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BIOL 303 > Lecture 2: Chemical Basis of Life > Flashcards

Lecture 2: Chemical Basis of Life Flashcards

1
Q

Compound

A

A substance consisting of 2+ diff. elements combined in a fixed ratio

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2
Q

Many compounds in living organisms contain ____ , ____ , ____ , & ____

A

C, H, O, & N

DNA: C, H, O, & N
Carbs: C, H, O
Proteins: C, H, O (in some cases N)

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3
Q

Proton

A

+ electrical charge

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4
Q

Electron

A
  • (-) electrical charge
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5
Q

Neutron

A

Electrical neutral

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6
Q

How do atoms make their outermost shell full?

A

By sharing their electrons –> covalent bond formed

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7
Q

Which atoms are the most abundant in biological molecules and readily form covalent bonds?

A
  • Hydrogen
  • Oxygen
  • Carbon
  • Nitrogen
  • Phosphorus
  • Sulfur
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8
Q

All biological building blocks are organized around carbon atoms forming _____ or _____ bonds

A

3 or 4

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9
Q

Electronegativity

A

The extent o/ an atom’s ability to attract an electron

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10
Q

Non-polar covalent bonds

A

Electrons are equally shared between atoms that form the covalent bond
- e.g. C—C, C—H

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11
Q

Polar covalent bond

A

Covalent bonds between atoms that have diff. electronegativity —> unequal sharing o/ electrons
- e.g. O–H bonds in H2O

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12
Q

Ionic bond

A

One atom loses 1+ electrons to another atom

  • Results in formation of positively (cation) and negatively (anion) charged ion
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13
Q

How are ionic bonds formed?

A

Formed as the result o/ attraction between OPPOSITELY-charged ions
- e.g. NaCl

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14
Q

Why are ionic bonds so rare in cells?

A

Ionic bonds are weak and break easily in H2O
- e.g. Salt dissolving in water

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15
Q

Why are hydrogen bonds important in cells?

A

Electrostatic attraction between a proton in one molecule + electronegative atom in the other

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16
Q

Why are Van der walls interactions important in cells?

A
  • Weak attractive force between atoms or nonpolar molecules
  • Caused by a short change in dipole moment caused by a momentary transfer of orbital electrons to one side of one atom or molecule, causing a corresponding shift in surrounding atoms or molecules.
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17
Q

How is chemistry in living things different from that in the rest of the world?

A

Fewer elements, more water! (Cells are 70% water)

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18
Q

Why is so special when it comes to cells?

A
  • Both O–H bonds are highly polarized
  • All 3 atoms readily for H-bonds
  • It’s an excellent solvent
  • It determines the interaction between all types o/ molecules within the cell and actively participates in these reactions
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19
Q

Hydrophilic molecules

A
  • “Water-loving”
  • Ones that can form H-bonds in aqueous solutions and dissolve in H2O
  • e.g. sugars, some amino acids, etc.
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20
Q

Hydrophobic

A
  • “Water-hating”
  • Molecules can’t form H-bonds and are insoluble in water
  • Hydrophobic interactions hold these structures together
  • e.g. fats
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21
Q

What are the macromolecules found in cells?

A
  1. Proteins
  2. Carbs
  3. Nucleic acids
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22
Q

What are the 4 classes of biological macromolecules?

A
  1. Carbs
  2. Lipids
  3. Nucleic acids
  4. Proteins
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23
Q

General principles of macromolecular polymerization

A
  1. Macromolecule synthesis proceeds by the stepwise polymerization o/ monomers
  2. H2O molecule is removed w/ addition of each monomer
  3. Addition o/ each monomer to a growing macromolecule requires energy
  4. Synthesis occurs in a particular diction, and the 2 ends o/ polymer chain are chemically diff. from each other
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24
Q

What are the functions of carbohydrates?

A
  • Energy storage
  • Cell structure
  • Modification on other macromolecules (e.g. glycolipids)
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25
Q

Name examples of carbohydrates

A

Simple sugars- glucose, fructose, etc

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26
Q

What are di- and oligo-saccharides?

A

Simple sugars joined linearly by glycosidic bonds
- e.g. Sucrose, Lactose, etc.

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27
Q

Name examples of polysaccharides.

A

Glycogen, starch, cellulose

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28
Q

Branched polymers are found in which organisms? What are they used for?

A

a. Animals
b. Energy storage

29
Q

Helical polymers are found in which organisms? What are they used for?

A

a. Plants
b. Energy storage

30
Q

Unbranched polymers are found in which organisms? What are they used for?

A

a. Plants
b. Structure

31
Q

What functions do nucleic acids serve?

A
  • Serve & transmit genetic info.
  • Some serve as enzymes
32
Q

What are the two major types o/ nucleic acids?

A
  1. DNA
  2. RNA
    - mRNA
    - tRNA
    - rRNA
    - Various small RNA molecules
33
Q

What are nucleotides made up of?

A
  1. Pentose sugar
  2. Nitrogenous base
  3. Phosphate group linked to pentose sugar
34
Q

What is the difference between a nucleoSIDE and a nucleoTIDE?

