Histones are proteins found in the nucleus of eukaryotic cells. DNA wraps itself around histones to further condense. Also, depending on how tightly the DNA is wrapped around the histones, it may or may not be availible for activity (e.g. replication or transcription). Cells modify the interaction between DNA and histones around certain genes under certain conditions to make those genes available or unavailable as needed.

The Golgi apparatus is a series of flattened membrane sacs found in the cell. It receives vesicles filled with proteins from the rough endoplasmic reticulum. The Golgi apparatus is responsible for recognizing proteins based on their signal sequences and sending concentrations of similar proteins to various parts of the cell. It can also deliver proteins out of the cell using secretory vesicles. The membrane sacs of the Golgi apparatus are constantly used and regenerated to create vesicles of packaged proteins.

Vacuoles are membrane-bound structures that are found in bacterial, plant, fungal, and occasionally, animal cells. Vacuoles function in storage of water and waste and in maintenance of turgor pressure in plants.

The process of secretion of a newly synthesized molecule destined for use outside of the cell follows the following path: Rough endoplasmic reticulum, smooth endoplasmic reticulum, Golgi apparatus, secretory vesicle. This pathway must be accomplished for proper secretion to occur as vital peptides are added in the process in different organelles to make sure they are properly delivered.

While free ribosomes are present independently in the cytosol, bound ribosomes are attached to the rough endoplasmic reticulum. Their presence gives this organelle its "rough" appearance and distinguishes it from the smooth endoplasmic reticulum, which does not contain ribosomes. The nuclear envelope, which surrounds and protects the eukaryotic nucleus, is also the site of some bound ribosomes and is connect to the rough endoplasmic reticulum. The Golgi apparatus, lysosomes, and mitochondria have no ribosomes bound to their membranes.

Each of these answers correctly describes characteristics of mitochondria. Mitochondria are semi-autonomous: they are capable of synthesizing some of their own proteins with DNA and ribosomes. The proteins are then embedded in the inner mitochondrial membrane, and function in the electron transport chain. Mitochondria have two membranes, an inner membrane and an outer membrane. Mitochondria are the sites of cellular respiration and ATP production, often called the "powerhouse" of the cell. After glycolysis, pyruvate is transported to the mitochondrial matrix for the Krebs cycle and electron transport chain. Mitochondria are not involved in the endomembrane system; they are separate organelles.

The nucleolus is a specialized structure within the nucleus that is the site of ribosome synthesis and assembly. The nucleolus is not directly involved in DNA replication, translation, or ATP synthesis. While the DNA of eukaryotic cells is stored in the nucleus, it is not stored in the nucleolus since this part of the nucleus is specialized for ribosome assembly.

Mitochondria and chloroplasts are organelles within eukaryotic and plant cells, respectively. All eukaryotic organisms contain mitochondria, but only photoautotrophs will contain chloroplasts. The function of these organelles is to produce energy for the cell to survive and function. Mitochondria produce energy through respiration and chloroplasts produce energy through photosynthesis. These organelles have their own DNA to express their own set of genes and have ribosomes to make the proteins necessary to make energy for the cell. The proteins for the electron transport chain, for example, are transcribed and translated within the mitochondrial matrix before being implanted in the inner mitochondrial membrane.

Homeostasis is the mechanism that allows for organisms to maintain equilibrium of their internal environments. Certain variables of the internal environments are regulated such that the conditions of the organism remain stable and relatively constant. This is often accomplished via negative feedback loops and hormone regulation.

Reproduction refers to an organism's ability to generate offspring. Respiration refers to the method of gas exchange in the lungs. Synthesis refers to the generation of certain molecules. Mitosis refers to cellular division. While any of these processes could be used to affect the equilibrium state of an organism, they are all mediated by homeostatic mechanisms in order to maintain biological stability.

The Golgi apparatus is where transport vesicles are developed and is known as the transport and processing center. Proteins and other compounds are taken to the Golgi apparatus. The Golgi has several membrane-bound sacs that allow proteins to become engulfed in vesicles or integrated into the membranes of vesicles. Complete vesicles are then transported within the cell or to the cell membrane, where they fuse and release their contents into the extracellular space. The membrane of the vesicles is incorporated into the cell membrane, along with any integrated proteins.

Lysosomes are processed in the Golgi apparatus and contain enzymes that are activated by low pH to get rid of waste and damaged organelles. The smooth endoplasmic reticulum is responsible for absorbing and removing drugs and poisons. The rough endoplasmic reticulum manufactures and modifies proteins before they are packaged in the Golgi apparatus. Ribosomes function in translation, producing proteins from mRNA.