Biology Chapter 3
Which of these is found in amines? 1. R-NH2 2. R-OH 3. R-COOH 4. R-COH
1. R-NH2
Which is an organic molecule? 1. NaCl 2. Ne 3. H2O 4. CH4
4. CH4 Compounds containing carbon are said to be organic.
Lactase deficiency is more common in Asian, Native American, Mediterranean and some African populations than it is among people with northern or western European ancestry. How would you explain why this is so?
Although most mammals, including humans, are not able to digest the milk sugar, lactose, after infancy, the ancestors of northern and western Europeans relied on dairy products as an important part of their food supply. When other food sources were in low supply, mutations that allowed the expression of the enzyme lactase to persist past childhood conveyed an advantage to adults who were able to include dairy products in their diet.
What do phospholipids and cholesterol have in common?
Both are important components of cell membranes.
Which element is closely associated with the field of organic chemistry?
Carbon
What are the properties of carbon skeletons?
Carbon skeletons vary in LENGTH. Skeletons may be BRANCHED or UNBRANCHED Skeletons may have DOUBLE BONDS Skeletons may be arranged in RINGS
The oil and vinegar in your salad dressing remain separate from one another due to the _____ properties of the oil.
Hydrophiliac
Lactose is a disaccharide (two monosaccharides joined together). To metabolize lactose, individuals require an enzyme known as lactase. What is true about this reaction?
The reaction hydrolyzes the sugar.
What do nucleic acids and proteins have in common?
They are large polymers. ; Both can be very long, although many small proteins are biologically active.
The peptide bond is _____.
a covalent bond ; The covalent bond joining two amino acids is a peptide bond.
The formation of a peptide bond forms through _____.
a dehydration reaction between the amino group of one amino acid and the carboxyl group of a second amino acid
Hydroxyl is to _____ as _____ is to amine.
alcohol ... amino
In the process of converting cornstarch into high fructose corn syrup, one of the first products is _____. Then, enzymes are used to convert some of this product to fructose.
glucose
Dehydration reactions _____. They do so by _____.
link monomers to form a polymer ... removing a water molecule
A glucose molecule is to starch as _____.
nucleotide is to a nucleic acid. Because glucose molecules are the building blocks of starches just as nucleotides are the building blocks of nucleic acids
Anabolic steroids are prescribed to _____.
people who suffer from muscle-debilitating diseases
Cellulose is a _____ made of many _____.
polymer ... glucose molecules ; Cellulose is a polysaccharide, constructed from many monosaccharides.
A molecule with the formula C6 H12 O6 is
possibly glucose or fructose
Besides water, most of the mass of a typical cell is present in the form of one of these four categories of macromolecules: _____.
proteins, nucleic acids, carbohydrates, and lipids
Which of the following is a function of carbohydrates (as a class)?
structural support
When two monosaccharides link to form a disaccharide, the by-product is _____.
structural support Cellulose is an example of a structural polysaccharide.
The overall three-dimensional shape of a single polypeptide is called the _____.
tertiary structure = The tertiary structure is determined by hydrogen bonds, hydrophobic groups, and ionic bonds between R groups.
Lactose tolerance is an adaptation _____.
that was advantageous to individuals after the age of 2. Lactose tolerance became prevalent in people of Northern European descent because it offered a survival advantage. Milk became an essential food source for these individuals because the climate only offered one harvest a year and milk was available year-round.
The "primary structure" of a protein refers to _____.
the number and sequence of amino acids ; The primary structure of a protein is its unique sequence of amino acids.
A fatty acid containing at least two double bonds is called _____.
unsaturated ; An unsaturated fatty acid has one or more double bonds.
The ionized or dissociated carboxyl group may be written as _____.
-COO - When an oxygen atom is double-bonded to a carbon atom that is also bonded to a hydroxyl group, the entire assembly is called a carboxyl group (-COOH).
