Topic 2-Glossary Flashcards
(115 cards)
1
Q
Mucus
A
A thick slimy fluid secreted by the cells lining many organs. Mucus is produced for example, by cells in the gas-exchange system, the digestive system and the reproductive system. Apart from water, its main component is a protein called mucin. Mucus acts as a lubricant and a protective layer.
2
Q
Cilia
A
Hair-like extensions of the cell membrane in cells lining the airways, that help keep microbes/dust/particles out of the lungs
3
Q
Epithelial
A
Cells which form the outer surface of many animals, line cavities and tubes and cover the surface of internal organs
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Q
Epithelium
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Epithelia, cells working together form this tissue
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Q
Columnar epithelium
A
Column-shaped epithelial cells, often with mircrovilli on free surface
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Q
Trachea
A
Vertebrate windpipe. Kept open by C shaped rings of cartilage, with smooth muscle in its wall and ciliated lining.
7
Q
Bronchus
A
One of the large airways that take air into and out of the lungs. The trachea splits into 2 main bronchi, one going to the right lung and one to the left. Each bronchus has cartilaginous plates and smooth muscle in its walls and a ciliated lining with mucus producing cells.
8
Q
Bronchiole
A
Small airway ending in alveolus. Contains smooth muscle abundantly in the walls, lacks cartilage and mucus glands of bronchi.
9
Q
Diaphragm
A
A thin sheet of muscle situated between the lungs and the abdominal organs of a mammal. Contraction of this muscle causes the diaphragm to flatten and air to be drawn into the lungs.
10
Q
Pathogen
A
An organism capable of causing disease
11
Q
Alveoli/Alveolus
A
The tiny air sacs in the lungs where gas exchange takes place. The alveoli are lined by a layer of cells known as squamous epithelium. These cells are very thin and this helps to ensure efficient diffusion of oxygen from the alveoli into the blood and of carbon dioxide from the blood into the alveoli. The total surface area of all the alveoli in the lungs is very large. This large surface area also helps to ensure efficient diffusion. Also contains surfactant producing cells.
12
Q
Macrophages
A
These cells remove dust and debris and bacteria
13
Q
Concentration gradient
A
A concentration gradient occurs when a substance (e..g. oxygen) exists at a higher concentration in one place than another, with intermediate concentrations in between.
14
Q
Surface area to volume ratio
A
Calculated by dividing the total surface area of a cell or organism by its volume. As an organism gets larger its surface area to volume ratio decreases.
15
Q
Gas exchange surface
A
The layer across which oxygen and carbon dioxide are exchanged
16
Q
Fick’s Law
A
A law which relates some of the factors affecting the rage of diffusion across a gas exchange surface. Fick’s law states that rate of diffusion is proportional to : surface area x difference in concentration/thickness of gas exchange surface
17
Q
Amine Group
A
NH2 attached to central carbon
18
Q
Carboxylic acid group
A
COOH attached to central carbon
19
Q
Residual (R) group
A
The variable side chain - varies between different amino acids. Attached to the central carbon.
20
Q
Peptide bond
A
The bond joining 2 amino acids in a protein. Amino acids together by condensation. When a protein is digested, the peptide bonds are broken down by hydrolysis.
21
Q
Primary structure
A
The sequence of amino acids in a polypeptide chain which determines the final (tertiary) shape of a protein.
22
Q
Secondary structure
A
Interactions between the R groups cause the polypeptide chain to form some three dimensional shapes (2 main types: a - helix and B - pleated sheet) prior to folding into the final specific three dimensional shape.
23
Q
a - helix
A
Common secondary structure where the chain of amino acids is coiled around its long axis, stabilised by hydrogen bonds between the C=O of the carboxylic acid and the -NH of the amine group of different amino acids.
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Q
B - pleated sheet
A
Common secondary structure where the polypeptide chain folds back on its self in the same plane, also stabilised by hydrogen bonds.
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Tertiary structure
The specific three-dimensional structure of a protein. The tertiary structure of a protein is very important in determining its function.
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Quartenary structure
A protein made of several polypeptide chains held together e.g. haemoglobin
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Globular protein
Proteins which assume a compact spherical shape. Functions of these proteins often rely on their specific shape allowing interaction with other molecules e.g. enzymes, antibodies.
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Fibrous protein
Proteins which remain as long chains, often cross-linked together for extra strength . Structural function.s
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Phospholipid
A phospholipid molecule is a lipid with two distinct sections. It has a head region consisting of glycerol and a phosphate group. This part of the molecule is attracted to water. The other end consists of 2 fatty acid tails. This end of the molecule repels water. Phospholipids are important components of cell membranes where they are arranged in a bilayer with the heads pointing outwards and the tails pointing towards each other
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Polar
A molecule or part of a molecular is polar when the sharing of the electrons within it is not quite even; one end becomes slightly positive and the rest is slightly negative
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Hydrophilic
Water-attracting. For instance, in a phospholipid molecule the phosphate group attracts water molecules and the fatty acid part of the molecule repels water molecules.
