Cell Ultrastructure: Nucleus & Plasma Membrane

These flashcards cover key concepts from the lecture on Cell Ultrastructure, focusing on the structure and function of the nucleus and plasma membrane.

What is the fluid mosaic model of the plasma membrane?

It describes the plasma membrane as a structure where phospholipid molecules form a bilayer with embedded proteins, allowing for fluidity and movement.

What are integral and peripheral membrane proteins?

Integral proteins are permanently attached to the membrane, while peripheral proteins are temporarily associated with the membrane surface.

What is the function of membrane proteins in semipermeable membranes?

They facilitate the transport of substances across the membrane and assist in cell signaling.

Describe the structure of the nucleus.

The nucleus includes the nuclear envelope, pores, karyoplasm, chromatin, and nucleolus.

What is the difference between euchromatin and heterochromatin?

Euchromatin is lightly packed and accessible for transcription, while heterochromatin is tightly packed and not transcribed.

What is the role of the centromere?

The centromere is the region of a chromosome where the two sister chromatids are joined and where spindle fibers attach during cell division.

What are histone proteins and nucleosomes?

Histones are proteins around which DNA is wrapped to form nucleosomes, the fundamental building blocks of chromatin.

What are the main functions of the nucleus?

The nucleus controls genetic information, heredity characteristics, protein syntheses, cell division, and stores RNA and DNA.

How do the nuclear envelope and pores operate?

The nuclear envelope consists of two membranes that protect the nucleus; pores allow regulated transport of molecules between the nucleus and cytoplasm.

What is chromatin, and how is it structured?

Chromatin is made of DNA and proteins; it can be in the form of euchromatin (transcribed) or heterochromatin (not transcribed).

What is the significance of the nucleolus?

The nucleolus is where ribosomal RNA is synthesized and combined with proteins to form ribosomal subunits.