Life Sciences Research for Lifelong Health

 

Glossary

 
Term   Synonyms
+  Ageing

The process of growing older. Ageing is the deterioration over time of key functions needed for survival and fertility. This can include physical and mental weaknesses as well as increased susceptibility to a range of illnesses.

 

+  Alzheimers disease

A progressive mental deterioration that typically occurs in middle or old age. Effects can vary greatly between patients and can include loss of memory, problem solving and language skills. Alzheimer’s is the most common cause of dementia and affects around 850,000 people in the UK. The disease is was first described by German psychiatrist Alois Alzheimer in 1901.

 

+  Amino acid sensing

The process of monitoring the availability of chemicals called amino acids inside cells. Amino acids are the building blocks of proteins, which cells need to grow and survive. High amino acid levels can promote growth, whilst low levels can activate autophagy processes to breakdown existing proteins and release amino acids to help the cell survive.

 

+  Antibodies

Proteins secreted by B cells in response to causes of infections or illness (pathogens). Up to 10 billion different antibodies can be generated by the body. They lock-on and stick specifically to molecules that aren’t normally found in the body and help other cells from the immune system to neutralise or destroy them.

 

+  Autophagy

A pathway by which cells engulf and digest unnecessary cell components, allowing them to be reused for energy when other energy sources are limited.

 

+  Axon degeneration

Axons are a part of nerve cells, they are like long, thin wires that connect one nerve cell to another. In certain diseases axons can degenerate – weaken and break down – stopping nerve cells from communicating. In nerve wasting diseases such as Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, glaucoma and diabetic neuropathy, the nerve axons are usually the first parts to degenerate.

 

+  Axonal transport

A process for transporting proteins, cell components and waste products around a nerve cell. Nerve cells include a thin, wire-like section called an axon. In humans, axons can be up to a metre long, allowing them to carry signals over long distances. Keeping such a large cell alive requires a complex transportation system. Failures in axon transport can be one reason for axon degeneration.

 

+  B Cells

Types of cells that provide a specialised response to infections by identifying the specific cause of infection (pathogens) and producing antibodies to help combat the illness.

 

b-lymphocytes
+  Bioinformatics

A type of research that develops methods and computer tools to help understanding biological data, particularly large and repetitive data like genome sequences. Bioinformatics combines computer science, statistics, mathematics, and engineering to analyse and interpret biological data.

 

+  Biological Noise

Random variations in the number of certain molecules when compared between cells or over time. For example, cells with the same genes and in the same environment often have different levels of some proteins, different sizes and structures. These apparently random differences can have important biological and medical consequences.

 

+  Blastocyst

A structure formed in the early development of mammals, including humans. A blastocyst typically resembles a ball of cells around a hollow space. It includes a group of cells called the inner cell mass which will become all the cells in the embryo, the other cells support the developing embryo before birth, for example by forming the placenta and umbilical cord.

 

+  BRAF

A human gene that makes a protein called B-Raf. The B-Raf protein is involved in sending signals inside cells and direct growth by encouraging cells to divide. Changes to this gene, called BRAF mutants are found in some cancers. The activity of the B-Raf protein can be shut down using BRAF inhibitor drugs. 

 

+  C. elegans

A species of round worm that can be found in soil, each adult worm is about 1 mm long. They are commonly studied in biology because they are small and easy to keep in the lab. They are particularly popular for studying embryo development and the creation of different types of cell from stem cells.

 

+  Cell Adhesion

The process of cells attaching to their surroundings, particularly other cells. Cell adhesion can be highly complex and involves many different molecules. Different molecules allow cells to stick to different surfaces and with different strengths. Understanding cell adhesion is important in understanding embryo development and can have impacts on the progression of certain diseases, including cancer.

 

+  Cell Biology

The field of biology that studies the processes and functions of living cells. All living things are made of cells and each cell is a complex collection of chemicals that interact to produce energy, move molecules and make new chemicals, all of which are needed to keep the cell alive and functional. Understanding the biochemical complexity of cells is a fundamental part of understanding human health and disease and finding new ways for us to stay healthy for longer.

 

+  Cell Memory

The concept in biology that life events can have a lasting impact on the inner workings of a cell and that these changes can be inherited over generations i.e. that cells can remember what has happened to them in the past. For example, in the field of epigenetics, chemical marks on DNA can have a lasting effect on how some genes behave.

