L4- the structure of DNA, and what are its key properties Flashcards
(6 cards)
What is DNA made of?
DNA (Deoxyribonucleic Acid) is made of nucleotides, each containing:
Deoxyribose sugar
Phosphate group
Nitrogenous base (A, T, C, or G)
Each nucleotide connects to the next through a phosphodiester bond, forming a single DNA strand.
Two strands pair together to form a double helix structure.
How are the two DNA strands arranged and held together?
The two DNA strands are:
Complementary (A pairs with T, C pairs with G)
Antiparallel (they run in opposite directions: 5’→3’ and 3’→5’)
Held together by hydrogen bonds between the nitrogenous bases
A=T has 2 hydrogen bonds
C≡G has 3 hydrogen bonds
What are the key structural properties of the DNA double helix?
DNA forms a double helix with constant diameter
Has major and minor grooves along the coil
The outside is hydrophilic (due to the phosphate backbone)
The inside is hydrophobic (due to stacked nitrogenous bases)
The helix structure helps with stability and protection of genetic information
What are the biological functions of DNA?
Stores genetic information in the base sequence
Directs protein and RNA synthesis
Passes genetic traits to offspring through replication
Guides gene expression via transcription and translation
Organizes into chromatin and chromosomes for efficient packaging
What are the unique features of DNA location and organization in eukaryotic cells?
DNA is located in the nucleus, organized as chromatin
DNA wraps around histone proteins, forming nucleosomes
During cell division, it compacts into chromosomes
Telomeres protect chromosome ends and shorten with age
DNA can be modified via epigenetic mechanisms like methylation and acetylation
What are the 5 most important properties of the DNA molecule?
Double-stranded and forms a helix
Antiparallel strands with base complementarity
Carries genetic code in the sequence of bases
Capable of replication and transcription
Located in the nucleus, compacted as chromatin/chromosomes
