Podcast
Questions and Answers
What is the term used to describe a specific location in the genome?
What is the term used to describe a specific location in the genome?
Which term describes variations in the DNA sequence?
Which term describes variations in the DNA sequence?
What describes having two identical alleles for a gene?
What describes having two identical alleles for a gene?
What is the arrangement of alleles referred to as?
What is the arrangement of alleles referred to as?
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Which of the following describes a group of genes or alleles inherited together?
Which of the following describes a group of genes or alleles inherited together?
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What is a characteristic feature of highly repetitive DNA?
What is a characteristic feature of highly repetitive DNA?
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Which of the following correctly describes transposons in the context of middle repetitive DNA?
Which of the following correctly describes transposons in the context of middle repetitive DNA?
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What is the function of α-satellite DNA?
What is the function of α-satellite DNA?
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What can be a consequence of the movement of mobile DNA elements in an individual's genome?
What can be a consequence of the movement of mobile DNA elements in an individual's genome?
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How often does the movement of mobile DNA elements occur in human births?
How often does the movement of mobile DNA elements occur in human births?
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What is primarily used for identifying criminals and paternity cases?
What is primarily used for identifying criminals and paternity cases?
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What is the approximate genetic difference between any two individuals?
What is the approximate genetic difference between any two individuals?
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How many base pairs are typically involved in a microsatellite?
How many base pairs are typically involved in a microsatellite?
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Which DNA variant has a frequency of less than 1-2% in the population?
Which DNA variant has a frequency of less than 1-2% in the population?
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What kind of variations do the SGM+ markers analyze in forensics?
What kind of variations do the SGM+ markers analyze in forensics?
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Which technique was primarily used for profiling DNA variations before modern sequencing?
Which technique was primarily used for profiling DNA variations before modern sequencing?
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What role does the AMEL gene play in forensic DNA profiling?
What role does the AMEL gene play in forensic DNA profiling?
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What are microsatellites useful for in genetics?
What are microsatellites useful for in genetics?
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How are polymorphic markers used in food quality assessment?
How are polymorphic markers used in food quality assessment?
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Which of the following describes a feature of minisatellites?
Which of the following describes a feature of minisatellites?
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What is a significant advantage of using SNPs in genetic research?
What is a significant advantage of using SNPs in genetic research?
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In the concept of biological sex determination, the presence of which alleles indicates a male?
In the concept of biological sex determination, the presence of which alleles indicates a male?
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Why do various individuals and chromosomes have different numbers of repeats in microsatellites?
Why do various individuals and chromosomes have different numbers of repeats in microsatellites?
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Study Notes
Locus
- A locus is a specific location on a genome.
- The plural is loci.
- Each chromosome has two copies, so the term locus typically refers to both copies of a gene.
Polymorphism
- Variations in DNA sequences.
- Can be single nucleotide differences (SNPs) or larger segments.
- Occur across individuals and chromosomes.
- Polymorphisms can exist with or without phenotypic effects.
Allele
- A specific variant of a polymorphism found within a gene.
- For example, a gene might have a C or T allele.
- Different combinations of alleles result in different genotypes.
Variant
- Any difference in DNA sequence.
Mutation
- A change in a DNA sequence, often associated with diseases or phenotypic changes.
Copy Number
- The number of copies of a specific gene or region of DNA.
Genotype
- The individual's complete genetic makeup.
Phenotype
- Observable physical and biochemical characteristics.
- Influenced by both genotype and environment.
Homozygous
- Having two identical alleles for a gene.
Heterozygous
- Having two different alleles for a gene.
Marker
- A gene or DNA sequence used in genetic mapping studies.
Linkage
- Genetic linkage between loci.
Recombination
- Exchange of genetic material during meiosis.
Contig
- A set of overlapping DNA fragments.
Phase
- Arrangement of alleles within a haplotype.
Haplotype
- A group of genes or alleles inherited together.
De novo
- New mutations not present in parents.
Inherited
- Mutations or variations passed down from parents through generations.
Polymorphism vs Mutation
- Polymorphisms can be ancient and prevalent across generations with or without phenotypic effects.
- Mutations often show genetic variation and are frequently associated with specific diseases or phenotypic effects.
Rare Variants
- Variants occurring less than 1-2% in a population.
- Can be de novo (new mutations).
Human Variation
- Roughly 0.1% sequence difference exists between individuals, equating to about 6 million differences.
Types of Polymorphic DNA Sequences
- SNPs: Single-nucleotide polymorphisms.
- Microsatellites (STRs/SSRs): Short tandem repeats (2-7 base pairs).
- Minisatellites (VNTRs): Variable number tandem repeats (8- >50 base pairs).
- CNVs: Copy number variants (0, 1, 3, or more copies in large sequences, >1000 bp to Mb).
Microsatellites vs Minisatellites
| Feature | Microsatellite | Minisatellite |
|---|---|---|
| Repeat Length | 2-7 base pairs | 8- >50 base pairs |
| Repeat Frequency | 5-200 times | 10-1,500 times |
| Repeat Size | 10-1,000 base pairs | 0.5-15 kb |
| Homogeneity | Mostly homogeneous | Heterogeneous |
Applications of Polymorphisms
- Forensic science, assessing biodiversity, food quality control, ancestry and archaeology, human genome sequencing, mapping disease genes, and RFLPs.
Restriction Fragment Length Polymorphisms (RFLPs)
- An older technique for DNA profiling, utilizing restriction enzymes.
- Restriction enzymes are bacterial enzymes that cut specific DNA sequences.
- The sizes of fragments are altered by changes in or between enzyme recognition sites, reflecting differences in DNA sequences.
DNA Fingerprinting Techniques
- Polymorphisms are used for DNA fingerprinting in forensics, paternity testing, and disaster victim identification.
- Developed by Alec Jeffreys in 1985.
- Currently PCR methods are used over RFLP.
SGM+ Markers in Forensics
- Specific markers used in the UK for genetic profiling (examples include FGA, TH01, VWA, D2S1338, etc.).
Determining Biological Sex through AMEL Gene
- The AMEL gene locus (AMELX on X chromosome, AMELY on Y chromosome) is used to distinguish biological sex.
- AMELX and AMELY indicate male (XY), while only AMELX indicates female (XX).
Polymorphisms and Ancestry
- Polymorphisms reflect genetic origins and diversity across populations.
Food Quality and Genetic Integrity
- DNA polymorphisms produce genetic fingerprints for breeds, used to verify labels (organic, region-specific), identify species, and assess genetic diversity.
Other DNA Features
- Repetitive DNA: Multiple copies of sequences (often considered "junk DNA").
- Highly Repetitive DNA (Satellite DNA): Found at telomeres and centromeres, exhibiting long tandem repeats.
- Middle Repetitive DNA (Mobile DNA Elements): Includes transposons (DNA-based LINES, SINES, ALUs) and retrotransposons (RNA-based LTRs). They can move within a genome.
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Description
Test your knowledge on key genetic terms such as locus, polymorphism, allele, and mutation. This quiz covers essential concepts that are fundamental to understanding genetics and molecular biology. Dive into the world of DNA and discover how these terms relate to genetics and phenotype.
