1. 6-1 Notes: Chromosomes pg

2. fact
We have 9 million kilometers of DNA. That’s enough DNA to stretch from the sun and back more than 13 times!! How is all that DNA packed so tightly and squeezed in a nucleus??

3. DNA condenses into chromosomes using histones

4. Chromosomes Chromosome: coiled and compact DNA in nucleus
Histones: proteins that DNA wraps tightly around

6. Chromosomes Chromatid: half of a duplicated chromosome
went through replication and ready for cell division
Chromatids held together by a centromere

7. Chromosomes
Chromosome Number: each organism has a specific number of chromosomes
Humans have 46 chromosomes (23 pairs).
Chromosome number is not linked to complexity of organism.

8. Karyotype Photo of chromosomes
Stain chromosomes during cell division when DNA is condensed

9. Karyotype Purpose: Stained bands used to identify chromosomes
Identify genetic disorders due to the wrong number of chromosomes
Identify sex

10. Homologous Chromosomes
Your body has 23 pairs of chromosomes
Each pair referred to as homologous pair
Homologous Chromosomes: two chromosomes- one from father and one from mother
Both carry instructions for same gene/trait (ex: eye color)

11. Types of Chromosomes Autosomes: chromosomes #1- 22
Determine most physical traits
Homologous

12. Types of Chromosomes
Sex chromosomes: #23 determine sex of the organism
(X or Y)
female: XX
male: XY (not homologous)

13. Types of Cells Haploid vs. Diploid
Use “n” to indicate nuclear state of cell (pairs of chromosomes)
Haploid (n): only 1 set of chromosomes (n=23 chromosomes)
Diploid (2n): having 2 sets of chromosomes (2n=46 chromosomes)
one set from mom and one set from dad

14. Types of Cells Haploid vs. Diploid
2 haploid cells (sperm and egg) can combine to make a diploid (zygote)

15. Type of Cells Somatic vs. Gametes Somatic Cells: body cells
Make up most of your body tissues and organs.
Diploid (2n)
Formed by Mitosis

16. Somatic vs. Gametes Type of Cells Gametes: sex cells
Form egg and sperm cells
Haploid (1n)
Formed by Meiosis