human genetics concepts and applications eighth edition overview of genetics chapter 1

HUMAN GENETICS CONCEPTS AND APPLICATIONSEIGHTH EDITION

OVERVIEW OF GENETICS

Chapter 1

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

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Superboy Case Study

Description/symptoms of disorder- What causes superboy syndrome? What is the function of myostatin? Bioengineering-

What are some possible ways myostatin could be used? Do you see any disadvantages?

Bioethics- definition field of study of the ethical problems arising from scientific advances, esp. in biology and medicine. –organ transplants, genetic engineering, terminally ill care; nonhuman issues- environment, animal testing.

Bioethical issues?

Bioethics Resource Site- NIH http://bioethics.od.nih.gov/

http://bioethics.od.nih.gov/

http://bioethics.od.nih.gov/

Genetics

•What is Genetics? Why study Genetics?

•Branch of Biology•Study of inherited traits and their variations.•What is included in this field?


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1.1 Levels of Genetics

Genes units of heredity composed of DNA

(Deoxyribonucleic Acid)-

the code that directs cells to manufacture proteins.

Proteins control characteristics

Most Human genetics-are multifactorial- result of genes and the environment.

Red hair, fair skin, freckles- melanocortin 1 receptor- protein that controls pigments in skin-

Found in 80% individuals.


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The Genome Complete set of genetic information for an organism Includes:

All of the genes present in an organism Includes protein encoding genes and non-

encoding genes. Human genome sequenced in 2000

20,600 genes OMIM- Online Mendelian Inheritance in Man-

online database for disorders or traits Research continues in what the information

means and gene interaction. Rapidly expanding area of biology.


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Levels of Genetics

DNA- genes-chromosomes-genomes, individuals, families, populations

Deoxyribonucleic Acid (DNA)

Polymer of nucleotides (monomer)Double stranded helixRemains in the nucleus.Deoxyribonucleotide components:

• Phosphate• Sugar: Deoxyribose• Base- 4 different bases

Guanine G Adenine AThymine T Cytosine C

• Nucleotides are named for the base they contain.• The sequence of the bases code for the amino acid sequence in a protein


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The nucleotide chains are anti-parallel.

Read 5` to 3` direction


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Ribonucleic Acid (RNA)

Polymer Single stranded Chain of ribonucleotides (monomer) Ribonucleotides components: (3)

• Phosphate• Sugar: Ribose• Base:

Guanine G Adenine AUracil U Cytosine

C Several types- mRNA , tRNA , rRNA Uses information in DNA to make proteins


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Flow of Information:

DNA RNA Protein


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Genome

Proteomics – which genes are expressed in cell types

Only 1.5% of the DNA in the human genome encodes protein

Rest includes highly repeated sequences with unknown functions

Includes about 24,000 protein encoding genes

Cataloged in database Mendelian Inheritance in Man (MIM)


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Alleles-

Alleles are variants of genes They form by mutation Mutations in sperm or egg cells are

passed on to the next generation May be positive, negative, or neutral Examples -


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Variations

Polymorphisms are variations in the DNA sequence that occur in at least 1% of the population

Single nucleotide polymorphisms (SNPs) are single base sites that differ among individuals and are important as markers


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Chromosomes

Composed of DNA and protein Found in the nucleus of the cell Human cells have 46 chromosomes (23

pairs) #1-22 - autosomes #23- sex chromosomes X and Y

Females have two X chromosomes Males have one X and a Y

A Karyotype

• chart of the chromosomes organized by size (#1-longest)

• determine sex, abnormal chromosome number, or missing sections of chromosomes • can NOT view individual genes.


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Cells

All cells with a nucleus in the body contain the same genetic information

Differentiation causes cells to differ in appearance and function. This is controlled by variation in gene expression.

Stem cells are less specialized and can become many different cell types


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Levels of Organization

Cells Tissues Organs Organ systems Organism

Figure 1.3


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Individual

The genotype of an individual is the alleles they carry.

The phenotype is the visible trait or physical appearance. Dominant alleles are expressed if the

individual carries one or two copies of the allele.

Recessive alleles are only expressed if the individual carries two copies of the allele.

The Family

• Inheritance of traits can be observed in families.

• A pedigree indicates the structure of a family schematically.

Figure 1.2

Population-• Is a group of interbreeding individuals (members of the same species in a specific area)

• The gene pool is the sum of the alleles in a population

• Evolution is the changing allele frequencies in populations over time.


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Evolution

Comparison of DNA sequences indicates the amount of similarity between two species.

98% of human DNA sequences are shared with chimpanzees.

Humans share genes with mice, fish, fruit flies, yeast, and bacteria.


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Review of Genetic Terms

Table 1.1


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Most Genes Do Not Function Alone

• Mendelian traits are determined by a single gene

• Most traits are multifactorial and not controlled by a single gene. They are influenced by more than one gene and the environment

• Some illnesses may occur in different forms: Mendelian, multifactorial, and non- inherited


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Genes and Disease Risk

Mendelian traits have simple inheritance- 1 gene

Multifactorial traits more complicated BRCA1 gene and breast cancer

Ethnic influences as well as environmental

Knowing risk can help us make good choices


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Applications of Genetics

• ForensicsIdentifying victims, DNA at crime

scenes, overturning convictions, adoptions

• Rewriting historyThomas Jefferson offspring, the Jewish

Lemba• Common ancestry


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Health care Legislation

HIPAA (Health Insurance Portability and Accountability Act) of 1996 -federal law

Title I of HIPAA protects health insurance coverage for workers/their families when change/lose jobs.

Title II of HIPAA, known as the Administrative Simplification (AS) provisions, establishment of national standards for electronic health care transactions and national identifiers for providers, health insurance plans, and employers

requires employers to protect employee medical records as confidential.

provides rights and protections for participants and beneficiaries in group health plans.

prohibit discrimination against employees and dependents based on their health status


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GINA

GINA- 2000, 2008 May 21 2008 — President, George W. Bush -

Law-Genetic Information Nondiscrimination Act (GINA) that will protect Americans against discrimination based on their genetic information when it comes to health insurance and employment.

Importance of this legislation? Because of this legislation, Americans will be free

to undergo genetic testing for diseases such as cancer, heart disease, diabetes, and Alzheimer’s without fearing for their job or health insurance,” said House speaker Nancy Pelosi


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Other related issues

Prediction of disease Genetic testing, concerns over privacy

Development of treatments

Family planning


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Applications of GeneticsAgriculture-

field of genetics arose from agriculture Biotechnology-

use of organisms to produce goods Crop and animal breeding Genetically modified foods-

Altered to have new genes or over or under express their own genes.

Transgenic- genes from another species “golden rice” Advantages disadvantages


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Applications of Genetics

Ecology Metagenomics – new field sequencing DNA from a habitat examples Sargasso Sea, air samples, human

body-mouth, digestive tract

Global perspective and human health Malaria and mosquitos.

human genetics concepts and applications eighth edition overview of genetics chapter 1

Documents

mcgrawhill companies

protein copyright

study genetics

genes present

human genetics concepts

nonencoding genes

dna deoxyribonucleic

human genome