Which of the following molecules is a carbohydrate? 1. C60H100O50 2. C45H84O8P4 3. C22H49O10N5 4. C51H98O6
1. C60H100O50 Carbohydrates have molecular formulas that are multiples of CH2O.
Which of these is found in amino acids? 1. R-NH2 2. R-OH 3. R-COH 4. R-PO42
1. R-NH2
Linus Pauling made significant contributions to our understanding of enzyme structure and chemical bonding. However, his theory regarding DNA was wrong because he proposed that _____.
DNA consists of a triple helix structure
When calorie intake is low, proteins are the last resource the body uses for fuel. Why?
When the body uses proteins as fuel, it is breaking down substances vital to its structure and essential functions.
Which of the following components of a tossed salad will pass through the human digestive tract with the least digestion? 1. cellulose (in the lettuce) 2. oil (in the dressing) 3. starch (in the croutons) 4. sugar (in the dressing)
1. cellulose (in the lettuce) ; Cellulose contains bonds that cannot be broken by human digestive enzymes.
How does DNA differ from RNA?
1. different sugars (Deoxyribose vs. Ribose) 2. different nitrogenous bases (thymine vs. uracil) 3. RNA is single stranded, DNA is double
which is not a disaccharide? 1. fructose 2. maltose 3. sucrose 4. lactose
1. fructose
Which of the following would be affected when a protein is denatured? 1. tertiary structure 2. side chains 3. primary structure 4. amino groups
1. tertiary structure
Select the hydrocarbon from the following choices 1. H2CO3 2. C3H8 3. C6H12O6 4. CO2
2. C3H8
How many different kinds of amino acids are there in most proteins?
20
Which of the following would bind to a sweet receptor most tightly? 1. malted milk shake 2. milk 3. grapes 4. table sugar
3. grapes
Enzyme molecules require a specific shape to perform their catalytic function. Which of the following might alter the protein shape? 1. changing the concentration of the reactants 2. changing the concentration of the products 3. cooling the protein 4. changing the concentration of salt in the environment
4. changing the concentration of salt in the environment
To what does the term polypeptide specifically refer?
A polypeptide is a chain of amino acids that have been linked together by dehydration synthesis.
Some athletes use anabolic steroids to build their body mass. Why is this considered a problematic practice, especially in adolescents?
Anabolic steroids can prevent bone growth.
A shortage of phosphorus in the soil would make it especially difficult for a plant to manufacture _____.
DNA The backbone of a nucleic acid consists of alternating sugar and phosphate groups.
The term amino acid consists of what?
It consists of an amino group and a carboxyl group.
How does a protein's quaternary structure differ from other levels of protein structure?
It involves two or more polypeptide chains. ; All other levels of protein structure involve only a single polypeptide chain.
Two proteins have the same number and type of amino acids. How is it that they can have different shapes and therefore different functions?
It is the sequence and arrangement of the 20 amino acids that determines the shape of a protein and thereby the function. Different sequences can yield different proteins.
A polysaccharide called starch consists entirely of glucose molecules. During early stages of starch digestion, starch would be broken down into _____.
Maltose
Generally, animals cannot digest the linkages between the glucose molecules in cellulose. How then do cows get enough nutrients from eating grass?
Microorganisms in their digestive tracts hydrolyze the cellulose to glucose. ; Cows have digestive chambers of microorganisms that can produce the enzymes that cows lack, in order to digest the cellulose.
Nutritionally, saturated triglycerides are considered to be less healthy than unsaturated triglycerides. Consider the differences between the two molecules shown below. What is one major difference between them?
Saturated triglycerides are saturated with hydrogens. Unsaturated triglycerides have double bonds in their carbon chains. Each carbon is bonded to just one hydrogen and not two.
Describe bonds of the secondary structure of proteins?
Secondary structure involves hydrogen bonding between atoms of the polypeptide backbone.
The most common disaccharide is _____.
Sucrose, normal table sugar, is the most common disaccharide.
Tetrahydrogestrinone (THG) is an anabolic steroid. How does it differ from more traditional anabolic steroids that have been used in the past by athletes?
THG was structurally manipulated.
