BIOS 260 Chapter 2 with Verified Solutions
1. The nucleotides in DNA are held together in a double-stranded helix, list the specific pair of
bases that bond to form a DNA molecule. What is the
1. The nucleotides in DNA are held together in a double-stranded helix, list the specific pair of
bases that bond to form a DNA molecule. What is the importance of this specificity?
Correct Ans-DNA is two polynucleitide chains. Thymine bonds with Adenosine, Cytosine
bonds with Guanine.
These pairings are important because they make a hydrogen bond - which is weaker than a
covalent bond.
A hydrogen bond is important because it is weak enough to be reversibly broken - but strong
enough to stabilize the double helix structure.
2. What determines the shape of a protein? How many levels of structure do proteins have?
Correct Ans-The shape of a protein is determined by its primary structure (sequence of
amino acids). Proteins have four levels of structure: primary, secondary, tertiary, quaternary
3. Name three conditions which can denature a protein. What does this mean for the function
of the protein? Correct Ans-1. Too much heat
2. Too cold
3. Changing to a non-suitable pH
Denatured means the protein loses its function.
, BIOS 260 Chapter 2 with Verified Solutions
4. Can you explain how small insects such as water striders walk on water? Correct Ans-
Cohesion causes surface tension.
Cohesion is defined as "the sticking together of particles of the same substance."
5. What are the four subunits of proteins? And the bonds that join them? Correct Ans-
Subunits for Carbohydrates: Sugars
Subunits for Lipids: Fatty Acids
Subunits for DNA: Nucleic Acids
Subunits for Proteins: Amino Acids
The bonds that join them are: Peptide Bonds
1. What is the respective approximate ratio of carbon, hydrogen and oxygen atoms found in
all carbohydrates? Give an example for a carbohydrate. Correct Ans-1:2:1 Ratio
1 Carbon for every 2 Hydrogens for every for every 1 Oxygen
Why do unsaturated fats tend to be liquid while saturated fats tend to be solid? What unique
property does each possess? Correct Ans-Unsaturated fats have one or more double bonds
inside their fatty acid chains. The 2 Carbons each have triple or double bonds and hydrogens
, BIOS 260 Chapter 2 with Verified Solutions
cannot saturate them. This makes the entire molecular structure weaker so its stays liquid at
room temp.
Saturated fats do not have double bonds in their fatty acid chains so they are solid at room
temp.
What is the pH scale? What does it mean if there are lots of H+ ions in a solution? What does
it mean if there are lots of OH- ions in a solution? What is the function of a buffer? Correct
Ans-A measure of how acidic/basic something is. If there are a lot of H+ ions in a solution, the
solution is an acid. If there are a lot of OH- ions in a solution, it is a base. The function of a
buffer is to minimize the change in pH when a base or acid is added to the solution.
4. What is adenosine triphosphate (ATP)? Describe the function of this molecule. Correct
Ans-An ATP molecule is composed of Carbon, Hydrogen, Nitrogen, Oxygen and Phosphorus
atoms. There are three phosphorus atoms in the molecule. ATP provides energy - through the
break down of food.
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