The function of the nucleus is to store the genetic blueprint in order to make proteins during transcription and translation. The nucleus is enclosed by the nuclear envelope that acts as protection for the nucleus. The nucleolus which produces ribosomes to conduct protein production is also within the nucleus. 

University of California, Berkeley

The process of copying a gene's DNA sequence to make a single-stranded messenger RNA (mRNA) molecule in the nucleus. The process of transcription is mainly performed by RNA polymerases, an enzyme that matches the correct RNA nucleotide with the template strand. After transcription, mRNA molecules are sliced (resulting in variability in mRNA generated from the same DNA sequence) and stabilized with a 5' guanine cap and poly-A tail. 

Transcription

Animal cell organelles are specialized entities in a cell that performs a particular function. 

- Nucleus
- Endoplasmic Reticulum
- Golgi Apparatus
- Ribosome
- Mitochondria
- Lysosome
- Peroxisome 
- Cell membrane

Animal Cell Organelles

https://www.khanacademy.org/test-prep/mcat/cells/eukaryotic-cells/a/organelles-article

Cellular organelles and structure

RNA polymerase builds mRNA molecules through base pairing. If the DNA nucleotide is a C, the polymerase will add a G to the RNA (and similarly, a A to a T). RNA polymerase always builds RNA from the 5' to 3' position.

RNA Polymerase

Nucleus

There's two types of the endoplasmic reticulum (ER): the rough and smooth, which are characterized by whether it has ribosomes attached. The rough ER has ribosomes attached to its membrane; the function of the rough ER is to produce proteins that either are part of a membrane or to be secreted outside of the cell which allows for further specialization of cells. The smooth ER, on the other hand, is specialized to produce steroids and lipids, as well as, to get rid of toxins within the cell. 

Endoplasmic Reticulum 

The purpose of the Golgi Apparatus is to sort protein packages to different destinations. The different molecules usually come from the ER and their final destinations can be differentiated by the several sugar compounds attached to them. These packages of proteins are transported by vesicles to their final destinations. The 3 possible destinations are cell membrane (for membrane protein or ion channels), extracellular secretion (for molecules that should exit the cell) and the lysosome (which destroys and recycles the molecules).

Golgi Apparatus 

Ribosomes' job is to synthesize proteins, as it binds together amino acids on tRNA to make peptides during translation.

Ribosomes

"The mitochondria is the powerhouse of the cell" is probably the most well-known saying in all of biology. This is because the job of the mitochondria is to produce energy from the breakdown of glucose. The initial lysis of glucose occurs in the cytoplasm but the bulk production of ATP(energy) is produced in the Krebs Cycle and ETC within the mitochondria. 

Mitochondria

This organelle is the location for recycling, the lysosome has enzymes within that only are active at an acidic pH of 5. The lysosome will hydrolyze whatever goes inside the membrane and reuse the raw material from that substance; the lysosome will also help break down intruding viruses and bacteria.

Lysosome

Similar to the lysosome, the peroxisome also has enzymes for hydrolysis; however, it mainly does fatty acid breakdown. The peroxisome also defends the cell against reactive oxygen species such as peroxides that are produced during our regular cellular respiration. 

Peroxisome 

The cell membrane acts as a semi-permeable wall to block off intruders and let in specific molecules that the cell actually needs. To perform these tasks, the cell membrane has a lipid bilayer which excludes entry to all polar molecules except if there is a protein transporter specific for that exact molecule.

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