Cycle 7 Flashcards
Q: How do molecules recognize patterns?
A: They look for specific sequences but do not use letters like T/G/C/A; instead, they recognize different structures.
Q: What are the two main types of molecular signals?
A: Conformational changes (shape changes) and phosphorylation (addition of a molecule).
Q: How can you tell if transcription and translation are occurring in a prokaryotic cell?
A: If both processes occur simultaneously—while RNA polymerase transcribes mRNA, a ribosome attaches and begins translating.
Q: Why can’t transcription and translation occur simultaneously in eukaryotic cells?
A: Eukaryotic cells produce pre-mRNA, which must be fully transcribed and processed (introns removed) before translation begins.
Q: Where does transcription occur in prokaryotic and eukaryotic cells?
Prokaryotes: Cytoplasm
Eukaryotes: Nucleus
Q: What sequences does RNA polymerase recognize in prokaryotes vs. eukaryotes?
A: Prokaryotes: -35 and -10 regions in the promoter
Eukaryotes: Transcription factors bound to the TATA box
Q: What sequence helps ribosomes recognize mRNA in prokaryotes vs. eukaryotes?
Prokaryotes: Shine-Dalgarno (SD) box
Eukaryotes: 5’ cap
Q: Does prokaryotic transcription involve alternative splicing?
A: No, prokaryotic mRNA is immediately translated and does not undergo splicing.
Q: What is the function of the 5’ cap and poly A tail in eukaryotic mRNA?
A: They protect mRNA from degradation and help with translation initiation.
Q: What mechanism terminates transcription in prokaryotic cells?
A: A terminator sequence forms an inverted repeat that creates a hairpin loop, stopping transcription.
Q: What is the direction of transcription and translation?
A: Both occur in the 5’ to 3’ direction.
Q: How do ribosomes identify the oldest mRNA strand in prokaryotic translation?
A: The ribosome at the 3’ end of mRNA is the oldest, as translation progresses from 5’ to 3’.
Q: What molecule does RNA polymerase recognize in transcription?
A: DNA sequences (promoters: -10/-35 in prokaryotes, TATA box in eukaryotes).
Q: What are examples of transcription regulatory sequences?
: - Promoters (-10/-35 in prokaryotes, TATA box in eukaryotes)
Enhancer regions (eukaryotes)
Q: What molecules use complementary base pairing?
DNA: Self (alpha helix), DNA (replication), mRNA, rRNA, tRNA, snRNA
mRNA: Self, DNA (transcription), snRNA (splicing), rRNA (SD box in prokaryotes), tRNA (translation)
rRNA: Self, DNA (transcription), mRNA (SD box in prokaryotes)
tRNA: Self, DNA (transcription), mRNA (translation)
snRNA: Self, DNA (transcription), pre-mRNA (splicing in eukaryotes)
Proteins: No complementary base pairing (they use amino acids).
Q: What are the components of a protein-coding gene in prokaryotes?
Promoter
Shine-Dalgarno sequence
Start codon
Coding sequence (codons)
Stop codon
Terminator sequence
Q: What are the three locations where transcription occurs in Chlamydomonas cells?
A: Nucleus, chloroplast, mitochondria
