Structure And Replication Of DNA Flashcards
What is DNA?
A substance that encodes genetic information of heredity in a chemical language. Genetic information is inherited.
What does DNA look like?
DNA is a very long double-stranded molecule in the shape of a double helix.
Each strand of DNA is made up from chemical units called nucleotides.
What three parts is a nucleotide made from?
- Deoxyribose sugar
- Phosphate
- Base
Deoxyribose molecules have five carbon atoms which are numbered 1-5.
What are the four DNA bases called?
Adenine (A), Guanine (G), Thymine (T), Cytosine (C)
Bases pair in a complementary way:
G pairs with C and vice versa.
A pairs with T and vice versa.
What are base pairs held together by?
Very strong hydrogen bonds.
State the organisation of DNA in chromosomes.
Chromosomes consist of tightly coiled DNA which is packaged with associated proteins.
What is the meaning of the term ‘Antiparallel’?
Parallel strands in DNA that run in opposite directions in terms of chemical polarity.
What is DNA Replication?
The process by which DNA molecules can direct the synthesis of identical copies of themselves.
What happens during Replication?
- DNA unwinds and unzips to form two template strands
- The enzyme DNA polymerase adds complementary DNA nucleotides to the 3’ end of a DNA strand
- DNA polymerase requires primers to start Replication
What happens after the complementary adding of nucleotides to the 3’ end of a DNA strand during Replication?
-the 3’-5’ lead strand is replicated continuously in the direction from its 3’ end towards its 5’ end.
What are primers?
Short, complementary sequences of nucleotides that allow binding of DNA polymerase.
How are nucleotides added on the lagging strand?
Nucleotides are added as fragments on the lagging strand and they are joined together by a ligase enzyme.
