Download HW Questions on Lipids and Proteins

Biochemistry Review Questions ANSWERS
1. What are the four major groups of organic macromolecules found in living things?
Carbohydrates, Lipids, Proteins, Nucleic Acids
2. What SIX atoms make up the majority of organic macromolecules? CHNOPS
BonusQ1: What does the term Organic mean? Contains carbon
BonusQ2: What does the term Inorganic mean? Does not contain carbon
BonusQ3: What is a Hydrocarbon made of? H & C
3. What three atoms make up carbohydrates? C, H, O
4. The simplest carbohydrate is called a _monosaccharide__.
5. What functional group(s) is/are found in fatty acids carbohydrates? hydroxyl
groups
6. Why are carbohydrates important to living things? What function(s) do they serve?
For energy storage in plants & animals, also for plant structure (fiber in stems,
leaves & roots).
7. What are the monomers (the building blocks) of a carbohydrate molecule called?
monosaccharides
8. How many of each of the monomers mentioned above do you need to make a
disaccharide?
Two
A polysaccharide? 3 or more
9. Name and describe the process by which monosaccharides are chemically combined
to form disaccharides and polysaccharides: Dehydration synthesis – for each new
covalent bond linking monosaccharides an H and OH are removed, forming a
water molecule.
10. Why is hydrolysis an appropriate name for the reaction that breaks apart di- and
polysaccharides into monosaccharides?
Hydro => water. Lysis => splitting. Hydrolysis splits polymers into monomers,
using water in the process.
11. Where & when in your body might this reaction (mentioned above) take place?
• Digestion of food in the mouth, stomach & small intestine (in digestive syst.)
• During Cell Respiration in the breakdown of glucose to release energy
12. How are the concept of monomer and polymer related to monosaccharides and
polysaccharides?
Monosaccharides are the monomers that make up polysaccharide polymers.
13. Give three specific examples of each of the following. Also list where in nature they
can be found. The first one is done for you.
EXAMPLE
WHERE FOUND
Monosaccharide #1: Glucose
Blood Sugar, Plant Sap
Monosaccharide #2: Fructose
Fruits
Disaccharide #1:
Sucrose
sugar cane & beets
Disaccharide #2:
Lactose
milk
Polysaccharide #1: starch
plants (for energy storage)
Polysaccharide #2: cellulose
plants (for plant struct./cell walls)
Polysaccharide #3: glycogen
animals (for energy storage)
BonusQ4: What are the functions of your three polysaccharides? See above info in
parentheses
14. Which atoms make up lipids? Mostly C & H, and some O (sometimes P)
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15. What functional group(s) is/are found in fatty acids?
Carboxyl group
-C=O
|
OH
16 & 17. What are the two main chemical components (monomers) of a fat molecule
called? How many of each of the components mentioned above do you need to make
one fat molecule? 1 Glycerol & 3 fatty acids
18. What is the process called by which you form a triglyceride (fat molecule)?
Dehydration synthesis
19. What other molecule(s) is/are formed when you make a triglyceride (fat molecule)?
(How many?)
3 water molecules
20. Using your notes if needed, draw the reaction showing the formation of a
triglyceride. LABEL all the molecules in the reaction.
See textbook, figure 3.8.
21. What are three different roles or uses for lipids in living things?
- energy storage, padding of bones, heat insulation, form biological membranes,
signal transmission/chemical messengers (hormones)
22. What is a saturated fatty acid saturated with? What is the difference between a
saturated and an polyunsaturated fatty acid in terms of chemical structure?
Saturated f.a. has all the hydrogens it can hold in its Hydrocarbon chain (& thus
no double bonds in the HC chain).
23. Give one food that is mostly saturated fat: Red meat, Bacon, Butter, Whole milk
or yogurt, cheese
24. Give one food that is mostly polyunsaturated fat: Peanut butter, olive oil, plant
oils in general, nuts & seeds
25. Saturated lipids are found mostly in ___ANIMALS__ while unsaturated lipids are
found mostly in ___PLANTS___.
26. At room temperature, ___POLYUNSATURATED__ lipids are liquids. (WHY?)
Double-bonds cause bends/kinks in hydrocarbon chains which cause molecules
to be spaced farther apart from each other, hence being in liquid form.
27. What are trans fats? What are some sources of them in food? What is their health
impact on humans?
Trans fats are partially hydrogenated fats that are created in an industrial
process that adds hydrogens to polyunsaturated oils. They are found in foods
with “partially hydrogenated oils”, particularly in fried foods and baked goods.
Trans fats are linked to high LDL (bad) cholesterol, higher risk of heart disease,
stroke, and type 2 diabetes.
28. Which atoms are found in proteins? __CHON (S)_____
29. Protein molecules are polymers. What is the basic component (or monomer) of a
protein molecule? Amino Acid
30. What two functional groups does an amino acid have? Name and draw them.
Amino (-NH2) and Carboxyl (-COOH)
31. How do amino acids differ from each other? They have different R groups
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32. How many of each of the monomers mentioned above do you need to make a
tripeptide? Three
33. What is the process called by which you make a polypeptide? Dehydration synthesis
34. What other molecules are produced when you make a polypeptide? water
35. What is the bond that links amino acids to each other called? Peptide bond
36. What chemical element do you find in proteins that you do not find in carbohydrates
or in fats? Nitrogen
37. What two functional groups can you find on every amino acid? Draw and label them.
Same question as #30
38. What sorts of foods are high in protein and high in fat? Red Meat, Peanut Butter,
Nuts
39. What sorts of foods are high in protein and low in fat? White chicken meat, most
fish, beans, soybeans/tofu
40. Classify each of the following molecules are hydrophilic, hydrophobic, or
amphipathic and explain why you classified them this way:

