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AP Biology > Biochemistry Exam > Flashcards

Biochemistry Exam Flashcards

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1
Q

ionic bond

A

a chemical bond that forms due to the complete transfer of electrons from one atom to another.

The atom that gains electrons is given a negative charge, while the atom that gives up electrons is given a positive charge.

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2
Q

covalent bond

A

A covalent bond is a chemical bond that forms via the sharing (not complete transfer) of electrons.

When the electrons are shared unequally, the bond is polar covalent.
When the electrons are shared equally, the bond is nonpolar covalent.

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3
Q

hydrogen bond

A

Hydrogen bonds are intermolecular, which means they occur between two or more different molecules.

a weak chemical bond that forms when a hydrogen atom with a partial positive charge of a polar covalent bond in one molecule is attracted to the slightly negative atom of a polar covalent bond in another molecule

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4
Q

electronegativity

A

the attraction of an atom for the electrons of a covalent bond
(i.e. electronegativity of oxygen atom in a water molecule results in polarity)

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5
Q

structure of water

A

Two hydrogen atoms with partial positive charges joined by a single covalent bond to an oxygen atom with a partial negative charge to form H2O

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6
Q

Cohesion

A

the attraction of water molecules to other water molecules through hydrogen bonds
-causes surface tension and helps hold together the column of water being transported upwards within the xylem during transpiration

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7
Q

Adhesion

A

the attraction between water molecules and another substance due to the polarity of the water molecule
-allows water molecules to cling to the cell walls of the xylem during transpiration to resist downward pull of gravity

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8
Q

Moderation of Temperature

A
  • Water freezes at 0˚C and boils at 100˚C
  • due to high specific heat (1 cal/g/°C), water is a heat bank and resists changes in temperature by absorbing or losing a large quantity of heat for each degree of temperature change
  • evaporative cooling allows for the molecules with the most kinetic energy to evaporate and convert to the gaseous state, cooling the surface
  • maintain homeostasis in organisms, stabilization of the temperature of land and bodies of water, moderates climate
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9
Q

Expansion during Freezing

A

Water expands as it freezes and becomes less dense due to its crystalline structure formed by hydrogen bonds
- Ice floating at the top of lakes and ponds insulates the water below preventing them from freezing solid as well as allowing life to exist below the frozen surface

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10
Q

Solubility

A

the chemical property of water referring to the ability for a given substance (the solute) to dissolve in the solvent

  • based on the polarity (positive and negative charge) of the molecule
    • cations (+) are attracted negatively charged oxygen regions of water molecule while anions (-) are attracted to the positively charged hydrogen regions
  • as a result, water molecules surround the individual ions and dissolves the solute through the formation of a hydration shell
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11
Q

Transport happens on three different scales:

A
  • Transport of water & solutes by individual cells
  • Short distance transport at the tissue & organ level
  • Long distance transport through the xylem & phloem across the entire plant
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12
Q

transport by individual cells

A

Osmosis
- Water transport across a semi permeable membrane based on solute concentration
Water Potential (Ψ)
- A property that predicts the flow of water based on solute concentration & physical pressure

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13
Q

transport at the tissue & organ level

A

Lateral transport: Short distance movement through
plant tissues
-plasmodesmata are pores in cell walls that allow cytoplasms to fuse together in cells of the same tissue- faster transport and communication

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14
Q

transport over long distances

A

Bulk flow of fluid through the whole plant:

  • Water & solutes move through the xylem
  • Sugars move through the phloem
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15
Q

water’s pathway

A

Water and mineral salts from the soil enter through the root epidermis with the aid of root hairs and mycorrhizae. Water is then transported to the root cortex and then to the xylem. The transpiration-coheion-tension mechanism is the main source of water’s movement from the xylem to the leaves. Transpiration pull occurs as the oustide air has a lower water potential than the air inside the leaf. This results in diffusion of water vapor from the leaf to the atmosphere (diffusion). Lost water is replaced by water in the xylem due to
cohesion.
- transpiration requires no energy

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16
Q

stomata

A

allows gas exchange to occur, water to evaporate during transpiration
-guard cells regulate the opening and closing of stomata in response to stimuli

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17
Q

pH

A

A scale that compresses the range of H+ and OH concentrations by using logarithms. It is the negative log of hydrogen ion concentration
• pH=-log[H+]

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18
Q

acids

A

a substance that increases the [H+] in a solution by releasing H+ ions

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19
Q

base

A

a substance that reduces the [H+] in a solution by directly accepting H+ ions (weak) or dissociating to release OH- to bond with H+ ions in the solution to form H2O

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20
Q

buffer

A

a substance that minimizes changes in the concentraion of OH- ions and H+ ions in a solution by accepting or releasing H+ ions
- usually composed of weak acid and corresponding base

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21
Q

carbon structure

A

CH4
Carbon’s diversity arises from its ability to bond with four other atoms (covalent)
Tetravalence: carbon with single covalent bonds will form tetrahedrons
Carbons with double covalent bonds will form planar molecules
4 valence electrons; can bond to four other atoms

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22
Q

hydrocarbons

A

– Molecules consisting of only carbon & hydrogen
– Not found often in cells, but rather are organic
molecules have regions that are hydrocarbons
– Ex: hydrocarbon tails found in fats

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23
Q

Isomers

A

molecules with the same molecular formula but different

structures and properties

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24
Q

Structural Isomers

A

changes location of covalent bonds to create new molecules

25
Q

Geometric Isomers

A

cis - special group on the same side
trans - special group on opposite sides
covalent bonds remain unchanged, but rather differs in the spatial arrangement and position of atoms and arrangement about a double bonds

