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CELS191 - Grace Watson > Lecture 10 - Nucleus > Flashcards

Lecture 10 - Nucleus Flashcards

1
Q

What are ribosomes?

A

Complexes made of ribosomal RNAs & proteins

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2
Q

What are the two types of ribosomes?

A

Bound ribosomes and free ribosomes

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3
Q

Where are ribosomes found?

A

Bound ribosomes - Attached to the rEr
Free ribosomes - In the cytoplasm

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4
Q

What are the function of ribosomes?

A

Carry out translation

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5
Q

What is the nucleus?

A

The cell’s control centre
- Contains most of the cell’s genes
- Serves as repository of inherited genetic information

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6
Q

What is the size of the nucleus?

A

5-10 µm diameter

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7
Q

What is the structure of the nucleus?

A

Nuclear envelope, nuclear pores, DNA and nucleolus

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8
Q

What is the structure of the nuclear envelope?

A

Two membranes (outer and inner) each containing a phospholipid bilayer

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9
Q

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

A

The ER

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10
Q

What is the nuclear lamina?

A

Lining of the inner surface of the nuclear envelope

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11
Q

What is the role of the nuclear lamina?

A
  • Maintain shape of nucleus
  • Helps organise the packing of the DNA within the nucleus
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12
Q

What is the nuclear lamina composed of?

A

Intermediate filaments

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13
Q

What happens if the nuclear
lamina is defective?

A
  • Cells cannot produce a normal nuclear lamina
  • Thus their nuclei are unable to retain a spherical shape
  • This limits the ability of affected cells to divide

Results in abnormal features
and premature aging

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14
Q

What are nuclear pores?

A

Channels made of proteins
(nucleoporins) that form the
Nuclear Pore Complex

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15
Q

Where are nuclear pores found?

A

Spanning nuclear envelope

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16
Q

How many nuclear pores are there per cell?

A

Approx 1000

17
Q

What is the role of nuclear pores?

A

Controls the movement of
molecules out of, or into, the
nucleus (nucleo-cytoplasmic
exchange)

18
Q

What moves from the nucleus to the cytoplasm? (3)

A

mRNA, tRNA and
ribosomal subunits

19
Q

What is the role of mRNA (messenger RNA)?

A

Carries information from a gene

20
Q

What is the role of tRNA (transfer RNA) and ribosomal subunits?

A

Needed to build proteins

21
Q

What moves from the cytoplasm to the nucleus? (3)

A

Control signals, building
materials and energy

22
Q

T or F

The nuclear envelope consists of a
single membrane

A

False

The nuclear envelope has two membranes (inner and outer)

23
Q

T or F

The nuclear pore complex allows mRNA and tRNA to move out of the nucleus

A

True

24
Q

T or F

The nuclear lamina is made of
microtubules

A

False

The nuclear lamina is made of intermediate filaments

25
Q

What is the nucleolus?

A

Non-membrane bound
specialised region within the
nucleus

26
Q

What is the nucleolus responsible for?

A

Making ribosomal RNA & ribosomal
subunits

27
Q

How many nucleolus in a cell?

A

May be two or more nucleoli per cell depending on species and stage of cell cycle

28
Q

How much DNA does each human cell have?

A

About 2.5 metres

29
Q

What type of proteins does DNA interact with?

A

Histones

30
Q

How long in diameter is a DNA double helix?

A

2nm

31
Q

After interacting with histones, how long in diameter is a DNA double helix fibre?

A

10nm

32
Q

Further interactions between the DNA and another histone (H1) cause
the 10nm fibre to coil to form the…

A

30nm fibre

33
Q

This 30nm fibre then loops to
form…

A

300nm fibre

34
Q

During cell division the
300nm fibres coil to form…

A

Metaphase chromosomes

35
Q

Chromosomes can be displayed as a…

A

Karyotype

36
Q

What is the difference between euchromatin and heterochromatin?

A

Euchromatin - less dense, contains genes being used by that cell

Heterochromatin -more dense, contains genes not being used by
that cell

CELS191 - Grace Watson (14 decks)

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