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biology 120 > molecular biology > Flashcards

molecular biology Flashcards

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AP® Biology flashcards
1
Q

what is the characteristics of genetic material

A

-replication
-storage of information
-expression of that info
-variations of mutation

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2
Q

early studies inducated that genetic material resides in the…

A

nucleus

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3
Q

when the nucleus was stained with specific dyes it was shown to consist of…

A

proteins and nucleic acid

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4
Q

in body calls the amount of DNA was constant, how ever in gametes in was

A

reduced to 1/2

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5
Q

what is nucleic acid

A

it is polymers consisting of many nucleotide monomers, including DNA and RNA

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6
Q

what components do nucleotides consist of

A

-nitrogenous base
-a pentose (ribose 5 c sugar)
-a phosphate group

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7
Q

what are the two kinds of nitrogenous bases

A

purines, double rings (adenine, guanine)
Pyrimidines, single rings (cytosine, thymine, uracil)

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8
Q

what is nucleoside composed of

A

a nitrogenous base and a ribose/deoxyribose sugar

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9
Q

how are nucleosides and nucleotides named according to

A

the specific nitrogen base (A,C,G,T,U)

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10
Q

what is thymine replaced with in RNA

A

uracil

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11
Q

what are the 3 major types of RNA

A

mRNA messenger
tRNA transfer
rRNA ribosomal

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12
Q

what is mRNA

A

messenger RNA is a transcript of the gene that carries information (as a sequence of codons) for the synthesis of proteins

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13
Q

what is tRNA

A

transfer RNA is an RNA molecule that functions as an interpreter between nucleic acid and protein language by picking up specific amino acids and recognizing the appropriate codons in the mRNA

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14
Q

what is rRNA

A

ribosomal RNA is the most abundant type of RNA which together with proteins forms the structure of ribosomes

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15
Q

for the hereditary material how is the genetic information coded in the DNA molecule

A

the basis information must lie on the linear sequence of the nitrogenous bases, i.e the arrangement of the bases

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16
Q

for the hereditary material how is the information passed on from one cell to the next (i.e. during mitosis)

A

it must be because of the complimentary base pairing of nitrogenous bases, that one strand serves as a template to form a new strand (DNA replication)

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17
Q

in hereditary material how does the genetic material function

A

it must be that the DNA passes on its information (transcription) where this uses in the cell function

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18
Q

what is the DNA replication process

A

the process in which DNA is duplicated (DNA—>DNA)

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19
Q

what did meselson and stahl exprarament demostrate

A

it showed that DNA replication is semi-conservitive

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20
Q

what is a semi conservative process

A

in which a double helix gives rise to double helices, each with an old strand and a newly synthesized strand

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21
Q

what is the molecular process of DNA replication

A

-untwisting of the DNA molecule (occurs by breaking of H bonds between N bases, promoted by certain enzymes
-each of two strands now serve as a template to synthesize a new complementry strand
-a enzyme called DNA polymerase helps in the linking of free nucleotides to form a new strand
-nucleotides are always added 3’-end (which has a free OH) of the new strand
-the template (old) and complementry (new) strands are anti parallel; the 3’-end of one strand in paired with 5’-end of the other
-both parent strands are replicated and replication in eukaryotic cells proceeds in many locations of each strand froming DNA peices
-DNA peices are linked together by enzyme DNA ligase
-the two DNA molecs are identical, i.e in the base sequence to the parent molec
-each DNA molec is 1/2 the old and 1/2 the new molec- semi conservative

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22
Q

what is the structure of RNA

A

it is usually a single strand polynucleotide although in somecases it may fold up on itself

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23
Q

what pyrimidines is replaced with uracil in RNA

A

thymine

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24
Q

what is the sugar molecule in RNA

A

it is ribose instead of deoxy

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25
Q

what are the 3 possible mechanisms for DNA repliation

A

1) semiconservative mechanism
2) conservative mechanism
3) dispersive mechanism

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26
Q

what is the semiconservative mechanism for DNA replication

A

DNA replication produces DNA molecules with one parental strand and 1 newly made strand

