Cell Organelles Flashcards
Cell Structure Pic.
Blank on purpose.
Nucleus
- Largest organelle
- Two membranes form the nuclear envelope
- Contains the nucleolus
What is the nucleolus?
A small dense structure composed largely of:
- RNA
- Most of the cellular DNA;
- Histones: DNA binding proteins, that regulate its activity
Primary function of nucleus
The primary functions of the nucleus are
- Cell division and
- Control of genetic information.
Other functions include:
- Replication and repair of DNA
- Transcription of the information stored in DNA.
Discuss genetic information transcribed into RNA:
When genetic information is transcribed into RNA it can be processed into:
- Messenger
- Transport
- Ribosomal RNA
It is then introduced into the cytoplasm, where it directs cellular activities.
Where does most of the processing of RNA occur?
In the nucleolus
What represents about 1/2 the volume of a eukaryotic cell?
Cytosol
What is cytosol?
The aqueous solution in the cytoplasm that fills the cytoplasmic matrix.
- 55% of cell volume
Functions:
- Intermediary metabolism
- Enzymatic biochemical reactions
- Ribosomal protein synthesis
- Storage of:
- carbs,
- fat and
- secretory vesicles
What is the cytoplasmic matrix?
Space between the nuclear envelope and the plasma membrane.
What also functions as a storage unit for fat, carbohydrates, and secretory vesicles?
Cytosol
What are ribosomes?
- RNA-protein complexes (nucleoproteins) that are synthesized in the nucleolus and secreted into the cytoplasm through pores in the nuclear envelope called nuclear pore complexes (NPCs).
- may float free in the cytoplasm or
- attach themselves to the outer membranes of the endoplasmic reticulum
What is the chief function of ribosomes?
Provide sites for cellular protein synthesis
What is the endoplasmic reticulum (ER)?
- Membrane factory that specializes in the synthesis and transport of protein and lipid components
- Consists of network of tubular/saclike channels (cisternae) that extend throughout the cytoplams and are continuous with the outer nuclear membrane
What two characteristics can the folded membranes that form the cisternae of the endoplasmic reticulum be?
- Rough (granular)
- Smooth (agranular)
Why is rough ER (rER) rough?
Ribosomes and ribonucleoprotein particles are attached to it.