The Chemical Nature of the Cell Flashcards
T-A pairs have ___ hydrogen bonds
two
G-C pairs have ____ hydrogen bonds
three
DNA has ______ sugar
deoxyribose (no oxygen)
The strands in DNA run _____
antiparallel (opposite direction)
in RNA, _____ replaces thymine
uracil
RNA has _____ sugar
ribose (with an OH)
a _______ linkage connects the 5’ phosphate group and the 3’ OH group of adjoining nucleotides
phosphodiester
what is the DNA backbone made up of
deoxyribose sugars, linked by phosphate
what is the DNA backbone linked with
phosphate
what are the bases in DNA
A,T,G,C
what type of end does DNA have
5’
How many strands does DNA have
2
What are the bases in RNA
A<u></u>
What type of end does RNA have
triphosphate
how many strands does RNA have
one
what is eukaryotic genome organization
how we go from double stranded DNA to a metaphase chromosome
what are the steps in eukaryotic genome organization
DNA duplex - Nucleosome- chromatin- coil- condensed chromatid
greater than 80% of all colon cancers are caused by mutations in which gene
APC
RNA is ____ to the non-template strand, and ____ to the template strand
similar (with U instead of T)
complimentary
(expressed/not expressed)
Introns
not expressed
(expressed/not expressed)
exons
expressed
which way does the template strand run
3’-5’
how many different amino acids are there
20
how many codon are there for the 20 amino acids
64
what percentage of DNA actually codes for protein
3-5%
RNA has a _____ group on the 2’-carbon atom of its sugar component
hydroxyl
DNA has a _____ on its sugar component
hydrogen
(more/less)
RNA is ____ reactive than DNA
more
How does RNA form secondary structures
RNA fods to form secondary structures because of the hydrogen bonding between complementary bases on the same strand
What is ribosomal RNA
structural and functional component of the ribosome
what is messenger RNA
carried genetic code for proteins
what is transfer RNA
helps incorporate amino acids into polypeptide chain
describe the synthesis of an RNA molecule
- from a DNA template (3’-5’)
- the transcribed strand is the template strand
describe the transcription unit of RNa
includes a promoter RNA coding sequence, and a terminator
RNA synthesis is ____ and _____ to the template strand
complimentary, antiparallel
where are new nucleotides added during RNA synthesis
they are added to the 3’-OH group of the growing RNA
which way does transcription proceed
5’-3’ (left to right)
does RNA synthesis require a primer to be initiated
no
what is a consensus sequence
sequences that possess considerable similarity between different species
where does transcription occur (eukaryotes)
in the cytoplasm
how many genes er mRNA transcript
typically 1
how many spaces are there between codons
none
each nucleotide is part of ___ codon(s)
1
what is meant by “the genetic code is degenerate”
most amino acids are specified by more than one codon
what is meant by “the genetic code is (nearly) universal”
with minor exceptions, each codon has the same meaning in all organisms
What is the ribosomal complex composed of
many proteins and ribosomal RNA
a small and a large subunit
three binding sites for tRNA
what are the three binding sites for tRNA
APE
aminoacyl, peptdyl, exit
How many tRNAs are there
there is a unique tRNA for each codon, so technically there should be 64 tRNAs but not all of them are used equally
what do aminoacyl tRNA syntheses bind to
each aminoacyl tRNA syntheses bind to one UNCHARGED tRNA and its corresponding amino acid
there is a specific ____ for each amino acid
enzyme
where do enzymes attach the amino acids to
the enzyme attaches the amino acid to the 3’ end of the tRNA
what is the process of getting a charged tRNA
free amino acid and an uncharges tRNA get blinded together by an aminoacyl tRNA synthase
which amino acid does translation always begin with
met (aug)
which way is the polypeptide synthesized
the polypeptide is synthesized from the amino end to the carboxyl end
which amino acid is on the amino end of the polypeptide?
