Endomembrane System Flashcards
What is the endomembrane system?
Network of membranes and organelles that work together to transport, package, and modify proteins and lipids
What is the endosymbiotic theory?
That aerobic and photosynthetic prokaryotes were engulfed by pre-eukaryotic cells to become mitochondria and chloroplast
What are the three main parts of the nucleus?
- Nuclear envelope
- Chromatin
- Nucleolus
What is the main function of the nucleus?
- Storage of genetic material
- Regulation of gene expression
- Assembly of ribosomes
What is the nuclear enevlope?
It is two concentric membranes separating the nuclear from the cytoplasm
What allows transport from the cytoplasm into the nucleus?
Nuclear pores
What is the outer nuclear membrane connected to?
The endoplasmic reticulum
What is chromatin?
It is the DNA in association with histones
What is the structure of interphase chromatin?
A network of elongated threads
What is the structure of metaphase chromatin?
Densely packed in dividing cell to form individual chromosomes
What is heterochromatin?
Interphase chromatin that is condensed and densely stained
What is the euchromatin?
Interphase chromatin that is uncoiled and less stained
What are pyknotic nuclei?
Condensed and shrunk nuclei indicating a dying cell
What is the nucleolus?
The site of ribosomal RNA production and initial ribosomal assembly
How can the nucleolus be identified?
It is basophilic and more darkly stained than the nucleus
What does the ribosome consist of?
A large subunit and a small subunit
What are polyribosomes?
Groups of ribosomes that translate the same mRNA
What are free ribosomes?
Unattached ribosomes that synthesise intracellular proteins
What type of stain will ribosomes pick up?
They are basophilic hence basic dyes
What is the endoplasmic reticulum?
A network of membrane bound channels
What is the endoplasmic reticulum connected to?
The outer nuclear membrane
What is the difference between smooth and rough ER?
Smooth has no ribosomes rough does
What is the role of sER?
Synthesis and transport of lipids and detoxification of chemicals
Where can sER be found in large amounts?
Liver and adrenal cortex cells
What is the role of rER?
Synthesis and transport of some proteins
What is the golgi body?
Several layers of cisternae and a network of associated tubules and vesicles
What is the role of the golgi body?
Allows directed transport of proteins and lipids and chemical modification
What are the three types of vesicles that leave the Golgi complex?
- Transport vesicles containing lysosomal enzymes
- Transport vesicles of the constitutive secretory pathway
- Secretory vesicles to the plasma membrane
What is constitutive secretion?
Continuous secretion
What is regulated secretion?
When stimulus is required to trigger secretion
