Microbiology Exam 1 Module 2

Question Set 2

What is the term for anything that has mass and takes up space?

Matter

Electron

Outside the cell

Negatively charged (—)

Involved in chemical bonding

Neutron

No charge

Inside the nucleus

Proton

Inside the nucleus

Positively charged (+)

What are elements?

Any substance that cannot be reduced to any simpler set of constituent substances through chemical means.

What defines an element?

Defined by the # of protons in its nucleus 

Isotopes

atoms with the same element that contain equal # of protons but different # of neutrons

Ions

Elements that differ in their # of electrons

Covalent bonds

Atoms share one or more electron

Ionic bonds

Atoms lose and accept electrons from each other

Hydrogen Bond

a covalently linked hydrogen atom can react with an electronegative atom ( like oxygen )

Fluorine has 9 protons, 9 neutrons, and 9 electrons. What is fluorine’s atomic number? What is fluorine’s mass number?

Atomic number 9

Mass number = 9+9 =18 

What is it about carbon-12, carbon-13, and carbon-14 that makes them all carbon? What is different between carbon-14 and carbon-12?

Carbon-14 and carbon-12 are isotopes of carbon. Carbon-14 has 6p and 8n. Carbon-12 has 6p and 6n

How many electrons are in the first electron shell? How many electrons are in second electron shell? How many in the third? When is an atom stable?

1st shell: 2 electrons 

2nd shell: 8 electrons 

3rd shell: 8 electrons 

The atom is stable when it has a full shell

What are ions? How do you know if an atom is an ion (i.e. what is different in the atom)?

A ion is a charged atom/ molecule.

An ion is an atom with a net positive/ negative charge.

An atom contains the same # of electrons as protons and no net charge.  

Compound

A substance made up of atoms of two or more different elements joined by chemical bonds (NaCl, H2O)

Molecule

two or more atoms held together by covalent bonds (H2O, NaCl is not a molecule)

Is a NH3 molecule polar or non-polar? How do you know? How about a CH4 molecule?

N and H have different e- —> N is more electronegative—> share e- unequally —> polar 

—Both C and H are half full —> similar electronegativities —> share e- equally —> non-polar 

Why does sodium and chloride form a bond?

A sodium atom donates an electron to chlorine atom to form a sodium ion and chlorine ion. This is ionic bonding. The positive and negative ions attract each other.

What atoms do organic molecules always contain? What atom do inorganic molecules usually lack?

carbon and hydrogen. inorganic molecules lack carbon

Why is water polar? In hydrogen bonding, what will the hydrogen of one water molecule bond with?

Water is polar because hydrogen and oxygen have different electronegatives —> when they share electron —> they don't share equally→ oxygen get a S- and hydrogen gets a S+ 

Bind with an O on a different H2O molecule 

What property of water allows water to be transported up a plant from the roots to the leaves?

Cohesion allows water to be transported up a plant

Water has a great capacity to absorb and retain heat. Because of this, we say that water has a high

Specific heat

What property of water allows life to live in water even when the water freezes in colder climate?

Ice is less dense than water and therefore stays at the top

Solution

a homogenous substance made of 2 or more substances

What is solute?

the substance that is dissolved (Salt)

What is a solvent

the dissolving agent

What makes a compound hydrophobic or hydrophilic

The extent to which it can hydrogen bond
-If polar or ionic, there are changes that allow it to interact with water = hydrophilic
-no changes = hydrophobic

Hydrophilic

loves water; substance that can hydrogen bond with water; Polar and ionic 

Hydrophobic

substances that cannot hydrogen bond with water; non-polar, non-ionic; oil

Acid

substances that releases H in solution and increase H concentration (Lemon Juice)

Base

substances that release OH in solution and decrease H concentration (Bleach)

If acid is added to water, will the pH of the solution increase or decrease? Why?

Hydrogen will go up and pH will go down. The water will become more acidic. If acid is added, pH goes up because it releases hydrogen ions in the solution

If a base is added to water, will the pH of the solution increase or decrease? Also, what happens to the hydroxide ion concentration as a result of a base being added?

OH is added, pH will go up since H is reduced. 

Alkaline decreases the H concentration

The base removes hydrogen ion and the pH would go up

What is a buffer?

a solution that resists changes in pH when acid or alkaline is added.

How does a buffer work?

It neutralizes small amounts of added acid or base. 

Hydrogen is in excess, the solution is acidic, the buffer neutralizes it.

Why is carbon central to life (i.e. what is it about its structure that makes it important)?

Carbon has a great bonding capacity due to it structure.

