Frederick Griffith def
Britush scientist who experimented with bacterial strains of pneumonia in mice and discovered transformation
Transformation def
Process in which one strain of bacteria is changed by a gene or genes from another strain of bacteria, ex: rough, harmless bacteria becoming smooth and disease causing
Oswald Avery def
Canadian biologist who repeated Griffith's work and found that DNA causes transformation in bacteria
His work showed that....
DNA stores and transmits genetic info from one generation of an organism to the next
Alfred Hershey and Martha Chase def
American scientists who experimented with radioactive markers in viruses and concludes that the genetic material of the bacteriophage was DNA not protein
Virus def
Nonliving particles smaller than a cell that can infect living organisms
Bacteriopage def
Type of virus that infects bacteria
Scientists conclude that genes are made of...
DNA
DNA (delxribonucleic acid) def
Nucleic acid that contains the sugar deoxyribose; the molecule of heredity
DNA is made up..
nucleotides
Nucleotides have three bake parts
1. 5 carbon sugar (deoxyribose)
2. Phosphate group
3. Nitrogenous base
There are 4 kinds or nitrogenous bases found in DNA
1. Adenine (A)
2. Guanine (G)
3. Cytosine (C)
4. Thymine (T)
Purines def
Have 2 rings in their structures and include adenine and guanine
Pyrimidines def
Have 1 ring in their structure and include cytosine and thymine
The backbone of the DNA molecules is formed by...
Sugar and phosphate groups of each nucleotide and the nitrogenous bases stuck out sideways of the chain. Nucleotides can be joined together in any order to make different sequences of bases
Chargaff's Rules:
In any sample of DNA, the percentages of guanine and cytosine bases are nearly equal and percentages or adding and thymine bases are nearly equal
Rosalind Franklin def
British scientist who used a technique called X-ray diffraction to record information about the structure of DNA
Her work revealed that...
DNA is shaped like a helix
James Watson and Franis Crick def
American biologist and British physicist who build the FIRST accurate structural model of DNA, after viewing Rosalind Franklin's work
Watson and Crick's model or DNA...
Was a double helix, in which 2 strands were wound around eachother l
A double helix looks like...
A twisted ladder or a spiral staircase
In DNA, hydrogen bonds only form between certain nitrogenous bases in the double helix to hold it together, this is known as...
Base pairing
Every adenine molecules binds with a thymine
And very cytosine molecules hinds with a guanine
Prokaryotes def
Have no organelles, so DNA is located in their cytoplasm
Most have a...
Single circular DNA molecule, referred to as the chromosome
Eukaryotes def
Have about 1,000 times more DNA than prokaryotes
Eukaryotic DNA is found in the nucleus...
Of the cell in the form of chromosomes
DNA molecules are...
Very long DNA is just folded into tiny chromosomes
Eukaryotic chromosomes contain both...
DNA and protein (called histones) tightly packed together to form chromatin
DNA + Justine molecules=
Nucleosome
Nucleosome def
A nuclear particle that is a basic aspect of chromosome structure
DNA molecules are semi-conservative meaning that...
Half of each original strand in a double helix can be used to make a new strand
Each strand of the DNA double helix has all the info needed to reconstruct the other half by....
Base-pairing (complements)
Replication occurs in 100's or places and proceeds in both directions...
Until each chromosome is completely copied
Sites where separation and replication occur are called...
Replication forks
Replication def
Copying process by which a cell duplicated its DNA.
During DNA replication:
1. The DNA molecule separates into 2 strands
2. Produces 2 new complementary strands by base-pairing
DNA replication os carries out by a series of enzymes that unzip the DNA molecule by...
Breaking the hydrogen bonds between base pairs
The principle enzyme involved in DNA replication is...
DNA polymerase because it joins individual nucleotides to produce a DNA molecule
DNA polymerase also...
Proofreads each new copy of DNA to make sure that it is a perfect copy of the original DNA
Basic steps or DNA replication:
1. Helicase is noumena unzip and separate the 2 strands of DNA in a double helix
2. Each strand serves as a template for a new complementary strand to copy
3. DNA polymerase matches the new bases to the template bases
4. String sugar-phosphate bonds form