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Hydrophobic
Water-repelling. in a phospholipds molecule the fatty acid part of the molecule repels water molecules and the phosphate group attracts water molecules
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Micelle
A phospholipid monolayer that has formed a spherical shape so that the hydrophobic fatty acid tails point inwards and the hydrophilic phosphate head points outwards..
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Fluid mosaic model
Name given to current model of the structure of the unit (cell) membrane, composed of a phospholipid bilayer (which gives fluid properties to the membrane) in which proteins may be imbedded (giving the mosaic like effect).
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Glycoprotein
A protein molecule with a polysaccharide attached.
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Glycolipid
A molecule consisting of a lipid and a carbohydrate. They form part of the cell-surface membrane. They have similar functions to glycoproteins; for example, they help cells to bind to each other to form tissues.
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Channel protein
Molecules that span the cell membrane. They have water-filled pores. They have a specific shape so only molecules/icons with matching shapes can pass. Some of the pores can be opened or closed.
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Diffusion
The movement of molecules from where they are in a high concentration to where they are in a lower concentration. Small molecules such as oxygen diffuse through cell membranes into cells.
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Facilitated diffusion
Transport across a cell membrane that is passive (requires no additional energy), moves substances down their concentration gradient (from high to low) and uses carrier Large molecules and ions can only cross cell membranes with the aid of carrier proteins.
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Carrier protein
Proteins within cell membranes that have specifically shaped binding sites for ions or molecules that are required to cross membranes.
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Osmosis
Osmosis is a special sort of diffusion. It is the net movement of water from a dilute solution (a high concentration of water molecules) to a concentrated solution (a low concentration off water molecules) through a partially permeable membrane. Alternatives: "down a water concentration gradient" or "from a high water potential too a low water potential."
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Osmotic pressure
Pressure which causes the movement of water from a solution of higher water potential/lower solute concentration to solution of lower water potential/ higher solute concentration
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Water potential
A measure of the ability of water molecules to move. Water always moves from a higher water potential to a lower water potential. A solution in which there is a higher concentration of free water molecules has a higher water potential than one which has a lower concentration of free water molecules. In osmosis water moves from the solution with the higher water potential through a partially permeable membrane into the solution with the lower water potential.
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Active transport
Movement of substances across a membrane against a concentration gradient. Active transport involves the use of specific carrier proteins in cell membranes. It also requires energy in the form of ATP.
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ATP
Adenosine triphosphate (ATP) is an important molecule found in all living cells. IT is involved in the transfer of energy. Most of the ATP in a cell is produced from ADP and phosphate using energy transferred during the process of respiration. When ATP is broken down, ADP and phosphate are produced and a small amount of energy is made available. This energy may be used in active transport; to synthesise large molecules such as proteins from smaller ones such as amino acids; and for movement in cells such as sperm and muscle cells.
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Exocytosis
A process which involves the transport of substances out of cells. Proteins made in a cell are often modified in the Golgi apparatus. Vesicles are pinched off from the Golgi apparatus and these contain the modified protein. The vesicles move through the cytoplasm and fuse with the cell surface membrane, releasing the protein from the cell.
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Endocytosis
A process which involves the transport of large particles or fluids into cells. The cell surface membrane surrounds the particles concerned. A vesicle is pinched off from the membrane and moves into the cytoplasm of the cell.
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CFTR channel
The channel protein that allows diffusion of chloride ions out of an epithelial cell in the lungs - when it is defective (due to a gene mutation) extra-sticky mucus forms and cystic fibrosis results.
= Cystic Fibrosis Transmembrane Regulator protein
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Endocrine
A gland that secretes substances directly into the blood
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Exocrine
A gland that secretes substance into a duct
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Enzyme
Proteins that speed up chemical reactions in living organisms. For instance, inside a typical cell, many different reactions are taking place. Each of these is catalysed by a specific enzyme. Without these enzymes, the reactions would take place very slowly at the temperatures inside cells.
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Catalyst
A substance that increases the rate of a chemical reaction but remains unchanged at the end of the reaction.
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Active site
The part of an enzyme molecule into which a substrate molecule fits during a chemical reaction. It is like a pocket on the surface of the enzyme and it has a specific shape. Only a substrate molecule with the complementary shape will be able to fit into this active site.
