1.Zygote- THIS IS 2 N !!!!the diploid cell formed by fertilization of an egg cell- it's basically the first cell of a person, the egg and sperm DNA unite to get back to that 46 chromosome number, the zygote replicates (mitosis) and becomes YOU! YOU with half of your DNA from Mom and half from dad- two bits of info. for nearly every trait in your body.
2.ALLELE- a segment of your DNA (or gene)that codes for a trait in your body. You have two alleles for every trait in your body (with one exception- naturally!).
3.Homozygous alleles- this is what we call the genetic situation when both parents give the same information (genes) for a trait. For example: both of your parents give you the gene for blonde hair, you have no other choice than to have blonde hair.
4.Heterozygous alleles- this is what we call the genetic situation when your parents give you two different genes for a trait. For example: Your Mom gives you the gene for brown hair and your dad gives you the gene for blonde hair- now your Genome has to decide which proteins to make- ones for brown hair OR ones for blonde hair- who will win? read on to find out!
5. Dominant traits (or alleles or genes)- This is when one of the alleles from a parent is stronger than the allele from the other parent so it's the one you use and, therefore,it's the trait that you have. Brown hair is dominant to blonde hair, therefore, you will have brown hair and you won't even know that you have a secret hidden gene from your other parent! (you can probably figure it out though- either by what your parents look like or what your kids look like) We only use one letter to represent a trait when we are trying to predict what traits a person will have, the Dominant trait determines what the letter will be and it (dominant one) will be uppercase- the recessive trait will use the same letter as the dominant trait, but we show that it is recessive by making it lower case!
6.Recessive traits (or alleles or genes)- This is when one of the alleles you get from a parent is weaker than another. You don't use this gene because you favor the stronger gene. In this way it is a hidden, secret gene, that you may never know you have. Even though you don't use this gene in your body, you do have the potential to give this "recessive" gene to your children and (depending on how the shuffling goes during meiosis) they could end up having that recessive trait. EVER see two brown headed people with a blonde baby- their baby- they both had a recessive allele for blonde hair!!!!!!
7. Co-dominant alleles- this is when you have heterozygous alleles for a trait (that's two different alleles) and they are equally strong so they both show up!! This is how you get stripes and spots in fur- neat,hugh?
8. Incompletely dominant alleles- this is when you have heterozygous alleles for a trait (that's two different alleles) and they are equally strong, so they duke it out and decide to compromise- they meet in the middle- you no longer see the original traits but a medium version of each trait- think Pink! As in: Red mixed with White makes PINK!
9. Genotype- this is how we refer to the "letters" or alleles you carry- you always have two- one from mom and one from dad. TT or Tt where "T" is tall (dominant) and "t" is short (recessive).
10. Phenotype- this his how we refer to the visible PHYSICAL features that result from your alleles - "Tall" or "Short". It's what we see and know you have with and/or without knowing what your DNA says.
11.Gregor Mendel- a Monk/ gardener that figured out "genetics" using pea plants. He just cross pollinated pea plants that had different colored flowers and figured out the whole dominant/ recessive trait thing. Genetics that deals with only dominant and recessive traits is even called "MENDELIAN GENETICS".
12. HYBRID- this is how we sometimes refer to the crossing (or breeding) of two different different organisms of the same species. Hybrid is actually a good synonym for heterozygous! YOU are a hybrid of your parents!!! when we are crossing to test one trait it's refered to as a monohybrid cross ( two traits would be a dihybrid cross)
13.Punnett square - you may have used this tool in Math class- it's how we set up a cross between two different individuals to get the probability of a given trait(s) appearing in their offspring. We use the letters that represent the trait to complete the punnett.
14.Test cross- this is how we find out if an individual is purebred for a dominant trait. You cross the individual with the dominant phenotype with an individual expressing the recessive phenotype. If any of the offspring express the recessive trait then you know that the Dominant individual is not a purebred (homozygous) but is in fact heterozygous for the trait.
15. monohybrid cross- this is when you are just doing a cross for one trait! most of the crosses we will do in class, if not ALL of them, are going to be monohybrid.
16. Sex linked traits ( x-linked)- these are the traits that can be found on the last pair of chromosomes, the ones that determine your sex. We call them the 23rd pair or XX if you’re a girl , XY if you’re a boy. Male will only have one allele for traits that occur on certain regions of the “x” in the 23rd pair (most common x-linked traits are; colorblindness, hemophilia and balding)
17. carrier- This is how we refer to a person who is Heterozygous for a trait, they have a recessive allele for something that they will never get, but they can give that allele to their children who may possibly get the trait. ( Mom of cystic fibrosis child is not sick, but child is because she and her husband were carriers of the trait).
18. Pedigree- a chart that shows who of your ancestors carries a trait. circles are girls, squares are guys and shaded shapes have the trait being charted. https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiX56bRVBks0jhnCcpe51oCCa2pBgI__vKsQPDaYYojK67uG2Z0i3nDGCZmmFTzxWvsjGsDaNlxgmAzxiTnMEY291ydSlFu6kxOmjfps8wFhQXucVovWJrZN5KdZHf1RhHA0ujLXCrbpZgN/s1600/ftree.gif
19. Karyotype- a picture that shows paired chromosomes- can use it to determine the sex of a person or to check for Down's syndrome or any other tri-somy ( 3 chromosomes instead of 2).
20.Intermediate inheritance- another term to describe a trait as being a result of co-dominant alleles or incompletly dominant alleles.
21. Polygenic- when more than one gene contributes to a trait- skin color is a result of the interaction between 7 different genes (which means 14 different alleles!), eye color is the result of 3 different genes.
22. Autosomal inheritance (or autosome)- when an allele is found on any of the 22 chromosomes that don't determine sex, so chromosomes 1 through 22 are autosomes. chromosome 23 is a sex chromosome.
23. Huntington's disease- is a disorder passed down through families in which nerve cells in certain parts of the brain waste away, or degenerate. It is an autosomal dominant disorder located on chromosome 4.
24. Fertilization- when the egg and sperm unite to create the first cell of an organism ( the zygote =2n!)
go here to see how this is done!!!!!! DON'T look at dihybrid stuff- too confusing for you now. http://www.athro.com/evo/gen/punnett.html practice:http://www.athro.com/evo/gen/punexam.html overview of genetics:http://www.google.com/search?sourceid=navclient&hl=en-GB&ie=UTF-8&rlz=1T4GGLJ_en-GBUS290US290&q=punnet+square+introduction it's the first link- it's a ppt.
