Biology Chapter 5 Flashcards

Questions and Answers

Which polymers are composed of amino acids?

Proteins

Which of the following is not attached to the central carbon atom in an amino acid?

An oxygen (correct)

A hydrogen

An amino group

A carboxyl group

Which part of an amino acid is always acidic?

Carboxyl functional group

Which monomers make up RNA?

Nucleotides Signup and view all the answers

Which of the following statements about the formation of polypeptides from amino acids is true?

A bond forms between the carboxyl functional group of one amino acid and the amino functional group of the other amino acid. Signup and view all the answers

Enzymes in the digestive tract catalyze hydrolysis reactions.

True Signup and view all the answers

A dehydration reaction (or condensation reaction) is the process in which _____.

water molecules are produced as a polymer is formed from monomers Signup and view all the answers

The four main categories of large biological molecules present in living systems are _____

proteins, nucleic acids, carbohydrates, and lipids Signup and view all the answers

How many molecules of water are released during the polymerization of a 20 monomer-long cellulose molecule?

19 Signup and view all the answers

Plant cell walls consist mainly of _____

cellulose Signup and view all the answers

A molecule with the chemical formula C6H12O6 is probably a _____

monosaccharide Signup and view all the answers

The molecule shown is ________.

a hexose Signup and view all the answers

Which of these is NOT a lipid?

RNA Signup and view all the answers

This figure is an example of a(n) _____

saturated fat Signup and view all the answers

Which of these is a phospholipid?

Phospholipids are composed of a phosphate group, a glycerol, and fatty acids. Signup and view all the answers

Which of these is rich in unsaturated fats?

olive oil Signup and view all the answers

A function of cholesterol that does not harm health is its role _____

as a component of animal cell membranes Signup and view all the answers

How many fatty acids are in a phospholipid?

2 Signup and view all the answers

What functional feature(s) does the phosphate group contribute to the structure of a phospholipid?

negative charge to interact with water; place to attach another small charged molecule Signup and view all the answers

What holds phospholipids together in a bilayer formation?

hydrophilic and hydrophobic interactions with water Signup and view all the answers

Which molecule is less soluble in water--a fat or a phospholipid? Why?

A fat molecule is less soluble in water because it has three non-polar fatty acids and no polar or charged head like a phospholipid has. Signup and view all the answers

The characteristic that all lipids have in common is that _____.

none of them dissolves in water Signup and view all the answers

What makes lipids/fats hydrophobic?

presence of relatively nonpolar CH bonds Signup and view all the answers

The molecule illustrated in the figure ________.

will be liquid at room temperature Signup and view all the answers

Proteins are polymers of _____

amino acids Signup and view all the answers

What type of bond joins the monomers in a protein's primary structure?

peptide Signup and view all the answers

Which of these illustrates the secondary structure of a protein?

Signup and view all the answers

The secondary structure of a protein results from _____

hydrogen bonds Signup and view all the answers

Tertiary structure is NOT directly dependent on _____

peptide bonds Signup and view all the answers

Some regions of a polypeptide may coil or fold back on themselves. This is called _, and the coils or folds are held in place by _.

secondary structure...hydrogen bonds Signup and view all the answers

A hydrophobic amino acid R group (side group) would be found where in a protein?

on the inside of the folded chain, away from water Signup and view all the answers

A glycosidic linkage is analogous to which of the following in proteins?

a peptide bond Signup and view all the answers

You disrupt all hydrogen bonds in a protein. What level of structure will be preserved?

primary structure Signup and view all the answers

The chemical reaction illustrated ________.

results in a peptide bond Signup and view all the answers

Your body contains tens of thousands of different proteins, each with a specific structure and function. The unique three-dimensional shape of each of these diverse proteins is based on several superimposed levels of structure. Which of the following statements is an accurate description of proteins?

The primary structure of a protein is the order of amino acids in a polypeptide, as coded for in the DNA of a gene. Signup and view all the answers

Identify the level(s) of protein structure present in this molecule.

