Physiology and Genetic Information BCU

What determines an individuals development? Genetic (nature) Environment (nurture) What is DNA? Deoxyribose Nucleic Acid 2 coiled chains: Double helix Carry info for: development, functions, growth and reproduction Nucleotides in DNA and their binding Cytosine (C) binds to Guanine (G) Adenine (A) binds to Thymine (T) Chromosomes Made up of DNA Humans have a total of 46 chromosomes Offspring get 23 from each parent Chromosomes pair 1 to 22: called autosomes Chromosome pair 23: called sex chromosomes Female chromosome XX Male chromosome XY Proteins 3 nucleotides make a codon ----> this codes for a protein ----> protein delivers a function Genes Specific sequence of DNA that codes for a protein Chromosome: contains 100-1000 genes (around 21000 in total) consists of two sister chromatids and a centromere Structure of a chromosome Transcription turns DNA into a protein which provides a function 1/7 Step 1 (Transcription) 1. DNA is unwrapped 2. DNA acts as the template strand 3. Complementary messenger RNA (mRNA) created Step 2 (Transcription) 1. Ribosome reads mRNA strand 2. Amino acid chain created called a polypeptide Step 3 (Transcription) 1. Amino acid chain folds into 3D shape 2. Protein created ---> provides function Haploid having a single set of unpaired chromosomes (23) .eg. gametes (egg or sperm) Diploid 2 sets of chromosomes (46) .e.g. offspring (23 from each parent) What determines physiology and appearance? 1. genes from parents 2. protein expressed depends on the expression of the gene from mom or dad 3. gene is either dominant or recessive Dominant gene Capital letter .e.g. AA, CC, DD (can be any letter dependent on disease) Recessive gene Lowercase letter .e.g. aa, cc, dd (can be any letter dependent on disease) Example of dominant and recessive gene Dominant A: codes for dark hair Recessive a: codes for light hair Three possible combos are: AA, Aa or aa 1. AA: homozygous dominant: code for dark hair 2. Aa: Heterozygous: code for dark hair 3. aa: homozygous recessive: code for light hair Name of only a dominant or recessive gene Homozygous dominant: AA, BB, CC Homozygous recessive: aa, bb, cc Name of a dominant and recessive gene Heterozygous: Aa, Bb, Cc 2/7 How do genes cause disease? 1. Depends on whether there is a dominant or recessive gene inherited from the other parent eg. Dominant gene causes Polydactyly (extra fingers) Dad has polydactyly (Dd) Mom does not (dd) Possible outcomes are: Dd, Dd, dd, dd Result: 2 offspring will have polydactyly (50%) and 50% wont Autosomal recessive inheritance two recessive alleles must be present for trait to be displayed Cystic Fibrosis Affects: 10,550 people in UK Lifespan: reduces life span (median age of death was 35 in 2017) Symptoms of Cystic Fibrosis Build up of mucus Recurring chest infections Wheezing and coughing Shortness of breath Damaged airways (bronchiectasis) Weight increase Jaundice Diarrhoea or constipation Bowel obstruction in newborns Inheritance of Cystic Fibrosis CFTR gene Makes protein that pumps chloride ions (Cl-) Found on respiratory epithelia 1. Cl- moved from inside the cell to respiratory lumen 2. Sodium ions (Na+) and water follow 3/7 3. This corrects the thickness of mucus produced CFTR gene in cystic fibrosis Gene is mutated Cl- pump does not work Thick stick mucus produced Symptoms of cystic fibrosis occur Huntington's disease Autosomal Dominant Found on chromosome 4 Progressive loss of muscle function Causes jerkiness and stumbling Cognitive decline Down's Syndrome Caused by having an extra Chromosome 21 (known as Trisomy 21) From birth Other genetic diseases DMD Sickle cell Coeliac disease BMD Bloom's syndrome Noonan syndrome Information you need to collect from patients 1. WHO is your patient? 2. WHO is their closest relative? 3. WHO are the people affected? 4. What is the pattern? Genome Entire genetic makeup of an organism Human Genome Project 1990-2003 Aimed to map nucleotides in the human haploid (more than 3 billion) Genome is unique to each person (multiple variations of genes) Genetic mutation changes in an organism's DNA sequence which can cause a disease or condition (not always bad) Genomic Healthcare uses pieces of genetic info to inform diagnosis and treatment of a medical condition 4/7 Genomics vs Genetics Genomics: 1. study of organisms complete set of genetic info 2. includes coding and non-coding DNA Genetics: 1. study of hereditary, single genes Gene expression The process by which information encoded in DNA directs the synthesis of proteins Causes of genomic alterations Carcinogens Hormonal factors Response to DNA damage Autism ADHD (attention deficit hyperactivity disorder) Types of genetic illness: Mental Health Clinical depression Bipolar Schizophrenia Uses of genomes in healthcare 1. refine diagnoses and understand disease 2. clinical care 3. predict drug effects 4. diagnose infections and track epidemics 5. develop new therapies Predictive genetic testing Tells individuals whether they are carriers of mutation May not give indication of whether individual will develop disease Pre-natal screening known genetic condition .e.g downs adult onset disorder (gene present from birth) Non-invasive prenatal testing analyses genetic material released from the placenta that circulates in a pregnant woman's blood stream 5/7 Pre-implantation genetic diagnosis Removing a cell from an early embryo to test for specific gene mutation and select healthy embryo for implantation for IVF Benefits of testing Negative test: no mutation= Removes concerns about self and offspring Positive test: mutation= arranges surveillance and preventive treatment also inform children Prenatal testing: ethical consideration Could cause loss of fetus with potential of developing condition Biomedical Ethical Principles beneficence nonmaleficence justice respect for autonomy Potential issues Confidentiality Truth-telling Patient professional relationship duty of care right to know vs right not to know Personalised medicine a type of medical care in which treatment is customised for an individual patient Types of cancer which target therapy is used Melanoma Lung Different types of leukaemia Ovary Colon Breast HER2 in breast cancer protein known as epidermal growth factor receptor everyone already has this in their body naturally Over expression of HER2 is target for treatment Only work when there are a increase in HER2 receptors side effects: heart damage, infusion re6/7 Herceptin action leading to shortness of breathe and allergic response this is a personalised treatment approach Effect on drugs adverse drug effects can happen in the way the drug moves around the body (pharmacokinetics effects) or how it interacts with the body (pharmacodynamic effects) Both can be influenced by variations in the genome Abacavir HIV/AIDS drug some patients suffered hypersensitivity to this drug= could be fatal genomic studies discovered what specific gene alteration was causing this testing is now carried out before prescribing drug reduced risk from between 5-10% to near 0 7/7