1. Chapter 6 Chromosomes and Cell Reproduction

2. Important Vocabulary
Chromosomes – tightly coiled packages of DNA. Held together by proteins called histones.
DNA wraps around the histones then supercoils to form chromosomes.

3. Important Vocab
Chromatid – two exact copies of a chromosome held together by a centromere. Forms as DNA copies itself before cell division
Centromere – holds the chromatids together until they separate

4. Types of Chromosomes
Sex Chromosomes – are the chromosomes that determine the sex of an organism.
Female: XX
Male: XY
Autosomes – all other chromosomes
Humans: 44 autosomal chromosomes

5. Chromosomes 22 homologous pairs of autosomes. 2 sex chromosomes
Karyotype – is a picture of the chromosomes in a somatic (body) cell.
22 homologous pairs of autosomes.
2 sex chromosomes

6. Chromosomes
Homologous chromosomes – two copies of each autosome (maternal and paternal)
Homologous chromosomes are the same size, shape, and carry genes for the same trait. One comes from mom and one comes from dad.

7. Chromosomes
Diploid – cells have two sets (maternal and paternal) of chromosomes.
Humans have 46 chromosomes.
Represented by 2n (means a full set of DNA)
Somatic Cells (cells making up the body)
Haploid – cells have one set of chromosomes.
Human haploid cells have 23 chromosomes.
Represented by n (means a half set of DNA)
Gametes (reproductive cells : egg and sperm)

8. Diploid Cells Somatic Cells Cells that make up the body of organisms.
Somatic Cells are produced through Mitosis (cell division results in 2 genetically identical cells).

9. Interphase: G1, S, G2 Mitosis PMAT Cytokinesis
The longest stage of a Cell’s life
The time spent between divisions
Produces all materials required for growth
Preparation for division
Phases of the Cell Cycle
Interphase:
G1, S, G2
Mitosis
PMAT
Cytokinesis

10. Part of one of Interphase is also known as the G1 Phase of the Cell Cycle.
This is the Growth Phase where the cell grows and perfoms all of its necessary functions.

11. The Second part of Interphase is known as the S Phase
Synthesis Phase is when DNA replicates copying itself ensuring there will be one full copy of DNA in each daughter cell.

12. The third part of the Cell Cycle, G2, is a second growth phase where the cell makes the cell is ready for Mitosis.
Also a checkpoint to ensure the DNA correctly replicated.

13. Mitosis: Cell Division Mitosis has 4 phases. Prophase Metaphase
Anaphase
Telophase

14. and begin to move chromosomes toward the center of cell.
In Prophase the nuclear envelope disintegrates, centrioles move to the poles, spindle fibers develop
and begin to move chromosomes toward the center of cell.
Spindle Fibers
Pair of Centrioles
Chromosomes consisting of 2 Sister Chromatids

15. During Metaphase the Chromosomes line up across center of the cell, also called the equator, or Metaphase plate.
Spindle Fibers
Equator, or Metaphase Plate
Chromosomes

16. In Anaphase the Chromatids that make up each Chromosome move apart and travel to opposite poles of the cell.
Daughter Chromosomes
Chromosome

17. In Telophase an envelope surrounds each set of Chromatids to form new Nucleus and the Cytoplasm starts to divide
2 identical sets of chromosomes
Cleavage Furrow

18. Cytokinesis takes place when the Cytoplasm divides and two cells with identical genetic material are formed
Daughter Cells

19. Let’s Review