UNIT 2 | DNA Flashcards
What are the 3 main components of DNA nucleotides?
Sides: 1. Sugar (deoxyribose) 2. Phosphate Rungs: 3. Base (nitrogenous)
Pair the correct pyrimidines and purines of DNA:
Adenine, Guanine - purines
Thymine, Cytosine - pyrimidines
Adenine - Thymine
Guanine - Cytosine
Define purine
Two carbon rings
Define pyrimidine
One carbon ring
Helicase
Unwinds and unzips by breaking hydrogen bonds between bases
DNA polymerase
Builds a new DNA strand by reading the parent strand and matching the nucleotides
Primase
Initializes the entire process and sets a path for DNA polymerase to follow
Ligase
Glues Okazaki fragments on the lagging strand of DNA (5’ - 3’)
How many bonds exist between Guanine and Cytosine?
Three hydrogen bonds
How many bonds exist between Adenine and Thymine?
Two hydrogen bonds
Okazaki fragments
Short, newly synthesized DNA fragments that are formed on the lagging template strand during DNA replication
Which way is DNA replicated?
3’ to 5’ (leading strand)
Compare and Contrast:
DNA and RNA
- DNA is double stranded while RNA exists in single strands
- DNA contains the sugar deoxyribose in its backbone, whereas RNA contains ribose, which has one more oxygen atom
- Both nucleic acids contain three bases: adenine, guanine and cytosine. However, RNA contains uracil as its fourth base, while DNA contains thymine.
What are the 3 main components of RNA nucleotides?
- Sugar (ribose)
- Phosphate
- Bases (nitrogenous)
Pair the correct pyrimidines and purines of RNA:
Adenine, Guanine - purines
Uracil, Cytosine - pyrimidines
Adenine - Uracil
Guanine - Cytosine
Codon
A sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule
Anticodon
A sequence of three nucleotides forming a unit of genetic code in a transfer RNA molecule, corresponding to a complementary codon in messenger RNA
How many amino acids are there?
20 amino acids
Define tripeptide
A peptide with three amino acids joined by peptide bonds
Define mutation
The change in genetic material of a cell
What are the two types of mutations?
- Gene mutation - produce changes in a single gene
2. Chromosomal mutation - changes the whole chromosome
Substitution (gene mutation)
A single nucleotide is replaced. There may be a change in amino acids
Insertion (gene mutation)
A single nucleotide is inserted into the DNA sequence. A frameshift occurs and all amino acids after the mutation may be changed
Deletion (gene mutation)
Similar to insertion, it can change all amino acids after the mutation occurs
Define point mutations
Occurs at a single point in the sequence (insertion and deletion)
Duplication (chromosomal mutation)
Loss of part, or all, of a chromosome
Inversion (chromosomal mutation)
Reverses direction of parts of a chromosome
Translocation (chromosomal mutation)
Part of one chromosome breaks off and attaches to another chromosome
Mutations
Chemical or physical agents that interact with DNA and may cause this
Examples:
Chemical - pesticides
Physical - X-ray radiation
Give an example of a good mutation
Insects can resist pesticides
Give an example of a bad mutation
Sickle cell disease (dramatically change protein structure)
Gene therapy
Transplantation of normal genes into cells in place of a missing or defective cell to correct issues
How is gene therapy used?
To make cells more resistant to chemotherapy and tumour cells more sensitive
What is ex vivo gene therapy?
Cells are modified outside of the patients body and transplanted
What is in vivo gene therapy?
Cells are treated inside of the patients body
Recombinant DNA
DNA produced by the combination of DNA from different sources
Define xenotransplantation
Grafting, or transplanting, organs or tissues between a different species
Hybridization
Breeding that involved crossing dissimilar organisms to bring together the best traits of both individuals
Polyploid cell
A cell that contains more than two paired homologous sets of chromosomes, often stronger and larger
