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87 Cards in this Set

  • Front
  • Back
monomer units of DNA and RNA are called?
nucleotides
a nucleotide consists of?
1) nitrogen containing heterocyclic base
2) a ribose or deoxyribose sugar
3) a phosphoric acid unit
major purine bases
1) adenine
2) guanine
mojor pyrimidine bases
1) cytosine
2) thymine
3) uracil (only in RNA)
what is the repeating unit of the DNA or RNA?
a nucleotide
in RNA, nitrogen base is attached?
beta to the ribose
in DNA, nitrogen base is attached?
beta to deoxyribose
sugar in nucleotide is phosphorylated at?
carbon 5
naming purine
adenine and guanine
--osine
adenosine and guanosine
naming pyrimidenes
cytosine, thymine, and uracil
--idine
cytidine, thymidine, and uridine
dTMP
deoxythymidine 5-monophosphate
dAMP
deoxyadenosine 5-monophosphate
dCMP
deoxycytidine 5-monophosphate
UMP
uridine 5-monophosphate
GMP
guanosine 5-monophosphate
when nucleotides polymerize, the 5 phosphate on one unit esterifies to?
the 3 OH on another unit
the terminal 5 unit retains the?
phosphate
the most common form of DNA is?
B form
DNA structurs was determined by?
Watson and Crick in 1953
DNA consisits of?
2 chains of nucleotides coiled around one another in a RIGHT handed double helix
the chains run?
antiparallel
the chains are held together by?
hydrogen bonding between compimentary base pairs
how many H bonds between A=T
2
how many H bonds between G=C
3
the 2 strands of DNA are saide to be?
complimentary
what are complementary strands?
the opposite strands of the double helix are H-bonded to one another such that A=T, G=C are always paired
major groove
1) outside diameter = 2nm
2) interior diameter = 1.1 nm
minor groove
1) length of one turn of helix = 3.4 nm
2) contains 10 base pairs
what are in the core of the helix?
H-bonded base pairs
backbone of B DNA segment?
sugar-phosphate backbone
choromosomes?
pieces of DNA
chromosomes contain?
genetic instructions or genes
prokaryotes
1) single chromosome
2) NO true nucleus
prokaryote
an organism with simple celluler structure in which there is no true nucleus enclosed by a nuclear membrane and there are no true membrane-bound organelles in the cytoplasm
eukaryote
1) # and size of choromosomes vary
2) true nucleus
3) nucleosome
eukaryote
an organism having cells containing a true nucleus enclosed by a nuclear membrane and having a variety of memebrane-bound organells that segregate different cellular functions into different compartments
what is nucleosome?
the first level of chromosome structure consisting of a strand of DNA wrapped around a small disk of histone proteins
RNA structure
1) sugar-P backbone
2) ribonucleotide
3) linked by 3'-5' phosphodiester bonds
RNA molecules usually
single stranded
deoxyribose is replaced by (RNA)?
ribose
thymine is replaced by (RNA)?
uracil
replication
DNA duplicates itself
transcription
RNA is made on a DNA template
translation
protein is synthesized from AAs and the 3 RNAs
reverse transcription
RNA directs synthesis of DNA
transfer RNA (tRNA)
1) transfers AAs to the site of protein synthesis (ribosomes)
2) has the anticodon
ribosomal RNA (rRNA)
rRNA forms ribosomes by reacting with proteins
messenger RNA (mRNA)
1) directs the AA sequence of proteins
2) is a complimentary copy of a gene
3) has the codon for an AA in a protein
transfer RNA
1) single stranded
2) about 80 nucleotides
the overall shape structure of tRNA is?
cloveleaf in a L-shaped conformation
transcription is catalyzed by?
RNA polymerase
4 steps of transcription
1) RNA polymerase binds to promoter region
2) initiation
3) chain elongation
4) termination
chain elongation forms?
3'-5' phosphodiester bond
eukaryote mRNA must be processed
1) 5' cap structure is added
2) 3' poly A tail is added
3) extrons are cut out
4) introns are spliced together
extrons
noncoding base sequences
introns
coding sequences
what help recognize intron-extron boundaries?
splicosomes
splicosomes are composed of?
small nuclear ribonucleoproteins (snRNPs)
the genetic code (DNA)
the message on DNA translated to mRNA
1) degenerate
2) specific
3) nonoverlapping and commaless
4) universal
1) generate
more than one 3-base codon can code for the same AA
2) specific
each codon specifies one AA
3) nonoverlapping and commaless
1) none of the bases are shared between consecutive codons
2) no noncoding bases appear in the base sequence
4) universal
except in a few instances, all organisms use the same codon
all 64 codons have meaning
1) 61 code for an AA
2) 3 code for the "stop" signal
protein synthesis is called?
translation
protein synthesis is carried out on?
ribosomes, complexes of rRNA and proteins
the mRNA plus the multiple ribosomes are called?
a polysome
tRNA binds a specific AA aided by?
aminoacyl tRNA synthethase
the genetic code (DNA)
the message on DNA translated to mRNA
1) degenerate
2) specific
3) nonoverlapping and commaless
4) universal
1) generate
more than one 3-base codon can code for the same AA
2) specific
each codon specifies one AA
3) nonoverlapping and commaless
1) none of the bases are shared between consecutive codons
2) no noncoding bases appear in the base sequence
4) universal
except in a few instances, all organisms use the same codon
translation process
1) initiation
2) chain elongation
3) termination
1) initiation
1) initiation factors (proteins)
2) mRNA
3) initiator tRNA
4) small and large ribosomes
---come together---
P-site binds to?
the growing peptide
A-site binds to?
the aminoacyl tRNA
2) chain elongation
1) aminoacyl tRNA binds to A-site
2) peptide bond formation
3) translocation (movement) of ribosome down the mRNA chain to next codon
3) termination
1) upon finding a "stop" codon a release factor binds a the empty A site
2) the bond between the last AA and peptidey tRNA is hydrolyzed releasing the protein
mutations
are mistakes introduced into the DNA sequence of an organism
1) point
substitution of a single nucleotide for another
2) deletion
one or more nucleotides are lost
3) insertion
one or more nucleotides are added
mutagens
1) chemicals causing a change in the DNA sequence
2) also carcinogens
UV light causes formation of?
a pyrimidine dimer on a DNA strand
failure to repair this defect (pyrimidine dimer) can lead to?
xeroderma pigmentosum
restriction enzymes
are bacterial enzymes that cut the backbone of DNA at specific nucleotide sequences