FOM: molecular genetics Flashcards
Genome:
- The genetic information of an organism
Gene:
- Basic unit of inheritance, a region of DNA that encodes a function
Chromosomes:
- The human genome is divided into 46 chromosomes in somatic cells (non-sex)
- 22 pairs of autosomes and either:
- 2 X chromosomes (females)
- 1 X and 1Y chromosome (males)
Direction of DNA synthesis:
- From 5’ to 3’
- 3’ has a free OH group for a phosphodiester bond to form
Nucleotide structure (DNA): (3)
- Phosphate group
- Sugar (deoxyribose)
- Nitrogenous base (T,A,C,G)
RNA nucleotide structure:
- Phosphate group
- Sugar (ribose)
- Nitrogenous bases (A,C,G,U)
DNA structure (big):
- Double helix consisting of two antiparallel complimentary strands
RNA structure (big):
- Single strand, can form complex shapes due to stretches of complementary base pairing
Exons in DNA:
- Required information for protein coding sequence
Introns in DNA:
- Non-coding information
Pseudo genes:
- Conventional
- processed
- Conventional: non functional genes due to mutations which have accumulated over time
- Processed: DNA copies of mRNAs produced by reverse transcription ( copying RNA to DNA)
Tandom repeats:
- Found at centromeres, ends of chromosomes and throughout genome
Interspersed genome wide repeats:
- Retroviruses (long dead)
- Derived from RNA sequences
Reverse transcription:
- The enzyme reverse transcriptase copies RNA to double stranded DNA for genome insertion
Discontinuous DNA Replication:
- Leading strand
- Lagging strand
- Leading strand: Synthesised in the direction of unwinding
- Lagging strand: synthesised away from direction of unwinding
Role of primes in DNA replication:
- DNA polymerase limitation:
- Primase role
- NTP removal
- DNA polymerase cannot synthesise de nova
- Primase (a form of RNA polymerase) lays an RNA primer to start the daughter chain
- DNA polymerase 1 removes the NTP and replaces them wit dNTP’s
Types of mutation: (3)
- Point mutation
- Insertion
- Deletion
Causes for DNA damage: (5)
- Cellular metabolism
- UV light exposure
- Ionizing radiation
- Chemical exposure
- Replication errors
DNA repair pathways: (5)
- B E R
- N E R
- M E R
- D R
- D S B R
- Base excision repair
- Nucleotide excision repair
- Mismatch excision repair
- Direct repair
- Double strand break repair
Excision repair pathway action: (3)
- Recognise offending bases
- Remove offending bases/nucleotides
- Repair resulting gap
Defects in repair mechanisms: (6)
- Increased C….
- N
- P A
- P
- G I
- I
- Increased cancer risk
- Neurodegeneration
- Premature aging
- Photosensitivity
- Growth insufficiency
- Immunodeficiency
Types of RNA molecule: (3)
- mRNA: messenger RNA, copy of protein coding sequence
- rRNA: ribosomal RNA, component of ribosome
- tRNA: transfer RNA, carries amino acid to ribosome
RNA polymerase, 3 types in eukaryotes
Eukaryotes:
I: synthesises rRNA’s
II: synthesises mRNA’s
III: synthesises tRNAS’s and 1rRNA
RNA transcription:
- Requirements
- Direction
- Primer???
- DNA dependent enzymes (requires a DNA template)
- Synthesis 5’-3’
- No primer required