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Microbiology > Chapter 2 Chemical Principles > Flashcards

Chapter 2 Chemical Principles Flashcards

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Biology 101 flashcards
1
Q

Atom

A

The smallest chemical unit of matter

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2
Q

Element

A

Matter composed of one type of atom

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3
Q

Molecule

A

Two or more atoms combined

  • Either the same type of atom
  • Or different called a compound
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4
Q

Structure of Atoms

A
  • Every atom has a centrally located nucleus
  • Nucleus has: Protons (+) and Neutrons (neutral charge)
  • Nucleus bears a net positive charge
  • Nucleus is stable and does not participate in chemical reactions
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5
Q

Electrons

A
  • Circle the nucleus and are negatively charged
  • Stabilize the positive charge of the nucleus
  • Equal number of electrons and protons give net charge equal to neutral
  • Orbit the nucleus in “shells”
  • Shells correspond to different energy levels
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6
Q

Chemical Bonds

A
  • Form between atoms through interactions of electrons in their outer shells
  • Goal is to become stable: achieved by filling the outermost shell ( 1st- 3e, 2nd - 8e, and 3rd - 8e)
  • Atoms achieve a full complement of electrons by combing together to form molecules
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7
Q

Ions

A
  • If an atom loses an electron it has an overall positive charge
  • If an atom gains an electron it has an overall negative charge
  • An atom (or group) that has a positive or negative charge is called an ion
    1) Cation= loss of an electron
    2) Anion = Gaining an electron
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8
Q

Ionic Bonds

A
  • Results from attractions between ions of opposite charges
  • Anions and Cations can form ionic bonds to neutralize their charges
  • Attraction holds the ions together to form a compound
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9
Q

Covalent Bonds

A
  • form when atoms share pairs of electrons
  • Found in many compounds, easily those that contain carbon
  • They’re very strong bonds
  • Carbon atoms can form up to 4 covalent bonds
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10
Q

Hydrogen Bonds

A
  • Occur between covalently bonded molecules that display polarity
  • Loose attraction between oppositely charged regions of different molecules
  • Weaker than ionic and covalent bonds
  • Serve to bridge separate molecules together
  • Example: water has hydrogen bonds
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11
Q

Water as the Solvent of Life

A
  • Approx. 75% of cell weight is water
  • Water has an unequal charge distribution - can form up to 4 hydrogen bonds (unique properties)
  • Imparts a high boiling point (100 degree C)
  • Makes water resist changes in temperature
  • Water is a polar solvent
  • Unequal charge distribution allows it to dissolve many ionic compounds
    • region of water molecules surrounds negative ions
  • Holds the ions in solution
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12
Q

Polar Nature of water gives it the Following Characteristics (#1)

A

Therefore, strong attraction between water molecules. High boiling point exists in state on most of the Earth’s surface

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13
Q

Polar Nature of water gives it the Following Characteristics (#2)

A

Due to polarity: many polar substances undergo dissociation: positive portion of solute molecule attracted to negative O, and negative portion of solute attracted to positive H. Therefore, salts like NaCl tends to separate into cations and anions

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14
Q

Polar Nature of water gives it the Following Characteristics (#3)

A

Water is key for many digestive processes: large molecules broken down into smaller. Also for synthetic reactions: important source of H and O atoms that are incorporated into numerous organic compounds in living cells

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15
Q

Polar Nature of water gives it the Following Characteristics (#4)

A

Heat absorption by molecules tends to increase kinetic energy and their rate of motion. With water, heat first results in breaking H-bonds rather than increasing rate of motion. Consequently, it doesn’t heat and cool as fast as other liquids

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16
Q

Water as the Solvent of Life Part 2

A
  • Water’s polarity facilitates the splitting and joining of hydrogen ions (h+) and hydroxide (OH-)
  • Makes these ions available for chemical reactions
  • pH scale describes the concentration of Hydrogen ions in a solution
17
Q

