Show Menu

AP Bio Chpt. 17 Cheat Sheet by

DNA transforms Bacteria

Fred­erick Griffith studied two strains of pneumonia
pathogenic and nonpat­hogenic
heat-k­illed pathogenic + nonpat­hogenic bacteria
= pathogenic bacteria (live diseas­e-c­ausing)
change in genotype and phenotype due to assimi­lation of external DNA by a cell
scientists studied to find the genetic material of chromo­somes - protein vs. DNA

DNA transforms Bacteria (cont.)

Oswald Avery also proved that DNA was the molecule that transf­ormed bacteria


DNA or RNA in a protein coat
infect by taking over a cell's metabolic machinery
viruses that infect bacteria
Henry and Chase showed that DNA was the genetic material that infected the bacteria
Used radioa­ctive isotope markers to label DNA and proteins of phages. Phage DNA entered the bacteria cell, but protein did not.

Chargaff's Rule

concen­tration of … [A] = [T] [C] = [G]

Rosalind Franklin

x-ray crysta­llo­gra­phy
image of DNA produced by x-rays diffra­cting when passing through DNA fibers
DNA is a double helix, with two anti-p­arallel sugar-­pho­sphate backbones, and nitrog­enous bases in the molecule's interior
anti-­par­allel - subunits run in opposite directions

DNA is a polymer of nucle­otides

compon­ents: nitrog­enous base, deoxyr­ibose sugar, phosphate group
bases: adenine, guanine, thymine, cytosine

Structure of DNA

DNA is a polymer of nucle­otides connected by covalent bonds
4 nitrog­enous bases:
Purines (double ring) [A] [G]
Pyrimi­dines (single ring) - [C] [T]
DNA base pairing
PURINE always pairs with PYRIMIDINE
2 of the same would be too wide/n­arrow
3 hydrogen bonds between C and G
2 hydrogen bonds between A and T

DNA Replic­ation

S phase of Interp­hase
DNA made from existing DNA strand
semi­con­ser­vative model
one parent strand serves as a template to a comple­mentary strand
half of parent strand is conserved in each daughter strand
- Meselson and Stahl

DNA Replic­ation (cont.)

origins of replic­ation
where replic­ation of DNA molecule begins
bacterial chromosome
circular, single origin
eukaryotic chromosome
linear, thous­ands of origins
repl­ication fork
Y-shaped region formed by unwinding of parent strands
- reference drawings to unders­tanding rest of replic­ation -

Proofr­eading DNA

DNA polyme­rase
proofreads each nucleotide as it's covalently bonded
mismatch repair
other enzymes remove and repair incorrect nucleo­tides
nucl­eotide excision repair
mutated strand is cut out by enzyme nucl­ease, and the gap is filled with DNA polymerase and ligase
- seen in skin cells when correcting thymine dimmers cause by UV rays

Evolution Signif­icance of DNA Nucleo­tides

Mutations occur when uncorr­ected mismatched nucleo­tides are replicated and passed onto a daughter cell. Usually harmful and permanent genetic changes that support natural selection.

Replic­ation at Molecule Ends

- reference drawings -

Inside a Chromosome

eukaryotic cell
one long DNA double helix with large amnt. of protein =
the long DNA fits in the nucleus through packing
- reference drawings -

Help Us Go Positive!

We offset our carbon usage with Ecologi. Click the link below to help us!

We offset our carbon footprint via Ecologi


No comments yet. Add yours below!

Add a Comment

Your Comment

Please enter your name.

    Please enter your email address

      Please enter your Comment.

          Related Cheat Sheets

          More Cheat Sheets by annadanpd