chem 26 - 2 Flashcards
leading strand is…(number) (the leader is first)
5 to 3
original DNA is parallel or not?
anti-parallel, so new DNA will be anti-parallel as well
only one new strand know as leading strand is able to…
grow continuously - this is from 3 - 5’. This strand will grow along w/ replication fork. this is on the other strand.
DNA polymerase is moving in the opposite direction of the…(poly does the opposite)
replication fork. lagging strand which is replicated in short segments known as okazaki fragments
DNA ligase
they join small molecules to make big molecules. They join okazaki fragments on the lagging strand
genome is..
A-T and C-G. we have 3 billion base pair possibilities
DNA vs. RNA
DNA is longer, it’s double helix. RNA is single strand. DNA is deoxyribose, RNA is ribose or D-ribose. DNA is in nucleus, RNA is synthesized in the nucleus but do function in cytoplasm.
different types of RNA
formed in nucleus then leave to the cytoplasm. mRNA, rRNA, tRNA
mRNA is a…
identical copy of a gene (DNA) - remember T is replaced by U
mRNA job is to…
carry code transcribed from DNA to the ribosome where the protein synthesis takes place
rRNA
ribosomal RNA. this is the RNA that is complexed w/ protein in ribosome. made of nucleic acid and protein
tRNA
transfer RNA, one single strand. clover leaf structure. (upside down cross) base pairing is done through H bonding. 3 nucleotides that are complimentary of codons (anti-codons)
tRNA job
read the codons and translate to amino acids, find that amino acid and bring it to the site.
only the gene…
opens up when DNA is copied. They contain triplets.
transcription
short segment of DNA, gene unwinds,
RNA polymerase is an..
enzyme in mRNA synthesis. helps form a complimentary of template strand. remember this copy is RNA
only difference between informational and template strand are…
the DNA bases are converted to RNA, so just the T and U. Only difference, otherwise they are identical
genetic information consists of…(just code the genetics)
triplets of 3 consecutive bases, or nucleotides, known as codons
codons carry..
codes for amino acids to be assembled into proteins
at the end of transcription, the messenger rNA has…
a matching bases for every base that was in the informational strand.
2 types of codons in initial messenger RNA (enter and exit)
introns and exons
exons are…(opposite of what you’d think)
good, introns are not. they are impurities.
the inital mRNA is called…(piano)
hnRNA (hetragenous nuclear RNA)
exons are codes for…(what everything does)
protein synthesis, but introns are not
introns are..
non-coding genes. they need to be removed.
exons need to be…
spliced.
after removing introns, you have…
mRNA. Before they are removed its hnRNA.
ribonucleotides sequence in mRNA chain is like…
a coded sentence that spells out the order in which amino acid residue should be joined to make protein
how many codons?
64: the 3-bases combo in RNA. 61 are codons for specific amino acids. The other 3 are termination codons (stop codon)
stop codons are…(ugg, stop)
UAA, UAG, UGA
get familiar with..
tRNA structure
tRNA is..
one single strand of RNA folded and held together by H-bonding
how many tRNA? (t goes w/ amino)
20 - bc there are 20 amino acids
tRNA is charged, means..
amino acid is joining RNA
anti codon (anti for mina)
sequence of 3 nucleotides that are complimentary to codons for mRNA.
ex of anti-codon
if mRNA is 5’ CUG 3’ then anti-codon would be 3’ GAC 5’
3 steps of translation (I ET)
- initiation 2. elongation 3. termination
initiation (mina initiates ribs w/ T)
- small subunit of the ribosome and mRNA bind together. 2. the first tRNA brings first amino acid to the site.
initiation
- small subunit of the ribosome and mRNA bind together. 2. the first tRNA brings first amino acid to the site. fir
first amino acid usually brought to chain is..
methionine. not all the proteins need met (methionine) at the end of the chain.
if the protein doesn’t need methionine, it…
will be removed by a process called post translation modification.
elongation (elongate the mRNA and translate the code)
growing the peptide chain - when 2 subunits of ribosomes is moving along mRNA, translating all the codons into amino acids.
enzyme called ribozyme (z is new)
it catalyzes the formation of a new peptide bond. it uses GTP for energy.