Tertiary Signup and view all the answers

What could happen if a mutation in a gene caused a hydrophobic amino acid in a polypeptide to be replaced by a hydrophilic amino acid?

The new amino acid would not form the same interactions with hydrophobic R groups, and the protein's shape would likely be affected. Signup and view all the answers

If a strand of DNA has the nitrogen base sequence 5'-ATTTGC-3', what will be the sequence of the matching strand?

3'-TAAACG-5 Signup and view all the answers

If a DNA double helix is 100 nucleotide pairs long and contains 25 adenine bases, how many guanine bases does it contain?

75 Signup and view all the answers

The two strands of a DNA double helix are held together by _____ that form between pairs of nitrogenous bases.

hydrogen bonds Signup and view all the answers

A nucleotide is composed of a(n) _____

phosphate group, a nitrogen-containing base, and a five-carbon sugar Signup and view all the answers

When nucleotides polymerize to form a nucleic acid _____

a covalent bond forms between the sugar of one nucleotide and the phosphate of a second Signup and view all the answers

Which of the following is a major difference between RNA and DNA?

Type of sugar Signup and view all the answers

Identify three possible components of a DNA nucleotide.

deoxyribose, phosphate group, thymine Signup and view all the answers

These figures show the four levels of protein structure: primary, secondary, tertiary, and quaternary structure. Which level of protein structure is characteristic of some, but not all, proteins?

Quaternary level of protein structure Signup and view all the answers

Study Notes

Proteins and Amino Acids

Proteins are polymers made of amino acids.
In amino acids, an oxygen atom is not attached to the central carbon atom.
The carboxyl functional group is always acidic in an amino acid.
Polypeptides form when the carboxyl group of one amino acid bonds with the amino group of another.

Nucleic Acids

RNA is composed of nucleotides.
DNA has a complementary strand based on base pairing rules, e.g., 5'-ATTTGC-3' matches 3'-TAAACG-5'.
DNA is made of nucleotides consisting of a phosphate group, nitrogenous base, and five-carbon sugar.

Biological Molecules

Large biological molecules include proteins, nucleic acids, carbohydrates, and lipids.
Cell walls of plants are primarily made of cellulose.

Lipids

Lipids are defined by their inability to dissolve in water.
Fats contain three non-polar fatty acids, making them less soluble than phospholipids, which have a polar head.
Phospholipids comprise a phosphate group, glycerol, and fatty acids, contributing to membrane structure.

Chemical Reactions in Biomolecules

Hydrolysis reactions in the digestive tract are catalyzed by enzymes.
A dehydration (condensation) reaction produces water when forming polymers from monomers.
Glycosidic linkages in carbohydrates are analogous to peptide bonds in proteins.

Protein Structure

Proteins exhibit four levels of structure: primary, secondary, tertiary, and quaternary.
The primary structure is the linear sequence of amino acids coded in DNA.
Secondary structure results from hydrogen bonding; coils and folds are held by these bonds.
The tertiary structure is influenced by various interactions, including hydrophobic interactions of amino acid R groups.
Quaternary structure involves multiple polypeptide chains interacting, seen in some but not all proteins.

Characteristics of Amino Acids

A hydrophobic R group in an amino acid is typically found on the inside of a folded protein, away from water.
Mutations affecting R groups can alter protein structure and function due to changes in interactions.

Nucleotide Composition

A DNA nucleotide can consist of deoxyribose, a phosphate group, and a nitrogenous base like thymine.
RNA nucleotides differ from DNA due to their sugar type.

Structural Stability

Proteins retain primary structure even when hydrogen bonds are disrupted.
Hydrogen bonds between nitrogenous bases connect the two strands of DNA, stabilizing the double helix.

Fatty Acids and Cholesterol

Saturated fats have no double bonds in their fatty acid tails, while unsaturated fats contain double bonds.
Cholesterol is crucial as a component of animal cell membranes, contributing to membrane stability.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on essential concepts from Chapter 5 of MasteringBiology. This quiz covers topics such as amino acids, proteins, and RNA structure. Perfect for students looking to reinforce their understanding of biological macromolecules.