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biology 111 - intro to organisms - section ii > intro to dna - (lecture 8) > Flashcards

intro to dna - (lecture 8) Flashcards

1
Q

who discovered dna in 1869?

A

miescher

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2
Q

what did miescher do?

A
  • investigated the chemical composition of the nucleus
  • isolated on organic acid that was high in phosphorus and nitrogen
  • called it nuclein
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3
Q

what does dna mean?

A

deoxyribonucleic acid

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4
Q

before thorough research, the general belief was that ______ were the genetic material

A

proteins

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5
Q

scientists at the time who believed that proteins were the genetic material’s line of thinking was…

A
  • heritable traits are diverse
  • molecules containing traits must be diverse
  • proteins are made of an “infinite” assortment of 20 amino acids and are structurally diverse
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6
Q

the four nucleotides are…

A

adenine, thymine, cytosine, and guanine

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7
Q

the two purines are…

A

adenine and guanine

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8
Q

the two pyrimidines are… (they both have y’s)

A

thymine and cytosine

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9
Q

who discovered transformation in 1928?

A

griffith

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10
Q

what did griffith do?

A
  • attempted to develop a vaccine for pnemonia
  • isolated two strands of Streptoccocus pneumoniae
  • rough strand: harmless
  • smooth strand: pathogenic
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11
Q

what happened when griffith injected a mouse with a rough strand? with a smooth strand?

A

rough strand: the mouse lived
smooth strand: the mouse died

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12
Q

what happened when griffith injected a mouse with heat treated smooth strand cells?

A

the mouse lived, since all bacteria were dead

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13
Q

what happened when griffith injected the mouse with dead rough strands with smooth strand?

A

the mouse died, since the harmless rough cells had been transformed by material from dead smooth cells
- descendants of the transformed cells were also pathogenic

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14
Q

who defined the “transforming material” within these prokaryotic cells?

A

avery and mccarty

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15
Q

what did avery and mccarty do?

A
  • they found that cell extracts treated with protein digesting enzymes could still transform bacteria
  • the cell extracts that were treated with dna digesting enzymes lost their transforming ability
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16
Q

what is the bottom line of avery and mccarty’s experiments?

A

dna is the transforming material; when it is destroyed then they can no longer transform

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17
Q

avery and mccarty went one step further, defining that…

A

proteins weren’t necessary at all:
- injections without the protein vs. ones without the dna = dna is the transformative material

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18
Q

what is the name of a virus that infects solely bacteria; dna with a protein coat?

A

bacteriophage

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19
Q

describe what a virus is

A

nonliving structures with protein coats protecting genetic material (either dna or rna; usually rna)

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20
Q

who took avery and mccarty’s work and used it on bacteriophages?

A

hershey and chase

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21
Q

what did hershey and chase do?

A

created labelled bacteriophages
- radioactive sulfur (in protein but not dna)
- radioactive phosphorus (in dna but not protein)
then allowed labelled viruses to infect bacteria, looked for where the radioactive labels were after infection

22
Q

where was the radioactive sulfur? where was the radioactive phosphorus?

A

the sulfur was around the bacteriophage’s shell, the phosphorus was inside of the infected cell

23
Q

all nucleotide bases have…

A

a nitrogenous base, a 5-carbon sugar, and a phosphate group or groups

24
Q

acids _____ hydrogens and _____ the pH

A

donate, lower

25
Q

bases _____ hydrogens and _____ the pH

A

accept, raise

26
Q

which two nucleotides have “two ringed” bases?

A

adenine and guanine

27
Q

which two nucleotides have “one ringed” bases?

A

thymine and cytosine

28
Q

who researched the composition of dna in 1949?

A

chargaff

29
Q

what did chargaff do?

A
  • showed that the amount of adenine relative to guanine differs among species
  • the amount of adenine always equals the amount of thymine and the amount of guanine always equals the amount of cytosine
30
Q

adenine ____ bonds to thymine

A

double

31
Q

guanine _____ bonds to cytosine

A

triple

32
Q

who pioneered x-ray crystallography?

A

rosalind franklin!

33
Q

what did rosalind franklin do?

A
  • she was an expert on x-ray crystallography
  • used this technique to examine dna fibers
  • she was the first to put dna into a “wet” form
  • concluded that dna was some sort of helix
34
Q

what did watson and crick do?

A
  • stole
35
Q

watson and crick model

A

they stated that dna consists of two nucleotide strands, running in opposite directions
the strands are held together by hydrogen bonds
the bonds form between bases

36
Q

a bonds with __

A

t

37
Q

c bonds with ___

A

g

38
Q

a also can bond with ___

A

u (in rna)

39
Q

what roles do the carbons hold in the five carbon sugar?

A
  • carbon 1’ holds the base
  • carbon 5’ holds the phosphate
  • carbon 3’ holds the nucleotides
40
Q

sugar phosphate backbone

A

the 5-carbon sugar in combination with its phosphate group(s) form the double helix’s backbone

41
Q

there can only be __ rings per rung

A

3

42
Q

A to T is (number of h bonds)

A

2

43
Q

C to G is (number of h bonds)

A

3

44
Q

what is the complementary strand to
g c c a c t t?

A

c g g t g a a

45
Q

eukaryotic chromosome anatomy

A
  • centromere: the middle bit
  • duplicated chromosome: the x shaped one
  • chromatin: loose dna in the nucleus
  • sister chromatids: the x shaped thing again
46
Q

dna can wind up into organized chromosomes because of a “spool…” called

A

a histone protein

47
Q

somatic cells

A

diploid (2n)
two of each type of chromosome (46)

48
Q

gametes

A

haploid (n)
one of each chromosome type (23)

49
Q

karyotype

A

an individuals complete set of chromosomes, arranged in numerical order

50
Q

autosomes

A

any chromosomes that is not a sex chromosome

biology 111 - intro to organisms - section ii (4 decks)

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