Chromosomal DNA Structure and Composition Quiz

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Questions and Answers

What is the length of the human mitochondrial genome?

  • 16,569 base pairs (correct)
  • 120,000 base pairs
  • 37 genes
  • 120 genes

What percentage of all the RNAs and proteins needed by the mitochondrion does the human mitochondrial genome encode?

  • 5% (correct)
  • 10%
  • 15%
  • 20%

What is the approximate length of circular DNA molecules in chloroplasts?

  • 37 genes
  • 120 genes
  • 120,000 bp (correct)
  • 16,569 bp

Where are the chromosomes localized and replicated within the eukaryotic cell?

<p>Nucleus (C)</p> Signup and view all the answers

What is the function of nuclear pores?

<p>Provide direct contact between the cytosol and the nucleoplasm (C)</p> Signup and view all the answers

What is the size limit for small particles to freely move through nuclear pores via simple diffusion?

<p>10 nm in diameter (B)</p> Signup and view all the answers

What enables the active transport of large proteins across the nuclear membrane?

<p>Nuclear localization signals (NLS) (C)</p> Signup and view all the answers

What is the nuclear matrix?

<p>An insoluble fibrous network that helps maintain the shape of the nucleus (B)</p> Signup and view all the answers

Where are ribosomal subunits assembled within the nucleus?

<p>Nucleolus (A)</p> Signup and view all the answers

What do fibrils in the nucleolus contain?

<p>DNA being transcribed into ribosomal RNA (rRNA) (B)</p> Signup and view all the answers

Which protein stabilizes DNA loops 50,000–100,000 bp in length in chromatin packing?

<p>Cohesin protein (D)</p> Signup and view all the answers

What is the function of histone deacetylase (HDAC) in chromatin packing?

<p>Removal of acetyl groups from histone side chains (A)</p> Signup and view all the answers

How are cells able to regulate the portions of chromatin that are active or inactive?

<p>Through altering histones and histone code (A)</p> Signup and view all the answers

What is the structure in which the 30-nm fiber seems to be packed together?

<p>An irregular, three-dimensional zigzag structure (B)</p> Signup and view all the answers

What can serve as a signal for activation or repression of transcription, depending on the lysine involved?

<p>Methylation of lysine via histone methyltransferase (C)</p> Signup and view all the answers

What is the opposite function of histone acetyltransferase (HAT)?

<p>Catalyzed by histone deacetylase (HDAC) (D)</p> Signup and view all the answers

What is the length of the DNA loops stabilized by cohesin protein?

<p>50,000–100,000 bp (B)</p> Signup and view all the answers

What can alter chromatin packing and regulate the portions of chromatin that are active or inactive?

<p>Changes in histones and chromatin remodeling proteins (A)</p> Signup and view all the answers

What can create a histone code?

<p>Various combinations of tags like methyl, acetyl, phosphate, or other groups (B)</p> Signup and view all the answers

What is the function of histone acetyltransferases (HATs) in chromatin packing?

<p>Acetylation of histone side chains (C)</p> Signup and view all the answers

What is the function of centromeres during cell division?

<p>Maintain sister chromatid cohesion (A)</p> Signup and view all the answers

What is the difference between facultative heterochromatin and constitutive heterochromatin?

<p>Facultative heterochromatin can convert to euchromatin, while constitutive heterochromatin remains permanently compacted (A)</p> Signup and view all the answers

What is the composition of telomeres?

<p>Highly repetitive DNA sequences (D)</p> Signup and view all the answers

What are euchromatin and heterochromatin based on their packing?

<p>Euchromatin is more loosely packed, and heterochromatin is highly compacted (C)</p> Signup and view all the answers

What happens to all chromatin in preparation for cell division?

<p>It becomes highly compacted (B)</p> Signup and view all the answers

What is the role of repeated DNA sequences in eukaryotic chromosomes?

<p>Constitute a large portion of the genome (C)</p> Signup and view all the answers

What is the function of tandemly repeated DNA in a typical mammalian genome?

<p>Accounts for 10–15% of the genome (A)</p> Signup and view all the answers

What is the role of interspersed repeated DNAs in mammalian genomes?

<p>Account for 25–50% of the genome (D)</p> Signup and view all the answers

What did Roy Britten and David Kohne discover about eukaryotic chromosomes in the 1960s?

<p>They contain large amounts of repeated DNA sequences (A)</p> Signup and view all the answers

What is the purpose of Giemsa staining in identifying chromosomes?

