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

Question 1

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.

Answer 1

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.

Question 2

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

Answer 2

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

Question 3

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

Answer 3

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

Question 4

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

Answer 4

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

Question 5

Euchromatin and Heterochromatin:

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

Euchromatin - opposite

Answer 5

Euchromatin and Heterochromatin:

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

Euchromatin - opposite

Question 6

Characteristic regions of a chromosomes:

Centromeres and telomeres contain repetitive DNA sequences.

Answer 6

Characteristic regions of a chromosomes:

Centromeres and telomeres contain repetitive DNA sequences.

Question 7

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

Answer 7

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

Question 8

Centromeres - link sister chromatids

Telomere - Region of repetitive nucleotide sequence

Answer 8

Centromeres - link sister chromatids

Telomere - Region of repetitive nucleotide sequence