Biology (Cliff Notes) Flashcards
What is a peripheral protein?
Proteins that may attach loosely to the inner or outer surface of the membrane.
What is an integral protein?
Proteins that may be integrated into the membrane (are amphipathic.
What is transmembrane protein?
Proteins that are integral proteins that can span across the membrane, appearing at both surfaces.
What is the function of a channel protein?
Provide passageways for certain hydrophilic substances such as polar or charged molecules
What is the function of ion channels?
Provide passageways for ions. Ion-gated channels in nerve and muscle cells open in response to specific chemical or electrical stimuli.
What is a carrier protein?
Proteins that bind to specific molecules and carry them across the membrane after the protein undergoes a change in shape. Glucose is carried into the cell by a carrier protein.
What is a transport protein?
Proteins that use ATP to transport materials across the membrane. The use of ATP makes this transport active transport. (Na+-K+ pump uses ATP to maintain higher concentrations of Na+ and K+ on opposite sides of the membrane.
What is a recognition protein?
These proteins give each cell type a unique identification and distinction between “self” and foreign.
What is another term used to described recognition proteins?
They are also glycoproteins because they have short polysaccharide chains attached. The oligosaccharide part of the glycoprotein extends away from the surface of the membrane.
What is an adhesion protein?
Proteins that attach cells to neighboring cells and act as an anchor for the internal filaments and tubules that give stability to the cell
What is a receptor protein?
Proteins that provide binding sites for hormones or other trigger molecules.
What happens when a hormone or trigger molecule binds to a receptor?
In response to the hormone or trigger molecule, a specific cell response is activated.
What is the function of cholesterol in the plasma membrane of animal cells?
Provide rigidity
What is a sterol in plant cells?
A sterol is a substance related to cholesterol found in the cell membrane of plants and provides rigidity
Define glycocalyx and its function
Glycocalyx is a carbohydrate coat that covers the outer face of the cell wall of some bacteria and the outer face of the plasma membrane of certain animal cells. It consists of various oligosaccharides attached to glycolipids and glycoproteins. It may provide adhesive capabilities, act as a barrier to infection, of markers for cell-cell recognition
Define oligosaccharide
carbohydrates made up of less than 20 monosaccharides
What encloses the nucleus?
The nucleus is enclosed by a double membrane (two phospholipid bilayers) called the nuclear envelope.
What is enclosed in the nucleus?
The nucleus contains DNA, the hereditary information of the cell. It also contains nucleoli, which are concentrations of DNA in the process of manufacturing the components of ribosomes. The nucleus also serves as a the site for the separation of chromosomes during cell division.
How is DNA spread out in the nucleus?
In a threadlike matrix called chromatin.
When cells begin to divide, what happens to chromatin?
It condenses into rod-shaped bodies called chromosomes, each of which, before dividing, is made up of two long DNA molecules and various histone molecules.
What is the function of histones?
Histones serve to organize the lengthy DNA, coiling it into bundles called nucleosomes
What is a ribosome?
A ribosome assists in the assembly of amino acids into proteins.
Explain the process of ribosome formation
It’s subunits are manufactured in the nucleus and consist of RNA molecules and proteins. The two subunits labeled 60s and 40s move across the nuclear envelope and into the cytoplasm where they are assembled into a single 80s ribosome.
Describe the ER and its function.
ER is made up of stacks of flattened sacs involved in the production of various materials.
Describe the Rough ER
When ribosomes are present, its called rough ER and here, glycoproteins are created by attaching polysaccharide groups to polypeptides assembled by ribosomes.
Describe the Smooth ER
ER without ribosomes and is responsible for various activities, such as the synthesis of lipids and hormones. In liver cells, it is involved in the breakdown of toxins, drugs, and toxic by-products from cellular reactions.
Describe the Golgi apparatus
A group of flattened sacs arrange like a stack of bowls that modify and package proteins and lipids into vesicles that bud from the outside surface of the Golgi.
What is a lysosome?
Vesicles from the Golgi that contain digestive enzymes. A low pH, favoring enzymatic activity, is maintained inside the lysosome (not viable in the cytoplasm if escaped).
Do lysosomes occur in plant cells?
No