Lesson 1 - Introduction Flashcards
basic structural and functional units of life
cells
“all organisms are composed of one or more cells.”
“the cell is the structural unit of life”
- Matthias Schleiden
- Theodor Schwann
(1838-1839)
“cells can arise only by division from a preexisting cell”
Rudolf Virchow (1855)
Living things, though infinitely varied when viewed from the outside, are fundamentally __ inside
similar
transfer of characters or traits from the parents to their off springs
Heredity
differences between the characters or traits among the individuals of the same species
Variation
What do cells carry that define each species
hereditary information (DNA)
long, unbranched, double-stranded molecule formed by four types of nucleotides
DNA
forms DNA
nucleotides
Four types of nucleotides in the DNA
- Adenine
- Guanine
- Cytosine
- Thymine
charge of the DNA
negative
forms the nucleotide
- phosphate
- sugar
- base
link the nucleotides in each strand
covalent bonds
hold the two DNA strands together
hydrogen bonds
bond between the phosphate and sugar
phosphodiester bond
bond between the sugar and base
glycosidic bond
determines the genetic information
sequence of bases
two types of bases
- purine
- pyrimidine
purines
Adenine
Guanine
pyrimidine
Cytosine
Thymine
Uracil
hydrogen bonds between adenine and thymine
2
hydrogen bonds between cytosine and guanine
3
the first experiment which suggested that bacteria can transfer genetic information through a process called transformation
Griffith’s transformation experiment
full name of Griffith
Frederick Griffith (1928)
what type of bacteria did Griffith use
Diplococcus pneumoniae (Pneumococcus)
Smooth type (S)
- thick polysaccharide capsule
- smooth mucoid colonies
- pathogenic/virulent
Rough type (R)
- no capsule
- rough colonies
- non-pathogenic/avirulent
Who are the other scientists who had an experiment related to Griffith’s transformation experiment
- M.H. Dawson (1930) and
- J.L. Alloway (1932)
what did M.H. Dawson (1930) and J.L. Alloway (1932) do
- in vitro transformation
- mouse was not necessary
- extract from heat-killed S cells + live R cells -> live S cells
- purified biochemicals (proteins, DNA, RNA) from the heat killed S cells to see which ones could transform live R. cells into S cells
- discovered that DNA alone from S bacteria caused the bacteria to become transformed
Avery, MacLeod, McCarty
General Properties of Transforming Substance
- viscous, silky sheen
- loses activity in distilled water
- activity retained for months in physiological salt solution
- withstands heating at 65C for 30-60 minutes
- loses activity with increased acid concentration
showed that phages only injected their DNA into host bacteria, and that the DNA served as the replicating genetic element of phages
Hershey-Chase Experiment
what phages were used in the Hershey-Chase Experiment
T2 phages
the four scientists who codiscovered the double-helix structure of DNA, which formed the basis for modern biotechnolog
- Francis Crick
- Rosalind Franklin
- James Watson
- Maurice Wilkins
“DNA is made of nucleotides”
Phoebus Levene
“1 purine : 1 pyrimidine”
- Erwin Chargaff
- Rollin Hotchkiss
- Ronald Fisher