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BIOL 1090 > B: The nucleas (23) > Flashcards

B: The nucleas (23) Flashcards

1
Q

What are the functions of the nucleus

A
  1. Storage, replication, repair of genetic material
  2. Expression of genetic material
  3. Ribosome biosynthesis
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2
Q

Explain how the nucleus stores, replicates, and repairs genetic material

A

Contains all genetic material - compressed strand of DNA

Integrity of genome is preserved here
– Mechanisms repair any mutations or breakage that can happen

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3
Q

Explain how the nucleus aids in expression of genetic material

A

Transcription occurs: mRNA, tRNA, rRNA
– Promoter region is upstream: allows transcription factors to bind

rRNA splicing

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4
Q

What is the nuclear envelope made of

A

Nuclear membrane and ER is continuous base

Ribosomes found on surface of nuclear membrane

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5
Q

Explain how the nucleus biosynthesizes ribosomes

A

Nucleolus is membrane-less sub-organelle in the nucleus

Ribosomes are produced here
– Assembly of subunits - rRNA and protein

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6
Q

What subunits are ribosomes made in the nucleus? Where are they exported to

A

40S and 60S subunits are exported to cytoplasm where they are assembled as 80S ribosomes

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7
Q

What is the structure of the nuclear envelope

A

2 parallel phospholipid bilayers separated by 10-50 nm space
– Outer nuclear membrane
– Inner nuclear membrane

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8
Q

What is the importance of the nuclear envelope

A

Separation of interior and exterior nucleus separates processes of transcription and translation

Selective barrier allows limited movement of molecules between the nucleus and cytoplasm

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9
Q

What is the nuclear lamina?

A

A thin meshwork of filamentous proteins

  • Nuclear lamina bound to inner membrane
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10
Q

What is the role of the nuclear lamina

A

Supports nuclear envelope
Attachment sites for chromatin

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11
Q

Do plants have a nuclear lamina?

A

Plants have nuclear lamina, but not made of lamin protein

The equivalent of lamin protein in plants is still being researched

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12
Q

What type of proteins is the nuclear lamina made of in animal cells

A

Lamins (intermediate filaments) - found in animal cells only

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13
Q

What is the nuclear pore?

A

Gateway between cytoplasm and nucleus

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14
Q

Where is the nuclear pore found, how large is it

A

Pores are found where inner and outer membrane fuses

  • 3000 to 4000 pores
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15
Q

What is the shape and structure of the nuclear pore complex

A

Octagonal shape

Composed of nucleoporins (NUPs) - a large family of different proteins

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16
Q

What is the NPC

A

Nuclear pore complex

17
Q

What can enter the nuclear pore, what can’t

A

Anything 40kDA or smaller can freely enter and exit the nucleus

Larger movement is regulated

18
Q

How fast do small and large molecules enter the NPC

A

Small: About 1000 molecs/minute/pore

Large: 6 molecs/minute/pore

19
Q

What is the NLS

A

Nuclear localization signal (NLS)

20
Q

How do large molecules enter the NPC

A

Regulated movement of proteins into the nucleus require nuclear localization signal (NLS)

21
Q

What is the NLS made of

A

NLS = several + charged AAs within protein sequence

22
Q

What are the 3 steps of the NLS

A
  1. Recognition
  2. Transport
  3. Entry into nucleus
23
Q

Explain the first step of the NLS: recognition

A

Recognition: Inside the cell, proteins containing an NLS are recognized by nuclear transport receptors. These receptors bind specifically to the NLS sequence.

24
Q

Explain the second step of the NLS: transport

A

Transport: Once bound to the protein, the nuclear transport receptor guides the protein through the nuclear pore complexes, which are the gateways between the cytoplasm and the nucleus.

25
Q

Why is Nucleocytoplasmic trafficking important

A

Import and outport critical for cell function:

Helps in transcription
DNA packaging
Proteins for DNA replication repair and transcription
Proteins for RNA processing (splicing) and export
Proteins for ribosomes synthesis and export

25
Q

Explain the third step of the NLS: entry into the nucleus

A

Entry into the nucleus: The protein, along with the bound nuclear transport receptor, passes through the nuclear pore complex and enters the nucleus

26
Q

What is Nucleocytoplasmic trafficking

A

The transportation of molecules to and from the nucleus, ensuring that the cell can carry out its functions effectively by regulating what enters and exits the nucleus.

27
Q

What is the nucleolus

A

Largest structure within nucleus

Often multiple nucleolus within nucleus

BIOL 1090 (19 decks)

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