SEMINAR ON

GENETICS

Subject: Advanced Nursing Practice

MEDERATOR: PRESENTER:

Mr. Gopal singh Navpreet Kaur

MSc(N) Child Health Nursing MSc(N) 1st year

Lecturer SGL Nursing College

SGL Nursing College Semi Jalandhar.

Semi Jalandhar.

OBJECTIVES

At the end of teaching students will be able to:

a.) Define genetics.

b.) Define chromosome.

c.) Enlist the type of cell division.

d.) Define mutation.

e.) Define human genome project.

f.) Disadvantages of human genome project.

 

 

   

MEANING OF TERM GENETICS

The term genetics was introduced by Bateson in 1906.

It was derived from Greek word ‘gene’ which means ‘to become’ or ‘to grow into’. Therefore, genetics is the science of coming into being.

Definition:

Genetics is the branch of biological science which deals with the transmission of characteristics from parents to offspring.

GENE A gene is the basic physical and functional unit

of hereditary. Genes, which are made up of DNA, act as RNA instructor to make molecules called proteins.

In humans genes vary in size from a few hundred DNA bases to more than 2 million bases. The Human Genome Project has estimated that humans have between 20,000-25,000 genes.

Every person has two copies of each gene, one inherited from each parent.

CHROMOSOME In the nucleus of each cell, the DNA molecule is

packed into thread like structure called chromosomes. Each chromosome is made up of DNA tightly coiled

many times around proteins called histones that support its structure.

Chromosomes are not visible in the cell’s nucleus not even under a microscope when the cell is not dividing.

However, the DNA that makes up chromosomes becomes more tightly packed during cell division and is then visible under a microscope.

DEOXYRIBONUCLEIC ACID (DNA)

It is a nucleic acid that contains the genetic instructions for the development and function of living things. All known cellular life and some viruses contain DNA.

The main role of DNA in the cell is the long-term storage of information. It is often compared to a blueprint, since it contains the instructions to construct other components of the cell, such as proteins and RNA molecules.

The DNA segments that carry genetic information are called gene, but other DNA sequences have structural purposes, or are involved in regulating the expression of genetic information.

CELL DIVISION

1. MITOSIS

2. MEIOSIS

1. MITOSIS:

This is a continuous process involving four distinct stages seen by light microscopy.

 Prophase Metaphase Anaphase Telophase

MEIOSIS

Meiosis produces gametes. On fertilization when the male gamete(sperm cells) and the female gamete(ovum) unite, the resulting zygote is diploid, because each gamete was haploid.

Unlike mitosis, meiosis involve two distinct cell division rather than one. Additionally meiosis produce four daughter cells not two, all different from the parent cell from each other.

This is the basis of genetic diversity and the uniqueness of each human individual.

TYPES1. FIRST MEIOTIC DIVISION2. SECOND DIVISION DIVISION

MUTATION

The term mutation is defined as a physic-chemical change in the gene, large or small. The gene mutation is permanent change in DNA base sequence that makes up a gene. Mutation range in size from a single DNA building block to a large segment of a chromosome.

Gene mutations occur in two ways: Inherited from a parent, or Acquired during a person’s lifetime.

 TYPES OF GENE MUTATION

Missense Mutation Nonsense Mutation Insertion Mutation Deletion Mutation Duplication Mutation Frameshift Mutation Repeat Expansion

EFFECT OF GENE MUTATION ON HEALTH AND DEVELOPMENT:

To function correctly, each cell depends on thousands of proteins to do their jobs in the right places at the right times.

Something, gene mutation prevents one more of these proteins from working properly.

By changing a gene’s instructions for making a protein to protein, a mutation can cause the protein to malfunction or to be missing entirely.

GNETIC DISORDER: When it can disrupt normal development or cause a medical condition. A condition caused by mutations in one or more genes is called a

genetic disorder.

MECHANISM OF INHERITANCE A particular disorder might be described as

“running in a family” if more than one person in the family has the condition.

Some disorders that affect multiple family members are caused by gene mutations, which can be inherited. Other conditions that appear to run in families are not inherited.

Instead, environmental factors such as dietary habits or a combination of genetic and environmental factors are responsible for these disorders.

MENDELLAN THEORY OF INHERITANCE

Mendelian Inheritance is so called because our understanding of it started with the observations of an Augustinian monk named Gregor Mendel in the 19th century.

Genes provide the information for the growth, development and function of our bodies. When a gene is changed, there is a different massage sent to the cells. A gene change that makes the genes faulty is called a mutation.

PATTERN OF INHERITANCE

Autosomal Dominant:

One mutated copy of the gene in each cell is sufficient for a person to be affected by an autosomal dominant disorder.

