The nucleus is the control center of the cell. It is the largest organelle.









There is an organelle called the nucleolus located inside of the nucleus







The largest organelle.


Usually the only organelle that can be seen with a light microscope.


Surrounded by its own double membrane called the nuclear envelope


Nuclear envelope has very large pores for the transport of RNA, and proteins


The nuclear envelope contains unique nuclear fluid called nucleoplasm.


Contains the cell’s genetic material, known as chromatin.


Considered the cell control center.


Contains one or more nucleoli. A nucleolus is an organelle that synthesizes ribosomes


Ribosomes are organelles that are the sites of protein synthesis




Chromatin is the genetic material of the cell and is housed in the nucleus.







Chromatin is the genetic material of the cell


It is comprised of:

60% protein

30% DNA

10% RNA


Histone proteins help to organize, functionally shorten, and protect DNA

Histones also play an important role in DNA replication


Segments of DNA molecule wraps twice around histone protein and again at the next cluster

A cluster of histone proteins with DNA wrapped around it is called a nucleosome


RNA plays a role in stabilizing the chemical structure of chromatin



Nucleic acids are critical polymers. Remember, a polymer is a chemical made up of a chain of same or similar molecules.





The monomer of nucleic acid is called a nucleotide.

A nucleotide consists of a:


phosphate group

pentose sugar

nitrogenous base


A pentose sugar is a simple sugar


A pentose sugar contains 5 carbon atoms


Sugars are carbohydrates


Carbohydrates are organic molecules composed of carbon, hydrogen, and oxygen


The ratio of hydrogen to oxygen is 2:1


Carbohydrates are used for structural support and energy storage


The pentose sugar of DNA is called deoxyribose


The pentose sugar of RNA is called ribose






DNA

DNA holds the code for the synthesis of all body proteins


DNA is present in mostly every cell of the body


DNA is responsible for the expression of all heritable characteristics


DNA is composed of two strands of nucleotide polymers held together at the nitrogenous bases by hydrogen bonds


The interaction of the hydrogen bonds also cause the molecule to twist and form the typical double helix shape


The nitrogenous bases of DNA include:

Adenine

Thymune

Cytosine

Guanine


The bases bind in complementary pairs:

Adenine — Thymine

Guanine — Cytosine







RNA


RNA plays crucial roles in the protein synthesis process


RNA plays structural support roles in chromatin and other chemicals


RNA is composed of a single strand of nucleotides


The nitrogenous bases of RNA:

Adenine

Guanine

Cytosine

Uracil