Genetic Variation and Change
monohybrid crosses
Gregor Mendel (1822-1884)
A most important and clever scientist.
He is the chap responsible for laying the scientific groundwork for the field of genetics (the branch of biology that deals with the rules of heredity and variation)
A most important and clever scientist.
He is the chap responsible for laying the scientific groundwork for the field of genetics (the branch of biology that deals with the rules of heredity and variation)
First revision of the basics:
Ear enlargement (inside ear canal...what is DNA) and all sorts of other helpful stuff to remember / learn
http://gslc.genetics.utah.edu/units/basics/tour/
http://gslc.genetics.utah.edu/units/basics/tour/
hmmmm..... seems fine ....except second generation wtf (whats that flower)?
http://www.bioinformatics.nl/webportal/background/mendelinfo.html
To understand this stuff we do need to remember the details of mitosis, meiosis and fertilisation
|
A Khan academy thingy... worth a look?
I reckon that might be some useful homework |
Remember these words?
cross
F1 offspring
Gametes
Egg / ova
Sperm /pollen
pollination
fertilization
gene
allele
genotype
phenotype
dominant
recessive
cross
F1 offspring
Gametes
Egg / ova
Sperm /pollen
pollination
fertilization
gene
allele
genotype
phenotype
dominant
recessive
Do you remember the details of meiosis?
lets just cover the basics... we will come back to this again later when we look at the sources of genetic variation... there's more to it yet
if you get it you should be able to translate the clip below!!!!
can we see Vimeo clips at school?
(someone tell the boss we need to have Youtube unblocked)
if you get it you should be able to translate the clip below!!!!
can we see Vimeo clips at school?
(someone tell the boss we need to have Youtube unblocked)
Now for some more examples....
This couple "get together" and have a wee one. Can you figure the genetics of it all?
Note: blue eyes are recessive
.... and here is their pretty baby (note eye colour)....
now explain, ie figure out the fertilisation that occured
Spirit Bears...
The kermode bear (Ursa Americanus Kermodie) is a beautiful white bear that lives in the rain forests of British Columbia.
The Kermode bear is not a polar bear, nor is it an albino.
It is caused by a recessive allele found in the black bear population.
... and how come a white bear survives? (any advantage?)
Crikey... a white whale in Cook Straight
From the news July 2015 link here
http://www.radionz.co.nz/news/national/278057/rare-white-whale-spotted-in-cook-strait
Albino is a recessive trait, this white whale must be homozygous for that recessive trait ... right?
You would not necessarily expect many albino offspring .... afterall not many albino people father albino kids.
Whales tend to hang in family groups, so:
explain why Migaloo has fathered albino kids
http://www.radionz.co.nz/news/national/278057/rare-white-whale-spotted-in-cook-strait
Albino is a recessive trait, this white whale must be homozygous for that recessive trait ... right?
You would not necessarily expect many albino offspring .... afterall not many albino people father albino kids.
Whales tend to hang in family groups, so:
explain why Migaloo has fathered albino kids
And we can run into some tricky ethical issues...
Hypertrophic cardiomyopathy is inherited as an autosomal dominant trait and like other autosomal dominant diseases does not skip generations
and in this case affects both sexes. As this trait is dominant, we know that if a child has the the disease then at least one parent must also have the gene.
(some of the dates seem a bit out)
Girl III 5
....moral & ethical issues!!
I wonder...is she still alive
Should she be told she has the condition At what age?
Should her employer be told?
What if her employer was Air NZ and she was a pilot?
and in this case affects both sexes. As this trait is dominant, we know that if a child has the the disease then at least one parent must also have the gene.
(some of the dates seem a bit out)
Girl III 5
....moral & ethical issues!!
I wonder...is she still alive
Should she be told she has the condition At what age?
Should her employer be told?
What if her employer was Air NZ and she was a pilot?
workbook ref: pp 151 - 156
Now some trickier stuff:
Incomplete dominance in Andalusian chooks
Can we figure out the genetics of this then...
2 greys are crossed and have 3 chickens:
1 white
1 black
1 grey
1 white
1 black
1 grey
Another example of incomplete dominance
Can you see how we get the F2 ratio of 1:2:1 when we cross 2 F1's ?
Co-dominance
BOTH alleles are expressed in the offspring
the calf has both white hairs and brown hairs
the calf has both white hairs and brown hairs
Lethal alleles
Multiple alleles....
of course any individual only carries TWO alleles
we have 3 alleles here,
how many phenotypes can we get?
how many phenotypes can we get?
workbook ref pp 157 - 162