Lecture 11 Flashcards
Why is crossing over important?
-important in meiosis for the spindle alignment -somehow male drosphilas and lucillas overcome that (males:eyes further apart than females) -recombination especially double extremely uncommon but some regions of chromosomes are hot spots and other such as heterochromatin show nearly no recombination
Why is crossing over important?
-important in meiosis for the spindle alignment -somehow male drosphilas and lucillas overcome that (males:eyes further apart than females) -recombination especially double extremely uncommon but some regions of chromosomes are hot spots and other such as heterochromatin show nearly no recombination
h fz e - if change in h or fz which region crossed over?
region I
In which region is crossing over if h fz e – if change in e
region II (can also be both the h and fz change and e remains the same)
How do you map a gene?
: take two genes next to each other h-fz –region I add up all the recombinants in region I (include double recomb. Since they cross in both) - divide by the number of all the offspring (all including parental etc) - multiply by a 100 fz-e- region II add up all the recombinants in region II (plus double recomb) -divide by the total offspring - multiply by a 100
h fz e - if change in h or fz which region crossed over?
region I
Give examples of multifactorial traits? 2
-spina bifida= spinal cord not enclosed, the fluid herniates and children paralised cleft palate= when top of mouth not closed off =both result of mix of genes plus environmental factors
How do you map a gene?
: take two genes next to each other h-fz –region I add up all the recombinants in region I (include double recomb. Since they cross in both) - divide by the number of all the offspring (all including parental etc) - multiply by a 100 fz-e- region II add up all the recombinants in region II (plus double recomb) -divide by the total offspring - multiply by a 100
Is it important knowing the environment factors in multifactorial trait development?
-yes, if the traits are influenced by the environment then if we can identify them = reducing it may reduce the incidence
What are the attributes of multifactorial traits?
discontinuous distribution of phenotypes -either have it or you don’t, can be classified into discrete groups - you are type O or you’re not, either an albino or not - environmental factors -have genetic predisposition and if you have enough environmental factors and genes= reach threshold and show phenotype
What food should pregnant women avoid?
-potatoes (can prevent spina bifida and anencephaly) plus take folic acid!
What is the genetic and environmental component of developmental displasia of the hip?
-genetic: 10 fold more probable if parents had it, more common in caucasians than africans and asians -environmental: intrauterine position -breech positioning is associated with DDH, sex= female, firstborn child =first born female in breech position 1/15 probability =normally 1.5 births per 1000
What is a continuous phenotype (eg)?
-continuum of phenotypes, height= it isn’t just there or isn’t, comes on a scale -quantitative, can measure the differences between individuals
What is a quantitative trait?
continuous distribution of phenotypes -measurable and continuous range of phenotypes -height, weight, eye colour -often polygenic -affected by environmental factors
What does polygenic mean?
-controlled by many genes