1. Bell Work: Draw and label a chromosome
Chromatids
Centromere

2. More Vocabulary Centromere- holds the chromatids together
Chromatids- identical sides of the chromosomes
Contain same genetic information on both sides
Sister chromatids = when two chromatids are bound by a centromere

3. DNA, CHROMOSOMES, & Karyotypes

4. Objectives Evaluate the structure of a chromosome
Differentiate between prokaryotic and eukaryotic chromosomes
Infer the complexity of an organism based on chromosome number

5. Let’s start with vocab. Cell cycle = the life cycle of a cell
Interphase = all the time between cell divisions
Mitosis = division of the nucleus
Cytokinesis = division of the cytoplasm

6. Stages of the Cell Cycle
Interphase
M-phase (Mitosis)
Cytokinesis

7. Draw it out
With your table group, draw a chart of the cell cycle on your desk

8. DNA & Chromosomes in Interphase
G1 phase – Interphase
DNA is in the form of chromatin
S phase – Interphase
DNA chromatin coils itself tightly into chromosomes [ l shaped]
Each chromosome duplicates itself [X shaped]

9. Chromatin DNA wrapped around histone proteins
Structure of DNA between cell divisions.
Chromosomes are only present during cell division.

10. Rod or X- shaped structures made of tightly wound DNA & Proteins
Histones - sphere shaped proteins that the DNA wraps around
DNA
CHROMOSOMES
Proteins

11. Chromosomes Rod shaped prior to S phase
X- shaped after S phase (duplication)
Rod shaped after Anaphase

12. Follow the DNA
Early S phase

13. Draw it out
As a table group, draw out the process of the cell cycle on your desks
Show the DNA in each step

14. Chromosomes come in matching sets -these are called homologous pairs

15. Karyotype after DNA replication
Each homologous pair duplicates itself = homologous chromosomes

16. PROKARYOTIC VS EUKARYOTIC CHROMOSOMES
Larger
rod shaped
in Nucleus
Prokaryotic:
Circular
Smaller
NOT in Nucleus
Chromosome

17. Which is more complex in terms of DNA?
Adders Tongue Fern
Human OR

18. Which is more complex in terms of DNA?

19. Chromosome Numbers Organism # of chromosome Fruit Fly 8
Carrot & Lettuce 18
Cat 32
Earthworm 36
Human 46
Gorilla 48
Sand Dollar 52
Adder’s Tongue Fern
1262

20. Two Types of Chromosomes
SEX
Determine the gender of the individual
The 23rd pair
2 of the 46 chromosomes
AUTOSOMES
The other 44 out of 46 chromosomes

21. Autosomes vs. Sex Chromosomes

22. SEX Chromosomes
XX =
XY =

23. KARYOTYPE
A picture taken from a microscope of all the chromosomes within a cell.
The chromosomes are then arranged in homologous pairs and given a set of numbers

24. Diploid vs Haploid Cells
Description
Both sets of homologous chromosomes present
Only one of each homologous chromosome present
Type of Cell
All cells but sex cells (egg or sperm)
Only sex cells- Egg or Sperm
Abbreviation 2n 1n