1.3: Parts of a Cell Flashcards
The ______ encloses the main body of the cell.
cell membrane
The cell membrane may also be referred to as the:
plasma membrane and/or the cytoplasmic membrane.
The ______ is a semi-permeable barrier surrounding the cytoplasmic space of a cell.
cell membrane
The cell membrane is a bilayer composed primarily of ……
……amphipathic phospholipids, meaning they contain a polar hydrophilic (water loving) head group and a non-polar hydrophobic (water fearing) tail region.
How freely the lipids move is largely dependent on
the types of lipids present, the temperature of the environment (lipids are slower at lower temperatures and faster at high temperatures), and the presence of any additional molecules (proteins)
A key distinction between prokaryotic and eukaryotic cell membranes is the absence of ______, which play a major role in eukaryotic membrane composition.
sterol lipids (such as cholesterol)
Cell walls (or outer membrane)
are found in bacteria, plants, fungi, and algae and help to form the shape of the cell. The cell wall is an additional layer surrounding the cell membrane; it is rigid and for the most part cannot change its shape. As the outermost layer, the cell wall plays an important role in providing support, structure, and protection. The combination of the cell membrane and the outer membrane (cell wall) are referred to as the cell envelope.
The bacterial cell wall contains______ which can vary in thickness.
peptidoglycan, a peptide-polysaccharide matrix,
The combination of the cell membrane and the outer membrane (cell wall) are referred to as the _______
cell envelope.
despite the harsh conditions in which they are found, organisms in the class______ lack peptidoglycan in their cell walls.
Archaea
Cytoplasm
The cytoplasm constitutes the open volume within a cell. It is comprised mostly of water containing dissolved substances important to the functioning of the cell. Within the cytoplasm are organelles, membrane-enclosed structures that perform specific functions, as described below. All of these organelles, with the exception of the ribosomes, are exclusive to eukaryotic cells.
Nucleus
The nucleus is the defining organelle of all eukaryotic cells and is defined by a porous double lipid bilayer that contains the genomic content of the cell (DNA). The nucleus is thus the command center of the cell. In contrast, the genomic material of prokaryotic cells is found within the cytoplasm. Within the nucleus is the nucleolus, the site of ribosome synthesis.
Ribosomes
Ribosomes are responsible for protein synthesis. They are located in the cytoplasm of prokaryotic cells and are found attached to the endoplasmic reticulum in eukaryotic cells.
Endoplasmic Reticulum (ER)
The endoplasmic reticulum (ER) is a series of membrane-enclosed sacs and interconnected tubes (lumen). The membrane of the endoplasmic reticulum is continuous with the nuclear membrane. The endoplasmic reticulum is composed of the smooth endoplasmic reticulum (SER) and the rough endoplasmic reticulum (RER). The rough appearance is due to the presence of ribosomes that stud the ER membrane surface. Under a microscope, this particular section appears rough in texture.
Golgi Complex
The Golgi complex is series of interconnected flattened sacs (vesicles) located between the nucleus and cytoplasmic membrane. The Golgi complex serves as the distribution center of the cell. Here, the proteins may undergo modifications or be packaged before being distributed.
