lecture 10 - cell nucleus Flashcards

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1
Q

What is the typical size of the nucleus?

A

5-10 micrometres

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2
Q

What surrounds the nucleus?

A

Nuclear envelope

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3
Q

How many membranes are in the nuclear envelope?

A

2

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4
Q

What is the space between the 2 membranes of the nuclear envelope?

A

The perinuclear space

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5
Q

What is the outer membrane of the nuclear envelope continuous with?

A

the rough Endoplasmic Reticulum

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6
Q

What is the perinuclear space continuous with?

A

the lumen of the rER

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7
Q

What is the function of the nuclear pore complex?

A

Controls movement in and out of the nucleus.

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8
Q

What is transferred out of the nucleus via the nuclear pore complex?

A

mRNA, tRNA, ribosomal subunits, macromolecules

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9
Q

What is transferred into the cell via the nuclear pore complex?

A

Control signals, RNA building blocks, energy

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10
Q

What is the function of the control signals in the nucleus?

A

They control when genes are turned ‘off’ or ‘on.’

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11
Q

What is the inner surface of the nuclear envelope?

A

Nuclear lamina

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12
Q

What is the structure of the nuclear lamina?

A

Made up of intermediate filaments, consisting of the protein lamin

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13
Q

What are the two key functions of the nuclear lamina?

A

Maintain nucleus shape, organise DNA packing

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14
Q

What is the nucleolus?

A

A structure that sits inside the nucleus of a cell and makes ribosomal RNA, which can combine with proteins to produce ribosomes.

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15
Q

What is the diameter of a DNA double helix strand?

A

2nm

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16
Q

What histones are used to form nucleosomes?

A

H2-H4

17
Q

What is a nucleosome and how are they formed?

A

A ‘bead’ consisting on eight histones clustered around part of the DNA strand. 10nm wide

18
Q

How are 30nm DNA fibres formed?

A

10nm nucleosomes interact with H1 histones, to form coils with a 30nm diameter.

19
Q

What is chromatin?

A

A 300nm diameter fibre made up of loops of 30nm fibre.

20
Q

What happens to chromatin fibres during the metaphase of cell division?

A

They form chromosomes.

21
Q

What is a karyotype?

A

A representation of the chromosomes of each cell, which are normally arranged randomly within the cell.

22
Q

What are the less dense areas of the nucleus?

A

Euchromatin

23
Q

What are the dense areas of the nucleus?

A

Heterochromatin

24
Q

What is the function of euchromatin?

A

Allow genes currently being used to be easily accessible, by packing DNA less densely.

25
Q

What is the function of the heterochromatin?

A

Genes that are not currently in use are packed tightly so they are inaccessible.

26
Q

How can the relationship between euchromatin and heterochromatin be described?

A

Dynamic