LO13 Day 1 Flashcards
do all genes code only for proteins?
no they code for enzymes and other proteins
Linus Pauling showed what?
That a mutation in a single gene could result in a defective protein
Transcription converts what?
DNA to RNA
Translation produces what?
A polypeptide from RNA
What is the central dogma of molecular biology?
states that the nucleotide sequence of some DNA gene code for the amino acid sequence of a specific polypeptide via an RNA intermediate
Is a single stranded polymer of nucleotides
RNA
What are the two purine nitrogenous bases used in RNA
Adenine and Guanine
What two pyrimidines bases used in RNA?
Uracil and Cytosine
How is Ribose different from deoxyribose at the 2’ carbon
Has a hydroxyl group
Deoxyribose and ribose are both ______ sugars
pentose
What is at the 5’ end of RNA molecule
exposed phosphate group
What is at the 3’ end of RNA molecule?
exposed OH group
Phosphate group of a DNA or RNA nucleotide makes this molecules _____ and ____ charged
acidic and negatively
What is attached to the 1C of the ribose sugar
nitrogenous base
What bond forms between 3C of ribose and phosphate group of the next nucleotide?
covalent
mRNA is what?
messenger RNA
mRNA contain the infromation for making specific _______
proteins
mRNA is transcribed from _______________ in DNA
protein-coding genes
Definition: A set of three consecutive RNA nucleotides that specifies one amino acids
codon
3 nucleotides specify how many amino acids?
one
the number order and type of codons in a specific mRNA determines what?
the primary structure of protein
genetic code includes how many codons?
64
AUG is which codon and codes for what?
start codon and methionine
How many codons code for terminate translation?
3
The genetic code is ____ and virtually ______
redundant and universal
amino acids specified by ______________ codon
more than one
A codon never specifies ________ amino acid
more than one
tRNA carry what?
amino acids
A tRNA carries a specific amino acids at its ___ end
3’
Definition: enzymes that covalently link an amino acid to its respective tRNA
Aminoacyl-tRNA
During _______ a tRNA molecule interacts with a specific mRNA codon at a ribosome
translation
tRNA has a set of 3 nucleotides called _______
anticodon
definition: sequence of nucleotides determines which amino acid the tRNA will carry
anticodon
during translation the anticodon binds to the ___________ via __________ bonding
RNA codon; hydrogen
rRNA forms what?
ribosomes
rRNA molecules make up what?
ribosomes and ribosomal proteins
during translation ribosomes bring which molecules together?
mRNA and tRNA
How many binding site do ribosomes have for an mRNA molecule?
one
How many binding site do ribosomes have for an tRNA molecule?
three
What binds to a ribosome in the groove between the small and large subunits?
mRNA
definition: allows for interaction between the mRNA codon and the tRNA anicodon
A site
Definition: holds the growing polypeptide chain
P site
Definition: where an empty tRNA exits the ribosome
E site
transcription goes from what to what?
DNA to RNA
What do RNA polymerases do?
They form single-stranded RNA by temporarily pairing RNA nucleotides with DNA nucleotides
During transcription what is formed
a complementary RNA strand that is antiparallel to the template DNA
RNA is synthesized in which direction?
5 –> 3
Do RNA polymerases require a separate helicase or primer?
No
Definition: transcription begins
initiation
definition: a special sequence of base pairs on the DNA template strand that signals the beginning of a gene
promoter
downstream is which direction
towards the 3’ end of the RNA
upstream is which direction
towards the 5’ end of the RNA
What does RNA polymerase do?
unwinds the DNA and initiates transcription downstream from the promoter region
Does the strand that is used as the template vary?
Yes, from gene to gene
definition: RNA polymerase reads the DNA template and adds complementary RNA nucleotides to the 3 end of the growing RNA transcript
elongation
What happens to the DNA double helix after each portion is transcribed?
It reforms
Definition: RNA polymerase stops transcription upon reaching the termination sequence in the template DNA
termination
in eukaryotes what is modified after transcription
mRNA
definition: mRNA is before it has been modified
preMRNA
The 5’ and 3’ ends of mRNA molecules are modified why?
for protection and recognition by a ribosomes
What is added to the 5’ end of mRNA
5 cap
What is the 3 cap
long chain of adenine nucleotides
What is added to the 3’ end of mRNA
3’ poly-A tail
What is the 5 cap
modified guanine nucleotide
What happens to introns?
they are cut out by enzymes during modification
definitions: non coding regions that are located within the DNA sequence of protein-coding genes
Introns
What are exons?
the coding regions; that are spliced together
What gene expression process occurs in the nucleus of a eukaryotic cell?
transcription