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Lock and key theory
Model to explain the way in which an enzyme (the lock) helps a substrate (the key) to participate in a chemical reaction
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Substrate
In biochemical reactions, this is the molecule on which on which an enzyme acts. The substrate of the enzyme amylase, for example, is starch while that of maltase is maltose. Enzymes are very specific in their actions. Only a substrate molecule with a particular shape will fit the active site of a particular enzyme.
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Enzyme substrate complex
These are formed when substrate molecules form temporary bonds with the amino acids of the active site.
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Induced fit theory
Model to explain the way in which an enzyme enables a substrate to participate in a chemical reaction. When the substrate enters the active site, the enzyme changes shape, fitting more closely around the substrate and speeding up the rate of reaction.
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Activation energy
The energy required to break bonds and start a reaction
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Denaturation
Where the specific three dimensional shape of the enzyme become altered - often due to the effect of temperature, or PH which is not optimal. A change in shape means a loss of function.
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Gene
A section of DNA which has a specific sequence of nucleotide bases which codes for a specific polypeptide. An individual gene may have more than one form. These alternative forms (or alleles) differ from each other in the sequences of their nucleotide bases and, as a result, produce slightly different proteins.
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Genome
All the DNA inside a cell. The genome contains a full set of all the genes controlling the growth and development of the organism of which the cell is a part.
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DNA
The molecule that forms the genetic material of all living organisms. Chemically, DNA consists of 2 polynucleotide chains forming a double helix. Each chain consists of a sugar-phosphate backbone. One of four nucleotide bases is attached to each sugar in this backbone. These bases are joined, adenine to thymine and cytosine to guanine, by hydrogen bonding
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Deoxyribose
The 5 carbon sugar that makes up DNA (along with a phosphate group and an organic base)
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Uracil
Organic base found only in RNA
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Nucleotide
Nucleic acids are polymers made up from a number of nucleotides joined to each other by condensation. Each nucleotide has 3 components: a five-carbon or pentose sugar ribose in RNA and deoxyribose in DNA; a phosphate group; a nucleotide base.
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Nucleic acid
These are polymers made up from a number of nucleotides joined to each other by condensation. There are two sorts of nucleic acid: DNA and RNA
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Hydrogen bond
A weak chemical bond between electropositive hydrogen and other electronegative atoms such as oxygen. Although they require relatively little energy to break, hydrogen bonds are very important in helping to maintain the three dimensional shapes of some molecules.
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Complementary base pairing
The A-T (Or A-U), C-G pairing of bases in double stranded DNA, in transcription, and in translation between tRNA and mRNA
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Triplet code
The genetic code is this type of code, whereby 3 bases code for one amino acid
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Codon
Every triplet code on DNA gives rise to a complementary one of these on mRNA. A sequence of three nucleotide bases on a messenger RNA molecule that codes for a particular amino acid.
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mRNA
Messenger RNA (mRNA) carries information from DNA in the nucleus to the cytoplasm for protein transcription. Genes are sections of DNA which code for particular proteins. DNA is too large to pass through the nuclear pore, so mRNA takes a copy of the genetic code. RNA passes out into the cytoplasm, where is enables amino acids to be assembled in the correct sequence to make a protein.
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tRNA
A molecule of RNA which folded to form a shape resembling a t, which has a amino acid binding site at one end and a specific anticodon at the other.
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rRNA
Ribosomal RNA or rRNA is a type of RNA which is found in ribosomes - a complex structure of RNA and protein.
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Transcription
The synthesis of RNA using one strand of DNA as the template. This mRNA molecule leaves the nucleus to be translated.
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RNA polymerase
Enzyme which catalyses the polymerisation of RNA nucleotides in a 5' to 3' direction to form RNA
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Template strand
Antisense strand, strand of DNA used to produce mRNA
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Coding strand
Sense strand of DNA
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Translation
A process which takes place on a ribosome, where amino acids are joined to form a polypeptide. The mRNA produced during transcription leaves the nucleus and becomes attached to the ribosome where translation takes place. During translation, tRNA molecules collect the appropriate amino acid from the cytoplasm and bring it to the ribosome where the protein is being synthesised.
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Ribosomes
Sometimes free in the cytoplasm, sometimes linked to endoplasmic reticulum. A small organelle made of RNA and protein found either free in the cytoplasm or attached to the membranes of the rough endoplasmic reticulum. Protein synthesis takes place on ribosomes.
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Endoplasmic reticulum
Ribosomes maybe attached to these (a series of flattened membrane-bound sacs)
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anticodon
A sequence of three nucleotide bases on a transfer RNA molecule, which is complementary to the corresponding messenger RNA codon
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Semi-conservative replication
The process inn which a molecule of DNA produces two exact copies of itself. The old DNA molecule unwinds and each of the chains acts as a template for the formation of a new chain. Each new DNA molecule therefore consists of one of the existing chains and one completely new one.
