Exam 1 - Professor Review Microbiology 2421 (Chp. 1-4)

Which of the following is a particle found in the nucleus of an atom and that has no electrical charge?

Which of the following is a particle found in the nucleus of an atom and that has no electrical charge?

Neutron

Matter composed of a single type of atom is known as a(n)

Element

A stable atom has ________ in its valence shell

8 electrons

Which parts of the atoms interact in a chemical reaction?

Electrons

The outer ring in Figure 2-1 represents

An electron shell

The valence of an atom represents its

Ability to interact with other atoms

The type(s) of bonds produced when atoms share electrons equally is/are

A nonpolar covalent bond

The type(s) of bond produced when atoms with somewhat different electronegativities share electrons is/are

Polar covalent

A research microbiologist wants to determine whether a microbe can metabolize a new synthetic organic molecule composed of carbon, hydrogen and oxygen. Which of the following would be useful in tracing the fate of the compound?

14C isotope

Unstable isotopes can be useful

In medical diagnosis

Which of the following is a correct paring of metabolic term?

• dehydration: decomposition

• catabolism: endothermic

• hydrolysis: decomposition

• synthesis: catabolism

• synthesis: exothermic

Hydrolysis: decomposition

Compounds that readily dissociate in water are

Either polar or ionic

Which of the following is a property of water?

It has high capacity for heat

An acid dissociates in water to release

Both anions and hydrogen ions

The reverse of a dehydration synthesis reaction is a(n) ________ reaction

Hydrolysis

A hydroxyl ______ acts as a base

Anion

The chemical formula of a solid indicates it contains two groups with different electronegativities. This substance is most likely

A salt

You are performing an experiment in your chemistry lab class. The directions advise caution because the reaction is exothermic. Which of the following is the hazard the directions warn about?

The reaction may cause the container to become dangerously hot

The reaction described below is consistent with

An exchange reaction

Nucleic acid polymers, proteins, and complex carbohydrates are all produced by

Dehydration synthesis

Which of the following is an example of a polysaccharide?

• Glycogen

• Glucose

• Fructose

• Deoxyribose

• Sucrose

Glycogen

Research suggests taking antacids may make people more susceptible to infection withVibrio vulnificus by making the stomach environment more tolerable to the bacteria. Based onthis information and the name "antacid," which of the following are antacids likely to be?

Either base or buffer

All of the following are components of an amino acid except a(n)

• Carboxyl group

• Pentose group

• Amino group

• α-carbon

• R group.

Pentose group

Which of the following is found in nucleic acids?

Purines

Hydrogen bonds are found in all of the following except

• Between phosphate in ATP

• In the structure of complex polysaccharides

• Between water molecules

• In the DNA double helix between nucleotides

• Between the R groups of amino acids in proteins

Between phosphates in ATP

Tertiary and quaternary structure of proteins involves ________ bonds

Hydrogen, ionic, polar, and nonpolar covalent

Which of the following are examples of pyrimidines?

Cytosine and thymine

A macromolecule containing two fatty acids and a phosphate group is a

Phospholipids

The “backbone” of the DNA molecule is composed of

Alternating phosphate and pentoses

Which of the following would not normally be found as a component of a cell’s nucleic acids?

Uriacil deoxyribonucleotides

All of the following are associated with ATP molecules except

A long-term energy supply

Which of the following is true of both DNA and RNA

The purines and pyrimidines form hydrogen-bonded pairs

Which of the following is an incorrect pairing

• Primary structure; amino acid sequence

• Secondary structure; disulfide bridges

• Tertiary structure; covalent bonds

• Quaternary structure; two or more polypeptides

• Secondary structure; β-pleated sheets

Secondary; disfulfide bridges

Proteins contain both acidic and basic R groups, and can therefore function as

Buffers

Which of the following is characteristic of protein?

They have multiple layers of structural organization

Plant cell walls are composed of _______ held together by ________

Polysaccharides; hydrogen bonds

A(n) _______ is an arrangement of atoms found in a variety of macromolecules

Functional group

Decomposition reactions are commonly ______ reactions

Exothermic

Lipids found in the membrane of most eukaryotic cells are

Phospholipids

Which of the following lipids has the lowest ration of hydrogens to carbons?

Polyunsaturated fats

DNA is composed of repeating units of sugars, phosphate, and nucleic acids. This is an example of a

Polymer

Bactetial cell walls are composed of

Peptides and polysaccharides

Anna is conducting an experiment using a pH indicator that is red at low pH, green at neutral pH, and purple at high pH. She starts with a green solution. When she adds compound X to her solution it turns purple. Then she adds compound Z to the solution and it turns green. She adds more Z and the solution remains green. These observations suggest X is ________ and Z is________

A base; a buffer

A reaction requires water as a reactant and produces heat. What type of reaction is likely tobe involved?

A decomposition reaction

What functional groups are present in all amino acids?

Amino and carboxyl groups

Amylose is a(n) _______ carbohydrate

Polymer

The smallest chemical units of matter are elements.

