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BIO 101 EXAM 1 > CHAPTER 4 > Flashcards

CHAPTER 4 Flashcards

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1
Q

nucleic acids

A

polymers specialized for storage, transmission, and use of genetic information

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2
Q

DNA

A

deoxyribonucleic acid; has deoxyribose; has thymine

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3
Q

RNA

A

ribonucleic acid; has ribose; has uracil

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4
Q

nucleotides

A

monomers for nucleic acid: pentose sugar + nitrogenous base + phosphate group

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5
Q

two forms of nitrogenous bases?

A

-pyrimidines: single ring
-purines: fused double-ring

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6
Q

types of pyrimidines

A

-Cytosine
-Thymine
-Uracil

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7
Q

types of purines

A

-Adenine
-Guanine

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8
Q

how are nucleotides linked?

A

-through phosphodiester bonds
-phosphate groups link the 3 carbon in one sugar to the 5 carbon in another sugar
-nucleic acids grow in the 5’-to-3’ direction

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9
Q

DNA base?

A

-purines: adenine (A) & Guanine (G)
-pyrimidines: cytosine (C) & thymine (T)

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10
Q

complementary base pairing

A

purines pair with pyrimidines by hydrogen bonding
-can also take place between RNA and DNA

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11
Q

RNA base

A

-single-stranded, but base pairing can occur between different regions of the molecule which results in 3D structures
-RNA has uracil (U) instead of thymine

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12
Q

DNA

A

-two strands form a double helix
-all DNA molecules have the same structure
-genetic information is carried in the sequence of base pairs

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13
Q

Transcription

A

DNA sequences are copied into RNA

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14
Q

Translation

A

RNA sequence specifies the sequence of amino acids in a polypeptide

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15
Q

gene expression

A

transcription + translation

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16
Q

replication

A

when DNA reproduce itself

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17
Q

what does DNA replication & transcription depend on?

A

it depends on the base-pairing properties of nucleic acids

18
Q

genome

A

the complete set of DNA in an organism

19
Q

genes

A

sequences of DNA that are transcribed into RNA

20
Q

hereditary information

A

DNA carries hereditary information from one generation to the next; closely related living species have more similar base sequences than do species that are more distantly related

21
Q

what DNA sequencing used for?

A

to trace evolutionary relationships

22
Q

other roles for nucleotides?

A

-ATP: energy transfer in biochemical reactions
-GTP: energy source ini protein synthesis
-cAMP: essential in many processes, including hormone action
-carried in synthesis and breakdown of carbohydrates and lipids

23
Q

spontaneous generation? who disproved it?

A

some forms of life arose from decaying matter; Francesco Redi disproved this in 1668

24
Q

what experiment disproved spontaneous generation

A

an experiment by Louis Pasteur showed that microorganisms can arise only from other microorganisms

25
Q

describe the experiment

A

jar 1: meat was exposed to air and flies. maggots formed in the meat
jar 2: fine cloth covering jar meat was exposed to air but not flies. no maggots formed
jar 3: lid coving jar, meat was no exposed to air or flies. no maggots formed

26
Q

what are the two theories on how life first originated?

A
  1. chemical evolution
  2. life came from outside earth
27
Q

chemical evolution

A

-conditions on primitive earth led to information of simple molecules such as amino acids, which led to formation of life forms
-Miller and Urey (1950s) experimented with reconstructing those primitive conditions using gases thought to be in the early atmosphere: H2, NH3, CH4, H2O

28
Q

what did Miller and Urey experiments spark?

A

-volcanoes many also have added CO2, N2, H2C, and SO2 to the atmosphere
-adding these gases to the experimental atmosphere results in formation of many more small organic molecules

29
Q

life came from outside earth

A

-some meteorites contain molecule such as purines, pyrimidines, and amino acids, suggesting that living organisms might have reached earth within a meteorite
-some question if organisms could survive in a meteorite

30
Q

what are plausible explanations of how polymers formed?

A

-possible conditions including powdered clays, hydrothermal vents, and hot pools (similar to early earth conditions)

31
Q

what is a key to the origin of life?

A

-the appearance of catalysts (today catalysts are proteins called enzymes)
-proteins are synthesized from information in nucleic acids

32
Q

what came first, nucleic acids or protein catalysts?

A

-RNA may have been the first catalyst; which is a nucleic acid
-the 3D shape and other properties of some TNA molecules (ribozymes) are similar to enzymes
-RNA could have acted as a catalyst for its own replication and for synthesis of proteins.
-DNA could eventually have evolved from RNA

33
Q

evidence supporting the “RNA world” hypothesis

A

-ribose can be formed in prebiotic chemical synthesis experiments
-peptide linkages are catalyzed by ribozymes today
-in retroviruses, reverse transcriptase catalyzes synthesis of DNA from NRA
-short, naturally occurring RNA molecules catalyze polymerization of nucleotides in experimental settings
-an artificial ribozyme has been developed that can catalyze assembly of short RNAs into a longer molecule that is an exact copy of itself

34
Q

what must occur for life to occur

A

life must have been concentrated in a compartment
-living cells now are separated from their environment by a membrane

35
Q

what does a membrane allow for cells

A

-allows cells to maintain a chemical composition that is different from the external environment

36
Q

what do fatty acids form in water?

A

they form a lipid bilayer around a liquid compartment

37
Q

what are protocells? what do they allow?

A

A self-organized sphere of lipids proposed as a stepping-stone to the origin of life; these allow small molecules such as sugar and nucleotides to pas through

38
Q

what happens when nucleotides pass through the bilayer?

A

if short nucleic acid strands capable of self replication are placed inside protocells, nucleotides can pass through the bilayer and e incorporated into polynucleotide chains

39
Q

protocells may be reasonable model for the evolution of cells?

A

-they are organized systems of parts with substances interacting, in some cases catalytically
-the interior is distinct from the exterior environment
-capable of limited replication

40
Q

cyanobacteria

A

based on fossil evidence found in Australia cyanobacteria which are single celled algae that photsynthesize which means carbon was needed; since carbon has isotopes it a good way to date things

41
Q

carbon isotopes

A

-carbon isotopes indicative of photosynthesis were found I the fossils and also showed that several other types of bacteria were present as well
-probably took 500million to 1billion years for the first cells to appear on earth

BIO 101 EXAM 1 (5 decks)

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