Concept Map

Concept Map

Endomembrane System

Nucleus

Endoplasmic Reticulum

produces membrane for and sends products to...

Contains most of the genes in a eukaryotic cell. These genes are organized into units called chromosomes, which are wound tightly around proteins called histones when the cell is not dividing. This DNA provides instructions for messenger RNA synthesis in the nucleus, which is then transported to the cytoplasm through the nuclear pores. Free ribosomes in the cytoplasm then translate this into the primary structure of a protein.

An extensive network of membranous tubules and sacs called cisternae that is continuous with the nuclear envelope. The ER membrane separates the inside of the endoplasmic reticulum (called the ER lumen or cisternal space) from the cytosol. Endoplasmic reticulum can either be rough (meaning it has ribosomes bound to its outer surface) or smooth (no ribosomes). The rough ER aids in the synthesis of secretory proteins and other proteins from bound ribosomes, adds carbohydrate groups to proteins to produce glycoproteins, produces new membranes for the plasma membrane, nuclear envelope, Golgi, and lysosomes, and keeps proteins that are destined for other places in the endomembrane system for packaging. The smooth ER synthesizes lipids, metabolizes carbohydrates, stores calcium ions, and detoxifies drugs and poisons.

continuous

with...

Ribosomes

surrounded by...

Nuclear Envelope

produces

membrane for...

Attached to Rough ER...

is a double membrane that encloses the nucleus. It has pore structures that regulate the entry and exit of proteins, RNAs, and large complexes of macromolecules. The nuclear envelope is also lined by the nuclear lamina, which provides structure.

• Composed of ribosomal RNA and proteins
• Not membrane bound
• Consist of two subunits
• Can be suspended in the cytosol or attached to the endoplasmic reticulum or nuclear envelope.
• Free ribosomes synthesize proteins that function in the cytoplasm, and attached ribosomes synthesize proteins that get inserted into membranes, packaged within organelles, or are secreted from the cell.
• Ribosomes can switch between these two roles.

produces

membrane for...

ribosomes attached to..

Golgi Apparatus

Lysosomes

destroys bacteria

are membranous sacs that contain digestive enzymes. The membrane and the enzymes are both produced by the rough endoplasmic reticulum then sent to the Golgi for further processing. Lysosomes are responsible for the breakdown of damaged organelles for recycling, ingested substances, and macromolecules. Unicellular organisms eat by using a process called phagocytosis to where the lysosome engulfs and digests smaller organisms and food particles. Macrophages also use phagocytosis to engulf and destroy bacteria. Lysosomes use autophagy to digest the cell’s own organic material from damaged organelles.

forms some lysosomes

composed of flat membranous sacs called cisternae. Products from the ER (such as glycoproteins and phospholipids) are sent here to be modified, stored, and then shipped to other destinations. The Golgi apparatus has directionality. As proteins travel through, they move from the cis face (nearest to the ER) to the trans face, where they are sent off to other locations. The Golgi apparatus is also responsible for manufacturing and secreting some polysaccharides.

sends vesicles for export

produces membranes for...

Extracellular Space

ribosomes found in mitochondria

provides ATP

Cell Junctions

produces membranes for...

Extracellular Matrix

Plasmodesmata

Tight Junctions

-Found in plant cells.

-Channels in the cell walls that connect cells.

Plasma membranes of neighboring cells are very tightly pressed together, bound by specific proteins.

-Made up of glycoproteins (like collagen) and proteoglycans.

-Glycoproteins are proteins with covalent bonded carbohydrates.

-The glycoprotein fibronectin connects cells to the ECM

-Proteoglycans consist of small core proteins with many carbohydrate chains attached.

-Integrins transmit signals between the ECM an cytoskeleton

-ECM proteins bind to cell-surface receptor proteins called integrands that are built into the plasma membrane.

Desmosomes

Gap Junctions

-Cytoplasmic channels from one cell to an adjacent cell.

-Consist of membrane proteins that surround a pore.

Function like rivets, fastening cells together into strong sheets.

provides ATP

Plasma Membrane

Organelles that create energy for cells:

forms nuclear lamina

composed of a phospholipid bilayer, with phospholipids that consist of both a fatty acid tail, glycerol, and phosphate group. It functions as a selective barrier that allows molecules to pass in and out of the cell.

supports organelle shape and motility

Mitochondria

ribosomes produce proteins of cytoskeleton

Chloroplasts

the site of cellular respiration, the process in which ATP is generated by the extraction of energy from sugar, fats, etc. They are found in nearly all eukaryotic cells.The number of mitochondria in a cell correlates with the cell’s amount of metabolic activity. Mitochondria are surrounded by a double membrane, each of which is a phospholipid bilayer made up of unique proteins. The outer membrane is smooth, but the inner membrane is folded, with inner foldings called cristae, which increases the surface area. The area enclosed by the inner membrane contains enzymes, mitochondrial DNA, and ribosomes, and is called the mitochondrial matrix.

lens shaped organelles that are found exclusively in plant cells. They contain the green pigment chlorophyll, enzymes, and other molecules. Chloroplasts have a double membrane. Inside the inner membrane is another membrane system of flattened connected sacs called thylakoids. A stack of thylakoids is a granum, and thylakoids are surrounded by a fluid called stroma, which contains chloroplast DNA, ribosomes, and enzymes. Chloroplasts perform photosynthesis, the process in which solar energy is absorbed and converted to chemical energy in the form of organic compounds such as sugar.

supports overall cell shape and motility

Cytoskeleton

supports shape and motility

Dynamic component that aids in cell structure and motility. Made up of microtubules, microfilaments, and intermediate filaments.

Intermediate Filaments

Microfilaments

-Made up of fibrous proteins, such as keratin, coiled into cables.

-Function is to maintain cell shape, anchor the nucleus and other organelles, and to form the nuclear lamina.

-Two intertwined strands of actin filaments that maintain cell shape, muscle contraction, and division in animal cells.

Microtubules

-Hollow tubes that maintain cell shape, cell motility, chromosome movements in cell division, and organelle movements.

-Made up of tubulin protein.