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27
Q

what is the conservative mechanism for DNA replication

A

DNA replication produces 1 double helix with both parental strands and the other with two new daughter strands

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28
Q

what is the dispersive mechanism for DNA replication

A

DNA replication produces DNA strands in which segments of new DNA are with the parental DNA

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29
Q

what is the leading strand of DNA replication

A

the strand that is going the 3’—5’ way

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30
Q

what is the legging strand in DNA replication

A

the strand that is going the 5’—3’ way

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31
Q

what is helicase protein

A

it unwinds DNA helix

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32
Q

what is single stranded binding protein enzyme

A

stabilizes single stranded DNA and prevent the two strands at the replication fork form reforming double stranded DNA

33
Q

what is topoisomerearse enzyme

A

it avoids twisting of the DNA ahead of the replication fork (in circular DNA) by cutting the DNA, turning the DNA on one side of the break in the direction opposite to that of the twisting force, and rejoining the strands

34
Q

what is the enzyme primase

A

it assembles RNA primers in the 5’—3’ direction to initiate a new DNA strand

35
Q

what is the enzyme DNA polymerase III

A

main replicaiton enzyme in ecoli; it extends the RNA primer by adding DNA nucleotides to it

36
Q

what is DNA polymerase I enzyme

A

esherichia coli enzyme that uses its 5’—3’ exonuclease activity to remove the RNA of the previously synthesized okazaki fragment, and uses its 5’—3’ polymerization activity to replace the RNA nucleotides with DNA nucleotides

37
Q

what is the sliding clamp enzyme

A

tethers DNA polymerases III to the DNA template, making replication more efficent

38
Q

what it the enzyme DNA ligase

A

it seals the nick left between adjacent bases after RNA primers replaced with DNA

39
Q

why can bacteria replicate much faster then eukaryotes

A

because bacteria have one single origin whereas eukaryotes require multiple origins

40
Q

how fast can bacteria replicate compared to eukaryotes

A

it advances at a rate of about 500-1000 nucleotides per second in bacteria and about 50-100 per second in eukaryotes

41
Q

what is gene expression

A

its the flow of genetic information from the genotype to the phenotype
DNA-RNA-protein

42
Q

what is the one gene one enzyme (polypeptide) hypothesis

A

a single gene controlled the sysntesis of a single enzyme

43
Q

what is the central dogma

A

it is the process of DNA (transcription) RNA (translation) protein
-can also go from RNA to DNA

44
Q

what is transcription

A

its the process by which the info encoded in DNA is made into a complementary RNA. the segments of DNA transcribes into RNA molecules that can encode proteins are said to produce messanger RNA (mRNA). other segments of DNA are copied into RNA molecules called non-coding RNAs (ncRNAs)

45
Q

what is translation

A

it is the process of synthesizing a specific polypeptide by using the information encoded in the mRNA on a ribosome

46
Q

what happens to most genes

A

most are transcribes into mRNA and then the mRNA is translated into polypeptides

47
Q

where does gene expression take place in prokaryotes

A

both transcription and translation occur in the cytoplasm due to the absence of nucleus

48
Q

where does gene expression take place in eukaryotes

A

transcription occurs int he nucleus and translation occurs in the ribosomes present on the rough endoplasmic membrane in the cytoplasm

49
Q

what is a gene

A

an organization of DNA sequences that enables a segment of DNA to be transcribed into RNA and ultimately results in the formation of a functional product

50
Q

what is the gene composed of

A

the promoter, the regulatory sequence, the transcribed region and the terminator

51
Q

what is the promoter portion of a gene

A

the site in the DNA where RNA polymerase binds to begin transcription

52
Q

what is the regulatory sequence of a gene

A

the sites binding to regulatory proteins control whether a gene is turned on or off

53
Q

what is the transcribed part of a gene

A

a region of a DNA that is transcribed into a RNA molecule

54
Q

what is a terminator part of a gene

A

a sequence that causes the RNA strand to be released from the transcription complex

