1. Chapter 8 Cell Reproduction

2. Section 1 Vocabulary Pretest
Cells with one set of chromosomes
Cells with two sets of chromosomes
Rod-shaped structures made of DNA and proteins
Proteins found in DNA
X and Y chromosomes
A chromosome other than a sex chromosome
All chromosomes visible in a cell
Matching chromosomes
Copied half of a chromosome
Holds chromatids together
DNA during interphase
Chromosome
Histone
Chromatid
Centromere
Chromatin
Sex Chromosome
Autosome
Homologous Chromosome
Karyotype
Diploid
Haploid

3. Answer Key Chromosome C Histone D Chromatid I Centromere J Chromatin K
Sex Chromosome E
Autosome F
Homologous Chromosome H
Karyotype G
Diploid B
Haploid A

4. Why Cells Divide Growth and repair Creation of gametes (Sex Cells)
Method of reproduction in unicellular organisms

5. Chromatin
While cells are growing, their DNA appears as long, stringy chromatin material.
When cells are ready to divide, the chromatin condenses to form chromosomes.

6. Chromosomes
Chromosomes —DNA wrapped around proteins to form an X-shaped structure
Histones —proteins that DNA wraps around
Sections of chromosomes are called genes
m/watch?v=9kQpYdC nU14 (go to real player video folder on desktop: “How DNA is packaged”)
Histones

7. Chromosome Structure
Each chromosome is made of two identical halves called sister chromatids held together at a point called a centromere.
The sister chromatids are the result of DNA copying itself.
They are called double stranded and will need to separate before the cell divides.

8. Chromosome Numbers
Humans have 46 chromosomes in the nucleus of every cell
Two are the sex chromosomes (X and Y)
XX = female
XY = male
The other 44 are called autosomes
They occur in matching pairs
Called homologous chromosome pairs
One chromosome in each pair comes from mom and the other comes from dad

9. Karyotypes
A karyotype is a photograph of the matching pairs of chromosomes
(go to real player video folder on desktop: “What is a Chromosome?”)

10. Diploid vs Haploid
Diploid cells contain the full set of chromosomes (all 46)
All body cells are diploid
Haploid cells contain half the number of chromosomes (23)
One from each homologous pair
Sperm and egg cells are haploid

11. Section 2 Vocabulary Pretest
Binary fission
Mitosis
Asexual reproduction
Meiosis
Gametes
Interphase
Cytokinesis
Prophase
Spindle fiber
Metaphase
Anaphase
Telophase
Cell plate
Division of cell’s cytoplasm
Division of cell’s nucleus
Reproductive cells
Division of a prokaryotic cell
Pull chromatids apart
Chromosomes line up in middle of the cell
Chromatids separate
Two new nuclei form
Production of offspring from one parent
Time between cell divisions
Results in the formation of gametes
First phase of mitosis
Forms between two new plant cells

12. Answer Key Binary fission D Mitosis B Asexual reproduction I Meiosis K
Gametes C
Interphase J
Cytokinesis A
Prophase L
Spindle fiber E
Metaphase F
Anaphase G
Telophase H
Cell plate M

13. Cell Division How many new cells do you make every day?
(go to real player video folder on desktop: “Cell Division and the Cell Cycle”)
How many new cells do you make every day?
About 2 trillion (25 million cells per second)
Cells reproduce asexually (one parent)
One cell becomes two
The process is different in prokaryotes and eukaryotes

14. Cell Division in Prokaryotes
Prokaryotes reproduce by binary fission
DNA is circular (no chromosomes)
DNA copies itself
Cell divides--- Simple 

15. Cell Division in Eukaryotes
Eukaryotes use two types of cell division
Mitosis —produces body cells
Meiosis —produces gamete cells
Both mitosis and meiosis happen in stages

16. The Cell Cycle Mitosis is part of the Cell Cycle
Three stages in the Cell Cycle:
Interphase —period of growth, development and DNA replication
Mitosis —division of the nucleus
Cytokinesis —division of the cytoplasm
watch?v=lf9rcqifx34&feat ure=related (go to real player video folder on desktop: “Cell cycle” )

17. Interphase Cells spend most of their time in interphase Three phases
G1—first growth phase (Cells grow to full size)
S—DNA synthesis (copied)
G2—second growth phase (prepares to divide)

18. Some cells exit the cycle after the G1 phase and enter the G0 phase
Some cells exit the cycle after the G1 phase and enter the G0 phase. These cells no longer divide.
Muscle cells
Nerve cells

19. Mitosis Mitosis (division of nucleus) is divided into four stages:
Prophase
DNA condenses into chromosomes
Nuclear membrane disappears
Centrioles and spindle fibers appear
Metaphase
Chromosomes line up in the middle of the cell
Anaphase
Sister chromatids separate and move toward poles
Telophase
Chromosomes uncoil back into chromatin
Nuclear membrane forms around each set of chromosomes

20. Stages of Mitosis Interphase Prophase Metaphase Anaphase Telophase

21. Cytokinesis
The final stage of the cell cycle is cytokinesis (dividing the cytoplasm)
In animal cells, cytokinesis begins with a pinching in of the membrane forming a cleavage furrow.
In plant cells, cytokinesis begins with the formation of a cell plate.
End result is two identical diploid daughter cells

22. Meiosis Meiosis produces gamete cells (sperm and egg cells)
Gamete cells are haploid (half the number of chromosomes)
Full number of chromosomes is restored during fertilization.
A cell passes through interphase and copies its DNA.
The cell then divides twice resulting in haploid gamete cells.

23. Meiosis is also divided into stages:
Prophase I
Chromosomes form and find their homologous match
This is called synapsis (pairing of homologous chromosomes)
Each pair of homologous chromosomes is called a tetrad.
Crossing over can occur in each tetrad resulting in a genetic recombination of genes.

24. Telophase I and Cytokinesis I
Metaphase I
Matching pairs of chromosomes (tetrads) line up in the middle of the cell and attach to spindle fibers.
Anaphase I
Homologous chromosomes separate and move to the poles (independent assortment)
Telophase I and Cytokinesis I
Nucleus and Cell both divide for the first time. This reduces the number of chromosomes to one half. This is called a reduction division.
However, the chromosomes are still double stranded.

25. Telophase II and Cytokinesis II
Prophase II
Spindle fibers reappear
Metaphase II
Chromosomes line up in the middle of the cell and attach to spindle fibers
Anaphase II
Chromatids split and move to poles
Telophase II and Cytokinesis II
Nucleus and cell divide for the second time
This is essentially a mitotic division.
4 haploid gamete cells are produced. They have half the number of single stranded chromosomes.

26. (go to real player video folder on desktop: “Meiosis Sq. Dance”)

27. Meiosis occurs in the testes and the ovaries
Spermatogenesis —production of 4 mature sperm cells.
Oogenesis —production of 1 mature egg cell and 3
smaller polar bodies that degenerate.

28. Fertilization Fertilization —union of sperm and egg cell.
Sexual reproduction, involving the production of sperm and egg cells by meiosis followed by fertilization, ensures genetic variation in all offspring.