<p>Reveals unique banding patterns on chromosomes (B)</p> Signup and view all the answers

What can alter chromatin packing and regulate the portions of chromatin that are active or inactive?

<p>Histones and chromatin remodeling proteins (B)</p> Signup and view all the answers

What is the function of cohesin protein in chromatin packing?

<p>Stabilizing DNA loops 50,000–100,000 bp in length (A)</p> Signup and view all the answers

Which tagging reaction can serve as a signal for activation or repression of transcription?

<p>Methylation of lysine via histone methyltransferase (B)</p> Signup and view all the answers

What is the opposite function of histone acetyltransferase (HAT) in chromatin packing?

<p>Histone deacetylase (HDAC) (D)</p> Signup and view all the answers

What is the structure in which the 30-nm fiber seems to be packed together?

<p>Irregular, three-dimensional zigzag structure (A)</p> Signup and view all the answers

What is the length of DNA loops stabilized by cohesin protein in chromatin packing?

<p>50,000–100,000 bp (D)</p> Signup and view all the answers

What are the protruding tails of histones tagged by to create a histone code?

<p>Methyl, acetyl, phosphate, or other groups (D)</p> Signup and view all the answers

Where are the DNA loops stabilized by cohesin protein spatially arranged through attachment to?

<p>Nonhistone proteins forming a chromosomal scaffold (D)</p> Signup and view all the answers

What can serve as a signal for activation or repression of transcription, depending on the lysine involved?

<p>Histone methylation (B)</p> Signup and view all the answers

What enables cells to tightly regulate the portions of chromatin that are active or inactive?

<p>Altering histones and chromatin remodeling proteins (B)</p> Signup and view all the answers

What is the approximate length of the human mitochondrial genome?

<p>16,569 base pairs (C)</p> Signup and view all the answers

What is the approximate length of circular DNA molecules in chloroplasts?

<p>120,000 base pairs (B)</p> Signup and view all the answers

What is the function of nuclear pores?

<p>Provide direct contact between the cytosol and the nucleoplasm (C)</p> Signup and view all the answers

What is the size limit for small particles to freely move through nuclear pores via simple diffusion?

<p>Less than 10 nm in diameter (B)</p> Signup and view all the answers

What enables the active transport of large proteins across the nuclear membrane?

<p>Nuclear localization signals (NLS) (D)</p> Signup and view all the answers

What is the nuclear matrix?

<p>An insoluble fibrous network that helps maintain the shape of the nucleus (A)</p> Signup and view all the answers

Where are ribosomal subunits assembled within the nucleus?

<p>Nucleolus (C)</p> Signup and view all the answers

What do fibrils in the nucleolus contain?

<p>DNA being transcribed into ribosomal RNA (rRNA) (B)</p> Signup and view all the answers

What is the function of histone acetyltransferases (HATs) in chromatin packing?

<p>Add acetyl groups to histones, leading to chromatin relaxation (B)</p> Signup and view all the answers

What is the composition of telomeres?

<p>Repetitive DNA sequences (D)</p> Signup and view all the answers

What is the composition of telomeres?

<p>Highly repetitive DNA sequences (C)</p> Signup and view all the answers

What is the function of centromeres during cell division?

<p>Maintain sister chromatid cohesion (D)</p> Signup and view all the answers

What is the role of interspersed repeated DNAs in mammalian genomes?

<p>Account for 25–50% of mammalian genomes and can move around the genome (D)</p> Signup and view all the answers

What is the difference between facultative heterochromatin and constitutive heterochromatin?

<p>Facultative heterochromatin can convert to euchromatin and vice versa, while constitutive heterochromatin remains permanently compacted (A)</p> Signup and view all the answers

What is the size limit for small particles to freely move through nuclear pores via simple diffusion?

<p>9 nm (A)</p> Signup and view all the answers

What is the function of Giemsa staining in identifying chromosomes?

<p>Create unique banding patterns for identifying chromosomes (A)</p> Signup and view all the answers

What is the function of tandemly repeated DNA in a typical mammalian genome?

<p>Account for 10–15% of a typical mammalian genome (D)</p> Signup and view all the answers

What is the role of repeated DNA sequences in eukaryotic chromosomes?

<p>Constitute a large portion of the genome and can move around the genome (D)</p> Signup and view all the answers

What is the function of histone deacetylase (HDAC) in chromatin packing?

<p>Remove acetyl groups from histones, leading to chromatin condensation (A)</p> Signup and view all the answers

What is the function of nuclear pores?

