L5 Flashcards
Describe meiosis
Meiosis 1:
Early prophase: CS Condense
Mid prophase: Synapsis aligns homologs, CS condense further
Late prophase: CS coil/shorten + cross over exchanging genetic material.
Prometaphase: nuclear membrane breaks down
Metaphase: CS align on equatorial plate
Anaphase: homologous CS move to opp poles
Telophase: CS gather into nulcei and original cell divides
Cytokinese: Cytoplasm divides
Meiosis II:
Prophase: CS condense following brief interphase w no DNA replication
Metaphase:
Centrosomes of paires chromatids line up at equatorial plates.
Anaphase:
Chromatids separate becoming their own CS. Pulled to opp poles. Crossingover in prophase I each cell have a diff genetic makeup.
Telophase:
CS gather into nuclei and divide
This gives 4 cells with a nucleus and a haploid number of CS.
What is homologous recombination
During long prophase meiosis I. Nuclease cleaves double helix, both floating DNA strands bind to each other.
Examples of meiotic non-dysjunction
Failure of sister chromatids to separate. Lead to Trisomy and monosomy.
Downsyndrome
Turney Syndrome
How is genetic variation generated?
Mutation Diploid cells (inherit 1 set of CS from each parent) Homologous Recombination (HR) between CS in meisosis
How is genetic variation produced during gamete formation?
Independent assortment of CS.
Crossing-over during meiotic prophase I.
What are 4 common monogenic disorders?
A monogenic disorder is when one trait is determined by a single gene as opposes to polygenic where one train is determined by multiple genes.
Cystic fibrosis - Lung disease 1/2000
thick sticky mucus in the lungs, digestive system and other organs
Huntington’s - Neurodegeneration 1/2000
Loss of memory, difficulty concentrating, depression, involuntary movements, problems: moving/swallowing/speaking/breathing
Hemophilia A - Blood disorder 1/4000
Low clotting factor leading to excessive bleeding. joint damage from repetitive bleeding
deep internal bleeding
neurological symptoms from bleeding within the brain
Sickle-cell anemia - Blood disorder 1/10,000
a severe hereditary form of anaemia in which a mutated form of haemoglobin distorts the red blood cells into a crescent shape at low oxygen levels and can block blood vessels(sickle cell crisis) which can damage tissues and cause organ failure