Organic Molecules

A
  • Any molecule that contains both carbon and hydrogen
  • Because each C atom can participate in 4 covalent bonds, carbon can be used to build an enormous variety of compounds
  • 4 major classes
18
Q

Carbohydrates

A
  • Large group of compounds including sugars and starches
  • All contain the elements C, H and O often in the ratio C1H2O1 ( Glucose C5H12O6)
  • Generally polar (so they dissolve in water)
  • Ready source of energy for cells
19
Q

Monosaccharides (Type of Carb)

A
  • mono = one
  • Simple sugars
  • Example: Glucose
20
Q

Disaccharides (Type of Carb)

A
  • Di- = two

- Example: Glucose + Fructose = sucrose (table sugar)

21
Q

Polysaccharides (Type of Carb)

A
  • Poly = many
  • Hundreds of monosaccharides joined together
  • Often not soluble in water
22
Q

Lipids

A
  • Includes fats, complex lipids (phospholipids) and steroids
  • Essential to the structure and function of membranes
  • Used for energy storage
  • Non-polar molecules: Hydrophobic = water hating
23
Q

Fats (Lipids)

A
  • Made from a glycerol backbone +1 or more fatty acids;
    1) Monoaglycerides: 1 fatty acid
    2) Diacylglycerides: 2 fatty acids
    3) Triaclyglycerides: 3 fatty acids
    -Fatty acids can be:
    Saturated = no double bonds
    Unsaturated = double bonds
24
Q

Complex Lipids Such as Phospholipids

A
  • Contain glycerol, 2 fatty acids and a phosphate group
  • Phosphate group is polar: Hydrophilic
  • The fatty acid tails are non-polar: Hydrophobic
  • Allows phospholipids to form membranes in water
  • Saturated fatty acids tend to form membranes that are more solid
  • Unsaturated fatty acid - more fluid
25
Q

Biological Membranes

A
  • Are made from phospholipid bilayer
  • Are semi-fluid (contain mix of saturated and unsaturated ftty acids)
  • Separates the watery inside of the cell from the watery environment
26
Q

Steroids (or sterols)

A
  • Structurally different from other lipids
  • Built on hydrophobic 4 ring structure
  • Generally found in eukaryotes (not prokaryotes)
  • Ex. Cholesterol, ergosterol and vitamin D
27
Q

Proteins

A
  • Made up of building blocks: amino acids
  • all contain: C, H, O, N and some have S
  • Required in all aspects of cell structure and function
  • Some are structural
  • But most act as enzymes - increase the rate at which chemical reactions take place
28
Q

Proteins Usually Contain

A
  • 20 different amino acids
  • Have at least one amino (-NH2) and one carboxyl (-COOH) group
  • Side groups determine properties
  • Amino acids joined by covalent peptide bonds
29
Q

Nucleic Acid

A
  • DNA= deoxyribonucleic acid
  • RNA = ribonucleic acid
  • Built of building blocks called nucleotides
30
Q

Nucleotide Three Parts

A

1) Nitrogenous Base:
- Purine – 2 rings = A and G
- Pyrimidine – 1 ring = T, C and U
2) Pentose Sugar (5 carbon sugar)
- Ribose and deoxyribose
3) Phosphate
- Nucleotides are joined together by covalent bonds to form a strand of nucleic acid

31
Q

DNA

A
  • Nitrogenous bases: A, G, T and C
  • Sugar deoxyribose
  • Double stranded
  • Stores the genetic info of all cellular organisms
32
Q

RNA

A
  • A, G, U and C
  • Sugar ribose
  • Single stranded
  • Involved in communicating the instructions stored in DNA
33
Q

DNA Structure

A
  • Each strand is built from a sugar phosphate backbone
  • Two strands are held together by hydrogen bonds between nitrogenous bases (A-T and G-C)
  • Forms the double helix

Microbiology (17 decks)

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