A nucleotide is made of which of the following chemical components?
a nitrogenous base, a phosphate group, and a sugar ; Each nucleotide consists of three parts: an organic molecule, called a nitrogenous base; a sugar; and a phosphate group.
In a hydrolysis reaction, _____. In this process, water is _____.The reaction causes reactants to be formed.
a polymer breaks up to form monomers ... consumed The meaning of "hydrolysis" is to break with water.
Carboxyl is to _____ as _____ is to base.
acid; amino. A carboxyl group has acidic properties because it can donate a proton (hydrogen ion) to a solution. The amino group acts as a base because it can pick up or accept a protein (H) from a solution
Manufacturers make vegetable oils solid or semisolid by _____.
adding hydrogens ; The phrase "hydrogenated vegetable oils" found on food labels means that unsaturated fats have been synthetically converted to saturated fats by the addition of hydrogen.
Although the structures of the functional groups important to life vary in chemical structure, they share one thing in common: They _____.
all are hydrophilic and increase the organic compound's water solubility
Ethanol, propanol, and methanol are three simple alcohols. They can be grouped together because they _____.
all share the same functional group, a hydroxyl
Protein molecules are polymers of _____.
amino acid molecules ; Polymers of amino acids are called polypeptides. A protein consists of one or more polypeptides folded into specific conformations.
Lipids differ from other large biological molecules in that they _____.
are not truly polymers ; Lipids are not all made of the same type of monomer. Their association as a group is related to their behavior rather than their structure.
Carbohydrates are mainly used in our bodies _____.
as fuel Simple sugar molecules are a major fuel for cellular work.
Citric acid makes lemons taste sour. Which functional group that would cause a molecule such as citric acid to be acidic?
carboxyl
Hydrogenated vegetable oils are more like animal fats than other plant oils. Because they _____ than other plant oils, they can contribute to cardiovascular disease.
contain fewer double bonds ; Evidence suggests that a diet high in saturated fats may contribute to human cardiovascular disease.
The reaction that joins two monomers to form a polymer is known as a _____ reaction. The molecule of water formed is due to the interaction between _____ and a hydrogen ion.
dehydration ... a hydroxyl group
What is the process by which cells link monomers together to form polymers?
dehydration reaction Monomers are linked together with the removal of a water molecule by dehydration reaction.
DNA nucleotides are composed of _____.
deoxyribose sugars, which are bonded to a phosphate group and a nitrogenous base
Carbon atoms are the most versatile molecular building blocks used by living organisms because _____.
each carbon atom can form up to four covalent bonds with a wide variety of bond angles
A polysaccharide that we use for storing energy in our muscles and livers is _____.
glycogen ; Animals store a polysaccharide called glycogen.
Which is the correct term for compounds that do not mix with water?
hydrophobic ; Hydrophobic compounds are those that are insoluble in water.
Cholesterol belongs to which class of molecules?
lipids ; Steroids, such as cholesterol, are lipids characterized by a carbon skeleton consisting of four fused rings.
The lipids that form the main structural component of cell membranes are _____.
phospholipids ; Phospholipids, by being partially water-soluble, are suitable for holding the cell membrane in place.
Collagen is found in connective tissue, which is a structural component of bones, tendons, and ligament. Collagen has great strength because of its _____ structure.
quaternary structure = The quaternary structure is the combination of more than one polypeptide chain in a protein. In the case of collagen, there are three polypeptide strands twisted together.
The alpha helix and pleated sheet represent which level of protein structure?
secondary structure;. Both the alpha helix and the pleated sheet are polypeptides held in a given structure by hydrogen bonds.
The complex carbohydrate that you are most likely to have eaten recently is _____.
starch ; Starch is a storage polysaccharide of plants.
In what polysaccharide form do plants store sugar to be available later for energy?
starch ; Starch is the glucose-storage polymer that plants use.
The ovalbumin in egg white can be classified as which type of protein?
storage ; Ovalbumin is considered to be a storage protein source for the developing embryo.
When an RNA strand forms using DNA as a template, _____.
uracil pairs with adenine and cytosine pairs with guanine