26
Q

Enantomers

A

differ in spatial arrangement around an asymmetric carbon, resulting in molecules that are mirror images

27
Q

Dehydration Synthesis

A

Monomers are connected by a dehydration reaction:
– One monomer provides the hydroxyl group & the
other provides a hydrogen to form a water molecule that is removed
- this process is repeated continuously

28
Q

Hydrolysis

A

Monomers are removed from polymers by hydrolysis – Adding water molecules breaks the bonds between monomers
– One monomer receive the hydroxyl group & the other gets the hydrogen

29
Q

monomer

A

the repeating units that serve as the building blocks of a polymer

30
Q

polymer

A

a long molecule consisting of many similar or identical building blocks linked by covalent bonds

31
Q

general characteristics of carbohydrates

A

monomer: monosaccharides
polymers: disacchardies, polysaccharides
bond type: glycosidic linkage
- 3-7 carbons with carbonyl group and multiple hydroxyl groups and many structural isomers

32
Q

monosaccharides

A

• Use multiples of CH2O
• Glucose (C6H12O6) is essential for life due to its role in cellular respiration
• In solution, glucose & most sugars form rings
– The first carbon bonds to the oxygen on carbon 5

33
Q

disaccharides

A

Two monosaccharides connected by glycosidic linkage

• Sucrose (table sugar) is the most common & is how plants transport carbohydrates

34
Q

polysaccharides

A

Thousands of monosaccharides
– Storage material until hydrolyzed into sugar for cells
• Starch: plant storage made of glucose monomers; stored in plastids.
• Glycogen: human storage found in the liver and muscles
– Building material for protective structures
• Cellulose: part of the tough cell wall of plants
• Chitin: builds exoskeletons in arthropods & found in fungi cell walls

35
Q

lipids

A

monomers: fatty acids and glycerol
polymers: phospholipids, fats, steroids
bond type: ester linkage
Little or no affinity for water due to the molecular structure
– Mainly hydrocarbons
– Smaller than traditional macromolecules

36
Q

Fats

A

Formed through dehydration reaction of one glycerol and three fatty acids by an ester linkage
– Called triacylglycerol (triglyceride)

37
Q

Saturated Fats

A
  • have no double bonds between carbon atoms in the fatty acid chain (saturated with hydrogen).
  • solid at room temperature due to the ability of molecules to tightly pack together
  • animal fats (ie butter, lard)
38
Q

Unsaturated Fats

A
  • one or more double bonds formed by the removal of hydrogen atoms from the carbon skeleton
  • kink in hydrocarbon chain wherever a cis double bond occurs
  • liquid at room temperature
  • plants and fish fats (ie olive oil, fish oil)
39
Q

Energy Storage of Fats

A

adipose in animals

seeds in plants

40
Q

Phospholipids

A

Glycerol with two fatty acids and a phosphate group
– Phosphate head is hydrophilic and fatty acid tail is hydrophobic
– Creates double layer in water
• Main component of cell membranes (the phospholipid bilayer)

41
Q

Steroids

A

Carbon skeletons consisting of four fused rings
– Differentiation due to attached functional group
• Cholesterol is a steroid found in animal cell membranes
– High levels in the blood leads to cardiovascular disease
• Sex hormones are steroids that acts as messengers
– Testosterone & estrogen

42
Q

Proteins

A

monomers: amino acids
polymers: polypeptides
bond type: peptide bond
One or more polypeptides folded into a specific
conformational shape

43
Q

Protein function

A 
– Structural support
– Storage
– Transport
– Hormonal
– Cellular communication
– Movement
– Defense against foreign substance
– Speed up chemical reactions (enzymes)
44
Q

Proteins have • Incredibly diverse structures & functions due to _____________________________

A

three dimensional shape

45
Q

nonpolar and nonpolar amino acids form

A

hydrophobic interactions (Van der Waal)

46
Q

polar and polar amino acids form

A

hydrogen bonds

47
Q

positively charged base and negatively charged acid form

A

ionic bonds

48
Q

sulfhydryl interacts to form

A

disulfide bridge

49
Q

amino acid structure

A

– Amino acids (with an amino & carboxyl group) are the
monomers
– It is the side group (R) that determines the behavior of the amino acid
– All proteins are made from 20 amino acids

50
Q

nonpolar amino acids

A

carbon and hydrogen

ie methyl

51
Q

polar amino acids

A

hydroxyl and carbonyl

52
Q

negatively charged acidic

A

carboxyl group

53
Q

positively charged base

A

amino group

54
Q

Amino acid polymers

A

A peptide bond is formed between two amino acids

– Carboxyl group bonds with amino group of the next amino acid

55
Q

Protein Structure: Primary

A

The unique sequence of amino acids

56
Q

Protein Structure: Secondary

A

Folds & coils in the polypeptide chain due to hydrogen bonds between repeating sections

  • α helix
  • β pleated sheet
  • due to attraction of negatively charged carboxyl group and positively charged amino group
57
Q

Protein Structure: Tertiary

A

Overall shape of the polypeptide due to the interactions between side chains (R groups)

  • Hydrophobic interactions
  • Disulfide bridges
  • Ionic bond
  • Hydrogen bond
58
Q

Protein Structure: Quaternary

A

-same type of interactions as tertiary structure

Two or more polypeptide chains create one protein

59
Q

Denaturation of Proteins

A

• The environment can impact the conformation of protein causing denaturation
– pH
– Salt concentration
– Temperature

AP Biology (30 decks)

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