Gene expression Flashcards
What is an intron?
Non-coded DNA (cannot be made in to RNA)
What is an exon?
Code DNA that can be transcripted to RNA
Does mitochondrial DNA come from both parents?
No, only maternal
What are nucleic acids made of?
Sugars, phosphoric acid, nitrogen
How did Avery prove that DNA was genetic material?
Transformation of R strain bacteria to S strain
Who did Watson & Crick steal data from?
Rosalind Franklin
What are the nucleotides for DNA?
Adenine, Thymine, Guanine, Cytosine
What way does DNA curve?
To the right
What makes up the DNA backbone
Phosphate and sugar
Which nucleotides are purines?
Adenine & Guanine
Which nucleotides are pyrimidines
Cytosine & Thymine
What are the nucleotide pairs?
Adenine & Thymine
Cytosine & Guanine
What is attached to each sugar on a DNA strand?
Cyclic base (Purines, Pyrimidines)
How many hydrogen bonds are associated with the Guanine - Cytosine pairing?
3
How many hydrogen bonds stabilize the AT pairs?
2
What direction is DNA synthesized?
5’ to 3’
What adds nucleotides to the 3’ end?
DNA polymerase
How is the lagging strand duplicated?
Transcripted 5’ to 3’
DNA Ligase binds together Okazaki fragments
How often does an error occur during transcription?
1 in every 100,000
What is the purpose of exonuclease?
Checks T-A and C-G pairings and degrades wrong pairings
What are the mutation types?
Addition, Subtraction, Substitutions
Where are genes contained?
Within chromosomes
What is RNA ploymerase?
Copies DNA template strand to RNA
Is there higher or lower copying fidelity in transcription vs DNA replication?
Lower
Which strand is the coding strand?
3’ to 5’
Leading strand
What region of the DNA initiates transcription?
Promoter (DNA sequence)
What is the elongation process during transcription?
RNA polymerase extends RNA chain
What causes the termination of elongation/transcription in bacteria?
Hair-pin loop (double stranded RNA)
Unknown in eukaryotes
Where does transcription occur?
Nucleus
What is the purpose of capping during transcription?
Ensres stability during translation
What is the purpose of the poly-A tail on the 3’ end?
Protects mRNA from degradation and terminates transcription
Do introns appear in the mature RNA transcript?
No
What are the mature RNA types?
transfer RNA (tRNA) Ribosomal RNA (rRNA)
What is the purpose of tRNA?
Binds one specific amino acid
Recognizes messenger RNA sequences
What is the purpose of rRNA?
Makes ribosomes
Orients mRNA, tRNA & Amino Acids
Ensures accurate reading of genetic code
What is messenger RNA?
Contains info for proteins
Accounts for the most transcription within a cell
Allows for amplification of genetic message
What type of RNA has the highest turnover?
mRNA
What determines the amino acid sequence?
Nucleotide sequence
How are polypeptides synthesized?
In the cytoplasm, within ribosomes
Bind to A site (aminoacyl)
Move to P Site (Peptidyl)
Exits E site
What occurs at the Aminoacyl site?
Binds newly arriving tRNA
What occurs at the Peptidyl site?
tRNA carrying polypeptide chain resides & contacts mRNA
What occurs at the Exit site?
tRNA exits ribosome
What is the start codon?
AUG
What are the stop codons?
UAG, UGA, UAA
What are examples of posttranslational modifications?
Amino acids removed, sugars added
What are results of posttranslation modification?
Activate protein
Direct protein to correct location
How are proteins folded?
Protein attaches to endoplasmic reticulum and folds while inside ER
What is glycosylation?
Enzyme-directed, site specific process
A sugar is added to a protein
Where does glycosylation occur?
Er and Golgi Apparatus
What are the donor molecules for glycosylation?
Nucleotide sugars
What are the acceptor residues for glycosylation?
Asparagine, Serine, Threonine
What is PCR?
Amplifying a DNA segment in vitro
What are the steps of PCR?
- Denaturation
- Annealing
- Extension
What is denaturation in PCR?
Separation of DNA strands
What is annealing in pCR?
Primers bind DNA
What is extension in PCR?
New DNA is synthesized
What type of PCR is used for testing of diagnostic samples?
real time PCR (qPCR)