<p>Regulate the movement of molecules into and out of the nucleus (C)</p> Signup and view all the answers

What is the approximate percentage of mammalian genomes accounted for by interspersed repeated DNAs, including transposable elements like LINEs and SINEs?

<p>20-25% (C)</p> Signup and view all the answers

What is the composition of telomeres, which are found at chromosome ends?

<p>Highly repetitive DNA sequences (A)</p> Signup and view all the answers

What is the function of Giemsa staining in identifying chromosomes?

<p>Revealing unique banding patterns (A)</p> Signup and view all the answers

What is the approximate percentage of a typical mammalian genome accounted for by tandemly repeated DNA?

<p>5-10% (A)</p> Signup and view all the answers

What is the role of constitutive heterochromatin in eukaryotic chromosomes?

<p>Permanently compacted, serving structural functions (C)</p> Signup and view all the answers

What are the two types of chromatin, based on their packing?

<p>Euchromatin and heterochromatin (B)</p> Signup and view all the answers

What is the function of centromeres on chromosomes?

<p>Maintain sister chromatid cohesion during mitosis and meiosis (D)</p> Signup and view all the answers

What is the approximate percentage of mammalian genomes accounted for by interspersed repeated DNAs, including transposable elements like LINEs and SINEs?

<p>20-25% (D)</p> Signup and view all the answers

What is the composition of telomeres, which are found at chromosome ends?

<p>Highly repetitive DNA sequences (D)</p> Signup and view all the answers

What is the function of Giemsa staining in identifying chromosomes?

<p>Revealing unique banding patterns (C)</p> Signup and view all the answers

What is the approximate length of the human mitochondrial genome?

<p>16,569 base pairs (B)</p> Signup and view all the answers

What is the approximate length of circular DNA molecules in chloroplasts?

<p>120,000 base pairs (C)</p> Signup and view all the answers

What is the size limit for small particles to freely move through nuclear pores via simple diffusion?

<p>10 nm in diameter (C)</p> Signup and view all the answers

What enables the active transport of large proteins across the nuclear membrane?

<p>Nuclear localization signals (NLS) (A)</p> Signup and view all the answers

What is the nuclear matrix (nucleoskeleton)?

<p>An insoluble fibrous network that helps maintain the shape of the nucleus (A)</p> Signup and view all the answers

Where are ribosomal subunits assembled within the nucleus?

<p>Nucleolus (A)</p> Signup and view all the answers

What do fibrils in the nucleolus contain?

<p>DNA that is being transcribed into ribosomal RNA (rRNA) (D)</p> Signup and view all the answers

What is the function of the nuclear lamina?

<p>To maintain the shape of the nucleus (D)</p> Signup and view all the answers

What is the function of the nuclear envelope?

<p>To contain the nucleus with an inner and an outer membrane (B)</p> Signup and view all the answers

What is the function of the nucleolus?

<p>To assemble ribosomal subunits (C)</p> Signup and view all the answers

What is the function of histone acetyltransferases (HATs) in chromatin packing?

<p>Adding acetyl groups to histone tails, leading to a looser chromatin structure (D)</p> Signup and view all the answers

What is the opposite function of histone deacetylase (HDAC) in chromatin packing?

<p>Removing acetyl groups from histone tails, leading to a tighter chromatin structure (A)</p> Signup and view all the answers

What is the approximate length of DNA loops stabilized by cohesin protein?

<p>50,000–100,000 bp (C)</p> Signup and view all the answers

What can serve as a signal for activation or repression of transcription, depending on the lysine involved?

<p>Methylation of histone lysine (C)</p> Signup and view all the answers

Where are the 30-nm fibers packed together in an irregular, three-dimensional zigzag structure?

<p>Chromosomal scaffold (A)</p> Signup and view all the answers

What enables cells to tightly regulate the portions of chromatin that are active or inactive?

<p>Alteration of histone composition (D)</p> Signup and view all the answers

What is the role of cohesin protein in chromatin packing?

<p>Stabilizing DNA loops of specific lengths (C)</p> Signup and view all the answers

What do histone tails have that can be tagged by the addition of methyl, acetyl, phosphate, or other groups?

<p>Protruding tails (B)</p> Signup and view all the answers

What is the function of nuclear pores?

<p>Enabling the active transport of large proteins across the nuclear membrane (B)</p> Signup and view all the answers

What is the function of the 30-nm fiber structure in chromatin packing?

