Nucleus: Structure And Function

Question 0

Nuclear envelope

Answer 0

2 membrane system that encloses a perinuclear cisterna (space) and consists of inner nuclear membrane and outer nuclear membranes that are continuos at the nuclear pore complex

Question 1

Nucleus

Answer 1

Major organelle of eukaryotic cells in which chromatin is separated from the cytoplasm by the nuclear envelope. Contains cells linear DNA which encodes generic code for protein synthesis, growth, development, and reproduction

Question 2

Nucleolus

Answer 2

One or more small rounded structure within the nucleus in which the synthesis of ribosomal RNA and assembly of ribosomal subunits takes place

Question 3

Nuclear matrix

Answer 3

Protein latticework filling the nucleus that anchors chromosomes for DNA replication and transcription complexes and reinforces the nuclear envelope, imparting stability to the nuclear envelope and plays a role in the structural organization of chromatin

Question 4

Chromatin

Answer 4

Material, consisting of DNA and protein, in the nucleus of a cell that stains basic dyes

Question 5

Outer membrane

Answer 5

6 nm thick. Membrane that is continuous in some locations with the membrane of the ER and may have associated ribosomes

Question 6

Inner nuclear membrane

Answer 6

Membrane that is continuous with the outer membrane at perforations, nuclear pore complexes

Question 7

Perinuclear cisterna

Answer 7

20-40 nm. Space between outer and inner membranes, continuous with the lumen of the ER

Question 8

Nuclear pore complex (NPC)

Answer 8

100 nm. Sites of nucleo-cytoplasmic communication and attachment points for nucleoskeletal proteins

Question 9

Histones

Answer 9

Have high positive charges and have a high affinity for the negatively charged phosphates on the backbone of the DNA helix.

Question 10

Nucleosome

Answer 10

Basic structural unit of the chromatin, consisting of proteins and DNA. The functional unit is a core made of 8 molecules of histones plus 166 base pairs of DNA wrapped twice around the core

Question 11

Heterochromatin

Answer 11

The darkly staining, more coiled, less active chromatin in the interphase nucleus, usually concentrated at the periphery of the nucleus and around the nucleolus as well as scattered throughout the nucleoplasm. Ex. Barr body or sex chromatin, which corresponded to one of the two X chromosomes in nearly all somatic cells of female mammals

Question 12

Euchromatin

Answer 12

Lightly staining, less coiled more active chromatin in the interphase nucleus, transcriptionally more active than heterochromatin

Question 13

Chromosomes

Answer 13

Thread like highly coiled structures in the nucleus, that carry genetic information in the form of genes, consisting of chromatin (heterochromatin and Euchromatin) extensively folded into loops. Humans have 46 chromosomes

Question 14

Gene

Answer 14

A segment of DNA that produces RNA to produce a polypeptide