Nuclear Structure and Cell Cucle

What macromolecules are contained in the nucleus?

Proteins, DNA, RNA, and lipids are all contained in the nucleus

What is the nuclear envelope?

The nuclear envelope is a double unit membrane with an intramembrane space that is only permeable to small nonpolar molecules. The outer membrane is continuous with the endoplasmic reticulum.

What are nuclear lamins?

Nuclear lamins are thin fibrous proteins connected to the inner membrane that reinforces the nuclear envelope. Nuclear lamins are intermediate in size and attach to heterochromatin.

What is the nucleolus?

The nucleolus is the site of rRNA processing and the production and assembly of ribosomal subunits. 10 chromosomes lend their rRNA genes to the nucleolus. Active cells can contain multiple nucleoli.

What is the nuclear matrix?

The nuclear matrix serves as attachment sites for DNA and forms chromosome domains within the nucleus. The nuclear matrix, which includes lamins, is involved in replication, transcription, and repair.

What are nuclear pores?

Nuclear pores are gated holes in the nuclear envelope that allow the passage of macromolecules containing a nuclear localization signal (NLS)

What are the causes and symptoms of progeria?

Progeria is the accumulation of mutated lamin A/C in the nucleus, which interferes with normal lamin A/C function. Progeria causes premature aging.

How are cyclin proteins activated?

Cyclin proteins must be bound to CDKs in order to be active.

What cyclin and CDK combination promotes mitosis?

Mitotic cyclin B and CDK1

How are cyclin levels regulated during the cell cycle?

Cyclin levels slowly increase during the cell cycle, then are quickly degraded by the proteasomes after mitosis.

How are CDKs regulated during the cell cycle?

CDKs are regulated by phosphorylation.