DNA Structure and Function Quiz

DNA Structure and Function

• DNA is a double helix, twisted into a spiral shape
• The structure of DNA is like a ladder, with the "sugar-chain" backbone forming the sides and the complementary base pairs forming the rungs
• DNA consists of nucleotides, each of which contains a phosphate group, a sugar (deoxyribose), and a nitrogenous base (adenine, thymine, guanine, or cytosine)
• Adenine pairs with Thymine and Guanine pairs with Cytosine. This is known as complementary base pairing.
• The sequence of these bases carries the genetic information.
• The average human gene contains 10,000-15,000 nucleotides.
• DNA is very long and needs to coil and fold to fit into the cell's nucleus.
• Histones, proteins, hold DNA in its coiled state
• DNA codes for proteins, which build cells and tissues

DNA Replication

• Original DNA molecule uncoils and separates
• Free nucleotides move into place
• New bases join with old DNA bases
• Two new identical strands are formed

Eukaryotic DNA

• Eukaryotic DNA is organized into chromosomes
• DNA is tightly wound around histones
• DNA unwinds from histones for transcription (making mRNA from DNA)

DNA Discovery

• James Watson and Francis Crick, along with Rosalind Franklin and Maurice Wilkins
• DNA was twisted into a spiral shape known as a double helix

Genome Size Variation

• Genomes vary in size and complexity across different organisms

C-value paradox

• The amount of DNA in a genome (C value) does not strongly correlate to the complexity of an organism

Genetic Markers and Variation

• Genetic variation is observed through genetic markers

Microsatellites

• Microsatellites are simple sequence repeats (SSRs) which are di-, tri-, tetra-, or pentanucleotides (short repeating sequences of DNA)
• The number of repeats varies between individuals
• These variations can be used to tell individuals, populations, and species apart
• Useful for tests like paternity testing

Cloning and other Applications

• Cloning plants, and other animals
• Cells can contain the direction to form a whole organism
• Pluripotent cells are capable of giving rise to many different cell types.
• Totipotent cells are capable of giving rise to any cell type or a complete organism.
• Modern whole genome sequencing is routinely done for a wide diversity of organisms.

Humans and Related Species

• Despite diverging ~7 million years ago, humans and chimpanzees share 96% of their genomes
• Most of the human genome is not protein-coding but has functional elements.

Other Information

• The cost of sequencing genomes has significantly decreased over time.
• Components of the Human Genome include (but are not limited to) introns, LTR retrotransposons, DNA transposons, simple sequence repeats, segmental duplications, miscellaneous heterochromatin, miscellaneous unique sequences.
• The slides include diagrams, images, and questions, but no specific medical or paternity cases are mentioned.
• Covalent bonds keep carbon and oxygen together in the carbon dioxide molecule.
• Ray-finned fishes are the most abundant and diverse vertebrate group.
• Photosynthesis is not a characteristic of all life.