Topic 6 Flashcards
DNA replication, mutation & expression
When DNA is replicated why is it in a semi-conservative manner?
- 1 strand will be from the original template molecule
- 1 strand will be newly synthesised
- process of replication, where resulting double helix composed of both old strand + new strand
What is the process of DNA replication as it is discontinuous and initiated with RNA primers?
- during DNA replic, DNA + RNA primers removed from lagging strand of DNA to allow Okazaki fragments to create + bind to lagging strand
- once template becomes discontinuous, create an Okazaki fragment (short sequences of nucleotides)
Define the term mutation.
- replication without repair
- physical change introduced into DNA
- mutations within DNA region encoding protein (gene) may cause abnormal protein to be produced
What is spontaneous mutations?
- non-induced
- damage from unknown cause
- may occur frequently in organisms w/ short generation times
What is induced mutations?
- exposure to mutagens (agents that increase rate of mutations)
- may purposely induced for research purposes:
- chemical: NSG
- biological: virus
- physical: gamma rays
- natural mutagens eg radon, UV light
- human created mutagen eg asbestos, nuclear fall out
What is somatic mutations?
- mutations in body cells
- may affect entire developmental process of organism or particular region
Whta is germinal mutations?
- mutations in gamete cells (eggs & sperm)
- mutated gametes passed => offspring
What is the difference between spontaneous, induced, somatic and germinal mutations?
- spontaneous: non-induced
- induced: any change in DNA sequence that can be passed parent => offspring
- somatic: mutation in body cell of organism
- germinal: mutation in gamete cells
What are the different types of mutations and their effects?
- gross (change in chromosomal structure)
- point (single nucleotide)
- frameshift (indels of a number of nucleotides)
- missense
- nonsense
- silent
What is the process of transcription in prokaryotes?
- monocistronic or polycistronic
What is lac operon?
- group of genes (operon) with single promoter (transcribed as a single mRNA)
- genes in operon encode proteins that allow bacteria to use lactose as an energy source
How is gene expression controlled through actions of regulatory proteins?
- regulatory protein encodes for a repressor protein important for regulating gene expression
- if repressor binds to operator site, polym. => promoter + gene expressed as gene read + protein made
What are some of the similarities and differences between gene control in prokaryotes and eukaryotes?
PRO: - no role of chromatin - operon control - alll genes transcribed by single RNA polym. - RNA splicing rare EUK: - role for chromatin - operon control rare - 3 RNA polym. function - RNA polym. I (for mRNA) much larger + more complex - RNA splicing common
What is the enzyme that unwinds DNA?
DNA helicase
What are different types of gross mutations? (chromosomal structural change & number)
- insertion/deletion
- duplication
- inversion: 180° rearrangment
- polyploid: change in entire chromosomal set, more than 2 sets
- aneuploidy: change within chromosomal set, addition/deletion
