DNA Flashcards
Vector
A DNA molecule that is used as a vehicle to carry a particle DNA set,ent into a host cell as part of a cloning of recombinant DNA technique
Transgenic bacterium
Genetically modified bacteria that carry the gene from other sources and are used for the production of a desired gene
Plasmid
Circular DNA of bacteria molecule
What are chromosomes
Long, thin like thread structures composed of DNA that is wrapped around a protein called histones.
What is a gene
A short segment of DNA that codes for a particular protein - they carry the code for the synthesis of a particular protein and these proteins determine the characteristics of an organism
Who we’re the scientists who formulated the double helix structure
James Watson and Francis Crick
“Father of genetics” - by means of pea plant
Gregor Mendel
Describe the structure of DNA
a giant molecule with 2 strands twisted in a double helix ladder - polymer made up of monomers (nucleotides)
Nucleotides consist of 3 parts:
Sugar molecule (deoxyribose)
Phosphate group
Nitrogenous bases
Name the 4 different types of nitrogenous bases
Adenine
Guanine
Cytosine
Thymine
What are the purine bases
Adenine and guanine - larger molecules
What are the pyrimidine bases
Cytosine and thymine - smaller molecule
How are nitrogenous bases joined
By weak hydrogen bonds which are easily broken by enzyme action
Two hydrogen bonds between adenine and thymine
Three hydrogen bonds form between guanine and cytosine
What importance is the sequence of a nucleotide
The sequence provides the code that gives instructions for the synthesis of proteins - this code is the genetic code or code of life. Note one DNA strand is always complimentary
What is the role of DNA
- genetic code for protein synthesis
- regulates and controls expression of genes
- protects genes from mutations
- non coding DNA used in DNA fingerprinting
What is non coding DNA
Only 2 % of DNA codes for proteins- the rest is non coding DNA and it regulates and controls the expression of genes in the coding DNA and protects genes from mutations
DNA replication
Replication is the duplication of a DNA molecule to from to identical copies - this takes place during interphase of d the cell cycle
What is the process of replication
1.DNA helix unwinds
2. DNA helicase unzips the molecule by breaking hydrogen bonds between base pairs
3.free bases are now available and exposed
4. DNA polymerase binds free nucleotides to complementary bases
5. Copying the template for each dna strand
6. Two exact complies are produced
7. DNA reshapes into a double helix
8. This them winds itself around a large protein called a histones forming a chromosome
What is a codon
A sequence of 3 nucleotides which from a genetic code
What is the importance of DNA replication
During mitotic division one mother cell divides to from 2 identical daughter cells
It’s essential that dna makes identical copies before cell division to ensure each daughter cell contains the same genetic information as the mother cell
What is mtDNA
Occurs in mitochondria and is not related to chromosomal DNA that occurs in the nucleus
- it is the genes of mtDNA that code for ensures that control cellular respiration
- mtDNA is inherited via the maternal line + goes unchanged meaning it is possible to trace long lines of relatives
