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Unformatted text preview: 0 Genetics: From Genes to Genomes
3rd and 4th Editions
Hartwell ● Hood ● Goldberg ● Reynolds ● Silver Chapter 1
The Study of Biological Information 0 2 DNA molecules encode the biological info fundamental to all life forms Chapter Outline 0 Proteins are the primary unit of biological functions Regulatory networks specify the behavior of genes All cells in the body have the info for the body All living forms are closely related Genomes are modular, allowing rapid evolution Genetic techniques permit dissection of biological complexity Focus of this course is on human genetics, since they 3 are the most interesting Allele – alternative form of genes (dominant/recessive) 3 levels of biological information 3 levels of biological information
1. DNA 1. DNA Macromolecule made of nucleic acids
Repository of the genetic code (stores info) 2. Proteins Macromolecules made on amino acids
Amino acid sequence determined by DNA sequence Network of interaction b/w molecules of groups of Network cells cells 3. Biological systems Accomplish coordinated function Accomplish 4 The biological information in DNA generates an enormous diversity of living organisms an 5 Information in DNA generates diversity
0 Process of evolution has taken ~4 billion years to generate organisms seen today Four bases – G (guanine), A (adenine), T (thymine), and C (cytosine) are the nucleotide building blocks of DNA DNA is a double stranded helix composed of AT and CG complementary bases Hydrogen bonds b/w bases (relatively weak) Order of nucleotide sequences determine which proteins are synthesized When and where the synthesis occurs 6 Genetic Information is Digital 0 Although DNA is 3D info within the molecule is 1D and “digital” Automated DNA sequences can read about 10^6 bases/day Huge DNA databases potentially possible. Pros and cons of this???
7 There have been 265 post-conviction DNA exonerations in the United States to date. The first DNA exoneration took place in 1989. Exonerations have been won in 34 states; since 2000, there have been 198 exonerations. 17 of the 265 people exonerated through DNA served time on death row. The avg. length of time served by exonerees is 13 years. The average age of exonerees at the time of their wrongful convictions was 27. The true suspects and/or perpetrators have been identified in 116 of the DNA exoneration cases. 8 Genes are sequences of DNA that encode proteins 0 GENE: DNA region that encodes proteins EXON: coding region of DNA INTRON: noncoding region of DNA 9 DNA resides in within cells packaged as units called chromosomes 0 The entire collection of chromosomes in each cell of an organism is called a genome Human have 24 chromosomes The human genome had about 3 x 10^9 base pairs and 20,000 30,000 genes 10 Chromosome pair 23 represents the SEX CHROMOSOMES 11 Chromosome pairs 122 are the AUTOSOMES 0 Biological function emerges primarily from proteins
0 Amino acids have a basic amino group (NH) and an acidic carboxyl group (COOH) Alanine has a relatively simple CH side chain Tyrosine has a more complex aromatic side chain 13 Proteins are polymers of amino acids 0 Proteins have three dimensional structures Information in DNA dictates the sequence of its amino acids There are 20 different amino acids The order of amino acids determines the type of protein and its structure 14 The diversity of protein structure generates extraordinary diversity 0 15 Proteins interact with DNA and other proteins 0 Biological systems functions as complex interactive networks of proteins and DNA that interact with one another 16 Evolution of biological information on Earth
0 RNA may have been the first informationprocessing molecule DNA took over the linear formation and replication functions Proteins took over the 3D folding functions All organisms alive now descended from the first organisms that adopted this molecular specialization Has the ability to store, replicate, mutate, express, and fold in 3D RNA is unstable, so other stable macromolecules evolve 17 All living things are closely related 0 RNA is composed of four bases: guanine, adenine, cytosine, and uracil 18 All living organisms use essentially the same genetic code
0 19 Many genes have similar functions in very different organisms
0 Comparison of gene products in different organisms can reveal identical and similar amino acid sequences Cytochrome C protein
20 Terminology we need to define
Analogous structures: performs the same 0 function, but are structurally different • Human legs vs. insect legs. Both used for locomotion • Humans use muscles and tendons while insects use hydrolytic pumps Terminology we need to define Terminology we need to define
Homologous structures: similar structure 0 anatomically, but performs different functions • Human arms vs. front whale flipper. Both look as though are “arm” structures • Humans hold items while whales use fin to swim EVOLUTION EVOLUTION 0 CONVERGENT EVOLUTION: different taxa or species solve a problem in the same way evolutionarily. This examines ANALOGOUS characters Example: front flippers of whale and front fins of fish, BOTH used to SWIM DIVERGENT EVOLUTION: Process by which an ancestral characteristic becomes adapted to new roles. This examines HOMOLOGOUS characters Example: Human arms and wings of bats. Common ancestor to both which had 4 limbs. In humans the one pair evolved into hands used for grasping and bats they evolved to wings used for flight EVOLUTION 0 Relatedness among organisms is important for the study of human genes 0 Studies of genetics in model organisms help us understand how genes work in humans Some model organisms include bacteria, yeast, roundworms, fruit flies, and mice Model organisms may have simpler biological networks and can be manipulated experimentally.
25 Modular construction of genomes has allowed rapid evolution of complexity 0 Gene families arise from primordial genes through duplication and rearrangements Duplication and divergence of new genes can generate genes with new functions We’ll examine traits that are controlled be multiple genes and single genes (for example Widow’s peak, attached ear lobes)
26 The process of duplication and divergence 0 27 Duplication and divergence has made rapid evolution possible 0 28 Rapid change in regulatory networks specify how genes behave. 29 Genetic techniques permit the dissection of complexity
0 Genes can be identified and inactivated one at a time using genetic techniques Dissection of genomes genebygene unravels the complexity of biological systems The challenge for modern biology lies in the understanding how the multitude of networks of genes and higher level systems interact to produce complex systems 30 Genome sequencing projects are a step in understanding the complexity of genomes
0 Is there a direct relationship between genome size or the # of genes and evolutionary complexity?
31 ►►► 32 New technological tools facilitate the New dissection of genomes and integration of information of
0 •DNA chips detect the expression of thousands of genes in response to environmental changes 33 Focus on human genetics 0 Genetics is a field of science that will have an enormous impact on society Our understanding of biological complexity using genetic approaches is proceeding at a very rapid pace Recent technological advances have shifted the focus of genetics from analysis of single genes and proteins to entire networks – the System approach 34 Discovery of genes with variations that cause or predispose one to disease will continue at a rapid pace Genetics Predictive and Preventative Medicine 0 Gene therapy Diagnostics Therapeutic drugs to block or reverse effects of mutant genes Detection of disease and treatment before onset may increase life span significantly
35 Social issues and genetics 0 Should an individual’s genetic profiles be freely available to insurance companies, employers, government? Genetic Information Nondiscrimination Act was passed by the federal government in 2008 Should our government regulate the use of genetic and genomic information to reflect societies social values? Is it okay to permanently alter genes in humans for medical or social reasons? 36 ...
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