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Chemistry Of Life Flashcards

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AP® Biology flashcards Biology 101 flashcards
0
Q

Elements and their roles

A
  • Ca - messenger
  • Fe - oxygen transport (in hemoglobin)
  • Na - involved in generation of nerve impulses
  • P - part of phosphate groups in ATP and DNA
  • S - needed to make two of the 20 amino acids that proteins contain
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1
Q

Most frequently occurring elements

A

Carbon
Oxygen
Hydrogen
Nitrogen

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2
Q

Water cohesion

A

Water molecules stick to each other thanks to hydrogen bonds between them;
Use: strong pulling forces used to suck columns of water up to the tops of the highest trees (transport medium in the xylem of plants)

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3
Q

Solvent properties of water

A

Water is polar

  • other polar molecules dissolve easily
  • medium for metabolic reactions
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4
Q

Specific heat capacity of water

A

Large heat capacity = large amounts of energy are needed to break some of the hydrogen bonds and raise its temperature
Use: transport medium for heat; body doesn’t change temperature easily; stable temperature in water environments

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5
Q

Boiling point of water

A

High boiling point (100°C) - all of the hydrogen bonds have to be broken
Use: medium for metabolic reactions (water is below boiling point almost everywhere of earth)

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6
Q

Evaporation of water

A

Can evaporate at temp below boiling point; the heat energy used to break hydrogen bonds is taken from the liquid, cooling it down
Use: water acts as a coolant (sweat, plant leaves)

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7
Q

Organic compounds

A

Contain carbon, are found in living organisms

Most popular: carbohydrates, lipids, and proteins

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8
Q

Inorganic compounds

A

Contain no carbon, except for: carbon dioxide, hydrogen carbonates, calcium carbonates

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9
Q

Monosaccharides

A

Glucose, fructose, galactose, ribose

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10
Q

Disaccharides

A

Lactose, sucrose, maltose

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11
Q

Polysaccharides

A

Glycogen, starch, cellulose

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12
Q

Glucose

A

Carried by the blood to transport energy to cells throughout the body

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13
Q

Fructose

A

Fruit taste sweet - animals attracted - seeds dispersed

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14
Q

Lactose

A

Sugar in milk; provides energy to young mammals

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15
Q

Sucrose

A

Carried by the phloem to transport energy to cells throughout the plant

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16
Q

Glycogen

A

Short term energy storage in liver and muscles

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17
Q

Cellulose

A

Makes strong fibers used to construct plant cell wall

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18
Q

Amino acid + amino acid =

A

Dipeptide + water

Condensation

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19
Q

Monosaccharide + monosaccharide =

A

Disaccharide + water

Condensation

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20
Q

Monosaccharide + disaccharide
OR
disaccharide + disaccharide =

A

Polysaccharide + water

21
Q

Glycerol + 3 fatty acids =

A

Triglyceride + water

22
Q

Hydrolysis

A

The reverse of condensation
Water is required
Organic molecules are broken apart (catabolism)

23
Q

Condensation

A

Organic molecules are joined together (anabolism)

24
Q

FUNctions of lipids (3)

A

1) energy storage (fat in humans, oil in plants)
2) heat insulation
3) buoyancy (lipids are less dense than water - animals can float)

25
Q

Lipids as energy store

A
  • more energy per gram than carbs (9 kcal vs 4 kcal)
  • less oxygen than carbs = more concentrated energy store! same amount of energy weights less
  • insoluble in water - don’t cause problems with osmosis
  • not hydrolysed as quickly as carbs - don’t release energy as rapidly
26
Q

Carbohydrates as energy store

A
  • Less energy per gram than lipids
  • more easily digested - energy can be released more rapidly
  • soluble in water - easier to transport to and from the storage
27
Q

How DNA double helix if formed?

A

Two strands of nucleotides –> hydrogen bonds link the strands by complementary base pairing (A-T, C-G) –> strands wind into a double helix

28
Q

DNA replication (define)

A
  • copying DNA to produce two new molecules with the same base sequence
  • semi-conservative
  • thanks to complementary base pairing, each new strand is complementary to the template on which it was made and identical to the other template
29
Q

Stages of DNA replication (3)

A
  1. DNA double helix is unwound and separated into strands by breaking hydrogen bonds;
    Main enzyme: helicase (HELI(x/case))
  2. Free nucleotides largely present around the replication fork - their bases form hydrogen bonds with the bases on parent strands by. Complementary base pairing;
    Main enzyme: DNA polymerase
  3. Daughter DNA molecules each rewind into a double helix
30
Q

Structure of DNA (3)

A
  • 2 strands forming a double helix
  • sugar in nucleotides: deoxyribose
  • bases: A-T, C-G
31
Q

