ch 33 Flashcards
(24 cards)
The Main Characters:
DNA – The classy, long-term relationship type. Double-stranded, stable, and committed.
RNA – The rebellious younger sister. Single-stranded, flexible, and dramatic.
Nucleotides – The building blocks of their lives (aka their Tinder profiles): each comes with a sugar, phosphate, and a juicy base (A, T, G, C… or U for RNA because she’s quirky like that).
The Forbidden Love Affairs (Base Pairing):
DNA’s love life is all about exclusivity:
Adenine (A) is madly in love with Thymine (T) – they only bond with each other (2 hydrogen kisses).
Guanine (G) is all about Cytosine (C) – and they’re extra clingy (3 hydrogen kisses).
RNA stirs the pot by replacing Thymine with Uracil (U). A scandal!
The Double Helix – Their Bedroom Situation:
Think of it like a spiral staircase where the sugar-phosphate backbone is the railing, and the base pairs are the romantic steps.
It’s right-handed (because they have standards), and the strands run in opposite directions—a love-hate, “you go left, I go right” dynamic.
The Chemistry of Their Bond:
When they pair up just right, they’re stable and the relationship is strong.
But throw in heat, and the drama begins—they split. This breakup is called denaturation (melting). Total soap-opera moment.
Cool things down? They get back together—annealing. On-again, off-again toxic romance energy.
The DNA High Society:
DNA doesn’t just float around naked. Oh no, she gets all dressed up in histones, forming nucleosomes. Think of this as DNA wrapped in designer outfits, forming bead-like structures.
And when it needs to fit into that tight nucleus (ahem, a metaphorical red carpet event), it supercoils like it’s trying to squeeze into a corset.
The Messy Sibling Rivalry:
RNA can fold in on herself, forming loops and stems. Drama queen behavior.
She doesn’t need no man (aka no complementary strand)—she’s independent and extra with all her weird folds and non-standard base pairings.
The Epic DNA Experiment (a.k.a. “Meselson & Stahl’s Paternity Reveal”):
They figured out how DNA replicates—turns out it’s semiconservative: every new DNA strand is half old and half new. Just like a clingy ex who won’t let go even when you’re trying to move on.
When Love Goes Toxic:
Cisplatin is the villain—he comes in and messes up DNA’s structure to the point it can’t even function. It’s like putting gum in someone’s hair on prom night.
Bonus Drama – Melting Point (Tm):
Longer DNA = more intense relationship = higher Tm. It takes more heat to break them up.
More salt in the environment? It calms things down and stabilizes the relationship.
Less salt? Oof. Fights break out, and that DNA couple falls apart faster.
What’s the sugar in DNA and how is it different from RNA?
DNA has deoxyribose (no O on C2’), while RNA has ribose (extra OH = extra drama).
Which base pairs always hook up in DNA?
A + T (2 kisses), G + C (3 kisses) because G and C are clingy af.
What’s the steamy structure called when two DNA strands spiral together?
The double helix it’s like a sexy staircase of genetic secrets.
How do DNA strands stay together?
Hydrogen bonds like intense eye contact holding couples together.
What happens when you heat DNA?
They break up (denature/melt). But theyll rekindle (anneal) if you cool them down.
What’s the DNA packaging fashion called?
Nucleosomes DNA wrapped around histones like pearls on a string.
Q: How does DNA replicate its drama?
Semiconservatively each new strand keeps one OG strand. Half old flame, half new boo.
Why is RNA more unstable than DNA?
That 2-OH on ribose makes RNA reactive. Shes wild, dramatic, and falls apart in base.
What makes G-C bonds hotter than A-T?
Theyve got 3 hydrogen bonds (extra steamy). More heat needed to break ‘em.
Whats Z-DNAs vibe?
Left-handed helix with zigzag energy the edgy alt cousin of B-DNA.
How does cisplatin ruin DNAs party?
It locks up purines and blocks repair ultimate toxic ex energy.
Whats RNAs signature drama move?
Stem-loops she folds in on herself like a diva with layers.
What do histones do?
They let DNA wrap around them to slay the chromatin fashion game.
What increases DNAs melting temp (Tm)?
Longer strands = more base pair drama = more heat to break up.
What happens to Tm when salt is low?
Less salt = more repulsion = easier to fall apart = lower Tm.