<p>Facilitating the attachment of nonhistone proteins (C)</p> Signup and view all the answers

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Study Notes

Chromosomal DNA Structure and Composition

  • Euchromatin and heterochromatin are two types of chromatin, with heterochromatin being highly compacted and euchromatin being more loosely packed.
  • Active cells have euchromatic chromatin, but all chromatin becomes highly compacted in preparation for cell division.
  • Each chromosome is composed of two identical chromatids after replication.
  • Facultative heterochromatin can convert to euchromatin and vice versa, while constitutive heterochromatin remains permanently compacted, serving structural functions.
  • Centromeres appear as constrictions on chromosomes and maintain sister chromatid cohesion during mitosis and meiosis.
  • Centromeres are characterized by highly repetitive DNA sequences (CEN sequences) and vary across eukaryotic organisms.
  • Telomeres, found at chromosome ends, contain highly repetitive DNA sequences and protect chromosome ends from degradation during DNA replication.
  • Chromosomes can be identified by unique banding patterns and staining techniques, such as Giemsa staining.
  • Eukaryotic chromosomes contain large amounts of repeated DNA sequences, as discovered by Roy Britten and David Kohne in the 1960s.
  • Calf DNA consists of two classes of sequences that renature at different rates, with about 40% renaturing more rapidly than bacterial DNA.
  • Repeated DNA sequences include tandemly repeated DNA, which accounts for 10–15% of a typical mammalian genome.
  • Interspersed repeated DNAs, including transposable elements like LINEs and SINEs, account for 25–50% of mammalian genomes and can move around the genome.

Chromosomal DNA Structure and Composition

  • Euchromatin and heterochromatin are two types of chromatin, with heterochromatin being highly compacted and euchromatin being more loosely packed.
  • Active cells have euchromatic chromatin, but all chromatin becomes highly compacted in preparation for cell division.
  • Each chromosome is composed of two identical chromatids after replication.
  • Facultative heterochromatin can convert to euchromatin and vice versa, while constitutive heterochromatin remains permanently compacted, serving structural functions.
  • Centromeres appear as constrictions on chromosomes and maintain sister chromatid cohesion during mitosis and meiosis.
  • Centromeres are characterized by highly repetitive DNA sequences (CEN sequences) and vary across eukaryotic organisms.
  • Telomeres, found at chromosome ends, contain highly repetitive DNA sequences and protect chromosome ends from degradation during DNA replication.
  • Chromosomes can be identified by unique banding patterns and staining techniques, such as Giemsa staining.
  • Eukaryotic chromosomes contain large amounts of repeated DNA sequences, as discovered by Roy Britten and David Kohne in the 1960s.
  • Calf DNA consists of two classes of sequences that renature at different rates, with about 40% renaturing more rapidly than bacterial DNA.
  • Repeated DNA sequences include tandemly repeated DNA, which accounts for 10–15% of a typical mammalian genome.
  • Interspersed repeated DNAs, including transposable elements like LINEs and SINEs, account for 25–50% of mammalian genomes and can move around the genome.

Chromosomal DNA Structure and Composition

  • Euchromatin and heterochromatin are two types of chromatin, with heterochromatin being highly compacted and euchromatin being more loosely packed.
  • Active cells have euchromatic chromatin, but all chromatin becomes highly compacted in preparation for cell division.
  • Each chromosome is composed of two identical chromatids after replication.
  • Facultative heterochromatin can convert to euchromatin and vice versa, while constitutive heterochromatin remains permanently compacted, serving structural functions.
  • Centromeres appear as constrictions on chromosomes and maintain sister chromatid cohesion during mitosis and meiosis.
  • Centromeres are characterized by highly repetitive DNA sequences (CEN sequences) and vary across eukaryotic organisms.
  • Telomeres, found at chromosome ends, contain highly repetitive DNA sequences and protect chromosome ends from degradation during DNA replication.
  • Chromosomes can be identified by unique banding patterns and staining techniques, such as Giemsa staining.
  • Eukaryotic chromosomes contain large amounts of repeated DNA sequences, as discovered by Roy Britten and David Kohne in the 1960s.
  • Calf DNA consists of two classes of sequences that renature at different rates, with about 40% renaturing more rapidly than bacterial DNA.
  • Repeated DNA sequences include tandemly repeated DNA, which accounts for 10–15% of a typical mammalian genome.
  • Interspersed repeated DNAs, including transposable elements like LINEs and SINEs, account for 25–50% of mammalian genomes and can move around the genome.

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