Chapter 15-PowerPoint Flashcards
Where did the early ideas to explain how genes work
come from?
studying human diseases
What did Archibald Garrod do/experiment?
- Recognized that alkaptonuria is inherited via a recessive allele
- Proposed that patients with the disease lacked a particular enzyme
What was the significance of Archibald Garrod experiment?
connected genes to enzymes
When did Archibald Garrod do his experiment?
1902
What is alkaptonuria?
metabolic disease Characterized by hardening and blackening of the cartilage and urine that
turns black when exposed to air.
What is alkaptonuria caused by?
two mutated copies of a gene that normally encodes the
enzyme that breaks down homogentisic acid; these mutated versions are either not produced or produced only at low levels.
What is the central dogma?
DNA → RNA → protein
Who gave the name to the central dogma? when?
Francis Crick in 1956
What is transcription?
DNA template strand is copied into a
complementary RNA strand
What is translation?
uses the RNA copy to assemble amino acids into a polypeptide
What type of cells does coupling of transcription and translation occur in?
prokaryotic cells
transcription nuc—exist nuc pores, translation occurs in cytoplasm at ribosomes
eukaryotic cells
What happens to precursor m-RNA?
Pre-mRNA ends are modified and extra segments (entrons—non coding regions) are
removed by RNA processing – functional mRNA exits
the nucleus and is translated in the cytoplasm.
What are the extra non coding region on precursor-mRNA called?
entrons
What replaces T in RNA?
U
Where does transcription occur in eukaryotic cells?
nucleus
Where does translation occur in eukaryotic cells?
cytoplasm at ribosomes
Which type of cells produces a functional mRNA directly, with no modifications?
prokaryotic cells
What is a codon?
three-letter word (triplet) of the code
How many strands of DNA are chosen for transcription?
1
How many strands of DNA are chosen for replication?
2
What makes RNA?
RNA polymerase
Does RNA require free 3’ hydroxyl end?
no
Is RNA still anti-parallel?
yes
What direction is RNA? what is this similar to?
5’ to 3’ , same as DNA
What is the start codon?
AUG, Met
Do the base pairs before AUG matter?
no
Messenger RNA (mRNA)
RNA decoded to make proteins
Ribosomal RNA (rRNA)
ribosomes contain this
Transfer RNA (tRNA)
brings in amino acids to the ribosomes during protein synthesis
Small nuclear RNA (snRNA)
part of a complex involved in removing uncoding regions/entrons
Signal recognition particle RNA
SRP RNA
Micro-RNA (miRNA)
small stretches of RNA, anti-sense (can bind to mRNA and are complementary sequences to mRNA)
How many codons are there?
64
How many sense codons are there?
61
What are sense codons?
codons that specify an amino acid
What are the stop codons? (3)
UAA, UAG, and UGA
Which amino acids only have one codon? (2)
methionine and tryptophan
What is degeneracy?
amino acids that can be represented by more than one codon
What does it mean when the genetic code is commales?
there are no indicators to mark the end of one codon and the beginning of the next
What is the genetic code universal to?
all living organisms and viruses
What are the 2 man components of a gene?
Promoter and Transcription unit
What is a promoter?
control sequence for transcription
What is the transcription unit?
section of the gene that is copied into an RNA
molecule
What are the 3 stages of transcription?
- Initiation
- Elongation
- Termination
What type of polymerase is in prokaryotic transcription?
single RNA polymerase, one type not one copy
Does Initiation of mRNA synthesis require a primer in prokaryotic transcription?
no
What does prokaryotic transcription require? (3)
- promoter
- start site
- termination site
What is required for the initiation of transcription in eukaryotic?
series of transcription factors
• Necessary to get the RNA polymerase II enzyme to a promoter and to initiate gene expression • Interact with RNA polymerase to form initiation complex at promoter
What are the 3 qualities of RNA polymerase?
1) 5’—>3’
2) doesn’t require primer
3) RNA is anti-parallel to template strand
What does RNA pol 1 transcribe?
rRNAs
What does gene expression refer to?
transcription and translation
What does RNA pol 2 transcribe?
mRNAs
What does RNA pol 3 transcribe?
tRNAs
Where does the initiation complex form in eukaryotic cells?
promoter
Does Each polymerase recognizes a different promoter structure?
yes
Are mRNAs are modified after transcription?
yes
Are mRNAs are modified after transcription?
yes
Are RNA molecules are single or double polynucleotide chains?
single
What is involved in processing?
1) 5’ cap added
2) Poly A tail added to the end of the mRNA
3) splicing to remove non-coding regions
What is copied in transcription?
Only the sequence encoding a single gene is copied
• In eukaryotes, RNA polymerase II cannot bind directly to DNA, transcription
factors must first bind to the promoter – in bacteria, RNA polymerase binds
directly to DNA
• Termination in Prokaryotes is caused by the formation of the hairpin loop. This
stretch of A-U base pairing makes the RNA-DNA hybrid less stable and it falls
off the enzyme.
• In Eukaryotes, the end of transcription is not defined by RNA polymerase since
the transcript undergoes modification – capping at the 5’ end and addition of
the poly-A tail at the 3’end.
differences between eukaryotic and prokaryotic transcription
What is required to allow recognition of state site in prokaryotes?
single factor called sigma subunit
What is required to allow recognition of state site in eukaryotes?
whole host of transcription factors
What are the 2 subunits of a ribosome?
large and small subunit
What are the bonds between amino acids?
peptide bonds
What are peptide bonds formed by?
ribozymes
peptidyl transfase
large subunit
alpha, beta, delta, omicorn
varient names
differences between delta and omicorn?
number of mutations in spike protein difference
Where are the spike proteins located?
nuclear envelope
What is the genetic material in the virus?
RNA
omicorn spike mutation has 50 mutations
delta spike mutation has greater than 20 mutations
yes
How many deaths from the flu occur every year?
37,000
How do they differentiate the variants of COVID?
sequencing the genome
Was omicron present before delta came along?
yes