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Questions and Answers
In all DNA molecules, the number of adenines always equals the number of cytosines.
False
The first structural model of DNA was presented by Albert Einstein and Rosalind Franklin.
False
It is estimated that the human genome contains between 30,000 and 40,000 genes.
True
The central dogma of molecular biology links DNA to protein synthesis.
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Hermann J. Muller demonstrated that X-rays could induce mutations.
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The genome of the malaria-carrying mosquito contains 13,600 genes.
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The SARS-associated coronavirus genome sequence was released two years after the disease began spreading.
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The classic 'blender experiment' was conducted by scientists Watson and Crick.
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The dominant allele for pod shape is constricted.
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In genetics, capital letters represent dominant traits.
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The phenotype is determined solely by the dominant alleles.
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Mendel's experiments showed that recessive traits could reappear in the F₂ generation.
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A Punnett Square is used to visualize genetic crosses.
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Alleles are different forms of a gene.
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In Mendel's experiments, the F₁ generation consisted of only dominant traits.
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Mendel's conclusions indicated that recessive alleles had disappeared by the F₂ generation.
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Gregor Mendel was born in the year 1822.
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Mendel's primary focus was on studying animal traits.
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The human genome project was completed in 2003.
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Genomics is related to the study of individual genes only.
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Mendel studied seven contrasting traits in pea plants.
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True breeding plants produce offspring with varied traits.
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The complete set of genetic instructions is known as the genome.
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Gene dominance refers to the complete lack of influence of specific genes.
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Chromosome analysis is not influenced by the choice of specimen used for examination.
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T-Banding is specifically designed to stain the heat-resistant regions of chromosomes.
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Pseudodicentric chromosomes contain two centromeres.
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NOR staining is used to identify nucleolar organizer regions located on acrocentric chromosomes.
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CBG banding involves the use of Giemsa staining without any chemical treatment.
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Spontaneously proliferating cells can be obtained from bone marrow and lymph nodes.
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Chromosome banding is used to reduce the visibility of the constitutive heterochromatin surrounding centromeres.
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Amniotic fluid samples are not typically cultured to obtain dividing cells.
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Gel electrophoresis is a method used for separating electrically charged substances based on their molecular size.
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All molecules, regardless of their charge, migrate toward the anode in an electrical field.
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Arne Tiselius is known as the father of electrophoresis for his work in the 1930s.
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Whole genome sequencing involves determining the complete sequence of RNA in a person's DNA.
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Electrostatic attraction in electrophoresis causes biomolecules to migrate toward electrodes with the same charge.
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In gel electrophoresis, a supporting medium is used to help separate proteins and nucleic acids.
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The speed at which a charged substance migrates in an electric field is only dependent on its size.
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CDNA is formed from RNA through a process that requires reverse transcriptase.
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Study Notes
### History of Genetics
- Humans have known about inheritance for a long time.
- In 1926, Hermann J. Muller showed that X-rays induce mutations.
- Gregor Mendel, an Austrian monk, was born in 1822 in the Czech Republic.
- Mendel worked at the monastery and taught high school.
- He tended the monastery garden and became interested in the traits that were expressed in different generations of peas.
Levels of Genetics and Genomics
- Molecular
- Cellular
- Tissues
- Organs
- Individuals
- Families
- Population
- Evolution of Species
What is Genetics?
- It is the study of inherited traits and their variation.
- Certain difficult-to-define human characteristics might appear to be inherited if they affect several family members but may reflect shared genetic and environmental influences.
Genetic Information
- Genome: The complete set of genetic instructions.
- The human genome was completed in 2003, after starting in 1990.
- Genomics: Field that analyzes and compares genomes of different species
The Human Genome Project
- 1990 - 2003
- The human genome underlies the fundamental unity of all members of the human family, as well as their inherent dignity and diversity.
Genes and Dominance
- Mendel studied seven different pea plant traits.
- Each trait had a contrasting form.
- Recessive: Wrinkled
- Dominant: Round
- Recessive: Constricted
- Dominant: Inflated
- Recessive: Yellow
- Dominant: Green
- Recessive: Yellow
- Dominant: Green
### Segregation
- Mendel wanted to answer the question: Had the recessive alleles disappeared or were they still present in the F1 plants?
- To answer this question, he allowed the F1 plants to produce an F2 generation by self-pollination.
The F1 Cross
- The recessive traits reappeared! Roughly 1/4 of the F2 plants showed a recessive trait.
### Punnett Square
- A diagram used to determine genetic crosses.
- Named after Reginald C. Punnett.
- A way of visualizing various crosses.
- It aids in problem-solving.
- The square represents all possible random fertilization events.
### Chromosome Staining and Banding
- A chromosome band is a part of a chromosome that is clearly distinguishable from its adjacent segments comprised of alternating light and dark stripes.
- G-Banding: A photographic representation of a stained metaphase spread in which the chromosomes are arranged in order of decreasing length.
- C-Banding: DNA is selectively depurinated and denatured by barium hydroxide, and the fragments are washed away by incubation in a warm salt solution.
- T-Banding: A harsher treatment of the chromosomes diminishes staining except at the heat-resistant telomeres.
- NOR Staining: Nucleolar organizer regions (NORs) located on the satellite stalks of the acrocentric chromosomes.
Gel Electrophoresis
- A method of separating electrically charged substances in a mixture
- Gel material acts as a "molecular sieve.”
- The technique is widely used for separating proteins and nucleic acids.
- General Principle: Each charged substance migrates toward the cathode or the anode at a speed that depends on its net charge, size, and shape.
- When an electrical field is applied to a solution, solute molecules with a net positive charge migrate toward the cathode, and molecules with a net negative charge move toward the anode.
### Whole Genome Sequencing
- Involves finding out the whole sequence of a person's DNA.
- A laboratory procedure that determines the order of bases in the genome of an organism in one process.
### Significant Events
- 1952: Alfred Hershey and Martha Chase conducted the "blender experiment", demonstrating that phage DNA enters the cell and leads to its rupture. This experiment is often mistakenly considered the definitive proof that DNA is the genetic material.
- 1953: James Watson and Francis Crick presented a structural model of DNA, suggesting that it consists of two anti-parallel chains held together by hydrogen bonds. This model suggested a method for DNA replication.
- 1957: Francis Crick proposed the central dogma of molecular biology, elucidating the link between DNA, RNA, and protein synthesis.
- 2001: The International Human Genome Sequencing Consortium and Celera Corp published the human genome sequence (2900 Mbp). The genome was estimated to contain between 35,000 and 40,000 genes, later revised to approximately 30,000 genes.
- 2002: The Mosquito Sequencing Consortium published the genome sequence of the malaria-parasite-carrying mosquito (278 Mbp). The genome was shown to contain 13,600 genes, similar to the number found in Drosophila.
- 2003: The British Columbia Cancer Agency released the SARS-associated coronavirus genome sequence (30 Kbp). The genome contains 16 open-reading frames. The sequence was released less than five months after the disease began spreading worldwide.
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Description
Explore the fascinating journey of genetics from Mendel's initial discoveries to modern genomic science. Understand different levels of genetics including molecular, cellular, and population genetics. This quiz will test your knowledge on key historical figures and concepts in genetics.
