GENERAL HISTOLOGY

INTRODUCTION

CELL STRUCTURE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
The ____ is a densely packed area in a cell that contains the genetic material-DNA-for controlling the cell’s activities.
A
Chloroplast
B
Nucleus
C
Mitochondria
D
Vacuole
Explanation: 

Detailed explanation-1: -The nucleus (plural, nuclei) houses the cell’s genetic material, or DNA, and is also the site of synthesis for ribosomes, the cellular machines that assemble proteins. Inside the nucleus, chromatin (DNA wrapped around proteins, described further below) is stored in a gel-like substance called nucleoplasm.

Detailed explanation-2: -Figure 5: To better fit within the cell, long pieces of double-stranded DNA are tightly packed into structures called chromosomes.

Detailed explanation-3: -DNA is tightly packed up to fit in the nucleus of every cell. As shown in the animation, a DNA molecule wraps around histone proteins to form tight loops called nucleosomes. These nucleosomes coil and stack together to form fibers called chromatin.

Detailed explanation-4: -Most DNA is located in the cell nucleus (where it is called nuclear DNA), but a small amount of DNA can also be found in the mitochondria (where it is called mitochondrial DNA or mtDNA). Mitochondria are structures within cells that convert the energy from food into a form that cells can use.

Detailed explanation-5: -Chromatin is a complex of DNA and proteins that forms chromosomes within the nucleus of eukaryotic cells. Nuclear DNA does not appear in free linear strands; it is highly condensed and wrapped around nuclear proteins in order to fit inside the nucleus. Chromatin exists in two forms.

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