the energy released from hydrolysis of GTP to GDP can be used (just make new bonds)
to form peptide bonds
termination
when the ribosomes reaches the stop codon - that signals the end of translation
2 enzymes in the translation process (rizzo and RF are the translators)
ribozyme and releasing factor (this is an enzyme) this catalyzes releasing everything - tRNA, mRNA, peptide chain,
how everything is connected
DNA is made of genes, chromosomes are made of DNA, nucleic acids are made of nucleotides,
how to name nucleosides
AGTU end in osine and idine for RNA, and for DNA it’s the same just add deoxy as the prefix
what are the monomers of DNA and RNA?
nucleotides
ribonucleotides
Nucleotides containing ribose - they’re named AMP, UMP, etc.
deoxyribonucleotides
nucleotides containing DNA - named dAMP, dTMP, etc.
phosphate added to a nucleoside =
diphosphate or triphosphate
nucleotides in DNA and RNA are connected by…
phosphate diester bonds
bases (AT and GC) are connected by…(we connect by the usual)
H bonds
A and T form how many bonds?
2 H bonds
G and C form how many bonds?
3 H bonds
mutations are…
Mistakes in either copying or reading a given DNA sequence
The products of transcription are (transcription leads to RR)
(rRNA) ribonucleic acids. they carry the instructions stored by DNA to the sites of protein synthesis.
what do DNA polymerases do? (poly and I split after the transcript)
move into position on the separated strands right after they split —their function is to facilitate transcription of the exposed single-stranded DNA
DNA polymerase catalyzes…
covalent bonds between the 5’ phosphate group of the arriving nucleoside triphosphate and the 3’ –OH at the end of the growing polynucleotide strand
template strand is read in what direction?
3 to 5
new DNA strand can grow only
in the 5’ to 3’ direction
leading strand goes…
3-5 - same direction as replication fork
lagging strand goes…
5 to 3, opposite direction as replication fork
Messenger RNAs
carry information transcribed from DNA. They are polynucleotides that carry the same code for proteins as does the DNA
where is mRNA formed and moved to?
They are formed in the nucleus and transported to ribosomes, where proteins are synthesized.
ALL RNAs are formed where?
in the nucleus
Only one of the two DNA strands is transcribed during…
RNA synthesis
The DNA strand that is transcribed is the
template strand; its complement in the original helix is the informational strand
The genetic code in DNA consists of…
triplets of consecutive bases known as codons
The nucleotide triplets (codons) carried by…
mRNA code for amino acids to be assembled into proteins
nucleic acid code that corresponds to a complete protein is known as a…
gene
exon
The code for a gene is contained in one or more small sections of DNA
intron
noncoding sequence of bases that can interrupt the code for a given gene
initial mRNA strand is known as
heterogeneous nuclear RNA (or hnRNA
Codon
A sequence of three ribonucleotides in the mRNA chain that codes for a specific amino acid
Genetic code
The sequence of nucleotides, coded in triplets (codons) in mRNA, that determines the sequence of amino acids in protein synthesis
Codons are always written in the…
5’ to 3’ direction
cloverleaf shape is
tRNA
The anti codon of each tRNA is complementary to
the mRNA codon designating the amino acid that the tRNA carries
The three stages in protein synthesis are
The three stages in protein synthesis are
translation
Each ribosome is made up of two subunits called the small subunit and the large subunit, which contain protein enzymes and ribosomal RNA (rRNA)
translation 2
Protein synthesis begins with the binding of an mRNA to the small subunit of a ribosome, joined by the first tRNA. The first codon on the 5’ end of mRNA, an AUG, acts as a “start” signal for the translation machinery and codes for a methionine-carrying tRNA
translation initiation
Initiation is completed when the large ribosomal subunit joins the small one and the methionine-bearing tRNA occupies one of the two binding sites on the united ribosome
translation elongation
Next to the first binding site is a second binding site where the next codon on mRNA is exposed and the tRNA carrying the next amino acid is attached.
• A ribozyme in the large subunit catalyzes the new peptide bond and breaks the bond linking amino acid 1 to its tRNA
termination
This step also requires energy from GTP
