Genetic - Ch 2: Dna

Front 1

Griffith's Transformation Experiment (1928) purpose

Back 1

experiment with Streptococcus pneumonia bacteria in mice showed that genetic material passed from dead bacteria into nearby living ones, allowing them to change their cell surface

Front 2

Griffith's transformation experiment

Back 2

The R bacteria uptake some genetic material (that are required for making the sugar coat that hides the antigens) from the dead S bacteria, and are transformed into an infectious strain

Front 3

Griffith's transformation experiment results

Back 3

experiment that resulted in calling the unknown genetic material the "transforming principle"

Front 4

Avery's Transformation Experiments (1944)

Back 4

Aimed to determine the identity of the transforming principle:

Lysed dead S cells, separated cell extract, determined with component of the extract is capable of transforming an R strain into an S strain.

When DNase was added, there was no transformation --> transforming principle is DNA

Front 5

Hershey-Chase Bacteriophage Experiments (1953)

Back 5

more evidence for DNA as the genetic material from research on bacteriophage of T2

Front 6

Hershey-Chase experiment methods

Back 6

T2 DNA labeled with 32P

T2 proteins labeled with 35S

Front 7

Hershey-Chase experiment results

Back 7

32P labeled DNA was found inside host --> because phage injects its genetic material inside the host, DNA must be carrying the genetic information

The transferring principle was found to be the cellular material that could alter a cell's heritable characteristics

Front 8

Each nucleotide (monomers that make up DNA and RNA) has 3 parts:

Back 8

pentose sugar (5-carbon), nitrogenous base, phosphate group

Front 9

Purines

Back 9

Class of nitrogenous bases that are double-ring, nine-membered structures: A & G

Front 10

Pyrimidines

Back 10

Class of nitrogenous bases that are one-ring, six-membered structures: C & T, U

Front 11

Nucleoside

Back 11

the sugar-base combo - when a phosphate is added, it becomes a nucleotide

Front 12

What creates the backbone of a nucleic acid molecule?

Back 12

The phosphate groups on the 5'C of one nucleotide and the 3'C of another, held together by asymmetric phosphodiester bonds (stable covalent bonds)

Front 13

What is the 5'-3' polarity created by within the nucleic acid chain?

Back 13

Asymmetry of phospodiester bonds

Front 14

Erwin Chargoff's experiment

Back 14

G=C, A=T --> suggests base pairing also, but he didn't realize it

Front 15

Franklin and Wilkins experiment

Back 15

X-ray diffraction images of DNA showed a helical structure

0.34 nm - length between base pairs

3.4 nm - 1 helical turn

Front 16

Watson and Crick's model

Back 16

DNA has 2 poylnucleotide chains, that run antiparallel, wound around each other in a right-handed (clockwise) double helix

Front 17

Internal base pairing and RNA

Back 17

RNA is single stranded, but internal base pairing can produce secondary structure in the molecule (tRNA)

Front 18

The nucleic acid of a virus may be

Back 18

dsDNA, ssDNA, dsRNA, or SSRNA; linear or circular; single molecule or several segments

Front 19

Chromatin

Back 19

DNA-protein complex that constitutes chromosomes (only in eukaryotes)

Front 20

Nucleosome

Back 20

Basic unit of chromatin

Front 21

Euchromatin

Back 21

usually (transcriptionally) active (lightly packed), most of genome

Front 22

Heterochromatin

Back 22

usually inactive (tightly packed)

e.g. centromeres and telomeres (repeat sequences at chromosome end)

At the ends and middle of the chromosome

Front 23

Histone

Back 23

compact DNA, enable/regulate gene expression