RNA structure

A
  • only 1 strand
  • sugar: ribose
  • bases: A-U, C-G
32
Q

DNA transcription

A
  • copying of the base sequence of a gene by making an RNA molecule
  • same rules as in DNA replication BUT instead of thymine, uracil is paired with adenine
33
Q

RNA (function)

A

RNA carries the information needed to make a polypeptide out into the cytoplasm (mRNA) - made instead of using DNA genes directly to manage the synthesis of polypeptides

34
Q

Genetic code

A

Triplet code - 3 bases code for 1 amino acid

A group of three bases is called a codon

35
Q

DNA translation

A
  1. mRNA binds to a small subunit of the ribosome
  2. tRNA molecules, present around the ribosome, carry amino acids (corresponding to their anti codons) to the codons of the mRNA strand
  3. tRNAs bind to the mRNA at the ribosome accordingly to the rules of complementary base pairing, BUT only 2 can bind at once
  4. Amino acids carried by tRNA molecules bond together by a peptide linkage - a Dipeptide is formed
  5. The tRNA on the left detaches
  6. Ribosome moves along mRNA strand on the next codon
  7. Process is repeated until a polypeptide is formed
36
Q

One gene - one polypeptide hypothesis

A
  • assumes that one gene codes for one polypeptide
    EXCEPTIONS:
  • some genes code for tRNA or mRNA, not for polypeptides
  • some DNA sequences act as regulators for gene expression and are not translated into polypeptides
  • in lymphocytes: pieces of DNA from different parts of the genome are spliced together and transcribed and translated to produce antibodies; different lymphocytes produce different antibodies by splicing together DNA in different ways
37
Q

Enzymes

A
  • globular proteins that act as catalysts of chemical reactions
  • speed up the rate of reactions
  • by making some enzymes and not others, a cell can control what happens in its cytoplasm
  • are specific: catalyse very few different reactions
38
Q

Denaturation

A

Changing the structure of an enzyme (or other protein) so that it can no longer carry out its functions; usually permanent

39
Q

Active site

A

A region on the surface of an enzyme to which substrates bind and which catalyses a chemical reaction involving the substrates;
Has a very intricate and precise shape, so that only molecules of the substrate can fit and be attracted by the enzyme (key and lock hypothesis)

40
Q

Temperature vs enzyme activity

A

Enzyme activity often doubles with every 10°C rise;

higher temperatures = faster molecular motions = more frequent collisions between active site and substrate

41
Q

pH vs enzyme activity

A

pH varies from the optimum = enzyme activity reduced
pH alters the shape of active site (bonding patterns)
very high or very low pH = denaturation

42
Q

Substrate concentration vs enzyme activity

A

higher concentration = more frequent collisions between substrate molecules and active sites
very high concentration - raising the concentration has little effect on the speed of reaction since most active sites are occupied

43
Q

Lactose

A

Sugar naturally present in milk;

Can be converted into glucose and galactose by the enzyme lactase

44
Q

Lactase

A

Can be obtained from Kluveromyces lactis (yeast growing naturally in milk)
- biotech companies culture the yeast, extract and purify the lactase and sell it to food manufacturing companies

45
Q

Reasons for using lactase in food processing (5)

A

1) lactose intolerance in some people,
2) galactose and glucose are sweeter than lactose
3) lactose tends to crystallize during ice cream production, whereas galactose and glucose do not
4) faster production of cheese and yoghurt (bateria ferment galacotse and glucose more quickly)
5) lactase works efficiently at normal temperatures and pressures

46
Q

Ways of using lactase in food processing (2)

A

1) added to milk
2) immobilized on a surface in beads of a porous material (milk flows past it, lactose is converted into glucose and galactose, but the final product is not contaminated with lactase)

47
Q

Cell respiration

A

Controlled release of energy from organic compounds in cells to form ATP

48
Q

Chlorophyll

A

Main photosynthetic pigment
Reflects green light
Absorbs blue and red
–> some of this energy absorbed is used to produce ATP
–> some energy is used to split water molecules to form oxygen and hydrogen (photolysis of water)

—> hydrogen + ATP used to fix carbon molecules to make organic molecules! oxygen released as a waste

49
Q

Photosynthesis

A

Process used by plants and other organisms to produce their own organic substances from inorganic matter;
Involves conversion of light energy into chemical energy
Pigments absorb light

50
Q

Measuring rate of photosynthesis (3)

A

1) oxygen production (aquatic plants release bubbles - direct measurement)
2) carbon dioxide uptake (co2 absorbed - pH of water rises; indirect measurement)
3) biomass increase (indirect measurement)

Biology (9 decks)

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