A

Nucleoside: Nitrogenous base + sugar

Nucleotide: Nitrogenous base + sugar + 1+ phosphates

35
Q

What are the functions of nucleotdes?

A
  • Monomeric units o/ nucleic acids
  • High-energy compounds
36
Q

Adenosine triphosphate (ATP)

A

Adenosine nucleoside + 3 phosphate groups

37
Q

What is the pentose sugar present in DNA?

A

Deoxyribose

38
Q

What is the pentose sugar present in RNA?

A

Ribose

39
Q

What are the nitrogenous bases present in DNA?

A
  • Adenine
  • Guanine
  • Cytosine
  • THYMINE
40
Q

What are the nitrogenous bases present in RNA?

A
  • Adenine
  • Guanine
  • Cytosine
  • URACIL
41
Q

What bond holds the base pairs in DNA together?

A

Hydrogen bond

42
Q

How do lipids differ from other macromolecules?

A
  • Not synthesized by linear polymerization o/ monomers
  • Heterogenous category grouped together based on their shared distinctive hydrophobic character
43
Q

Why are lipids still considered macromolecules?

A
  • High molecular weights
  • Presence in important cellular structures, especially membranes
44
Q

What are the major cellular functions of lipids?

A
  • Membrane structure
  • Energy storage
  • Signaling molecules
45
Q

What are triacylglycerols (Triglycerides)?

A

Glycerol molecule + 3 fatty acids

46
Q

T/F: Triacylglycerols are more unsaturated in animals.

A

FALSE, they’re more SATURATED
- Typically solid at room temp. (e.g. fat on meat)

47
Q

T/F: Triacylglycerols are more unsaturated in plants.

A

TRUE, typically liquid at room temp. (e.g. vegetable oils)

48
Q

What is the most abundant class of phospholipid in biomembranes?

A

Phosphoglycerides

49
Q

What is a phosphoglyceride composed of?

A
  • 2 fatty acyl chains esterified to 2 hydroxyl groups in glycerol phosphate
  • A polar head attached to the phosphate group in glycerol phosphate
50
Q

What are the functions of cholesterol?

A
  • Regulate membrane fluidity
  • Precursor to steroid hormones
  • Amphipathic
51
Q

What are sterols made up of?

A

Cholesterol and its analogs

52
Q

What functions do proteins have?

A
  1. Catalyze reactions (enzymes)
  2. Structural roles
  3. Movement
  4. Transport across membranes
  5. Receive and transmit signals (between and within cells)
  6. Defense (protect against disease)
53
Q

Proteins are ________ polymers o/ amino acids

A

Linear

54
Q

What are the common features of proteins?

A
  • Central alpha carbon atom bonded to 4 diff. chemical groups
  • 1 amino (-NH2) group
  • 1 carboxyl or carboxylic acid (-COOH) group
  • 1 hydrogen (H) atom
  • 1 R group
55
Q

Amino acids are linked by what type of bond?

A

Peptide

56
Q

Proteins (or polypeptides) are composed o/ amino acid that joined together by _______________.

A

Dehydration synthesis reactions

57
Q

How is a peptide bond formed?

A

When H2O is removed

58
Q

________ defines function.

A

Structure

59
Q

Primary structure of proteins

A
  • Sequence o/ amino acids in a polypeptide chain
  • Read from N-terminus to C-terminus
  • All info. needed for higher-level structure is provided by the amino acid sequence
60
Q

Secondary structure o/ proteins

A
  • Local regions o/ structure formed by H-bonding between H in amino group + O in carboxy group o/ peptide backbone
61
Q

What are the most common elements of secondary structure?

A

Alpha helix- spiral arrangement o/ amino acids
- Looks like a coiled telephone cord

Beta sheet- sheet-like conformation composed o/ extended pleated strands
- Looks like a pleated skirt

62
Q

Tertiary structure o/ proteins

A
  • Global 3D structure o/ a single polypeptide chain
  • Controlled almost completely by R group interactions
  • Influenced by covalent & non-covalent interactions
63
Q

What determines the 3D protein conformation?

A

Amino acid sequence

64
Q

What are the types of non-covalent interactions?

A
  • Hydrogen bonds
  • Ionic bonds
  • Van der Waals interactions
  • Hydrophobic interactions
65
Q

What are the types of covalent interactions?

A

Disulfide bonds

66
Q

Quaternary structure o/ proteins

A

Overall architecture o/ a protein comprised o/ multiple polypeptide chains
- Multimeric protein/protein complex- a protein comprised o/ multiple polypeptides

67
Q

What factors/conditions might cause a folded protein to unfold (denature)?

A
  1. Extreme temps.
  2. Extreme pH
  3. High salt
  4. Mechanical agitation
68
Q

Why is a denatured protein a bad thing for a cell?

A

Denaturation breaks H-bonds & Van der Waals interactions
- These bonds hold the 3D shape o/ the protein
- No proper shape —> no function

69
Q

What is protein phosphorylation?

A
  • Like a chemical switch that can turn a protein “on” or “off
  • Phosphate group is added to a protein
  • This alters the protein’s shape + function, making it less active in carrying out its specific function within the cell

BIOL 303 (5 decks)

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