38. Hereditary material. Chromosomes - composition, submicroscopic and microscopic structure. Flashcards

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1
Q

Histones - proteins with a high proportion of positively charged amino acids which enables them to bind firmly to the DNA double helix. Play a role in gene regulation
Types: H1, H2A, H2B, H3 + H4. Except for H1, they occur in equal numbers.

A

Histones - proteins with a high proportion of positively charged amino acids which enables them to bind firmly to the DNA double helix. Play a role in gene regulation
Types: H1, H2A, H2B, H3 + H4. Except for H1, they occur in equal numbers.

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2
Q

Chromatin structures:

  • consists of segments of nucleosomes condensed to different degrees
  • In the DNA segments lying between series of nucleosomes, sequence specific DNA - binding proteins are found which regulate the expression (activity of genes) (H1 Histones)
  • chromosomes contain DNA, RNA, histones and Ca2+ ions associated with the DNA
  • chromosomes are densely packed in metaphase
A

Chromatin structures:

  • consists of segments of nucleosomes condensed to different degrees
  • In the DNA segments lying between series of nucleosomes, sequence specific DNA - binding proteins are found which regulate the expression (activity of genes) (H1 Histones)
  • chromosomes contain DNA, RNA, histones and Ca2+ ions associated with the DNA
  • chromosomes are densely packed in metaphase
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3
Q

Polythese chromosomes - over sized chromosomes - developed from standard chromosomes - commonly found in salivary glands of drosophila

A

Polythese chromosomes - over sized chromosomes - developed from standard chromosomes - commonly found in salivary glands of drosophila

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4
Q

DNA in lampbrush chromosomes

  • chromatin so densely packed - not directly visible
  • an exception is the interphase nuclei of certain cells
  • these chromosomes show RNA synthesis and from unusual loops
A

DNA in lampbrush chromosomes

  • chromatin so densely packed - not directly visible
  • an exception is the interphase nuclei of certain cells
  • these chromosomes show RNA synthesis and from unusual loops
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5
Q

Euchromatin and Heterochromatin:

Heterochromatin - a region in which a few or no active genes lie

Euchromatin - opposite

A

Euchromatin and Heterochromatin:

Heterochromatin - a region in which a few or no active genes lie

Euchromatin - opposite

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6
Q

Characteristic regions of a chromosomes:

Centromeres and telomeres contain repetitive DNA sequences.

A

Characteristic regions of a chromosomes:

Centromeres and telomeres contain repetitive DNA sequences.

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7
Q

Types of metaphase chromosomes:

  • Submetacentric - short arm (p arm) long arm (q)
  • metacentric - short and long arms are the same length
  • acrocentric - show a dense appendage called a satellite
  • telocentric - have neither a short arm nor a satellite. None of the human chromosomes are telocentric
A

Types of metaphase chromosomes:

  • Submetacentric - short arm (p arm) long arm (q)
  • metacentric - short and long arms are the same length
  • acrocentric - show a dense appendage called a satellite
  • telocentric - have neither a short arm nor a satellite. None of the human chromosomes are telocentric
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8
Q

Centromeres - link sister chromatids

Telomere - Region of repetitive nucleotide sequence

A

Centromeres - link sister chromatids

Telomere - Region of repetitive nucleotide sequence

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