GENETICS FOR NURSING STUDENTS UNIT 1.pptx

INTRODUCTION TO NURSING

1. GENETICS FOR NURSES S.SALOMIE JENNIFER

2. INTRODUCTION TO GENETICS

3. CONCEPT OF GENETICS Coined by “ BATESON ” IN 1906 – Means “to become” or “to grow into” Genetics – Branch of sciences that deals with transmission of characteristics from off-spring ; also, study of genetic or hereditary disorders Also deals with prenatal genetic counselling , identification of genetic disorders associated with birth defects.

4. TERMINOLOGY Karyotype :  A n individual's complete set of chromosomes. The term also refers to a laboratory-produced image of a person's chromosomes isolated from an individual cell and arranged in numerical order.

5. Diploid : A diploid nucleus contains two sets of chromosomes Haploid : A haploid nucleus contains a single set of chromosomes

6. Homologous chromosomes : Homologous chromosomes are the same size, same shape and have the same gene map

7. Genome : A genome is an organism’s complete set of DNA , including all of its genes . Gene Pool : The gene pool is the total genetic diversity of a particular species . Gene : A gene is a segment of DNA which controls the production of a particular characteristic . Allele : Alleles are different form of same genes . For any gene, an individual may possess only two alleles .

8. CHARACTERISTICS AND STRUCTURE OF GENES GENE - who are made up of DNA and act as RNA instructed to make molecules called proteins. Carries coded information associated with a specific function. Undergoes Crossing over as well as Mutation . Gene is a unit of hereditary with somatic structure or function that leads to a phenotype expression .

9. Central Dogma of gene: DNA RNA PROTEIN The Gene is the DNA sequence with instructions for making protein. Transcription: DNA RNA with the help of enzyme RNA Polymerase ( making RNA using directions from a DNA template ) Translation: RNA PROTEIN (making a polypeptide chain using directions in mRNA ) Exons : Functional portions of gene sequences that code for proteins

10. Introns : These are non coding sequences which separates the exons . TATA BOX: TATA Boxes consists of enzymes which initiates the site for transcription. Termination codon : The end of translation is signified by a termination codon at the 3’ end of genes. Silencer: It’s a DNA sequence that helps to reduce or shut off the expression of gene.

11. FUNCTIONS OF GENE Components of DNA and units of inheritance Maintains the morphology or phenotype of an individual Essential for cell division Responsible for transferring hereditary information from one generation to next. Responsible for the structures and metabolism of the body

12. Responsible for variation by reshuffling of genes at sexual reproduction- produce variation. Different linkages are produced due to crossing over or mutation. New genes are responsible for new traits and formation of different type of cells, tissues and organs in various parts of the body.

13. STRUCTURE OF CHROMOSOME Thread like structure composed of DNA, present inside the nucleus. When DNA is tightly coiled many times around protein is called histones . Packed by proteins into a condensed structure called Chromatin. Have 2 sections/Arms: Short arm called “p” arm and long arm called “q” arm, separated by a centromere . Humans: 23 pairs of chromosome. 22 pairs- Autosomes ; 23 rd pair- Sex Chromosome.

14. TYPES OF CHROMOSOMES Telocentric : Centromere at the very end of the chromosome. Acrocentric : Centromere in such a place leading to one very long and one very short section human chromosome. Sub metacentric : Centromere displaced towards one end, creating a long arm and a short arm. Metacentric : Centromere located approximately in the middle.

15. FUNCTIONS OF CHROMOSOMES Chromosomes carry hereditary information which is located in the genes. Chromosomes are responsible for protein synthesis. Chromosomes are responsible for Cell Division and Cell Growth. Chromosomes control the cellular differentiation. Chromosomes can replicate and produce carbon copies next generation.

16. CHROMOSOMAL MUTATIONS Disruptions in the normal chromosomal structure and are a major cause of genetic conditions in humans . Example: Deletion : Loss of part of a chromosome. Duplication : Extra copies of a part of a chromosome. Inversion : Reverse the direction of a part of the chromosome.

17. MECHANISM AND MODES OF INHERITANCE Two types: Mendelian pattern of inheritance or sex linked inheritance Non- Mendelian pattern of inheritance

18. Mendelian pattern of inheritance or sex linked inheritance AUTOSOMAL DOMINANT One copy of the causative agent is sufficient to develop the phenotype Occurs due to abnormality in protein , when mutated gene produces a novel protein – produce abnormal and malfunctioning activity Occurs in each generation Example: Huntington’s Disease, Breast Cancer and Ovarian Cancer AUTOSOMAL RECESSIVE Both copies of the gene carry mutated gene- able to produce the phenotype Carried by carriers Carriers are the person with more than one mutated gene Not present in every generation

19. X LINKED DOMINANT: Occur when there is changes in genes found in X chromosomes Female are more prone to get X-Linked dominant disorders than Men. X linked dominant families passed the disorders in each generation and can affect both males and females But fathers cant pass to their son X LINKED RECESSIVE: Caused by mutations in genes on the X chromosome Males are more affected than females and can pass in each generation But fathers cannot pass their X Traits to their son

20. Y LINKED INHERITANCE Occurs in male to male Affected fathers can affect all sons in their family Non- Mendelian pattern of inheritance or sex linked inheritance CO DOMINANT PATTERN OF INHERITANCE Mutated genes are present in two alleles and each allele makes different protein. Example: ABO Blood Group

21. MITOCHONDRIAL PATTERN OF INHERITANCE Also termed as maternal inheritance Because only female can transfer on mitochondrial conditions to their children This disorder present in every generation of a family and can affect both male and females but no male to male transmission

22. MULTIPLE ALLELES AND BLOOD GROUPS

23. MITOSIS AND MEIOSIS