Lab 3 Flashcards
Deoxyribonucleic acid (DNA)
Large organic molecules composed of two chains of nucleic acids
What is DNA’s three-dimensional structure?
Double helix twisted in the clockwise direction; resembles a spiral ladder
Nucleotides
Many individual molecules in a nucleic acid molecule; linked by covalent bonds between their sugar phosphate groups to form the nucleic strand
Three subunits of nucleotides
Phosphate group, deoxyribose sugar (five-carbon sugar), and one of four nitrogenous bases
Two categories of nitrogenous bases
Purines and pyrimidines
Purines
Composed of two nitrogen containing rings and two nitrogenous bases called adenine and guanine
Pyrimidines
Have one nitrogen containing ring and 2 nitrogenous bases called thymine and cytosine
Complementary base pairing
A-T, G-C
Template (nucleic acid)
Is a part or model which serves as a guide for the production of an oppositely shaped structure
What enzyme does DNA replication begin?
DNA helicase
DNA helicase
Temporarily “unzips” the hydrogen binds between the purine and pyrimidines bases in a short segment of DNA
What is the DNA replication process?
DNA helicase unzips the hydrogen bonds between the bases then the nucleotides move into place in the process of complementary base-pairing. DNA polymerase (enzyme) joins the nucleotides by pairing the sugar-phosphate groups to form a new complementary nucleic acid strand.
Why is DNA replication called “semi conservative?”
Because each new molecule results from one old nucleic strand and one new nucleic acid strand
Exonuclease
Enzyme that controls accuracy of DNA replication and prevents the incorporation of mismatched nucleotides into a new nucleic acid strand by removing any mismatched nucleotides from the strand and replaces it with appropriate nucleotide
Mutation
Mistakes that occur during replication and are very important to population because they create genetic variability
Genetic variability
Enables organisms to adapt to new environmental conditions
Protein
Large molecule that consists of one or more polypeptide molecules that are bound together to form single functional unit
Polypeptide
Molecule that is a string of bound amino acids; are made by using the information stored in DNA in the form of genetic code
Genetic code
Molecular language consisting of a four letter alphabet (four nucleotides), used to form combinations that are three letters long which are use to construct proteins
What are the three letter combinations called?
Triplets
At least how many triplets are required?
22 (20 amino acids and 2 that start and stop protein synthesis)
How many possible combinations can be made from 4 letters?
64
Structural gene
Particular segment of DNA that codes for a single polypeptide or a portion of polypeptide
mRNA (messenger RNA)
Single strand of RNA that is a complementary copy of the gene on DNA; dictates the primary structure of the polypeptide by directing the placement of individual amino acids
Codons
Three letter combination that is a complementary copy of the DNA triplet but uracil replaces thymine in RNA
tRNA (transfer RNA)
Binds with a particular amino acid and transport that amino acid to the site of protein synthesis; has two active ends
Anticodon
Complementary copy of a codon on the mRNA
Two active ends of tRNA
Anticodon and region which temporarily binds it to the specific amino acid it transport
rRNA (ribosomal RNA)
Large molecule consisting of large and small subunits; attaches to an mRNA molecule and aligns the anticodon on tRNA with the appropriate codon on mRNA, the adjacent amino acids on tRNA are then joined by their sugar phosphate groups to form a growing polypeptide
Amino acids
Structural unit, or building blocks, of polypeptides and proteins
