Genetics II

Where is our blueprint located? Chromosome – fine, thread like structure in the nucleus that controls heredity Gene – segment (section) of DNA that controls individual traits (dark bands on chromosomes) DNA – molecule that stores and passes on genetic information Nucleotide base pairs – A, T, C, G make up the DNA double helix

From where did our chromosomes come? If you reproduce asexually, all of your chromosomes came from a single parent When you reproduce, you will divide by binary fission or mitosis to create two identical diploid daughter cells

If you reproduce sexually, half of your chromosomes are from mom, and half are from dad. Your sex cells will be made through meiosis, creating four different haploid (half the chromosomes) cells from one parent cell. To reproduce, an egg cell must be fertilized by a sperm cell, giving the resulting zygote a diploid (full set) of chromosomes.

How to make more peacocks:

Predicting Offspring If we have the genotypes (gene combination) and phenotypes (physical characteristics) of two sexually reproducing parents, We can predict the possible traits (different characteristics) that the offspring that two sexually reproducing parents could produce!

The Genetics Code: Allele – each member of a gene pair that determines a particular trait Dominant – stronger trait (capital letter) Recessive - weaker or hidden trait (lower case letter)

To Predict Offspring we Use the Punnett Square Pp X Pp

With the Punnett Square we can predict: THE GENOTYPE (gene combination) Heterozygous or hybrid – having two different genes for a particular trait (Hh) Homozygous or purebred – having the same genes for a particular trait (HH or hh) THE PHENOTYPE (physical characteristic) Eye color, hair color, height, texture are examples

So, I proclaim that… Why? The phenotype depends on the genotype Because genes control your characteristics!

But wait… There is more! Incomplete dominance – a condition in which neither of the two genes masks (or hides) the other. The result is known as blending.

Check out these Geraniums RR (red) X WW (White) = RW (Pink) X =

Codominance Both alleles of a gene contribute to a phenotype, that is, neither is dominant…

Human Blood Types A is dominant to O B is dominant to O A is codominant to B