 

+  Chromatin

A complex of nucleic acids (DNA) and proteins that form chromosomes. Chromatin allows the DNA that makes up the genome to be folded and packaged into the confined space of the nucleus. It also plays an important role in controlling gene expression. In a human cell, around two metres of DNA can be packed into a space just 1/100th of a millimetre across.

 

+  Chromatin remodelling

The process of rearranging the connections between the DNA and proteins that make up Chromatin. These changes affect how genes encoded in the DNA behave allowing some of them to become more or less active. This process is an important part of how cells respond to signals and adapt to changes.

 

+  Chromosome

A single piece of DNA found in the nucleus of the cell. A human cell contains 46 individual chromosomes arranged as 23 pairs.

 

+  Computational Biology

The use of computers and computerised processing to support research in living systems.

 

+  Copy Number

The number of copies of the same gene inside a cells. In humans many genes have a copy number of two. Some genes naturally have different copy numbers, for example genes that are used a lot often have high copy numbers. Accidental copy number changes can lead to certain illnesses.

 

+  Copy number variation

Changes to the genetic code that result in some genes having a different number of copies in the genome. This can be beneficial or harmful depending on which genes are affected and how.

 

cnv
+  Developmental Biology

The study of the process by which animals and plants grow and develop. In humans and other mammals, this typically focuses on development before birth including the establishment of different types of cells, formation of organs and how the layout of the body is created from a ball of cells. Developmental biology also encompasses the biology of regeneration, asexual reproduction and metamorphosis and the growth and differentiation of stem cells in the adult organism.

 

+  Differentiation

The process by which cells, tissue, and organs acquire specialized features, especially during embryonic development. Stem cells differentiate to produce other types of cells including brain cells, skin cells and blood cells.

 

+  DNA

The type of molecule that carries the genetic instructions used in the growth, development, functioning and reproduction of all known living organisms. Genetic information is encoded and stored in the chemical structure of DNA as a sequence of the four building blocks (A, C, G and T) that make up all DNA strands. The shape of DNA molecules, the iconic double helix, is widely used in representations of genes and genetics. DNA molecules are self-replicating, meaning that (with a little help) they are able to duplicate themselves whilst retaining the genetic information they contain, this is key to life as it allows one cell to make more cells.

 

+  DNA packaging

The process of compacting DNA molecules to fit inside a cell. Each human cell contains around two metres of DNA. By wrapping DNA strands around proteins called histones, it’s possible to fit a huge amount of genetic information into a very small space.

 

+  Embryo

An organism in the early stages of development. Develops from a fertilised egg, called a zygote, and transitions into a foetus. Developing humans are typically referred to as embryos in the first 11 weeks of pregnancy.

 

+  Entosis

Also known as cell cannibalism. A process where one cell surrounds another. Often, the inner cell is then broken down and destroyed by the outer cell. Entosis is rarely seen in healthy cells but is often seen in tissue samples of cancer.

 

+  Epigenetic Rejuvenation

The concept that a mature tissue cell (e.g. a skin cell) can be reprogrammed back to being a stem cell, which can produce more new cells. This process does not typically occur in humans, but artificial rejuvenation could have many possible clinical applications. For example, an old and damaged liver cells could be healed using rejuvenated cells.

 

+  Epigenetics

The study of changes in cells that affect the activity of different genes rather than altering the genes themselves. Often this involves reversible chemical modifications attached to DNA that change gene activity.

 

+  Epigenome

The collective name for all epigenetic factors in a cell or living thing, akin to how the genome is the collective name for the complete set of genetic information.

 

+  Epithelial cells

Cells that make up the surfaces of the body, including the linings of organs and glands. Over 80% of human cancers are thought to start in these types of cells

 

+  Follicular Helper cells (TFH cells)

A type of white blood cell belonging to the group called T cells. These cells are found in lymph nodes and the spleen after infections or immunisations. TFH cells provide help to B cells – another type of white blood cell – to enable them to produce antibodies, which are used to directly neutralise the causes of infection.

 

+  Follicular Regulatory cells (TFR cells)

TFR help to moderate the body’s immune system by suppressing immune responses in the lymph nodes and spleen. They are important in controlling the strength of the response from the immune system after infection or immunisation.

 

+  Gene

A piece of genetic information stored as a piece of DNA, part of a chromosome. Each gene typically produces a molecule that fulfils a specific purpose within a cell. Different versions of the same gene result in slightly different molecules that can ultimately influence our overall appearance, including height, hair colour, blood type etc. 

