General Genetics an der University Of Tromsø | Karteikarten & Zusammenfassungen

Lernmaterialien für General Genetics an der University of Tromsø

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What is a housekeeping gene?

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Also known as constitutive gene

A gene that is (theoretically) expressed in all cells because it provides basic functions needed for sustenance of all
cell types.

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Explain three ways of categorizing genetic variation


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A. According to DNA content

  1. Changes that do not affect the DNA content
    1. Base pair substitution
    2. Multiple nucleotides relocated in the genome
  2. Changes in copy number of a nucleotide or DNA sequence
    1. Insertion and deletion:
    2. Abnormal chromosome segregation (Almost always harmful: spontaneous abortion, developmental syndromes)

B. According to scale of genetic variation (Arbitrary)

  1. Small-scale genetic variation (<50 bp)
  2. Moderate and large-scale genetic variation: Structural variation (>50 bp)

C. According to size of the changed sequence

  1. Chromosome mutations
  2. Regional or subchromosomal mutations
  3. Gene or DNA mutations
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What are effects of mutations in the introns of a protein coding gene?
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  • No direct effect on protein sequence
  • !Processing (splicing) of primary transcript can be hindered, usually deleterious
    • base substitutions in splicing junctions
    • Result: Inclusion of an intron, Splicing site changed
  • Generation of a STOP-codon: shorter protein
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What is evidence that supports the endosymbiotic theory?

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  1. Similarity between mitochondrial and genomes of α-proteobacteria:
    • Differences in RNA-Pol
    • mtDNA: small, circular, less bound protein, nucleoid as unit of segregation, high gene-density
    • Independent protein-synthesis machinery: 55S mitoribosomes, mitochondrial tRNA, 4 stop codons
    • large multigenic transcript which is cleaved
  2. Cell division is independent from the cell cycle and not as tightly controlled
  3. Integration of mitochondrial genes into the host genome: NUMTs
    • only 13 out of 80 proteins for oxidative phosphorylation encoded on mtDNA
    • 1700 nuclear genes mt. origin
  4. Double Membrane that was retained during engulfment, inner and outer membranes resemble the 'original' membranes in their composition
  5. Different 'states' of endosymbiosis in other organisms
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Give classes and subclasses of Retrotransposons.

  • Are they autonomous? 
  • How much of the human genome do they make up? 
  • How long are they? 
  • Where are they located?
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NON-LTR TRANSPOSONS

LINEs: Long Interspersed Nuclear Elements

  • LINE-1,2,3, LINE-1 have autonomously transposing members
  • 21%
  • Full-length >6000bp
  • Euchromatic (AT-rich) regions

SINEs: Short Interspersed Nuclear Elements

  • Subgroups among others: primate-specific ALU-repeats + MIR-elements
  • Nonautonomous: dependent on LINEs
  • 13%
  • Full length <400bp
  • GC-rich areas

LTR-TRANSPOSONS/Retrovirus-like elements

  • autonomous (have rt and/or integrase)
  • 8%
  • 2 Subclasses: HERVs and LTR-elements
  • HERV: 6-11kb, LTR-element: 1.5-3kb
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What are neutral mutations?
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Genetic variation thatv does not have an effect on the phenotype.
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What are Tandemly repeated sequences?

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Tandemly repeated short DNA sequences

  • located in constitutive heterochromatin: Centromeres, Telomeres, large additional regions on some chromosomes, STR/VNTR
  • 10% of the human genome
  • some also located in euchromatin regions (forensic)
  • non-coding DNA
  • can be subdivided into satellite, mini satellite and microsatellite DNA
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TESTE DEIN WISSEN

Explain, why transposons are seldomly identical copies of each other.

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TESTE DEIN WISSEN

The transcription of transposons often fails
• Reverse transcriptase stops before 5’end: truncated transposons
• RNA-polymerase proceed the 5’ end: the mRNA can contain neighboring gene or exon
• Or the reverse transcriptase can transcribe other mRNA: pseudogene or retrogen

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TESTE DEIN WISSEN

What is a Transposon?

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TESTE DEIN WISSEN

A DNA sequence able to insert itself, or a
copy of itself, at a new location in the
genome without having any sequence
relationship with the target locus.

They're also called 'jumping genes', transposable elements or mobile genetic elements.

There are 2 main classes (Retrotransposons and DNA Transposons) based on the mode of transposition.

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TESTE DEIN WISSEN

Two general ways in which genetic variation can occur


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TESTE DEIN WISSEN

• Inherited genetic variation, transmitted between generations in gametes
• Individual changes (novel mutations): germ-line cells and somatic cells

Lösung ausblenden
TESTE DEIN WISSEN

What is the difference between DNA variants and DNA mutations (in newer developments)

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DNA variant: neutral term to describe a DNA change produced by mutation
DNA mutation: DNA changes associated with an altered phenotype

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TESTE DEIN WISSEN

Explain the function and importance of telomeric DNA by explaining, what would happen without them.