False

The side groups of amino acids can interact with each other and with other molecules

True

A molecule composed of carbon and hydrogen is a compound

True

The electron shells of atoms hold eight electrons each

False

Carbon atoms have four valence electrons and typically form polar covalent bonds

False

An organic molecule with the chemical formula C4H5O1N3 is probably a pyrimidine

True

Denaturation of a protein is always permanent

False

Glycolipids are an example of a mixture

False

One of the products of dehydration synthesis reactions is water

True

Salts are produced from exchange reactions in which acids and base neutralize each other

True

Radioactive iodine is sometimes used to treat thyroid cancer. This is an example of the use of (isotopes/elements/radiation) in medical treatment

Isotopes

The phosphorylation of a protein by ATP is a(n) (exchange/transfer/group) reaction

Transfer

Neon generally does not react with other atoms because it has (2/3/6/8) electrons in its outer shell

8

An atom or molecule becomes a(n) (anion/ion/cation) when it loses an electron to a more electronegative molecule

Cation

A chemical reaction in which a water molecule is a reactant is known as a (dehydration/hydrolysis) reaction

Hydrolysis

A(n) (base/acid) is a molecule that binds with hydrogen ions when it is dissolved in water

Base

The folding of a polypeptide into a three-dimensional shape is its (secondary/tertiary/quaternary) structure

Tertiary

The “double helix” of DNA is the result of (covalent/ionic/hydrogen) bonds

Hydrogen

Figure 2-2 depicts the (primary/secondary/tertiary) structure of a protein

Primary

A(n) (catalyst/enzyme/protein) is any molecule that speeds up a chemical reaction

Catalyst

A fatty acid with two double bonds is a (saturated/monounsaturated/polyunsaturated) fat

Monounsaturated

A chemical reaction that traps energy within newly formed chemical bonds is an (exothermic/endothermic) reaction

Endothermic

A(n) (indicator/base/buffer) is a substance that maintains the pH even when the amounts of acid and/or base are changing

Buffer

The functional group of a monosaccharide is a(n) (amino/carboxyl/hydroxyl/carbonyl)

Hydroxyl

The (atoms/isotopes/stereoisomers) of an element vary in the number of neutrons in the nucleus

Isotopes

Compare and contrast synthesis reactions with decomposition reactions

Difference: Synthesis = A + B → AB | Decomposition = AB → A + B

Similarities: Both involve energy [S - give off energy (exothermic) | D - requires energy (endothermic)

Discuss the importance of hydrogen bonds in the chemistry of the cell

Sustain properties of water, aid in bonding molecules, structure of DNA and properties

Max is exploring the properties of various compounds. Some of his explorations involve the use of a pH indicator that is red at low pH, yellow-green at neutral pH, and blue to purple at high pH. He sets up several tubes containing water and the pH indicator and then begins to add some of the compounds he is characterizing in various combinations. His results are shown on the Figure 2.3.

What can Max conclude about his compounds based on these results? Describe the likely events in therms of hydrogen and hydroxyl ions.

L = acid M = base N = buffer

1xL and 5xM = equal concentration (green)

Red = [H+] > [OH-] Blue = [H=] < [OH-]

A student is given a compound to identify in an organic chemistry class. The first thing she notices is that it is not soluble in pure water or saline. Analysis of the ratios of atoms indicates the ratio of carbon to hydrogen to oxygen is 1:1.5:0.05. There is no nitrogen. Based on this information, what class of biological macromolecule is the student working with? Justify your answer.

Sterol (no nitrogen = no amino acids or nucleic acid)

Oxygen is less than 1, so it’s a lipid (hydroxyl group)

Low ratio between C:H = carbon bonded with other carbons

Nitrogen is an essential element for living things, as demonstrated by the fact that nearly all fertilizers contain nitrogenous compounds. Discuss why nitrogen is essential

Amino group of amino acid is key reactant in forming peptide bonds of protein. Participates in H bonding → contributes secondary, tertiary, and quaternary structure. Component of bases in nucleic acids, and participates in forming base pairs (double helix of DNA)

A useful unit for measuring the size of most cells is .

Micrometers .

Which of the following is an incorrect pairing?

• Magnification; refraction of radiation

• Contrast; staining techniques

• Numerical aperture; curved glass

• Dark field:high contrast

• Electron beams; shorter wavelength

Numerical aperture; curved glass

The ability of a lens to gather light is referred to as its

Numerical aperture

Which of the following are magnifying leses?

Both objectives and the oculars

The light source in a _____ microscope is ultraviolet (UV) light

Fluorescent

Why does immersion oil improve resolution?

It increases numerical aperture and maintains a uniform light speed

You are shown a micrograph from a light microscope in which the specimens appear bright compared to the background. The micrograph is probably from a(n) ________ microscope

Dark-field

Unstained cells that lack pigment are best observed on the ______ microscope

Phase-contrast

High resolution images of the internal structures of microbial cells are obtained using ________ microscopes

Transmission electron

Lasers are used to generate the images produced by ________ microscopes

Atomic force

Which of the following microscopes produce the highest resolution images?

Atomic force

If a microbiology lab student left the safranin out of the Gram stain procedure, what would be the result?

Gram-positive cells would be purple and Gram-negative cells would be colorless

All of the following are common to both the Gram stain and the acid-fast stain except

• Primary stain.

• Counterstain.

• A decolorizing agent

• A chemical mordant.

• A decolorizing agent and a counterstain.

A chemical mordant

Safranin dye is used as the counterstain in ______ stain(s)

Both the Gram and the endospore

Heat is used to drive the stain into cells in the ____ staining

Both acid-fast and endospore stains

The acid-fast stain is used to stain

bacteria with waxy cell walls

A sample is prepared using osmium tetroxide as a stain. This sample has been prepared for a(n) ___ microscope

Electron

The kingdoms included in the Linneaus system of classification are

Animalia and Plantae

The rules of naming organism are called

Nomenclature

Species and strains of microbes can be distinguished from one another phenotypically using

Serological tests

Which of the following is the correct order, from largest to smallest, of the modern taxonomic hierarchy?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species

Carl Woese proposed the concept of the domain based on differences of which of the following cellular molecules?

Ribosomal RNA

Carl Woese proposed the concept of the domain based on differences of which of the following cellular molecules?

Physical (phenotypic) characterisitcs

A new single-celled organism is discovered living in an ant colony. Which of the following classification methods would be appropriate for identifying to which domain it belongs?

Analysis of nucleic acids