 

+  Gene Expression

The process by which genetic information stored in DNA affects the cell it is in. Classically this involves using the information to make a protein that performs a certain task. A gene’s expression can be controlled to increase or reduce the number of proteins produced, this allows cells to respond to changing situations.

 

+  Gene regulation

The process of changing gene expression in response to certain triggers. Gene regulation ensures genes are more or less active in different cells and at different times. This allows one set of genetic instructions to make hundreds of different types of cells and allows individual cells to adapt to changes in their surroundings e.g. high temperature, increase sugar levels or lack of oxygen.

 

+  Genome

The complete set of genetic information in an organism. The human genome consists of around 3 billion genetic ‘letters’ – A’s, C’s, G’s and T’s (Adenine, Cytosine, Guanine, Thymine) – and contains between 10,000 and 20,000 genes.

 

+  Genome architecture

How the genome is physically arranged inside living cells. Long strands of DNA need to be looped and folded to fit inside cells and this can bring together pieces of genetic information that are normally far apart. Which genes are close to each other and where they are positioned is an important area of research because location in space can affect gene expression. Changing genome architecture is one way of altering gene regulation. By contrast to genome organisation.

 

+  Genome organisation

How genes are laid out in the genome. The genetic information for individual genes are arranged together onto pieces of DNA called chromosomes. Each chromosome contains many genes as well as lots of other bits of DNA that are often referred to as ‘junk’ but that typically do have uses in the cell. Genome organisation refers to how genes are arranged along each piece of DNA and what impact that has on the regulation and expression of each gene. By contrast to genome architecture.

 

+  Germ Cell

A cell that gives rise to the cells needed for sexual reproduction e.g. sperm or eggs in humans and other mammals. Germ cells can typically be identified before birth even though they only become relevant during adulthood.

 

+  Germinal Centre Response

A response to infection or immunisation where areas called germinal centres form in secondary lymphoid tissues – e.g. the spleen, lymph nodes and tonsils. Germinal centres provide a specialised environment for different types of cells – including B cells and T cells from the immune system – can interact to generate a strong immune response. Germinal centres produce antibody-secreting plasma cells and memory B cells, which respond to infections and provide lasting immunity.

 

+  Germinal Response

A response to infection where structures called germinal centres form in the spleen and other parts of the immune system. Germinal centres aid in the production and selection of B cells, white blood cells that are specifically equipped to fight off the cause of the infection.

 

+  Growth Factor

Molecules that encourage cells to grow and produce more cells. Typically this includes certain proteins or hormones that act as signals that promote growth, healing and the specialisation of stem cells into different types of cell. For example, bone morphogenetic proteins (BMPs) stimulate bone cell formation, while fibroblast growth factors (FGFs) and vascular endothelial growth factors (VEGFs) stimulate blood vessel growth.

 

+  GTPases

A large family of proteins that break down a chemical called guanosine triphosphate (GTP) into guanosine diphosphate (GDP). These proteins have a wide range of roles and effects in different cells. Vision, smell and taste all make use of GTPases to generate the signals that send information to the bran. GTPases help to move molecules between different parts of cells and help to transport them between locations, they influence the production of new proteins and affect the creation of new cells.

 

+  GTPases of the Immunity-Associated Proteins

A family of cell signalling molecules that may play a part in the survival of white blood cells called lymphocytes.

 

gimap
+  Histone modification

The attachment of other chemicals to histone proteins. These chemical changes can alter how histones interact with the DNA nearby and can also provide attachment sites for other proteins. Histone modifications are a reversible way to alter gene expression allowing cells to specialise and adapt to different situations.

 

+  Histones

Proteins that interact with DNA, helping to fold and compact it into the cell. Histones are also involved in regulating the expression of nearby genes in the DNA they bind to. Groups of eight histones form a structure called a nucleosome and DNA wraps around the outside of the nucleosome.

 

+  Homeostasis

Keeping things the same. The body typically tries to maintain the status quo of many factors and much of biology is involved in this. For example, your body will typically try to keep the same internal temperature even when the temperature of your surroundings changes.

 

+  Immune system

How the body defends itself from the causes of illnesses. The system is dispersed throughout the body and includes organs such as the spleen and lymph nodes as well as white blood cells which can be found in the blood and can also enter other parts of the body. The immune system is highly adaptable, able to fight off many causes of infection from viruses to bacteria, fungi and parasites, it is even able to identify rogue cells that could become cancer. The immune system can be divided into different subsystems. For example, the innate immune system is non-specific and responds to many illnesses in a similar way, whilst the adaptive immune system produces a unique response to each illness, creating antibodies that specifically target the cause of the disease. 

