Lecture7 Flashcards
What does mitochondria do?
Change energy from one form to another, the sites of cellular respiration and generates ATP
What is cellular respiration?
a metabolic process that uses oxygen to generate ATP
Where are chloroplasts found?
in plants and algae
Where is the site of photosynthesis?
chloroplasts
What is the structure of mitochondria and chloroplasts like?
enveloped by a double membrane
contain free ribosomes and circular DNA molecules
How do mitochondria and chloroplasts grow and develop?
somewhat independently in cells
What organisms do chloroplasts and mitochondria share similarities with?
bacteria
The similarities between bacteria and chloroplast and mitochondria led to what theory?
endosymbiont theory
What is endosymbiont theory?
Mitochondria and chloroplasts were once free living prokaryotes that were engulfed by an early eukaryotic ancestor ~1.5 billion years ago
Who was behind the endosymbiont theory?
Lynn Margulis
How are phospholipids form?
They are self-assembled due to the hydrophobic effect
What does amphipathic mean?
A molecule that has both hydrophilic and hydrophobic parts
What affects membrane fluidity?
molecule properties
What are the adaptations that allow the cell to maintain fluidity?
habitat (temperature)
nature of lipids
unsaturated vs saturated fatty acids
cholesterol
How should the fluidity of a membrane behave?
not too rigid and not too fluid
What is the essential molecule that maintains membrane integrity?
Cholesterol
What is the function of cholesterol?
maintain membrane integrity (fluidity buffer)
Who developed the fluid mosaic model?
SInger and Nicholson
What does the fluid mosaic model state?
that a membrane is a fluid structure (phospholipids) with a “mosaic” of various proteins embedded in it
Plasma membrane, nuclear membrane, membrane of organelles (ER, mitochondria), vesicles
How do phospholipids move?
in the plasma membrane freely within the bilayer
How do phospholipids drift?
laterally
True/False: Rarely, a lipid may flip-flop transversely across the membrane bilayer (usually enzyme mediated)
true
What are lipid rafts?
saturated phospholipids, cholesterol, and protein
what are non-rafts?
unsaturated phospholipids and proteins
Where are integral (transmembrane) proteins located?
They span the membrane
What substances cross the semipermeable membrane easily?
small hydrophobic molecules
What substances have a hard time crossing the semipermeable membrane?
charged molecules without a transport protein
What are transport proteins?
proteins that allow substances to cross the barrier
What are the two kinds of membrane transport?
passive and active
What is passive transport?
requires a protein but not energy. uses channels and carriers
What is another name for passive transport?
facilitated diffusion
What is active transport?
requires protein and energy e.g. ATP. uses pumps
What is osmosis?
The movement of water from an area of high concentration to an area of low concentration