met (because the amino side is synthesized first and Met is the first one synthesized)
describe translation initiation
the initiator aug codon is recognized and met is establishes as the first amino acid in the polypeptide chain
describe translation elongation
elongation is when successive amino acids are added one by one to the growing amino acid polypeptide chain
describe translation termination
termination is where the addition of amino acids stop and the completed stands is released from the ribosome
initiation of translation requires a number of ____
initiation factors
where do the initiation factors required for the initiation of translation bind
the initiation factors for the initiation of translation bind to the mRNA
where specifically do the initiation factors for translation bind to on the mRNA
one group of initiation factors binds to the 5’ cap, others bring up a tRNA charged with met
what type of bond holds together the polypeptide chain of amino acids
peptide bonds
what do elongation factors do
elongation factors are bound to GTP molecules, and then they break their high-energy bonds to provide energy for the elongation if the polypeptide
what are the stop codons
UAA
UAG
UGA
what happens when a stop codon is encountered
a protein release factor binds to the A site of the ribosome
When the protein release factor binds to the A site of the ribosome, what happens
this causes the bind connecting the polypeptide to the tRNA to break creating the carboxyl/terminus o the polypeptide. completes the chain
what is translation
the process in which the sequence of bases in messenger RNA specifies the order of successive amino acids in a newly synthesized protein
what is a protein
proteins are linear polymers of amino acids that form three-dimensional structures with specific functions
how do proteins evolve
proteins evolve through mutation and selection and by combining functional units
what determines a proteins function and structure
the exact order of amino acids in a protein determines the proteins function and shape
what does the structure fo amino acids have
amino acids differ in their side chins; they consist of a central carbon atom connected by covalent bonds to four different chemical groups (ammino, carboxyl, hydrogen, and a variable side chain)
what are hydrophobic amino acids
amino acids that do not interact with water
amino acids are linked together to form ____ by ______
amino acids are linked together to form proteins by peptide bonds
describe the process of bonding with peptide bonds
in forming peptide bonds the carboxyl group of one amino acids reacts with the amino group of the nest amino acid, and a molecule of water is released.
what is a polypeptide
a polymer of amino acids connected by peptide bonds
what is a primary structure
the sequence of amino acids in a protein
it determines the folds
what is a secondary structure
formed by interactions between stretches of amino cids
what is a tertiary structure
the overall 3D shape of the polypeptide. formed by long-range interactions between secondary structures
what is a quaternary structure
several individual polypeptides that interact with each other
what are ribosomes
complex structures of RNA and protein that bind with mRNA and are the site of translation
where does transcription take place
in the nucleus
where does translation take place
in the cytoplasm
what are the cellular components needed for translation
messenger RNA, initiation factors, elongation factors, release factors, aminoacyl tRNA synthase, transfer RNA, and a ribosome (ribosomal RNA and ribosomal protein)
each non-overlapping group of _____ adjacent nucleotides constitutes a codon
each non-overlapping group of THREE adjacent nucleotides constituted a codon
each codon codes for a _____ in the poly peptide chain
each codon codes for a single amino acid in the polypeptide chain
what is tRNA
small rna molecules of 70-90 nucleotides (clover leaf structure)
each tRNA has the sequence ___ at the 3’ end
CAA
what is the anticodon
- the three bases in the anticodon loop (bottom loop of the clover-leaf structure)
- these three bases are the three that undergo base pairing with the corresponding codon
the _______ of the caA is the attachment site for amino acids that correspond to the anticodon
the 3’ hydroxyl of the A is the attachment site foe the amino acids that correspond to the anticodon
what does aminoacyl tRNA synthase do
- the aminoacyl TRNA synthase enzyme connects specific amino acids to specific tRNA molecules
- directly responsible for actually translating the codon sequence in a nucleic acid to a specific amino acid in a polypeptide chain
how many aminoacyl tRNA syntheses are there
most organisms have one for each amino acid
how does aminoacyl tRNA synthase work
the enzyme binds to multiple sites on any tRNA that has an anticodon corresponding to the amino acid, and it catalyzes formation of the covalent bond between the amino acids and the tRNA
what is an uncharges tRNA
a TRNA that has no amino acid attached
what is a charges tRNA
a tRNA that has an amino acid attached