 

+  Immunity

The ability to resist a disease. Raising your immunity to a disease helps to reduce your chances of getting ill from that disease. If you’ve already had a disease or if you’ve been vaccinated, your immunity will be higher than it was before. This is because your adaptive immune system learns how to fight the illness and will remember for next time. Some illnesses, such as flu, have many forms and you can be immune to some but still vulnerable to others

 

+  Immunology

A branch of biomedical science that covers the study of all aspects of the immune system in all organisms.

 

+  Inflammation

Part of how the body responds to harm, irritants and infections. Inflammation helps to remove damage, fight infection and speed repair primarily by increasing blood supply to a damaged area. It tends to involve redness, heat, pain and swelling in the affected area.

 

+  Intestinal epithelium

A single layer of cells that line the inner surface of the intestines. They provide a barrier between digested food and the rest of the body, protecting the body from harm, and they are involved in absorbing nutrients into the bloodstream.

 

+  Intracellular

Inside cells. Cells are extremely complex internally containing elaborate structures and many thousands of molecules all with specific functions. The internal organisation of a cell relies on intricate communication networks and extensive transport systems that are highly specialised and adapt to the individual needs of each cell throughout its life.

 

+  Intracellular signalling networks

The systems of proteins and other molecules that are involved in carrying information within a cell, these can affect energy production, protein manufacturing, transport, gene expression and any number of other basic cell processes. Signals can be activated by factors inside the cell or can be initiated in response to changes happening outside. There are many different signalling systems and these are often highly interconnected making the study of intracellular signalling highly challenging.

 

+  Lipids

Fat molecules. Lipids play numerous roles in the body in addition to providing a way to store energy and use it as fuel, they form the membrane barriers that surround cells and separate different parts within them and also provide a way to transmit signals inside and between cells. The complete collection of different lipids in a cell is referred to as the lipidome.

 

+  Lymphocytes

White blood cells, which form part of the immune system. They are important for protecting the body from diseases and provide a cellular memory of prior infections, allowing the body to respond faster if exposed to the same disease again. Some illnesses like the flu and common cold are a group of many slightly different diseases, and the immune system must learn about each one individually. Each time you catch a cold it’s probably one that you haven’t had before. 

 

+  Macroendocytosis

‘Big cell eating’. A process related to autophagy where something is effectively eaten by a cell. The cell surrounds the object encasing it in a bubble called a vacuole. The object is then often broken down and absorbed by the cell.

 

+  Mathematical Modelling

Using related mathematical equations, often on a computer, to approximate a real-world system, such as part of a cell. This can be used to understand and visualise aspects of biology that can’t be studied directly. Creating an accurate mathematical model also makes it possible to estimate the effects that certain changes will have on the system as a whole. For example, this can be used to predict how effective a certain drug could be before testing it for real.

 

+  Mechanistic target of rapamycin

The name of a protein that plays a central role in regulating numerous cellular processes including growth, proliferation, survival and protein synthesis. It is part of many signalling networks and can influence longevity, brain health and cancer progression. Studying mTOR could lead to new treatments for cancer, Autism, Alzheimer’s and other diseases.

 

mtor signalling
+  MEK 1/2 Inhibitor

A drug that stops proteins called MEK1 and MEK2 from working; an example is the drug selumetinib. MEK1 and MEK2 carry signals inside cells, particularly promoting the growth and division of cells, as such they can contribute to the growth of cancer. As such, MEK1/2 inhibitors can in principle, be used to treat certain cancers.

 

+  Melanoma

Also called malignant melanoma. A type of cancer, that typically occurs on the surface of the skin but can occasionally occur internally. It is one of the rarer but more aggressive forms of skin cancer and affects over 15,000 people per year in the UK. Over 90% of people survive their diagnosis for 10 years or more. The majority of cases could be prevented by avoiding exposure to UV light.

 

+  Metabolism

The collective term for all of the chemical processes that take place inside living things and that are necessary for survival.

 

+  Methylation

The attachment of a small chemical called a methyl group to another molecule. Inside cells the other molecule is typically a protein or piece of DNA. In the DNA sequence, the letter C (a molecule called cytosine) is typically where methylations occur. Methylation of DNA, or of proteins attached to DNA often changes the expression of nearby genes.

 

+  Microorganisms

Organisms too small to be seen by the naked eye, such as bacteria or viruses.

