Terms YOU need to know!

What is the difference? Chromosome DNA Chromatin Gene Chromatid

Chromatin DNA and proteins in a non-structured form The term Chromatin = when the cell is not reproducing (Interphase)

Made up of DNA and proteins Chromosome Made up of DNA and proteins

Chromosome Chromatin

Chromatid ½ of a chromosome 2 chromatids = 1 chromosome TWO appear during the process of mitosis = sister chromatids

Contains hereditary information DNA Contains hereditary information Found in chromosomes

Gene “Instructions” Many genes within DNA Why we are who we are!

What does homologous mean? Homo = the same Hetero = different

Homologous The same!! We get ½ our chromosomes from … and ½ our chromosomes from

Karyotype Mom Dad Homologous Pair Dad Mom

Who you callin' a diploid?? Haploid vs. Diploid Who you callin' a diploid??

*Total number of homologous pairs of chromosomes in a cell* Haploid *Total number of homologous pairs of chromosomes in a cell* What is the haploid number of human cells? 23

Sperm and egg! = reproductive cells Gametes Sperm and egg! = reproductive cells ARE HAPLOID! 23 15

Total number of chromosomes in a cell Diploid Total number of chromosomes in a cell What is the diploid number of human cells? 46

All other cells! ARE DIPLOID! 46 17

Haploid vs. Diploid The reference to haploid cells is 1N The reference to diploid cells is 2N If N = 23 for humans (haploid) Then 2N ( 2 x 23 ) = 46 (diploid) Get it??

Sex chromosomes vs. Autosomes Sex chromosomes = this is what determines our sex (duh!) Autosomes = all the other chromosomes

Humans have 1 pair of sex chromosomes and 22 pairs of autosomes X and Y (male) X and X (female)

Any questions??

So Why Meiosis? Pg. 153 What is the purpose of meiosis? Define the following key words: Gamete Crossing-over Genetic Recombination Independent Assortment 3. Why is crossing-over important in the creation of new gametes? Think of the BIG picture 4. List TWO ways that you see meiosis is different from mitosis