Carbon can form 4 stable covalent bonds

Outer shell has only 4 electrons, it is able to form stable covalent bonds with a wide variety of atoms.

What are functional groups and why are they important?

Functional groups are atoms added to a molecule that give it a unique property

A group of atoms that confer a special property on a carbon-based molecule. 

It affects a biological molecule's function in a characteristic way.

What are the four classes of macromolecules

Proteins: C, H, O, N, Sulphur

Carbohydrates: C, H, O

Nucleic Acids: C, H, O, N, Phosphorus

Lipids: C, H, O ( may have P, S, etc) 

Dehydration Synthesis

Anabolic reaction where a water molecule is take out from between 2 monomers to bind them together

Hydrolysis

When 2 polymers are broken down, water is added

What are the four complex carbohydrates that are important for life?

starch, glycogen, cellulose, chitin

Macromolecules

Carbohydrates, protein, nucleic acids

Monomer

monosaccharide, amino acids, nucleotide

Polymer

polysaccharide, protein/ polypeptide, nucleic acid, polynucleotide

Starch

the nutrient storage form of carbohydrates in plants (seeds)

Cellulose

rigid structural carbohydrate found in the cell wall of many organisms; plants and algae cell walls

Chitin

tough structural polysaccharide that forms the external skeleton of arthropods; found in fungi cell walls

Glycogen

the nutrient storage polysaccharides form of carbohydrates in animals. muscles, and live cells

Triglyceride

1 glycerol and 3 fatty acid chains

Is the fatty acid polar or nonpolar?

Non polar b/c primarily hydrocarbons, carbon, and hydrogen similar electronegativity therefore share electrons equally

1 glycerol and 3 fatty acid molecules

Non-polar; large chains of carbon bonded to hydrogen. C-H bonds are non-polar.

What is the difference between saturated and unsaturated fats? Which is more likely to be solid at room temperature? Why?

Saturated fats: all carbon-carbon bonds are single bonds. Molecule is saturated with hydrogens; solid at room temperature.

Unsaturated fats: not saturated with hydrogen bonds; liquid at room temperature. Has at least 1 carbon double bond link

What class of macromolecules do steroids belong to?

Lipids

What class of macromolecules do phospholipids belong to?

Lipids

Describe how phospholipids orient themselves to form cell membranes (i.e. what part of the phospholipid interacts with the inside of the cell, etc.).

-hydrophilic heads will face the outside of the cell and inside cell where water is found
-hydrophobic tails are shielded from water in the middle

Phospholipids are amphipathic: one end is polar the and can interact with water, the other end is non-polar and can interact with other fats. Phosphate head and fatty acid tails.

Cell membranes are made of phospholipid bilayer that allows for a semipermeable membrane.

What is different between one amino acid and another? In other words, which part of the amino acid is variable?

There are 20 different amino acids.

Each amino acids differs in the R group. 

Each R group has a specific shape and chemical property.

3 Basic flavors of r group: polar, non-polar, charged

Primary

determined by the amino acid sequence. 

Secondary

Coiling and pleating of chain held by hydrogen bonds.

Tertiary

irregular folding due to bonding between different R groups of AA's in the polypeptide chain. 

Quaterine

Interactions between 2 or more polypeptide chains.

Why is a fever so bad for our body?

proteins in our body denature above 104 degrees F

Which monomer is composed of a sugar, phosphate group, and a nitrogenous base?

5 carbon sugar, phosphate group, nitrogenous base

DNA

deoxyribose sugar, phosphate group, CTAG, 2 strands, hydrogen bond linkage between nucleotides.

RNA

ribose sugar, phosphate group. CAUG, 2 strands, hydrogen bond linkage between nucleotides.

Prokaryotic cells

NO nucleus, circular DNA, NO histones, NO membrane bound organelles, smaller, asexual reproduction, circular chromosomes, 70s ribosomes

Eukaryotic cells

nucleus, linear DNA, histones, membrane bound organelles, linear chromosomes, sexual reproduction, larger, 80s ribosomes

Explain why Mycobacterium is medically-important, how its cell wall is unique, and any advantages this bacterium has towards survival in the external environment and inside the human body. Name one genus and species of Mycobacterium and the disease it causes.

—atypical cell wall (60% mycotic acid)

—Makes the cell wall sticky/ waxy

—resistant to chemicals (antibiotics, disinfectants)

—resist dehydration (can survive on surfaces up to 6 months)

—phagocytosis digestion

—mycobacterium tuberculosis - TB

Carbon is such an important molecule for life because

It can form chemical bonds with a maximum of 4 other atoms