Explain Genetic Causes of Variation - Biology
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What is a mutation?
What is a mutation?
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A heritable change in DNA nucleotide sequence. Can be passed to offspring and affect protein function.
A heritable change in DNA nucleotide sequence. Can be passed to offspring and affect protein function.
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Which two meiosis-related mechanisms create recombination without creating new alleles?
Which two meiosis-related mechanisms create recombination without creating new alleles?
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Crossing over and independent assortment. Both processes occur during meiosis I.
Crossing over and independent assortment. Both processes occur during meiosis I.
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What is a locus?
What is a locus?
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A gene’s specific location on a chromosome. Each gene has a fixed chromosomal address.
A gene’s specific location on a chromosome. Each gene has a fixed chromosomal address.
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Which meiotic stage directly produces independent assortment of chromosomes?
Which meiotic stage directly produces independent assortment of chromosomes?
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Metaphase I. When homologous pairs align randomly at cell equator.
Metaphase I. When homologous pairs align randomly at cell equator.
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What is random fertilization as a source of genetic variation?
What is random fertilization as a source of genetic variation?
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Any sperm can fertilize any egg, creating new genotypes. Combines genetic material from two different parents.
Any sperm can fertilize any egg, creating new genotypes. Combines genetic material from two different parents.
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Which genetic process can introduce alleles from one population into another?
Which genetic process can introduce alleles from one population into another?
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Gene flow. Migration connects previously isolated gene pools.
Gene flow. Migration connects previously isolated gene pools.
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What is independent assortment?
What is independent assortment?
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Random orientation of homologous pairs in meiosis I. Each homolog can go to either pole during division.
Random orientation of homologous pairs in meiosis I. Each homolog can go to either pole during division.
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What is polyploidy?
What is polyploidy?
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More than two complete sets of chromosomes. Often results from errors in meiosis or mitosis.
More than two complete sets of chromosomes. Often results from errors in meiosis or mitosis.
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During which meiotic phase does crossing over typically occur?
During which meiotic phase does crossing over typically occur?
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Prophase I. When chromosomes pair and exchange genetic material.
Prophase I. When chromosomes pair and exchange genetic material.
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Which meiotic event creates new allele combinations by exchanging DNA between homologs?
Which meiotic event creates new allele combinations by exchanging DNA between homologs?
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Crossing over (homologous recombination). Occurs between paired homologous chromosomes in meiosis.
Crossing over (homologous recombination). Occurs between paired homologous chromosomes in meiosis.
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Which process produces gametes and increases genetic variation in sexually reproducing organisms?
Which process produces gametes and increases genetic variation in sexually reproducing organisms?
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Meiosis. Combines crossing over and independent assortment for variation.
Meiosis. Combines crossing over and independent assortment for variation.
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What is nondisjunction in meiosis?
What is nondisjunction in meiosis?
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Failure of homologs or sister chromatids to separate. Results in gametes with incorrect chromosome numbers.
Failure of homologs or sister chromatids to separate. Results in gametes with incorrect chromosome numbers.
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Which chromosomal mutation moves a segment to a nonhomologous chromosome?
Which chromosomal mutation moves a segment to a nonhomologous chromosome?
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Translocation. Transfers genetic material between different chromosomes.
Translocation. Transfers genetic material between different chromosomes.
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Which chromosomal mutation reverses a segment within a chromosome?
Which chromosomal mutation reverses a segment within a chromosome?
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Inversion. Flips gene order but keeps genes on same chromosome.
Inversion. Flips gene order but keeps genes on same chromosome.
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Which chromosomal mutation repeats a segment of a chromosome?
Which chromosomal mutation repeats a segment of a chromosome?
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Duplication. Creates extra copies of genes within a chromosome.
Duplication. Creates extra copies of genes within a chromosome.
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Which broad category of mutations affects an entire chromosome segment?
Which broad category of mutations affects an entire chromosome segment?
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Chromosomal mutation (structural rearrangement). Involves large-scale DNA changes beyond single nucleotides.
Chromosomal mutation (structural rearrangement). Involves large-scale DNA changes beyond single nucleotides.
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Which mutation changes a codon but not the amino acid it codes for?
Which mutation changes a codon but not the amino acid it codes for?
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Silent mutation. Due to genetic code redundancy, protein remains unchanged.
Silent mutation. Due to genetic code redundancy, protein remains unchanged.
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Which mutation creates a premature stop codon?
Which mutation creates a premature stop codon?
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Nonsense mutation. Truncates protein synthesis early, often affecting function.
Nonsense mutation. Truncates protein synthesis early, often affecting function.
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Which mutation changes an amino acid in a protein sequence?
Which mutation changes an amino acid in a protein sequence?
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Missense mutation. Results in a different amino acid in the protein product.
Missense mutation. Results in a different amino acid in the protein product.
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What is a frameshift mutation?
What is a frameshift mutation?
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Insertion or deletion that shifts the reading frame. Changes how codons are read downstream from mutation site.
Insertion or deletion that shifts the reading frame. Changes how codons are read downstream from mutation site.
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Which mutation removes one or more nucleotides from a DNA sequence?
Which mutation removes one or more nucleotides from a DNA sequence?
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Deletion. Removes genetic material from the DNA sequence.
Deletion. Removes genetic material from the DNA sequence.
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Which mutation adds one or more nucleotides to a DNA sequence?
Which mutation adds one or more nucleotides to a DNA sequence?
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Insertion. Adds extra genetic material to the DNA strand.
Insertion. Adds extra genetic material to the DNA strand.
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Which source of variation is described: new alleles are created rather than reshuffled?
Which source of variation is described: new alleles are created rather than reshuffled?
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Mutation. Only mutation introduces completely novel genetic material.
Mutation. Only mutation introduces completely novel genetic material.
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What is genetic recombination?
What is genetic recombination?
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Formation of new allele combinations in offspring. Shuffles existing alleles into new arrangements.
Formation of new allele combinations in offspring. Shuffles existing alleles into new arrangements.
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Which two meiosis-related mechanisms create recombination without creating new alleles?
Which two meiosis-related mechanisms create recombination without creating new alleles?
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Crossing over and independent assortment. Both processes occur during meiosis I.
Crossing over and independent assortment. Both processes occur during meiosis I.
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What is the difference between mutation and recombination as sources of variation?
What is the difference between mutation and recombination as sources of variation?
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Mutation creates new alleles; recombination reshuffles alleles. Mutation adds novelty; recombination rearranges existing material.
Mutation creates new alleles; recombination reshuffles alleles. Mutation adds novelty; recombination rearranges existing material.
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Which point mutation replaces one nucleotide with another?
Which point mutation replaces one nucleotide with another?
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Substitution. One of three types of point mutations affecting single bases.
Substitution. One of three types of point mutations affecting single bases.
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Which type of mutation changes a single nucleotide in DNA?
Which type of mutation changes a single nucleotide in DNA?
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Point mutation. Affects only one DNA base position at a time.
Point mutation. Affects only one DNA base position at a time.
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What is a mutation?
What is a mutation?
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A heritable change in DNA nucleotide sequence. Can be passed to offspring and affect protein function.
A heritable change in DNA nucleotide sequence. Can be passed to offspring and affect protein function.
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What is the primary genetic source of new alleles in a population?
What is the primary genetic source of new alleles in a population?
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Mutation. Creates entirely new alleles that didn't exist before.
Mutation. Creates entirely new alleles that didn't exist before.
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