Watch this first!
http://www.youtube.com/watch?v=Q6ucKWIIFmg&safety_mode=true&persist_safety_mode=1&safe=active
1.Non-disjunction- When the chromosomes are not pulled apart evenly during anaphase of meiosis. This is what leads to Down’s syndrome (aka: trisomy 21 which means three of the 21st chromosome).
2. Chromosome- a condensed segment of DNA, humans have 46 chromosomes in every cell in their body,(except egg and sperm)
3. Chromatid- half of a duplicated chromosome- the whole X represents two sister chromatids!
4. Mitosis- the process of forming two new, genetically identical cells (skin, liver, hair, muscle, blood, etc. all of these cells are referred to as being 2N= the whole chromosome number, one set from Mom and one set from Dad)
http://www.youtube.com/watch?v=lf9rcqifx34&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
5. Meiosis – the process of forming 4 new, GENETICALLY DIFFERENT cells with half the genetic material of the original cell. These cells only have 23 chromosomes (they are called 1N)
http://www.sumanasinc.com/webcontent/animations/content/meiosis.html
6. Zygote- forms when the egg and the sperm unite and make the first cell of a new organism.
7. Allele- a choice for a trait, you have two alleles for every trait in your body, one from mom and one from dad.
8. Replication- the process of copying the original strand of DNA to form a new, IDENTICAL, strand of DNA so that when the cell divides the daughter cells have the same exact genetic information as the parent cell.
9. Trait- a physical characteristic or feature of a person (ex; brown hair, tall, diabetic, blue eyes)
10. Genes- the segments of a person’s DNA (or chromosome)that codes for a certain trait.
11. Fertilization- when the sperm cell unites with the egg cell.
12. Centromere- the structure that holds two sister chromatids together.
13. haploid- The “Half” number of chromosomes an organism would have in a regular/ non- sex cell. Sex cells are haploid!!!! (same thing as 1N)
14. Diploid- The full chromosome number in a regular/somatic cell, the prefix “di” relates to the fact that you have “two” bits of information (chromosomes) for nearly every trait in your body. One from Mom and one from Dad. (same thing as 2N)
15. Somatic cells- all of the cells in your body except for your egg or sperm cells.
16. Gametes- the cells in your body that participate in reproduction, either egg or sperm cells.
17.Homologous chromosomes- The chromosomes that Match up for given traits, the chromosome from Mom that codes for height and the chromosome for Dad the codes for height are “homologous”. They pair up during meiosis 1 and trade information to insure that offspring are not identical!
18. Crossing over- when homologous chromosomes pair up and trade genes during meiosis 1.
19.sexual reproduction- when organisms use meiosis to allow for genetic variation of offspring- this allows for increases chances of survival in a species.
20. asexual reproduction- when organisms use mitosis to duplicate their cells, this results in a “clone” or two identical cells. Your cells do this when you are growing or repairing damaged tissue. Some organisms do this to make offspring= bacteria and fungal spores do this.