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DNA polymerase
An enzyme that catalyses the joining together of individual nucleotides to form a molecule of DNA. DNA polymerase is essential to the process of DNA replication
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Mutation
An example of this: when DNA replicates, an incorrect base may slip into place. Missing bases, incorrect bases and swapped bases in DNA can all lead to this. Mutations are changes in genes, which are passed on to daughter cells.
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DF508
The most common mutation to the CFTR gene which results in cystic fibrosis. Deletion of three bases results in the loss of phenylalanine (single letter code =F), the 508th amino acid in the CFTR protein.
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Locus
The position of a gene on a chromosome
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Homologous chromosomes
Similar chromosomes i.e. a paternal chromosome and maternal chromosome form a pair of chromosomes. Homologous chromosomes will have the same sequence of genes and are capable of paring with each other when a cell divides by meiosis
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Alleles
Alternative forms of the same gene found at the same locus
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Homozygous
Having the same alleles for a particular gene
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Heterozygous
Having different alleles for the same gene
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Genotype
This describes an organism in terms of the alleles it contains
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Phenotype
The characteristics of an organism, which result from the genes the organism possesses and the environment
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Dominant
An allele is described as dominant if its effect is always shown
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Carrier
In genetics, a carrier individual is heterozygous and carries (rather than manifests) the recessive allele
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Monohybrid inheritance
Cystic fibrosis is an example of this, where the characteristic is controlled by one gene. Thalassaemia is another example of this type of inheritance.
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F1
A term used in genetics to refer to the offspring of a cross between two organisms
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Gene therapy
Treatment of inherited diseases by altering a person's genetic make-up. It involves the addition to a person's cell of a functional copy of their defective gene, so that a functional protein may be made
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Plasmid
A small, circular piece of DNA found in the cells of many bacteria. Plasmids can be transferred from one cell to another. They are very useful in genetic engineering because they can be used to insert new genes into the cells of bacteria and plants.
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Virus vectors
e.g. Adenoviruses. use of viruses to carry copies of functional genes and deliver them to target cells.
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Liposomes
Spherical phospholipids bilayers - can be combined with DNA to form a liposome DNA complex. Use to deliver functional copies of genes to target cells.
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SCID
Severe combined immune deficiency - the sufferer immune system does not function due to a mutation in one enzyme
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Somatic cells
body cells
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Germ cells
sperm or egg
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Germ line therapy
A type of gene therapy that is not currently permitted in the UK as it could alter the genetic content of every cell in the body
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Genetic testing/Genetic screening
Testing for the presence of the abnormal mutated gene
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Restriction enzymes
These cut DNA at specific base sequences (recognition sites)
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Amniocentesis
Carried out around 15-17 weeks of pregnancy, with a risk of between 0.5-1% of causing a miscarriage, this is a technique used to sample cells from the foetus by inserting a needle into the fluid surrounding it
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Chorionic villus sampling
Carried out at 8-12 weeks of pregnancy, with a risk of 1-2% of causing a miscarriage, involves the removal of a small amount placental tissue by inserting a needle either through the wall of the abdomen or through the vagina
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Pre-implantation genetic diagnosis (PIGD)
Genetic testing of one cell from a 8-16 stage embryo
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In vitro fertilisation (IVF)
Where sperm is used to fertilise an egg in culture, and then implanted into the uterus. Literally means "in glass"
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Rights and duties
Rights: Things that should nearly always be allowed. So, most people believe that humans have such rights as the right to life, the right to freedom of speech, the right to a fair trial and so on.
If someone has a right to something, it usually means that one or more people have duties to that person.
Duties: Things each of us ought to do. For example, if you have a child, you have the duty to look after him/her
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utilitarianism
An ethical approach with no moral absolutes. The ethical framework that holds that the right course of action is that which maximises the amount of happiness or other good in the world. If you are a utilitarian it means that while you might, for example, normally tell the truth, there could be occasions when you would believe that the right thing to do would be to lie (provided you can lie convincingly).
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Autonomy
The ability to make decisions for oneself. A person acts autonomously when such decisions can be put into effect
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Leading a virtuous life
A good character trait (behaviour) to possess. Precisely what the virtues are is open to disagreement, and may vary from place to place and at different times in history. However, certain virtues, such as kindness and courage, are valued by most cultures.
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Genetic counselling
Advice about the genetic tests available, the procedures involved, the chances of a child being affected, and the possible courses of action depending on the outcome of the tests.