Fatty acid: Amphipathic – carboxyl group is polar, long hydrocarbon chain is
nonpolar

Glucose: Hydrophilic – many polar hydroxyl groups surrounding entire ring
structure make this very soluable in water.

Triglyceride: Hydrophobic – there are a few polar bonds (C-O) but they are
surrounded by nonpolar bonds. Additionally, the nonpolar HC chains make
up the majority of this molecule.

Glycine (an amino acid with an R group = “H”): Mostly hydrophilic – due to
the polar amino and carboxyl groups that make the the bulk of its structure,
this molecule will be highly soluble in water.

Phenylalanine (an amino acid with an R group = large nonpolar ring):
Amphipathic – the main body of the amino acid is hydrophilic due to the
polar amino and carboxyl groups, however the large nonpolar R group
makes the molecule dual in its nature overall (& thus amphipathic).
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Be A Chemistry Detective!
In each of the following exercises, you are given two clues about an organic compound.
Using the knowledge you have gained in this unit and your deductive abilities, determine
the identity of the compound.
41. • A polysaccharide
• Animals store their excess sugar in this form
glycogen
42. • Speed up chemical reactions by binding to the reactants
• Usually are protein molecules
enzymes
43. • A polysaccharide
• Gives strength and rigidity to plants
cellulose (fiber)
44. • All have a similar chemical structure but differ in a region known as the R group
• Can be joined by peptide bonds to form proteins
amino acids
45. • A polysaccharide
• Plants store excess sugar in this form
starch
46. • Contain carbon, hydrogen, and oxygen atoms in an approximate ratio of 1:2:1
• Has the formula C6H12O6
____monosaccharides (glucose, fructose)
47. • Long chains of hydrogen and carbon atoms have a carboxyl group at one end
• Combine with glycerol to form lipids
fatty acids
48. • A disaccharide
• Other examples are maltose and lactose
sucrose
Food Testing – Matching
+ = abundant in sample
Food
Sample
W
X
Y
Z
- = not abundant in sample
Monosaccharide
Polysaccharide
Lipid
Protein
+
+
-
+
-
+
+
-
13. Sample W __D___
14. Sample X __B___
15. Sample Y __A___
16. Sample Z __C___
A. peanut butter
B. salmon filet
C. orange juice
D. potato
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