55
Q

what is transcription

A

DNA directed RNA synthesis (DNA–RNA)

56
Q

what is the molecular process of transcription

A

-initation of transcription requires transciption factors binding to promoter region of a gene
-TFs recuit DNA polymerase binding to a promoter region (with TATA box in eukaryotes and pribnow box TATAAT i prokaryotes
-unwinding of the DNA double helix
-in given region of DNA only one strand (called template strand) acts as a template. the template runs in the 3’-5’ direction
-elogation:RNA polymerase catalyzes the transcription, and U rather than T incorporates into RNA
-transcription ends at a termination site (termenator)(with an AAUUAAA signal for polyadenylation)

57
Q

what are the products of transcription

A

transcripts- RNAs (mRNA, tRNA, rRNA)

58
Q

what is the location of eukaryotic and prokaeryotic transcription

A

prokaryotic: cytoplasm
eukaryotic: nucleus

59
Q

what is the initiation of transcription on pro and eukaryotic cells

A

pro: a single sigma factor
euk: 5 general transcription factors

60
Q

how many polymerases do eukaryotes and procaryotes have

A

pro: a single type
euk: three types of polymerases (II,I&III)

61
Q

in eukaryotes what polymerizes transcribes what

A

RNA polymerase I transcribes rRNA genes, RNA polymerases II transcribes mRNA, miRNA, snRNA, and snoRNA genes and RNA polymerases III transcribes tRNA and 5S rRNA genes

62
Q

what does a typical eukaryotic protein coding gene have both of in transcription

A

a coding sequence (exons) and a non-coading sequence (internal non-coading sequences-interons;flaking sequences-cap and tail)

63
Q

in transcription what is a exon

A

a coding portion of a gene

64
Q

in transcription what is a intron

A

a non-coading portion of a gene that is excised form the RNA transcription

65
Q

what is RNA splicing

A

the removal of introns and joining of exons in euakaryotic RNA, forming a mRNA molecule with a continuous coding sequence

66
Q

what is intron RNA defined by

A

specific sequences within the intron and the intron-exon boundaries

67
Q

where does mRNA splicing occur

A

in a spliceosome (a large RNA-protein complex) before mature RNA

68
Q

how does tRNA and rRNA slicing occur

A

they are self spicing by a ribozyme

69
Q

what are biological functions of of introns

A

-alternate splicing generates different mRNA molecules form the same RNA transcript thus producing different proteins
-they may also contribute to genetic diversity
-may also regulate gene expression

70
Q

RNA processing also involves a flanking sequence what are the benefits to this

A

-could regulate the stability of mRNA in the cytoplasm
-seem to facilitate the export of mRNA
-help ribosomes attach to the 5’ end

71
Q

in RNA processesing+flanking what is capping

A

a 7-methylguanosine attached to the mature eukaryotic mRNAs at the 5’ ens

72
Q

in RNA processesing+flanking what is tailing

A

a tail is added to the most mature eukaryotic mRNAs at the 3’ end

73
Q

what is the genetic code

A

the nucleotide info that specifies the amino acid sequence of a polypeptide; the genetic code consists of triplets (codons) of nucleotides. each codon specifies an amino acid in a polypeptide or a signal to either start or terminate peptide synthesis

74
Q

how many possible codons is there

A

since there is four bases there is 64 possible codons

75
Q

what is a start codon and what does it inducate

A

(AUG) indicates starting point of translation, and codes for methionine

76
Q

what are the stop codons and that do they inducate

A

(UAA, UGA, UAG) inducate end of translation

77
Q

how many codons code for particular amino acids

A

60

78
Q

since there are only 20 amino acids the genetic code could be _____ for certain amino acids but the code is not____

A

redundant, ambiguous

79
Q

is the genetic code universal

A

yes. genes can be transcribed and translated after being transplanted form one species to another
how ever the genetic codes of different organisms are often biased towards using one of the several codons that encode the same amino acids over the others-codon usage bias

biology 120 (15 decks)

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