Week 3: Cell Structure and Function Flashcards
List the three domains into which living organisms are classified. Are organisms in different domains related? Explain.
Bacteria, archaea, Eykarya. Yes, organisms share a universal common ancestor.
Describe and compare the basic cellular organization of prokaryotic and eukaryotic cells. Is one group organized while the other is not? Explain.
Eukaryotic cells have a “true nucleus” that is membrane-enclosed. Also contains other membrane enclosed intracellular structures. Prokaryotic cells are “before nucleus”, lack a membrane- enclosed nucleus and other membrane -enclosed structures. Both have DNA and organization (think paper bag vs. backpack).
In a single sentence, describe the basic structure of the cell membrane. Of what types of molecules is it composed, and how are they arranged?
The cell membrane is composed of a fluid phospholipid layer that contains proteins. Composed of phospholipids arranged a tail to tail layer with the hydrophobic heads inward and the hydrophobic heads facing the outside.
Phospholipids
- membrane foundation
- two layers
- not covalently linked
- fluid and flexible
- hydrophilic heads and hydrophobic tails
In a single sentence, describe the basic function of the cell membrane.
Protects and creates structure for the cell to maintain internal environment while facilitating transportation of molecules in and out of the cell.
Describe the fluid mosaic model of membranes.
explains the fluid structure of the plasma membrane of animal cells as a mosaic of components such as phospholipids, proteins, cholesterol, and carbohydrates. Everything’s fits together like a puzzle.
Integral proteins
proteins that are inserted into the membrane
Peripheral proteins
associated with the membrane surface
What purpose to proteins serve in the plasma membrane?
Enzymes, transportation proteins, receptor proteins.
Describe the semipermeable nature of the cell membrane.
Maintains the cell’s interior as a distinctly different environment. movement into and out of the cell is regulated, not everything can cross the membrane.
How does active transport differ from passive transport?
PassiveActive transport does not require energy and can only move substance down their concentration gradient. While active transport requires energy usage (ATP) and can move substances against their concentration gradient
Describe and differentiate between the processes of diffusion and facilitated diffusion. How are they similar? How are they different?
Diffusion: movement of substance directly across phospholipid bilayer.
Facilitated diffusion: movement of substance across phospholipid bilayer via transport protein.
Both are passive transport, both only work in the direction down the concentration gradient. Differ in facilitation needs a transport protein.
Osmosis
involves the movement of water across the membrane through a specific water channel protein
Aquaporins
Channels used to move water via osmosis.
Hypertonic
solution has more solute and less water
hypotonic
solution has less solute and more water
Describe the process of osmosis using the terms hypertonic and hypotonic.
Movement of water across the membrane and down its concentration gradient. Occurs through channels called aquaporins. Net moment is from hypotonic solution to hypertonic solution.
List 3 types of passive transport
diffusion, facilitated diffusion, osimosis
What is group translocation? How is it important in gathering molecules such as glucose within a cell?
Form of active transport, the transported substance is chemically altered during the process and the membrane is impermeable by this modified substance. Example, glucose is converted to glucose-g-phosphate.
How does a bacterial cell membrane differ from its eukaryotic counterpart?
- Different phospholipid composition: different chemical groups that are immunologically important
- Lacks sterols: such has cholesterol or ergosterol
-Involved in energy transformations: capture of energy and storage for ATP
- Heavily infolded: increases surface area, facilitates transport and energy transformations.
List at least five bacterial cellular structures that are external to the cell membrane.
flagella
sheath
pili
glycocalyx
cell wall
List at least five bacterial cellular structures that are internal to the cell membrane.
Endospores
DNA
Ribosomes
gas vesicle
granules
What is the key function of the bacterial cell wall?
Provide structure/shape and protect from osmotic pressure. Also assists in attachment and resistance to antimicrobial drugs.
What molecule that is possessed only by bacteria is present in virtually all bacterial cell walls?
peptidoglycan