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BIO1090 Final Exam Review > Lecture 23 > Flashcards

Lecture 23 Flashcards

1
Q

Nuclear lamina

A
  • supports nuclear envelope

- think filamentous protein meshwork next to nucleoplasmic leaflet of INM

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2
Q

Where are tRNA and rRNA transcribed?

A

from DNA found in nucleolous

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3
Q

What is the nucleolus**

A
  • largest structure inside the nucleus of eukaryotic cells
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4
Q

What are biosynthesis of ribosomes?

A
  • synthesis of ribosomal rRNAs
  • rRNA processing
  • assembly of subunits- rRNA and ribosomal proteins
  • 40s and 60s subunits are exported to cytoplasm where they are assembled as 80s ribosomes
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5
Q

How many pores per nucleus?

A

3000-4000 pores

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6
Q

Nucelar import

A
  • regulated movement of proteins into nucleus requires a Nuclear Localization Signal (NLS)
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7
Q

INtermediate filaments

A
  • composed of keratins in cytoplasm (outside lines)

- composed of lamins in nucleus (middle)

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8
Q

What are nucleoporins (NUPs)?

A

large family of diff proteins

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9
Q

Ribosomes components**

A

Small ribosomes: read RNA
Large ribosomes: join amino acids to form a polypeptide chain
- these have 1 or more ribosomal RNA molecules and ribosomal protein variety

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10
Q

What is a lamina?

A

found in animal cells only

  • plants have nuclear lamina but NOT made of lamina protein
  • bound to inner membrane of nuclear envelope by integral membrane proteins
  • provides structural support for nuclear envelope
  • attachment sites for chromatin
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11
Q

Nucleocytoplasmic Trafficking

A

Nuclear import/export is critical for cellular function

  • nucleotides for transcription
  • structural proteins
  • DNA packaging proteins
  • proteins for DNA replication, repair and transcription
  • proteins for RNA processing (splicing) and export
  • proteins for ribosomes synthesis and export
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12
Q

What is the inner nuclear membrane (INM)?**

A

has integral proteins and connects to nuclear lamina

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13
Q

Nuclear pore complex

A

involved in the arrangement of diff types of proteins

  • composed of nucleoporins (NUPs)
  • octagonal symmetry
  • projects into cytoplasm and nucleoplasm
  • SUPRAMOLECULAR complex: very big
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14
Q

Nucleus Functions

A
  1. storage, replication and repair of genetic material
  2. expression of genetic material
    - transcription: mRNA, tRNA, rRNA
    - RNA splicing
  3. ribosome biosynthesis
    - noncoding RNAs don’t encode proteins, include tRNA and rRNA
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15
Q

Where are Nuclear Pores found?

A

inner and outer membrane fuses

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16
Q

What are Nuclear Localization Signal (NLS)?

A

several positively charged amino acids w/in protein sequence

17
Q

Nuclear envelope importance**

A
  • separate nuclear content from the cytoplasm
  • separates transcription and translation
  • selective barrier, allows limited movement of molecules between nucleus and cytoplasm
18
Q

Nucleus Structure

A
  • 2 parallel phospholipid bilayers, 10-15 nm separation
19
Q

How do NLS target proteins to nucleus

A
  1. proteins w/ NLS (cargo) interact w/ important protein in cytoplasm
  2. cargo/importin complex interacts w/ FG-NUPs at NPC and enters nucleoplasm
  3. Ran-GTP interacts w/ importin; cargo dissociates and stays in the nucleoplasm
  4. Ran-GTP/ importing complex exists nucleus through NPC
  5. GTP hydrolyzed to GDP
    - importin release in cytoplasm to find new cargo
20
Q

Nuclear Pore

A
  • gateways between cytoplasm and nucleus
21
Q

What is the outer nuclear membrane (ONM)**

A
  • binds ribosomes

- is continuous w/ rough ER

22
Q

What is a promoter region?

A
  • control of transcription RNA splicing before nuclear export of mRNAs
23
Q

What is heterochromatin?**

A

around nuclear membrane

- non essential genes are in here

24
Q

What is homochromatin?**

A

essential genes more spread out

25
Q

What is in a Nuclear envelope?

A
  • nuclear membrane
  • pores
  • lamina
26
Q

What is the primary function of the nucleolus?**

A

Biosynthesis of ribosomes

BIO1090 Final Exam Review (11 decks)

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