Biology 102 Chapter 4:
This chapter explains cell structure and function, focusing on the differences between prokaryotic (simpler, no organelles) and eukaryotic cells (complex, with organelles like the nucleus and mitochondria). It covers key cell components, including the plasma membrane, cytopl...
Biology 102: Learn Before Lecture #3
Q1. What is the name of the molecule that makes up an organism’s genome? DNA
(Deoxyribonucleic acid)
Q2. What are the two main parts of “cell theory”?
1. All living things are composed of one or more cells.
2. All cells come from pre-existing cells.
Q3. How did Gibson and Venter know that their “synthetic life” was alive?
The synthetic cell was able to grow and reproduce, just like a natural cell. The DNA they
created allowed the organism to function independently and carry out life processes.
Q4. What is the name of the molecule that makes up a cell’s plasma membrane? Phospholipid
Q5. A. If molecules are moving from a region of higher concentration to a region of lower
concentration, which of the following may be occurring? Circle all that apply.
diffusion osmosis active transport passive transport
B. Which one requires an input of energy? Active transport
Q6. Most cells are at least 70 % water.
Q7. What do hypertonic, hypotonic, and isotonic refer to? What is the difference among them?
They refer to the concentration of solutes in a solution relative to the inside of a cell.
● Hypertonic is a solution that has a higher concentration of solutes than the inside
of the cell.
● Hypotonic is a solution that has a lower concentration of solutes than the inside of
the cell.
● Isotonic is a solution with the same concentration of solutes as inside the cell.
Q8. A. What type of molecule is able to simply diffuse straight through a plasma membrane?
hydrophobic hydrophilic
B. What term describes the way the other type of molecule must diffuse through a membrane?
What type of protein is involved in this process?
Facilitated diffusion describes how hydrophilic molecules diffuse through the membrane.
Transport proteins (like channel or carrier proteins) are involved in this process.
Q9. What do endocytosis and exocytosis refer to? What is the difference between them?
● Endocytosis is the process where a cell takes in material by engulfing it with the
plasma membrane, forming a vesicle.
● Exocytosis is the process where a cell expels material by fusing a vesicle with the
plasma membrane and releasing its contents outside the cell.
● Difference: Endocytosis brings materials into the cell, while exocytosis expels
materials out of the cell
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, Biology 102 Chapter 4 - Cells: Intro and Membranes
Cells
Cell Theory
1. All living things are composed of one or more cells.
2. All cells come from pre-existing cells.
All cells have:
1. A plasma membrane - an outer layer that separates the contents of the cell from the outer
environment.
2. Cytoplasm - the liquid (cytosol) contained by the membrane and everything suspended in
it.
3. DNA - Hereditary material of all life
4. Ribosomes - protein makers
There are two different major types of cells:
● Prokaryotic:
○ Found in bacteria and archaea.
○ All single-celled
○ “Prokaryotes”
● Eukaryotic:
○ found in everything else:
■ Animals
■ Plants
■ Fungi
■ Protists
○ “Eukaryotes” can be single-celled or multicellular.
Prokaryotic cells are smaller and simpler than eukaryotic cells.
Eukaryotic cells have organelles - membrane-enclosed subunits of various functions.
● For example: a nucleus where DNA is held
Cell Membrane
All cell types
● The main components are phospholipids.
● Phospholipids have:
○ A hydrophobic "tail"
○ A hydrophilic "head"
Plasma Membrane
ALL cells have a plasma membrane composed of the phospholipid bilayer.
The plasma membrane acts as a barrier and a gatekeeper.
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