Bio exam

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Nucleotides have a phosphate group attached at the _ carbon atom of the sugar

5’

What what Hershey-Chase experiment

1952, showed that DNA is a genetic material of a phage known as T2. Used 35^S to label viral protein and 32^P to label viral DNA

What experiment did Hershey-Chase design

Designed an experiment to test whether DNA or protein enters an E.coil cell during infection. Centrifugated and found heavier bacterial cells formed a solid pellet while lighter detached protein shells remained in the supernatant at the top.

Which enzyme relieves the strain of the two strands

DNA Gyrase

Which protein unwinds the parental double helix at the replication forks

Helicase

Which protein binds to and stabilizes single-stranded DNA until it is used as a template

Single strand binding protein

Which protein relieves overwinding strain ahead of replication of forks by breaking, swiveling, and rejoining DNA strands

Topoisomerase

Synthesizes an RNA primer at 5’ end of leading strand and at 5’ end of each Okazaki fragment of lagging strand

Primase

DNA pol 3

synthesizes new DNA strands by adding nucleotides to an RNA primer or a pre-existing strand

DNA pol 1

Removes RNA nucleotides of primer from 5’ end and replaces them with DNA nucleotides added to 3’ end of adjacent fragments

DNA ligase

Joins Okazaki fragments of lagging strand. Leading strand joins 3’ end of DNA that replaces primer to rest of leading strand DNA

Compounds of nucleic acids

Organic nitrogenous base, pentose sugar, phosphate

Chemical bond connecting one nucleotide with the next along a strand of DNA molecule

Phosphodiester bond

Holds 2 complementary strands of DNA double helix together

Hydrogen bond

Chemical links phosphorus atom to oxygen atoms

phosphate bond

Joins a carbohydrate molecule to another group sometimes another sugar

Glycosidic bond

Lagging strand is replicated with a series of Okazaki fragments and its synthesis is considered

discontinuous

What makes up the rungs of the double helix

Purines & pyrimidines

Purines

Adenine (A) and Guanine (G) pure as gold

Pyrimidines

Cytosine (C), Thymine (T), and Uracil (U)

1933 T.H. Morgan

Showed that genes are located on chromosomes. Two components of chromosomes- DNA and protein became candidates for the genetic material of heredity. Proved the chromosome theory of inheritance

Genetic Material: Proteins

20 amino acids of varying shapes and lengths, known to control cell reactions

Genetic Material: DNA

Only 4 nucleotides long and stringy, stays within the nucleous

Frederick Griffith 1928

Worked with Two pathogenic strains, one pathogenic (S) and one harmless (R).

Mixed the heat-killed remains of the pathogenic strain with living cells of the harmless one and made them pathogenic

Griffith named this phenomenon Transformation

a change in genotype and phenotype due to assimilation of foreign DNA

Chargaff’s Rules 1950

-The base composition of DNA varies between species

-In any species, # of A-T bases & the # of G-C bases are equal

this evidence of diversity made DNA a more creditable candidate for the genetic material

Maurice Wilkins and Rosalind Franklin

used X-ray crystallography to study molecular structure , Franklins X-ray enabled Watson to deduce DNA was a double helical