Genetics Chapter 1

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What is gene therapy?
the direct alternation of genes to treat human diseases
What is evolution?
genetic change taking place through time
What do all living organisms have in common?
they all use similar genetic systems
What is a genome?
a complete set of genetic instructions for any organism and all genomes are encoded in nucleic acids-either DNA or RNA.
What else is common to all life?
the coding system for genomic information. Genetic instructions are in the same format and the code words are identical (with rare exceptions).
What is the two-step process of evolution?
first, inherited differences arise randomly and then the proportion of individuals with particular differences increases or decreases.
What is the foundation of all evolutionary change and is the basis of all life?
genetic variation
What is genetics?
the study of genetic variation.
What are the three major sub disciplines that the study of genetics consist of?
transmission genetics, molecular genetics, and population genetics
What is transmission genetics?
aka classical genetics, it encompasses the basic principles of heredity and how traits are passed from one generation to the next. This area addresses the relation between chromosomes and heredity, the arrangement of genes on chromosomes, and gene mapping.
What does transmission genetics focus on?
the individual organism, how an individual inherits its genetic makeup and how it passes its genes to the next generation.
What is molecular genetics?
it concerns the chemical nature of the gene itself: how genetic information is encoded, replicated, and expressed.
What does molecular genetics include?
the cellular processes of replication, transcription, and translation (by which genetic information is transferred from one molecule to another) and gene regulation (the processes that control the expression of genetic information).
What does molecular genetics focus on?
the gene, its structure, organization, and function
What is population genetics?
it explores the genetic composition of groups of individual members of the same species (populations) and how that composition changes over time and geographic space. Because evolution is genetic change, population genetics is fundamentally the study of evolution.
What does population genetics focus on?
the group of genes found in a population.
What is model genetic organisms?
organisms having characteristics that make them particularly useful for genetic analysis and about which a tremendous amount of genetic information has accumulated.
What are the six model organisms that have been the subject of intensive genetic study?
Drosophila melanogaster (a fruit fly), Escherichia coli (a bacterium present in the gut of humans & mammals), Caenorhabditic elegant (a nematode worm) , Arabidopsis thaliana (thale cress plant), Mus muscles (the house mouse), and Saccharomyces cerevisiae ( baker’s yeast)
Why is the zebrafish an important model in genetic studies?
it is a small vertebrate that produces many offspring and is easy to rear in the laboratory.
Light skin in humans is similarly due to __________?
fewer and less-dense melanosomes in pigment-containing cells.
What is responsible for the differences in pigmentation between Africans and Europeans?
SLC24A5
What did the first domesticated organisms include?
wheat, peas, lentils, barley, dogs, goats, and sheep
What is pangenesis?
Greek philosophers developed the concept of pangenesis. This concept suggested that specific pieces of information travel from various parts of the body to the reproductive organs, from which they are passed to the embryo.
What did pangensis lead the Ancient Greeks to propose?
the notion of the inheritance of acquired characteristics, in which traits acquired in a person’s lifetime become incorporated into that person’s hereditary information and are passed on to offspring.
What is preformationism?
all traits were inherited from only one parent-from the father if the monunculus was in the sperm or from the mother if it was in the egg.
What is blending inheritance?
it proposed that offspring are a blend, or mixture of parental traits. This idea suggested that the genetic material itself blends, much as blue and yellow pigments blend to make green paint. After having been blended, genetic differences could not be separated into blue and yellow pigments.
What is the pan genesis concept?
according to the pan genesis concept, genetic information from different parts of the body travels to the reproductive organs where it is transferred to the gametes.
What is the germ plasm theory?
according to the germ-plasm theory, germ-line tissue in the reproductive organs contains a complete set of genetic information that is transferred directly to the gametes.
Who is Nehemiah Grew?
In 1676, he reported that plants reproduce sexually by using pollen from the male sex cells. With this information, a number of botanists began to experiment with crossing plants and creating hybrids, including Gregor Mendel, who went on to discover the basic principles of heredity.
What is cytology?
the study of cells
who developed the cell theory?
Matthias Jacob Schließen and Theodor Schwann
What is the cell theory?
all life is composed of cells, cells arise only from preexisting cells, and the cell is the fundamental unit of structure and function in living organisms.
What did Walther Flemming observe?
the division of chromosomes in 1879 and published a superb description of mitosis.
What did August Weismann propose?
the germ-plasm theory, which holds that the cells in the reproductive organs carry a complete set of genetic information that is passed to the egg and sperm.
Who was the founder of modern genetics?
Gregor Mendel. He first discovered the principles of heredity by crossing different varieties of pea plants and analyzing the pattern of the transmission of traits in subsequent generations.
Which early concepts of heredity were correct?
germ-plasm theory, cell theory, and mendelian inheritance
Which early concepts were incorrect?
pangenesis, inheritance of acquired characteristics, preformationism and blending inheritance
When was the foundation for population genetics laid?
in the 1930s, when geneticists begin to integrate Mendelian genetics and evolutionary theory
Who described the three-dimensional structure of DNA in 1953, ushering in the era of molecular genetics?