 

+  Migration

Movement from one place to another. Cells can migrate through the body, particularly before birth when the different parts of the body are being organised into the right place.

 

+  Nerve

A cell that is capable of using electrical charge to carry information rapidly through the body, particularly over long distances. Nerve cells can be extremely long and loosely resemble wires. Chemicals called neurotransmitters carry a signal between two cells that are close together at locations called synapses.

 

+  Neurobiology

The scientific study of nerves and the nervous system, particularly including the brain.

 

neuroscience
+  Neurodegeneration

The progressive loss of structure or function and eventual death of nerve cells. Many major diseases including Parkinson's, Alzheimer's, and Huntington's occur as a result of neurodegeneration. Currently there is little that can be done to prevent this process and these diseases are incurable.

 

+  Neurons

Nerve cells which carry information within the brain and between the brain and other parts of the body.

 

+  Neutrophils

White blood cells that provide a rapid response to infection. They recognise signals emitted from the site of infection, travel to that area and destroy the cause of the infection; firstly surrounding it, then releasing toxic chemicals to digest it.

 

+  Non-coding RNA

RNA is a molecule in cells similar to DNA. The stored information in DNA can be used to make RNA and, in many cases, the RNA is then read to produce a protein. Non-coding RNAs have a role in cells that doesn’t involve making a protein.

 

+  Nuclear organisation

The arrangement of DNA inside the nucleus, the part of the cell where DNA is stored in many living things. How DNA is organised can influence the activity of different genes. See Chromatin Architecture.

 

+  Pathogen

Something which causes infection, this can include viruses, bacteria, fungi and parasites.

 

+  PI3-kinases

A family of proteins often involved in cell signalling that are critical for a number of cellular functions such as movement, growth and survival. These proteins work by converting a lipid molecule called PIP2 into another called PIP3, which is the signal that affects how the cell behaves.

 

pi3k
+  Placenta

A structure formed during pregnancy in mammals, it provides the point of contact between the developing embryo and the mother. In particular, the placenta allows close contact between the bloodstream of the mother an embryo allowing exchange of nutrients and gases but whilst preventing direct contact between the two blood flows, which could lead to complications and may harm the child.

 

+  Pluripotency

The ability of a cell to potentially develop into all cells of the adult body. This term is typically used to describe embryonic stem cells. Although these cells can form any part of the body, they cannot form other parts of the embryo, such as the placenta or umbilical cord.

 

+  Protein Kinases

A group of proteins that control the activity of other proteins by attaching a chemical group called a phosphate to them. Protein kinases are involved in many signalling pathways inside cells and can activate many other processes affecting cell growth, division and behaviour.

 

+  RAS

A type of GTPase protein. RAS is part of cell signalling systems that control cell survival and cell division. Changes to the RAS protein or how it is controlled are present in many cancers and it is a prime target for developing new treatments.

 

+  Regenerative Medicine

A developing field of medicine derived from studies of stem cells. It aims to enable the replacement or repair of damaged or diseased tissues by growing new ones from stem cells, or even reprogrammed adult cells.

 

+  Regulatory DNA sequence

A piece of DNA that changes how active certain genes are. Typically the DNA sequence provides an attachment point for proteins that change gene expression, increasing or decreasing their activity. Many regulatory sequences are close to the genes they affect but some act over long distances.

 

+  Reprogramming

The removal of epigenetic marks, chemical flags attached to genes, seen in mammals during early development. Since epigenetic marks can accumulate throughout life, this is part of resetting cells to a naïve state in a new embryo.

 

+  Ribonucleic acid

A molecule similar to DNA that plays multiple roles in the cell, including transferring information from the DNA into proteins and regulating gene expression. There are different types of RNA for different tasks, the different types are identified by lowercase letters before RNA, for example: mRNA, tRNA, lincRNA and siRNA.

 

+  RNA binding proteins

Proteins that play a part in biology by attaching to RNA molecules. RNA binding proteins have many roles including moving different RNAs inside cells, controlling the production of proteins from RNA templates and breaking down RNA.

 

+  Signal Transduction

When a molecule coming from outside a cell activates a specific type of protein called a receptor molecule. Cells have many receptors to detect different signals, some are on the cell surface while others are inside the cell and the signal molecules must enter the cell to reach them.

 

+  Signal Transduction

When a molecule coming from outside a cell activates a specific type of protein called a receptor molecule. Cells have many receptors to detect different signals, some are on the cell surface while others are inside the cell and the signal molecules must enter the cell to reach them.