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TESTE DEIN WISSEN

Maintain structural integrity and
stability of chromosomes

• Unstable ends tends to fuse with the end of other chromosomes
• The ends can be involved in recombination events (how -> medical genetics!)
• The ends can be degraded by nucleases (Why?)

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Q:

What is a housekeeping gene?

A:

Also known as constitutive gene

A gene that is (theoretically) expressed in all cells because it provides basic functions needed for sustenance of all
cell types.

Q:

Explain three ways of categorizing genetic variation


A:

A. According to DNA content

  1. Changes that do not affect the DNA content
    1. Base pair substitution
    2. Multiple nucleotides relocated in the genome
  2. Changes in copy number of a nucleotide or DNA sequence
    1. Insertion and deletion:
    2. Abnormal chromosome segregation (Almost always harmful: spontaneous abortion, developmental syndromes)

B. According to scale of genetic variation (Arbitrary)

  1. Small-scale genetic variation (<50 bp)
  2. Moderate and large-scale genetic variation: Structural variation (>50 bp)

C. According to size of the changed sequence

  1. Chromosome mutations
  2. Regional or subchromosomal mutations
  3. Gene or DNA mutations
Q:
What are effects of mutations in the introns of a protein coding gene?
A:
  • No direct effect on protein sequence
  • !Processing (splicing) of primary transcript can be hindered, usually deleterious
    • base substitutions in splicing junctions
    • Result: Inclusion of an intron, Splicing site changed
  • Generation of a STOP-codon: shorter protein
Q:

What is evidence that supports the endosymbiotic theory?

A:
  1. Similarity between mitochondrial and genomes of α-proteobacteria:
    • Differences in RNA-Pol
    • mtDNA: small, circular, less bound protein, nucleoid as unit of segregation, high gene-density
    • Independent protein-synthesis machinery: 55S mitoribosomes, mitochondrial tRNA, 4 stop codons
    • large multigenic transcript which is cleaved
  2. Cell division is independent from the cell cycle and not as tightly controlled
  3. Integration of mitochondrial genes into the host genome: NUMTs
    • only 13 out of 80 proteins for oxidative phosphorylation encoded on mtDNA
    • 1700 nuclear genes mt. origin
  4. Double Membrane that was retained during engulfment, inner and outer membranes resemble the 'original' membranes in their composition
  5. Different 'states' of endosymbiosis in other organisms
Q:

Give classes and subclasses of Retrotransposons.

  • Are they autonomous? 
  • How much of the human genome do they make up? 
  • How long are they? 
  • Where are they located?
A:

NON-LTR TRANSPOSONS

LINEs: Long Interspersed Nuclear Elements

  • LINE-1,2,3, LINE-1 have autonomously transposing members
  • 21%
  • Full-length >6000bp
  • Euchromatic (AT-rich) regions

SINEs: Short Interspersed Nuclear Elements

  • Subgroups among others: primate-specific ALU-repeats + MIR-elements
  • Nonautonomous: dependent on LINEs
  • 13%
  • Full length <400bp
  • GC-rich areas

LTR-TRANSPOSONS/Retrovirus-like elements

  • autonomous (have rt and/or integrase)
  • 8%
  • 2 Subclasses: HERVs and LTR-elements
  • HERV: 6-11kb, LTR-element: 1.5-3kb
Mehr Karteikarten anzeigen
Q:
What are neutral mutations?
A:
Genetic variation thatv does not have an effect on the phenotype.
Q:

What are Tandemly repeated sequences?

A:

Tandemly repeated short DNA sequences

  • located in constitutive heterochromatin: Centromeres, Telomeres, large additional regions on some chromosomes, STR/VNTR
  • 10% of the human genome
  • some also located in euchromatin regions (forensic)
  • non-coding DNA
  • can be subdivided into satellite, mini satellite and microsatellite DNA
Q:

Explain, why transposons are seldomly identical copies of each other.

A:

The transcription of transposons often fails
• Reverse transcriptase stops before 5’end: truncated transposons
• RNA-polymerase proceed the 5’ end: the mRNA can contain neighboring gene or exon
• Or the reverse transcriptase can transcribe other mRNA: pseudogene or retrogen

Q:

What is a Transposon?

A:

A DNA sequence able to insert itself, or a
copy of itself, at a new location in the
genome without having any sequence
relationship with the target locus.

They're also called 'jumping genes', transposable elements or mobile genetic elements.

There are 2 main classes (Retrotransposons and DNA Transposons) based on the mode of transposition.

Q:

Two general ways in which genetic variation can occur


A:

• Inherited genetic variation, transmitted between generations in gametes
• Individual changes (novel mutations): germ-line cells and somatic cells

Q:

What is the difference between DNA variants and DNA mutations (in newer developments)

A:

DNA variant: neutral term to describe a DNA change produced by mutation
DNA mutation: DNA changes associated with an altered phenotype

Q:

Explain the function and importance of telomeric DNA by explaining, what would happen without them.

A:

Maintain structural integrity and
stability of chromosomes

• Unstable ends tends to fuse with the end of other chromosomes
• The ends can be involved in recombination events (how -> medical genetics!)
• The ends can be degraded by nucleases (Why?)

General Genetics

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