Module 1: Lesson 3 Flashcards
What are the different components of the nucleus?
The nucleolus, nuclear membrane, chromatin structure, and nuclear pores.
What is the nuclear envelope contiguous with?
Endoplasmic reticulum
How did the nucleus and ER potentially arise?
Invagination of the plasma membrane in ancestral archaea by evolution.
What are the advantages of genome enclosure inside the nucleus?
Physical protection, protection from viruses, and more complex regulation via compartmentalization.
What is nuclear lamina?
A mesh of cytoskeleton intermediate filaments (lamin proteins) that line the inside of the nucleus.
What makes the nucleus tough and vault-like?
Nuclear lamina
What organelles have their own genome?
Mitochondria and chloroplasts
How many pairs of chromosomes do humans have? How many chromosomes are there in total?
23 chromosome pairs; 46 chromosomes total
What releases the nucleosome from chromatin?
Digestion of linker DNA with nuclease
What is the role of salt in chromosomal DNA packaging?
A concentration of salt dissociates DNA and the histone octamer from nucleosomes.
What is the role of histone H1?
H1 provides additional packaging of nucleosomes in denser chromatin fiber.
What is the model of chromosomal DNA packaging?
“Beads-on-a-string”
How is the size of chromatin loops regulated?
Sequence specific clamp proteins
What do condensins do?
Condensins form loops within loops on mitotic chromosomal DNA, creating compact configurations.
How is chromosome structure regulated?
ATP-dependent chromatin remodeling complexes pull on nucleosomal DNA to give access to other DNA-binding proteins.
How many histone proteins are in a single octamer?
4 histone proteins
What does histone tail modification do?
Allow gene expression or gene silencing.
What does heterochromatin and euchromatin look like in interphase?
Heterochromatin is highly condensed, but euchromatin is less condensed.
What regulates gene expression?
Chromatin structures. Specifically, less condensed euchromatin allows for gene expression.
What are nucleoli made of?
Proteins, DNA, and RNA
What is the role of the nucleolus?
It is the site of ribosome synthesis.
How do proteins and RNA get in/out of the nucleus?
Nuclear pores
What is the Nuclear Localization Signal?
A patch of positively charged amino acids that allow active transport into the nucleus.
What is the Nuclear Import Receptor protein?
A protein that recognizes the nuclear localization signal and passes through nuclear pores.
What is Ran and what is its role?
Ran is a GTPase protein that hydrolyzes GTP as a molecular switch to drive transport reaction in one direction for the nucleus.
What can Western blots do?
Enable detection of specific proteins
