Cell II Flashcards
What is the largest organelle in the cell?
Largest organelle in the cell
- ~10% cell volume
- DNA is sequestered in the nucleus
What are the components of the nucleus?
- Nuclear envelope
- Nuclear lamina
- Nuclear pores
- nucleolus
What are the parts of the nuclear envelope?
- inner nuclear envelope
- outer nuclear envelope
What is the function of inner nuclear membrane ?
- faces the nucleoplasm
- in contact with the nuclear lamina
What is the function of the outer nuclear envelope ?
- faces the cytoplasm
- Continuous with endoplasmic reticulum (ER)
- Cytoplasmic surface contains ribosomes
- Rough ER (rER)
Describe what is nuclear lamina
Thin, sheet-like meshwork beneath the inner nuclear membrane
- Nuclear lamins
- type of intermediate filaments
- Lamina A & B
- Scaffold for nuclear envelope, chromatin and nuclear pores
- Disassembles during mitosis
Where is the nuclear pore complex?
Spans the two nuclear membranes
- 80-100nm in diameter
How many proteins are in the nuclear pore complex? What type of proteins are they?
Made up of more than 50 proteins/ Nucleoporins
How much nucleopore complexes (NPCs) are in a typical nuclear envelope?
3000-4000 NPCs in a typical nuclear envelope
What is the function of the nuclear pore complex?
Allows transport of molecules between the nucleus and cytoplasm
What are the types of chromatin in the nucleus?
Euchromatin and heterochromatin
Differentiate euchromatin and heterochroatij
Euchromatin- less condensed, more transcriptionally active
Heterochromatin - condensed chromatin, lesss transcriptionally active
What 2 things are in the nucleus?
Chromatin and the nucleolus
What is the function of the nucleolus ?
Site of ribosome production
- ribosomal RNA is transcribed
- ribosomal subunits assembled
What are nucleosomes?
Fundamental structural unit of chromatin
Macromolecular complex
- 8 histone molecules (octamer)
- 2 loops of DNA wrap around the core octamer
- “beads on a string”