Podcast
Questions and Answers
What is the term for the entirety of genetic material within a cell or organism?
What is the term for the entirety of genetic material within a cell or organism?
What is the term for a variant form of a sequence present at a particular locus?
What is the term for a variant form of a sequence present at a particular locus?
What is the process that leads to mutations arising from exposure to natural processes that occur within the cell?
What is the process that leads to mutations arising from exposure to natural processes that occur within the cell?
What is the term for the sequence structure at the end of chromosomes?
What is the term for the sequence structure at the end of chromosomes?
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What is the term for the set of chromosomes within a cell?
What is the term for the set of chromosomes within a cell?
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What is the term for the genetic constitution of a particular individual?
What is the term for the genetic constitution of a particular individual?
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What is the term for two loci that are located close together on the same chromosome and are frequently inherited together?
What is the term for two loci that are located close together on the same chromosome and are frequently inherited together?
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What is the term for a mutation that involves the insertion or deletion of a single DNA base?
What is the term for a mutation that involves the insertion or deletion of a single DNA base?
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What percentage of the mammalian genome is made up of coding exons?
What percentage of the mammalian genome is made up of coding exons?
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Which class of genome variation involves large-scale DNA mutations that juxtapose previously unconnected DNA?
Which class of genome variation involves large-scale DNA mutations that juxtapose previously unconnected DNA?
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What commonly causes indels?
What commonly causes indels?
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Which type of genome variation involves gaining or losing whole chromosomes?
Which type of genome variation involves gaining or losing whole chromosomes?
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Which type of transposable elements encodes the machinery needed for transposition?
Which type of transposable elements encodes the machinery needed for transposition?
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How is genome variation typically discovered?
How is genome variation typically discovered?
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Which type of genome variation is inherited?
Which type of genome variation is inherited?
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Which statement is true about balanced structural variants?
Which statement is true about balanced structural variants?
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What typically joins sister chromatids together?
What typically joins sister chromatids together?
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What type of chromosome is an autosome?
What type of chromosome is an autosome?
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In mammals, what are the sex chromosomes?
In mammals, what are the sex chromosomes?
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What term describes a specific fixed genomic position where a gene is located?
What term describes a specific fixed genomic position where a gene is located?
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What does a reference genome represent?
What does a reference genome represent?
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What mutation can result from exposure to ultraviolet light?
What mutation can result from exposure to ultraviolet light?
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How would you describe a diploid cell?
How would you describe a diploid cell?
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What is the result when spontaneous deamination of 5-methylcytosine occurs?
What is the result when spontaneous deamination of 5-methylcytosine occurs?
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Study Notes
Genome Variation and Karyotypes
- Mammals have varying karyotypes and genome sizes, but a similar number of genes, which make up approximately 1-2% of the genome.
- Genome variation can be classified into five categories: single nucleotide variants (SNVs), small insertions and deletions (indels), structural variants, transposable element insertions, and cytogenetic variants.
Types of Genome Variation
- Single nucleotide variants (SNVs): the mutation of a single DNA base into a different base.
- Small insertions and deletions (indels): insertions and deletions less than 100 base pairs in length, frequently caused by polymerase slippage.
- Structural variants: large-scale DNA mutations that juxtapose DNA that was previously not connected, can be inter-chromosomal or intra-chromosomal.
- Transposable element insertions: autonomous (encode the machinery needed for transposition) or non-autonomous (use the transposition machinery of a different class of transposable element).
- Cytogenetic variants: the gain or loss of one or more entire chromosomes, causing aneuploidy.
Effects of Genome Variation
- Most genome variation is non-pathogenic, but a small subset of genetic variants cause or contribute to disease.
- Genome variation can be caused by exogenous or endogenous mutational processes.
- Unbalanced structural variants can lead to copy number variation.
Genome Analysis and Repair
- Genome variation is discovered by whole genome sequencing, which involves shearing DNA into small segments and aligning these to the reference genome.
- The cell has DNA repair mechanisms, and those genome variants that we observe are those that escape repair.
- Genome variation can be germline (inherited) or somatic (private to the individual).
Glossary
- Genome: the entirety of genetic material (DNA) within a cell or organism.
- Karyotype: the set of chromosomes within a cell.
- Autosome: any chromosome that is not a sex chromosome.
- Telomere: the sequence structure at the end of chromosomes.
- Centromere: the region of the chromosome that attaches to the mitotic spindle, and the region where two sister chromatids are joined.
- Reference genome: a completely sequenced genome isolate from a particular species that is used as a reference for genome analysis.
- Genotype: the genetic constitution of a particular individual.
- Phenotype: the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment.
- Locus: a specific fixed genomic position in the genome where a particular gene or genetic marker is located.
- Allele: a variant form of a sequence present at a particular locus.
- Linkage: two loci which are located close together on the same chromosome and which are frequently inherited together.
Genome and Chromosomes
- Genome: the entirety of genetic material (DNA) within a cell or organism
- Karyotype: the set of chromosomes within a cell
- Diploid: two copies of each chromosome are present
- Tetraploid: four copies of each chromosome are present
- Autosome: any chromosome that is not a sex chromosome
- Sex chromosome: X and Y chromosomes (in mammals)
Chromosome Structure
- Telomere: the sequence structure at the end of chromosomes
- Centromere: the region of the chromosome that attaches to the mitotic spindle, and the region where two sister chromatids are joined
- Sister chromatids: identical copies of a duplicated chromosome, joined at the centromere
Genome Analysis
- Reference genome: a completely sequenced genome isolate from a particular species that is used as a reference for genome analysis
- Genotype: the genetic constitution of a particular individual
Characteristics and Variations
- Phenotype: the set of observable characteristics of an individual resulting from the interaction of its genotype with the environment
- Locus (plural loci): a specific fixed genomic position in the genome where a particular gene or genetic marker is located
- Allele: a variant form of a sequence present at a particular locus
- Linkage: two loci which are located close together on the same chromosome and which are frequently inherited together
Mutations
- Single nucleotide variants (SNVs): the mutation of a single DNA base into a different base
- Exogenous mutational process: a process that leads to mutations that arises from exposure to exogenous agents, such as cigarette smoke carcinogens or ultraviolet light
- Endogenous mutational process: a process that leads to mutations that arises from exposure to natural processes that occur within the cell, such as spontaneous deamination of 5-methylcytosine
- Small insertions and deletions (indels): a mutation that involves insertion or deletion of a small sequence of DNA bases
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Description
Learn about the differences in karyotypes and genome size among mammals, as well as the types of genome variation and their effects on disease.
