ANTH-3153: Arch Sci II final exam

What chemical elements are in organic matter?

carbon, nitrogen, oxygen, hydrogen, sulfur

What are the 4 macromolecules?

proteins, lipids, nucleic acids, carbohydrates

Which conditions preserve organics?

extremely dry, extremely cold, anoxic, wet, alkali pH

Which conditions do organics not preserve in?

alternation between wet and dry, acidic pH, active soil processes

When was raw material sourcing introduced?

1950s

When did aDNA become popular?

2010s

What is this?

Hype cycle

What are the 4 major components in bone?

mineral, protein, lipid, water

What percentage of bone is mineral?

70%

what makes up the mineral component in bone?

calcium (hydroxyapatite)

what makes up the protein component in bone?

mostly type I collagen

what percentage of bone is protein?

20%

what percentage of bone is lipid?

3%

what percentage of bone is water?

5%

what are the characteristics of bioapatite?

can decide strength of bone, very small crystal size, directly interacts with collagen fibrils

what makes up bioapatite?

Ca10(PO4)6(OH)2

What does carbonate commonly substitute for?

phosphate

how much of protein does type I collagen make up?

>90%

What is the structure of collagen?

a triple helix

What holds collagen chains together?

hydrogen bonds

how many amino acids in each helix of collagen?

about 1000

What is interesting about collagen’s amino acid composition?

every third residue is glycine

where is the only place you can find hydroxyproline?

in collagen

what is an isotope?

atoms of the same element that have a different mass from different number of neutrons

what do protons determine in an element?

the chemical properties

what do neutrons determine in an element?

the physical properties

what are isotones

elements with the same number of neutrons

what are isobars?

elements with the same mass

What is the symmetry rule for stability of isotopes?

for all elements lighter than Ca N=Z or N/Z is >1

why does the symmetry rule work?

protons repel each other and need more neutrons to stabilize

what is the oddo-harkins rule? (even vs. odd)

the greatest stability in isotopes is when the Z# and N# are even

According to the oddo-harkins rule, what combination would be the least stable?

odd # of Z and N

How many isotopes do lighter elements tend to have?

2

how do isotopes differ from each other?

strength of bonds with other elements will be stronger or weaker depending on isotopes involved

what isotopes react more quickly?

lighter isotopes

which isotopes have stronger bonds?

heavy isotopes

what is fractionation?

partitioning of isotopes between two substances or phases of the same substance with different isotope ratios

what are the types of fractionation?

equilibrium and kinetic

what is kinetic fractionation?

when heavy isotopes want to be in the more stable phase

will light isotopes go into a more or less stable phase?

less stable

do heavier elements have more or less fractionation?

less fractionation

what kind of measurement is the delta value? (δ)

a relative measurement

what is δ?

represents the relative difference in the ratio of stable isotopes compared to an international standard

how is δ expressed?

per mil ‰

what kind of δ13C values are in organic material?

negative values

what kinds of δ15N values are in organic material?

positive values

what are the stable isotopes of hydrogen?

1H and 2H

what percentage of all hydrogen does 1H make up?

99.9%

what percentage of all hydrogen does 2H make up?

0.156%

what are the stable isotopes of oxygen?

16O, 17O, and 18O

what percentage of all oxygen does 16O make up?

99.6%

what percentage of all oxygen does 17O make up?

0.03%

what percentage of all oxygen does 18O make up?

0.19%

which oxygen isotope would most likely go into liquid phase when ice melts?

O16

which oxygen isotope would prefer to stay in the ice phase when in water?

18O

when rain falls, would 18O rather be in the rain or vapor from the cloud?

rain

are δ18O values of precipitation higher or lower in the winter?

lower

where are ice cores derived from?

glacial ice formed over 1000s of years

what is an isotope paleothermometer?

a way to get the known relationship between temperature and isotope values of material

what is meteoric water?

water that has fallen from the sky

where does most precipitation happen?

over oceans

what are the mechanisms that control the δ18O and δ2H of meteoric waters?

latitude, cloud temp, altitude, proximity to coast, amount effect

When a cloud rains, what isotope do we lose more?

heavy isotope

when latitude increases, what does the δ18O precipitation do?

decrease

when is ΔT (source-precip) lower?

the summer

when altitude increases, what does δ18O precipitation do?

decreases

where does the amount effect apply?

the tropics

when precipitation amounts increase, what happens to δ18O?

it decreases

if there are gentle tropic rains, what happens to the δ18O?

the values get higher

if there are heavy tropic rains, what happens to the δ18O?

the values get lower

what is phenylalanine?

an essential amino acid that does not come from water

where does the oxygen come from in phosphate and carbonate?

the water we drink

what does carbonate often substitute in for?

phosphate

what is the best source of carbonate to analyze?

tooth enamel

why is tooth enamel good for carbonate?

not porous, little organic matter to degrade, the minerals are large

what is the best source of phosphate to analyze?

tooth enamel

why is tooth enamel good for phosphate?

very hard to alter, lasts millions of years, very stable

what is a not good source of carbonate to analyze?

bone

why is bone not good for carbonate?

porous, lots of organic material, crystals small, prone to alteration/contamination

why is tooth enamel valuable for oxygen values?

O values are locked in from the time or formation

what are the most analyzed proteins in archaeological contexts?

collagen and keratin

where are CNS from the body derived?

CNS in foods we consume

when is contamination a problem?

when the contaminant isotope is really different from the target compound

what is degradation?

loss of target compound

which kind of amino acid is subject to fractionation during synthesis?

non essential amino acids

what are trophic discrimination factors?

offsets that represent the change in stable isotope ratios between diet and tissues

what do we need for diet reconstruction?

good tools, no alteration in burial, need to know the relationship between analyzed tissue and food isotopic compositions, turnover rate, routing, and isotope values of food consumed

what is routing?

the preferential incorporation of elements from certain macromolecules into certain tissues

what element is routing a problem for?

carbon

how does routing work?

the 3 macros all have carbon in them and the carbon gets directed towards particular tissues. This makes it nearly impossible to know which macro the carbon came from

what is the best source of baseline isotopic composition values?

materials from ancient contexts

What happens if two foods have the same isotopic composition?

you cannot tell which is more important in the diet

what are example of C3 plants

trees, moss, ferns

what are examples of C4 plants?

tropical grasses, sugar cane, millet

do marine animals have higher or lower δ13C and δ15N values than terrestrial animals?

higher

how many trophic levels in marine life?

5

how many trophic levels in terrestrial life?

3

which chemical element has the most stable isotopes?

tin

how many stable isotopes does tin have?

10

which one of tin’s stable isotopes are the most abundant?

Sn 120