 

+  Signalling

Also called cell signalling. The molecular systems and processes that allow cells to communicate and that enable communication between different parts of a cell. Allows cells to respond to threats and their changing environment as well as making it possible to form complex structures made up of many individual cells. Faulty cell signalling can lead to various diseases including cancer, diabetes and autoimmune disorders.
 
Various pathways – sequences of molecular interactions – have been identified and each pathway is involved in responding to certain signals and initiating various responses. Many of these pathways are connected to form signalling networks. Typically signalling involves activating or deactivating certain genes to cause a change in cell behaviour.
 
Various pathways, sequences of molecular interactions, have been identified and each pathway is involved in responding to certain signals and initiating various responses. Many of these pathways are connected to form signalling networks. Typically signalling involves activating or deactivating certain genes to cause a change in cell behaviour.

 

+  Signalling Pathway

Collections of interacting molecules that allow cells to communicate internally and externally. Each pathway responds to certain signals and initiates certain responses. Signal transduction is the process of activating one of these pathways. Many pathways include amplification steps, allowing a small change to have a big effect on cells.

 

+  Single-Cell analysis

A modern approach in biology that allows information to be gathered from a single-cell. Historically many studies have relied upon information collected across many cells giving an averaged view of biology. Single-cell studies make it possible to investigate how minute variations between cells can have an effect on biology as a whole. Random variations may alter what type of cell a stem cell will become for example.

 

+  Stem Cells

Cells with the unique ability to give rise to different types of cells in the body. Embryonic stem cells are particularly powerful as they are able to produce all of the body’s other cell types. Scientists can now revert adult cells into embryonic stem cells in the lab. Specialist types of stem cells are only able to produce a few different types of cell, they can be found in adults and help to replenish and replace old and damaged cells.

 

+  Stress Response

How cells respond to adverse changes such as a sudden rise in temperature. Cells are able to respond to different changes in different ways, allowing them to adapt to survive under different conditions.

 

stress responses
+  Super resolution microscopy

An advanced form of microscopy that allows particularly small objects to be studied in detail. The nature of light waves mean that molecules such as individual proteins can’t be accurately studied using standard microscopes. Techniques such as electon microscopy can be used but this requires specialist preparation and can’t be used to examine living samples. Different super resolution methods have been developed including structured illumination microscopy (SIM), Stochastic Optical Reconstruction Microscopy (STORM) and Photoactivated Localisation Microscopy (PALM).

 

+  Systems Biology

An experimental and theoretical approach to studying biological systems that attempts to consider the whole of a biological system, not just the individual parts it’s made up of. This approach often involves making use of computers to manage and examine large amounts of information.

 

+  T Cells

A group of white blood cells that form part of the immune system. They are united by the expression of a protein called the T cell receptor on their surface, which helps to identify the signs that signal the presence of an illness or infection. Different types of T cells perform many different roles including aiding the differentiation of B cells, preventing autoimmune responses and directly destroying the causes of disease.

 

t lymphocytes
+  Transcription

The first step of typical gene expression, in which a particular segment of DNA is copied into RNA by a group of proteins that make up an enzyme called RNA polymerase.

 

+  Translation

The final step of typical gene expression where RNA, that may have been processed or edited after transcription, is read by a complex molecular machine called the ribosome. The ribosome uses the information encoded in the RNA to produce a protein. Each sequence of three letters in the RNA sequence represents one of twenty amino acid building blocks that are constructed sequentially into the finished protein.

 

+  Trophoblast

During early development, the embryo of many animals reaches a stage called a blastocyst, where it resembles a mostly hollow ball of cells. The outer layer of the blastocyst is the trophoblast and it gives rise to the placenta.

 

+  Variation

Differences. This can be applied in a number of forms in biology, typically it refers to the differences between living things, either within or between the same species. Variation may also refer to changes in gene activity either between cells or over time as different genes are turned on or off in response to other changes.

 

+  VDJ recombination

A process that occurs in B cells in response to infections. VDJ recombination allows B cells to produce antibody molecules that can specifically lock onto and destroy any cause of infection. It involves shuffling different parts of the genes that are used to make antibodies together. Each time the antibody is unique. In the immune system many B cells produce many different antibodies and the one that is best at targeting the cause of the infection will be used to fight it off. Some of the B cells that make the successful antibody will survive in the blood so the immune system will be prepared to fight the same illness again if it ever comes back.

 

+  Zygote

The cell forms when two sex cells (e.g. the sperm and the egg) fuse. The first stage of development.