Unit 2: Nucleic Acids and DNA Flashcards
What are the 2 major biological functions of DNA?
- DNA stores genetic information that is encoded in the sequence of subunits along its length
- DNA transmits genetic information to other molecules and from one generation to the next
genetic information (2)
- information carried in DNA, organized in the form of genes
- some information in DNA encodes proteins that provide structure and do much of the work of the cell
genes (3)
- unit of heredity
- the stretch of DNA that affects one or more traits in an organism, usually through an encoded protein or noncoding RNA
- genes can exist in different forms in different individuals, even within a single species
gene expression
- production of a functional gene product
gene regulation
- various ways in which cells control gene expression
How do genes affect an organism? (2)
- usually have no affect on the organism until they are “turned on” and their product is made
- turning on of a gene is called gene expression
nucleotides
- constituent of nucleic acids, consisting of a 5-carbon sugar, a nitrogen-containing base, and one or more phosphate groups
what forms the backbone of the DNA structure
- the 5-carbon sugars and the phosphate groups for the backbone of the molecule with each sugar being linked to the phosphate group of the neighbouring nucleotide
what is role of each base that sticks out from the sugar
- give each nucleotide its chemical identity
Which carbon in the sugar is the phosphate group bonded to?
- the 5’ carbon
which carbon in the sugar is the base bonded to?
- the 1’ carbon and the base projects above the sugar ring
deoxyribose
- the sugar in DNA
what is the shape of the sugar in the nucleotide and how do you read the carbons (2)
- indicated by an pentagon where 4/5 of the vertices represent the position of a carbon atom
- carbon atoms of the sugar ring are numbered clockwise with the primes
How does the sugar in DNA differ from the sugar in RNA (2)
- chemical group projecting downward from the 2’ carbon is a hydrogen atom (–H) in DNA
- chemical group projecting downward from the 2’ carbon group is a hydroxyl group (–OH) in RNA
Why is DNA a mild acid (2)
- at cellular pH the free hydroxyl groups attached to the phosphorus atom are ionized by the loss of a proton and become negatively charged
- phosphate group has negative charges on 2 of its oxygen atoms
mild acid
- molecule that tends to lose protons to the aqueous environment
purines (2)
- bases that have a double-ring structure
- adenine and guanine
pyrimidines (2)
- bases that have a single-ring structure
- thymine and cytosine