Each affected person usually has one affected parent. Autosomal dominant disorders tend to occur in every generation of an affected family

MAIN CHARACTERISTICS OF AUTOSOMAL DOMINANT INHERITANCE

Vertical transmission, men and women equally affected, variable expression, reduced penetrance (in some disorder), and advanced paternal age associated with sporadic cases. Examples of autosomal dominant disorder:

Huntington disease Marfan syndrome Neurofibromatosis type 1 Hereditary breast and ovarian cancer

AUTOSOMAL RECESSIVE

Two mutated copies of the gene are present in each cell when a person has an autosomal recessive disorder. An affected person usually has unaffected parents who each carry a single copy of the mutated gene.

Autosomal recessive disorders are typically not seen in every generation of

an affected family.

MAIN FEATURES OF AUTOSOMAL RECESSIVE INHERITANCE

Horizontal occurrence in families, men and women affected equally, associated with consanguinity and association with particular ethnic groups.

Examples of autosomal recessive disorders: Cystic fibrosis Thalessemia Sickle cell anaemia Phenylketonuria

SEX LINKED INHERITANCE

a.) X- linked Dominant(affected father)

X-linked dominant disorders are caused by mutations in genes on the X chromosomes . Females are more frequently affected than males and the chance of passing on an X-linked dominant disorder differs between men and women.

B.) X-LINKED RECESSIVE

X-linked recessive disorders are also caused by mutations in genes on the X chromosome.

Males are more frequently affected than females and the chance of passing on the disorder differs between men and women.

X-LINKED RECESSIVE(AFFECTED FATHER)

In this example a man with an X-linked recessive condition has two unaffected daughters who each carry one copy of the gene mutation and two unaffected sons who do not have the mutation.

X-LINKED RECESSIVE (CARRIER MOTHER)

In this example an unaffected woman carrier one copy of a gene mutation for an X-linked recessive disorder. She has an affected son, an unaffected daughter who carries one copy of the mutation and two unaffected children who do not have the mutation.

HUMAN GENOME PROJECT

INTRODUCTION:

The genome is defined as the total genetic material contained within the chromosomes of an organism and carried by DNA. Transcriptome is the transcribed messenger RNA complement and the proteome the translated protein constitution.

The Human Genome Project (HGP) began formally in 1990 and is a 13year effort coordinated by the US Department of Energy and the National institute of Health (NIH). It finalized almost 2years earlier than expected. It was an enormous task as the aim was to sequence 3 billion base pairs and identified approximately 30,000 genes.

MAJOR WORK DONE UNDER HGP

1. Isolation of disease genesa.) Functional cloningb.) Positional cloning2. Comparative biology of humans

and other organisms3. Advances in molecular diagnostic4. Therapeutical benefits

OUTCOME OF HGP1. The complete genome sequence is likely to yield

predictable and unpredictable results and benefits. It will provide the ultimate genetics “blue print” of the human.

2. The amount of time required to identify genes via positional cloning and other approaches continue to decreases.

3. One of the unanticipated outcomes understanding of environmental as well as genetic factors in development and diseases.

4. Cloning of diseases gene helps in diagnosis of various genetics factor in development and diseases.

5. Helps in development of Pharmacogenomics.

CONT..........

5. Has a genetic basis in identifying various psychiatric disorders.

6. Helps in understanding of complex social trait.

7. Helps in improved knowledge on mutations.

8. Better understanding of developmental biology.

9. Improvement in gene therapy.

10. Understanding of polygenic disorders. E.g. cancer, diabetes.

11. Identification of human gene and their functions.

DISADVANTAGES

1. The research on human will make very sensitive data available that will affect the personal and private lines of individual.

2. Once it is known that a person carries genes for an incurable disease, the parson can go in depression by thinking how the society will treat wins.

3. Individuals’ substandard genome sequence may be discriminated.

Sr No. Journal’s name Abstract

1. Scientifical American journals

The study reported that 150 genetic variations that could be used to predict whether a person was genetically included to see their 100th birthday. The results were based on research through the genomes of more than 1,000 entrains. Previous studies have suggested that tiny contributions from hundred of genetic factors combine to account for about 25% of variation in human longevity. The remaining 75% is attributed to environmental influence.

2. Annual journals. Maynard V. Olson Vol.13. Page no. 1-27.

The central preoccupation of human genetics is an effort to understand the genotypic basis of human phenotypic diversity. Although recent progress in identifying the gene that when mutated, underline major genetic influences on the vast range of variables and at least partially heritable

BIBLIOGRAPHY

1. Versha Katira, Basics of human genetics, Published by CBS Publishers, Edition 1st Page no. 55-56.

2. Daniel l. Hartl, Elizabeth W. Jones, Essential genetics a genomics prospective. Published by Jones and Bartlett. Edition 3rd Page no. 250-251.

3. Navneet Kumari, Essential genetics, published by Lotus publisher, Edition 1st Page no.10-37.

4. Suresh Kumar Sharma, Human Genetics in nursing, Published by Jaypee publisher. Edition 1st. Page no. 1-45.

5. www.genome.gov.in