James Watson and Francis Clark, Maurice Wilkins and Rosalind Franklin
When were methods for rapidly sequencing DNA developed?
in 1977, which allowed whole genomes of humans and other organisms to be determined.
When was the human genome completely sequenced?
in 2003
What are the two basic types of cells?
eukaryotic and prokaryotic
What are the difference between prokaryotic and eukaryotic’s?
Prokaryotic cells lack a nuclear membrane and do not generally possess membrane-bounded cell organelles, whereas eukaryotic cells are more complex, possessing a nucleus and membrane-bounded organelles such as chloroplasts and mitochondria.
What is the fundamental unity of heredity?
the gene.
What is a gene?
a unit of information that encodes a genetic characteristic.
What are alleles?
the gene’s multiple forms. A gene that specifics a characteristic may exist in several forms, called ALLELES. for example, a gene for coat color in cats may exist as an allele that encodes black fur or as an allele that encodes orange fur.
What is the distinction between traits and genes?
traits are not inherited directly. Genes are inherited and alone with environmental factors, determine the expression of traits.
What is the genetic information that an individual organism possesses?
genotype
What it the individual trait an organism possesses?
phenotype
What is genetic information encoded in?
the molecular structure of nucleic acids.
What are the two types of nucleic acids?
deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
What are nucleic acids?
polymers consisting of repeating unites called nucleotides
What does nucleotides consist of?
a sugar, a phosphate, and a nitrogenous base
What are the four types of the nitrogenous bases in DNA?
adenine (A), cytosine (C), guanine (G), and thymine (T)
How many complementary nucleotide strands does DNA have?
two
What carries the genetic information in RNA?
few viruses
What are the four nitrogenous bases of RNA?
adenine, cytosine, guanine, and uracil (U)
What are the vehicles of genetic information within a cell?
chromosomes
What does chromosomes consist of?
DNA and associated proteins.
chromosomes separate through the processes of _________ and _________.
mitosis; meiosis
What does the mitosis and meiosis ensure?
that a complete set of an organism’s chromosomes exists in each cell resulting from cell division.
What is mitosis?
the separation of replicated chromosomes in the division of somatic (nonsex) cells.
What is meiosis?
the pairing and separation of replicated chromosomes in the division of sex cells to produce gametes (reproductive cells)
How is genetic information transferred from DNA to RNA to protein?
Genetic information is first transcribed from DNA into RNA, and then RNA is translated into the amino acid sequence of a protein
What are mutations?
changes in genetic information that can be passed cell to cell or from parent to offspring
What does gene mutations affect?
the genetic information of only a single gene
What do chromosome mutations alter?
the number or the structure of chromosomes and therefore usually affect many genes
What are some traits affected by?
some traits are affected by multiple genes that interact in complex ways with environmental factors. Human height, for example, is affected by hundreds of genes as well as environmental factors such as nutrition.
How is evolution a genetic change?
first, genetic variation arises and, second, some genetic variants increase in frequency, whereas other variants decrease in frequency
Q: How does the Hopi culture contribute to the high incidence of albinism among members of the Hopi tribe?
A:In the Hopi culture, albinos were considered special and given special status. Because extensive exposure to sunlight could be damaging or deal, Hopi male albinos did no agricultural work. Albinism was considered a positive trait rather than a negative physical condition, allowing albinos to have more children and thus increasing the frequency of the allele. Finally, the small population size of the Hopi tribe may have helped increase the allele frequency of the albino gene owing to chance.
Q: Give at least three examples of the roles of genetics in society today.
A: Genetics plays important roles in the diagnosis and treatment of hereditary diseases, in breeding plants and animals for improved production and disease resistance, and in producing pharmaceuticals and novel crops through genetic engineering.
Q: List the three traditional sub disciplines of genetics and summarize what each covers
A: Transmission genetics: The inheritance of genes from one generation to the next, gene mapping, characterization of the phenotypes produced by mutations.
Molecular genetics: the structure, organization, and function of genes at the molecular level.
Population genetics: The genetic composition of populations and how the genetic composition changes over time.
Q: Outline the concept of pangenesis and explain how it differs from the germ-plasm theory.
A: Pangenesis proposes that information for creating each part of an offspring’s body originates in each part of the parent’s body and is passed through the reproductive organs to the embryo at conception. Pangensis suggests that changes in parts of the parent’s body may be passed to the offspring’s body. The germ-plasm theory, in contrast, states that the reproductive cells possess all of the information required to make the complete body; the rest of the body contributes no information to the next generation.
What is preformationism? What did it have to say about how traits are inherited?
Preformationism is the idea that an offspring results from a miniature adult form that is already preformed in the sperm or the egg. All traits would thus be inherited from only one parents, either the father or the mother, depending on where the homunculus (the preformed miniature adult) resided in the sperm or the egg.
Categories: Genetics