BIO 322 midterm #1 study guide- Questions with
Complete Solutions
1. Explain the historical origin of mitochondria and chloroplasts
Both covert one form of energy into chemical energy that can be used by cell
Both have DNA, ribosomes, double membrane, and capable of division
Originated as prokaryotes that were engulfed by eukaryote ancestor - endosymbiosis
2. List the cell biological differences between prokaryotes and eukaryotes
▪Eukaryotes more complex
▪Eukaryotes have membrane bound organelles:
▪Mitochondria/chloroplast, ER, Golgi, lysosome, vesicles
▪Eukaryotes have a complex cytoskeleton
▪Microtubules, microfilaments, interm.filaments
▪Eukaryotes have a membrane-bound nucleus
▪Compact, organized DNA=chromatin
3. Name three functions of cellular membranes within a cell
(1) they keep toxic substances out of the cell; (2) they contain receptors and channels that allow
specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular
and extracellular activities to pass between organelles and between the cell and the outside
environment; and (3) they separate vital but incompatible metabolic processes conducted within
organelles.
4. Label a lipid bilayer in terms of specific phospholipids, protein components and
carbohydrates
, 5. Know the general differences between various phospholipids
-PHOSPHATIDYLCHOLINE IS THE MOST COMMON PHOSPHOLIPID IN CELL
MEMBRANES.
-DIFFERENT TYPES OF MEMBRANE LIPIDS ARE ALL AMPHIPATHIC (FORM A
BILAYER IN WATER)
-SPONTANEOUSLY CLOSE IN ON THEMSELVES TO FORM SEALED
COMPARTMENTS
6. Explain why the bi-layer is self-sealing
Phospholipids are made up of two parts, a hydrophilic head group and hydrophobic tails. The
hydrophilic head groups are automatically drawn to each other because of the similar properties
causing the hydrophobic tails to join together as well. This attraction is what causes to lipid
bilayer to self-seal because it is such a strong attraction. Micelles are membranes that are made
up of phospholipids with only 1 tail. Lipid bilayers are favored over a single layered micelle
because single there is only one tail, these phospholipids can join together more closely and
make a sphere like structure that is hydrophobic all the way through so nothing is able to pass
through the membrane.
-The Lipid Bilayer Is a Flexible Two-dimensional Fluid
-The Fluidity of a Lipid Bilayer Depends on Its Composition
-Membrane Assembly Begins in the ER
-Certain Phospholipids Are Confined to One Side of the Membrane
9. Discuss the role of flippases and scramblases
Complete Solutions
1. Explain the historical origin of mitochondria and chloroplasts
Both covert one form of energy into chemical energy that can be used by cell
Both have DNA, ribosomes, double membrane, and capable of division
Originated as prokaryotes that were engulfed by eukaryote ancestor - endosymbiosis
2. List the cell biological differences between prokaryotes and eukaryotes
▪Eukaryotes more complex
▪Eukaryotes have membrane bound organelles:
▪Mitochondria/chloroplast, ER, Golgi, lysosome, vesicles
▪Eukaryotes have a complex cytoskeleton
▪Microtubules, microfilaments, interm.filaments
▪Eukaryotes have a membrane-bound nucleus
▪Compact, organized DNA=chromatin
3. Name three functions of cellular membranes within a cell
(1) they keep toxic substances out of the cell; (2) they contain receptors and channels that allow
specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular
and extracellular activities to pass between organelles and between the cell and the outside
environment; and (3) they separate vital but incompatible metabolic processes conducted within
organelles.
4. Label a lipid bilayer in terms of specific phospholipids, protein components and
carbohydrates
, 5. Know the general differences between various phospholipids
-PHOSPHATIDYLCHOLINE IS THE MOST COMMON PHOSPHOLIPID IN CELL
MEMBRANES.
-DIFFERENT TYPES OF MEMBRANE LIPIDS ARE ALL AMPHIPATHIC (FORM A
BILAYER IN WATER)
-SPONTANEOUSLY CLOSE IN ON THEMSELVES TO FORM SEALED
COMPARTMENTS
6. Explain why the bi-layer is self-sealing
Phospholipids are made up of two parts, a hydrophilic head group and hydrophobic tails. The
hydrophilic head groups are automatically drawn to each other because of the similar properties
causing the hydrophobic tails to join together as well. This attraction is what causes to lipid
bilayer to self-seal because it is such a strong attraction. Micelles are membranes that are made
up of phospholipids with only 1 tail. Lipid bilayers are favored over a single layered micelle
because single there is only one tail, these phospholipids can join together more closely and
make a sphere like structure that is hydrophobic all the way through so nothing is able to pass
through the membrane.
-The Lipid Bilayer Is a Flexible Two-dimensional Fluid
-The Fluidity of a Lipid Bilayer Depends on Its Composition
-Membrane Assembly Begins in the ER
-Certain Phospholipids Are Confined to One Side of the Membrane
9. Discuss the role of flippases and scramblases
