synthetic biology.

Lent:

• Chloroplasts and Mitochondria: The first lecture series of Lent goes through the genetics of chloroplasts and mitochondria. Transcription, translation, and protein processing in these organelles are covered, as are the mechanics of protein import. Finally, genetic methods used to study the genomes of these organelles are discussed and are a constant theme during this series.
• Cytoskeleton & Mitotic Cell Division: A series that expands on what you have learnt about the cytoskeleton in IA BOC. The structure of the cytoskeleton is discussed before the dynamics of the cytoskeleton such as actin and microtubule nucleation and polymerisation are explored. The lectures also cover the structure and function of molecular motors such as myosins, kinesins, and dyneins. Lastly, the role of these motor proteins are discussed in the context of cell division, with the dynamic events occurring at the chromosome during mitosis being a key focus towards the end of the block.
• Membrane Trafficking: A major lecture block which covers two important pathways: the secretory and endocytic pathways in cells used for exporting and importing various proteins. You will first encounter the secretory pathway, where techniques used to elucidate the pathway will be discussed, before the structure and function of key components of the pathway such as the ER, ERGIC, GA and other parts are explained. The various proteins involved in vesicle assembly are also discussed, before the lecture block eventually moves on to the endocytic pathway and discussed in a similar fashion to the secretory pathway. Throughout this lecture block, the methods the cell use to achieve specificity and accuracy in targeting a large diversity of proteins to their destinations and correcting errors are discussed, and constant comparisons are made between these two pathways.
• Coordination of organelle and cellular function: A block of two lectures which focuses on how the cell coordinates function between various organelles, with the first lecture focusing on the machinery of cellular organelle degradation and turnover, and the second lecture dealing with mitochondria and the endoplasmic reticulum.
• Intercellular Communication I and II: This block is presented as 2 separate blocks in the lectures, but for brevity I have included them as 1 block in here. Both deal with cell signalling, with the first block focusing on photoperiodism and temperature in the control of flowering, while the second block discusses insulin signalling.
• Invertebrate Development: The first block of the development lectures. The goat Tim Weil will take you through development of C. elegans and Drosophila while contrasting the two different modes of development. This lecture block also plays an introductory role to the rest of the development lectures that you will have in Easter.

Easter:

• Plant Development: This block covers plant development using Arabidopsis as a model organism. The 4 lectures start off with an introduction to plant development and the key differences compared to animal development, before going on to discuss the role of auxin in plants, root and shoot development, and leaf development.
• Xenopus and Zebrafish Development: The first lecture block that introduces vertebrate development, using Xenopus and zebrafish as model organisms. You will learn the mechanisms underpinning the development of both organisms, from simple signalling pathways to major complex events such as organogenesis.
• Mammalian Development: The final lecture block in the subject, mammalian development uses the humble mouse as a model organism to study development in other mammals, including humans. You will learn both pre- and post-gastrulation events in mice, and the signalling pathways underpinning these events. This series also discusses stem cells, and the use of these stem cells in modelling human development.

Supervisions

Depending on your supervisor, one change you might notice from your IA supervisions is that you might be asked to start reading more scientific papers and dissect the figures to both prepare for either Part II or your future career. Otherwise, much like IA, supervisions are an ideal time to discuss essay homework and clarify concepts, which is critical as CDB is after all a biological subject with various intersecting pathways that can be confusing.

Practicals

Unlike IA BOC, you will have practicals pretty much every week. Like IA BOC, you have the option of sending your completed lab report to a demonstrator to get their comments, although your reports do not count towards your final grade and is mainly meant for your understanding. In addition, because the practical content closely tracks the lecture content and the complexity is a step up from IA, it is recommended that you minimally stay on par with the lectures before attending any of the practicals to ensure your maximal understanding of the content. That said, you do get to do some more fun stuff as well, such as expressing GFP in Drosophila larvae via transposons and watching them glow green under a microscope.

Revision and Exams

Exams consist of a 3-hour essay paper and a 3-hour written practical. The essay paper contains 3 sections, each with 4-5 questions, and you write a total of 4 essays with at least 1 essay from each section. As for the practical, there are 2 sections, A and B, where the former is an essay section. You choose 2 essays from a selection of around 5 questions, and unlike the pure essay paper, these essays tend to be integrative and much more general in nature. Section B contains around 8 questions centered around the practical content, with varying lengths for each question. Both papers are likely to be closed book and online on the Inspera platform.

Past year papers are a great resource for revision, and the greatest utility comes from papers after 2020 (note that the 2020 practical paper is essay-only). Papers from the years prior to 2020 contain a short answer section, which is not applicable for you. However, if you do go so far as to complete all the newest practical papers, you can still use the older papers for practice, but bear in mind that the course content may have changed from then.

Writing the exam: 3 hours for 4 essays is on the somewhat more lenient side, giving you roughly 5-10 minutes for essay planning. Once again, like all your supervisors and lecturers have probably mentioned before, read and address the question in your essays! In addition, you could theoretically pick only the bits of the course you like and revise for those because you are only writing 4 out of a possible 13 essay questions. However, do have backups so you will not get caught out if your favourite essay topic is a curveball, a merger with another topic, or worst of all, a no-show!

For practicals, the best strategy for the integrative essay is just to prepare for a wide range of general topics. Multiple questions can come out for development, so be sure to spend some effort on this topic (which helps for section C in the essay paper as well). In addition, coming up with a list on breakthroughs and experimental techniques that have aided cell biology is very handy for questions on experimental techniques, which is another examiner favourite. Other questions potentially involve a general question of the role of biomolecules such as ATP, membrane proteins, phosphoinositides… The possibilities are endless here, but so long as you have a decent grasp of the lecture material, you should be fine for these. For the practical questions, read up on the practical yellow sheets and try to understand what every reagent does and the rationale for every step you carry out in the practical, and address any doubts with the demonstrators in the live sessions. One last thing: split your time wisely and avoid spending more than too much time on the essay (40 minutes per essay is reasonable but find your own sweet spot and stick to it) so you can complete the practical section comfortably!

Useful resources

• Textbook:
  • Molecular Biology of the Cell by Alberts et al. Covers a lot of the course content, and I have found it helpful in explaining the more esoteric concepts in development. Get it on Amazon, or you can always, you know…
• Sources of papers that will help your essay stand out:
  • PubMed: https://pubmed.ncbi.nlm.nih.gov/
  • Google Scholar: https://scholar.google.com/