Bio 121 Exam 2 ACTUAL UPDATED Exam
Questions and CORRECT Answers
3 Main Functions of the Cell Membrane - CORRECT ANSWER - 1. Transport of
molecules in and out of the cell.
2. Communication between cells.
3. Cell adhesion: connecting cells together.
Cytosol - CORRECT ANSWER - A thick solution that fills each cell and is enclosed by
the plasma membrane, but does not contain organelles. Contains water, salts, nutrients, proteins,
etc.
Cytoplasm - CORRECT ANSWER - Different than cytosol. Includes everything inside the
plasma membrane: Cytosol, Nucleus, ER, Golgi, Lysosomes, and Cytoskeleton.
Different Types of Cytoskeleton Molecules - CORRECT ANSWER - -Microtubules
-Intermediate Filaments
-Microfilaments
Microtubules - CORRECT ANSWER - -Made of spherical subunits that come together to
form a tube.
-Largest in diameter.
-Can be rapidly formed and broken down.
Intermediate Filaments - CORRECT ANSWER - -Made of filament subunits that are
twisted together like braided hair.
-Intermediate in diameter.
-Cannot be easily broken down and formed, thus more stable.
Microfilaments - CORRECT ANSWER - - Also called actin filaments.
, - Made of spherical subunits, attached in long chains and twisted together.
- Smallest in diameter.
- Can be rapidly formed and broken down.
Roles of Motor Proteins - CORRECT ANSWER - - Transports molecules/organelles
around in cells by moving on the cytoskeleton proteins.
- Drives muscle contraction.
- Drives cilia/flagella bending.
Four Major Parts of the Nucleus - CORRECT ANSWER - - Nuclear envelope: double
membrane.
- Nuclear pores: regulates transport of molecules (like RNA or nuclear proteins) in and out of
nucleus.
- Nucleolus: little spot in nucleus where ribosomal subunits assemble.
- Inside the nucleus: holds the DNA (in form of chromosomes).
Roles of the Endoplasmic Reticulum (ER) - CORRECT ANSWER - - Smooth ER:
everything else (drug detox, stores glucose, releases calcium, lipid synthesis).
- Rough ER: studded with ribosomes, one major site for protein synthesis.
Flow of Proteins Through the Endomembrane System - CORRECT ANSWER - - Vesicles
leave ER, fuse with Golgi, then vesicles leave Golgi and fuse to another cellular destination.
Role of the Golgi (Post Office of the Cell) - CORRECT ANSWER - Receives proteins
(via vesicles) where they are processed, sorted and eventually transported away (via vesicles) to
different cellular destinations.
Destinations of Vesicles Once They Leave the Golgi - CORRECT ANSWER - - Cell
membrane: fusion results in delivery of membrane bound proteins, or the release of secreted
proteins outside the cell.
- Lysosome: delivery of enzymes to the lysosome.
Questions and CORRECT Answers
3 Main Functions of the Cell Membrane - CORRECT ANSWER - 1. Transport of
molecules in and out of the cell.
2. Communication between cells.
3. Cell adhesion: connecting cells together.
Cytosol - CORRECT ANSWER - A thick solution that fills each cell and is enclosed by
the plasma membrane, but does not contain organelles. Contains water, salts, nutrients, proteins,
etc.
Cytoplasm - CORRECT ANSWER - Different than cytosol. Includes everything inside the
plasma membrane: Cytosol, Nucleus, ER, Golgi, Lysosomes, and Cytoskeleton.
Different Types of Cytoskeleton Molecules - CORRECT ANSWER - -Microtubules
-Intermediate Filaments
-Microfilaments
Microtubules - CORRECT ANSWER - -Made of spherical subunits that come together to
form a tube.
-Largest in diameter.
-Can be rapidly formed and broken down.
Intermediate Filaments - CORRECT ANSWER - -Made of filament subunits that are
twisted together like braided hair.
-Intermediate in diameter.
-Cannot be easily broken down and formed, thus more stable.
Microfilaments - CORRECT ANSWER - - Also called actin filaments.
, - Made of spherical subunits, attached in long chains and twisted together.
- Smallest in diameter.
- Can be rapidly formed and broken down.
Roles of Motor Proteins - CORRECT ANSWER - - Transports molecules/organelles
around in cells by moving on the cytoskeleton proteins.
- Drives muscle contraction.
- Drives cilia/flagella bending.
Four Major Parts of the Nucleus - CORRECT ANSWER - - Nuclear envelope: double
membrane.
- Nuclear pores: regulates transport of molecules (like RNA or nuclear proteins) in and out of
nucleus.
- Nucleolus: little spot in nucleus where ribosomal subunits assemble.
- Inside the nucleus: holds the DNA (in form of chromosomes).
Roles of the Endoplasmic Reticulum (ER) - CORRECT ANSWER - - Smooth ER:
everything else (drug detox, stores glucose, releases calcium, lipid synthesis).
- Rough ER: studded with ribosomes, one major site for protein synthesis.
Flow of Proteins Through the Endomembrane System - CORRECT ANSWER - - Vesicles
leave ER, fuse with Golgi, then vesicles leave Golgi and fuse to another cellular destination.
Role of the Golgi (Post Office of the Cell) - CORRECT ANSWER - Receives proteins
(via vesicles) where they are processed, sorted and eventually transported away (via vesicles) to
different cellular destinations.
Destinations of Vesicles Once They Leave the Golgi - CORRECT ANSWER - - Cell
membrane: fusion results in delivery of membrane bound proteins, or the release of secreted
proteins outside the cell.
- Lysosome: delivery of enzymes to the lysosome.
