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Genetics > Module 8 Lec 7 > Flashcards

Module 8 Lec 7 Flashcards

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Biology 101 flashcards
1
Q

What is the complex of DNA and protein in eukaryotic chromosomes called?

A

Chromatin is the complex of DNA and protein in eukaryotic chromosomes.

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2
Q

What types of proteins are associated with eukaryotic chromosomes?

A

Histones and non-histone proteins are associated with eukaryotic chromosomes.

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3
Q

What is the ratio of DNA to histones to non-histone proteins in eukaryotic chromosomes?

A

The ratio is DNA : histone : non-histone = 1:1:1.

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4
Q

What are histones?

A

Histones are small proteins with basic, positively charged amino acids, like lysine and arginine.

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5
Q

What is the role of histones in relation to DNA?

A

Histones bind to and neutralize negatively charged DNA.

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6
Q

How many types of histones exist, and which ones make up the nucleosome?

A

There are five types: H1, H2A, H2B, H3, and H4. The core histones that make up the nucleosome are H2A, H2B, H3, and H4.

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7
Q

How is the synthesis of histones and DNA related?

A

Histone and DNA synthesis correlate in time, so both are synthesized together.

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8
Q

Why are histones highly conserved across species?

A

Histones are highly conserved because they are important for binding to DNA and show a high level of similarity among diverse organisms over millions of years of evolution.

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9
Q

What are non-histone proteins?

A

Non-histone proteins are a heterogeneous group of proteins with a large variety of functions.

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10
Q

What are some functions of non-histone proteins?

A

Non-histone proteins serve in functions like:

Scaffold (backbone of chromosome)
DNA replication (e.g., DNA polymerases)
Chromosome segregation (e.g., motor proteins of kinetochores)
Transcriptional regulation (largest group)

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11
Q

How do non-histone proteins vary in different tissues?

A

Non-histone proteins occur in different amounts in different tissues, reflecting their variety of functions.

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12
Q

What is the structure of nucleosomes?

A

Nucleosomes are composed of DNA wrapped around histone proteins, forming structures that resemble beads on a string.

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13
Q

What histones are involved in the nucleosome core?

A

The nucleosome core is made of H2A, H2B, H3, and H4 histones.

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14
Q

What is linker DNA?

A

Linker DNA is the stretch of DNA between nucleosomes, connecting them, and is not wrapped around histones.

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15
Q

What role does H1 histone play in nucleosomes?

A

The H1 histone binds to the linker DNA and helps stabilize the nucleosome structure, aiding in higher-order chromatin packaging.

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16
Q

How is DNA organized in nucleosomes?

A

DNA is wrapped around an octamer of H2A, H2B, H3, and H4 histones, creating the nucleosome core.

17
Q

What is a nucleosome?

A

A nucleosome is the basic unit of chromatin, consisting of eight histone proteins (an octamer) wrapped by around 160 bp of DNA.

18
Q

What histones make up the nucleosome octamer?

A

The nucleosome octamer consists of:

2x H2A
2x H2B
2x H3
2x H4

19
Q

How is the DNA wrapped around the nucleosome?

A

About 160 base pairs (bp) of DNA are wrapped twice around the histone octamer.

20
Q

What is the role of H1 histone in nucleosomes?

A

H1 binds to the linker DNA, stabilizing the nucleosome where the DNA enters and exits.

21
Q

What is linker DNA?

A

Linker DNA is the stretch of DNA, approximately 40 bp long, that connects adjacent nucleosomes.

22
Q

How does DNA sequence influence histone binding?

A

The DNA sequence can affect where and how histones bind, influencing the spacing between nucleosomes, which in turn impacts gene expression.

23
Q

How does nucleosome spacing affect gene expression?

A

The spacing of nucleosomes affects gene accessibility, influencing whether genes are turned on or off.

24
Q

How is nucleosome spacing inherited?

A

The spacing of nucleosomes is faithfully inherited by daughter chromosomes during cell division.

25
Q

How much does packaging into nucleosomes condense DNA?

A

Packaging into nucleosomes condenses DNA sevenfold, shortening 2 meters of DNA to less than 0.25 meters (250 mm).

26
Q

What is the average diameter of a eukaryotic cell?

A

The average diameter of a eukaryotic cell is approximately 10-30 micrometers (μm).

27
Q

What is the 300 Å fiber in chromosome compaction?

A

The 300 Å fiber is formed by the supercoiling of nucleosomes into a higher-order structure, helping further condense the chromatin.

28
Q

What is the Radial Loop-Scaffold Model in chromatin compaction?

A

The Radial Loop-Scaffold Model describes how loops of DNA (60-100 kb) are anchored to a scaffold of non-histone proteins, creating higher levels of chromatin compaction

29
Q

How much more compact is DNA in metaphase compared to its linear state?

A

In metaphase, DNA is 10,000 times more compact than in its linear state.

Genetics (29 decks)

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