1. Cell Growth, Division and ReproductionB1

2. B1. Basic Biological Principles
Describe the events that occur during 3 stages of the cell cycle: interphase, nuclear division, cytokinesis.
Compare and contrast processes and outcomes of mitosis and meiosis.
Explain how genetic information is inherited.
Explain the functional relationships between DNA, genes, alleles and chromosomes and their roles in inheritance.

3. B1. Vocabulary
Allele genetics Allele frequency inheritance Cell cycle meiosis Chromosomes mitosis Crossing over nondisjunction Cytokinesis nucleus Deoxyribonucleic acid (DNA) DNA replication Gene gamete

4. ANALOGY: What would happen to a growing town if it continued to grow?
Cell Size
Limits to Cell Size
Information Overload
Large cells place more demands on the DNA to provide what the cell needs to live
Information a cell needs to live is stored in DNA
When a cell is small, its DNA can meet all of its needs
If a cell gets too large, a cell’s DNA would not be able to keep up with the needs of the cell
ANALOGY – a growing town
ANALOGY: What would happen to a growing town if it continued to grow?

5. ANALOGY: Traffic Problems
Cell Size
Limits to Cell Size
Exchanging Materials
Cells rely on movement of material across the cell membrane
Large cells have trouble moving enough nutrients in and wastes out
ANALOGY: Traffic Problems

6. Limits to Cell Size Cell Size
ANALOGY: Lots of Growth can mean lots of trouble both in a town and in a cell

7. Cell Division Cell Size
A process by which a cell divides into two new cells
Solves the problem of overloading DNA and not being able to get enough materials in or out

8. Model it…
How does the surface area of a cube change as its volume increases?
How does the relationship support the information learned today.
Construct 3 different sized cubes. Ask students to determine the surface area (to represent the surface at which a “cell” can exchange material) and volume (significant of cell size). Volume increases at a much faster rate than the surface area.

10. The Process of Cell Division
Chromosomes
Cells store information in DNA
DNA is packaged into chromosomes
Prokaryotes = single circular chromosome
Eukaryotes = many chromosomes
Chromatin = all of the chromosomes in the nucleus

11. The Process of Cell Division
Changes to the DNA during division
DNA is copied before cell division (replication)
When a cell is not dividing, DNA is uncoiled (chromatin)
During division, DNA coils up (condenses) and individual chromosomes can be seen

12. Which is easier to separate?
Chromosomes during cell division
Chromosomes before cell division

13. The Process of Cell Division
Changes to the DNA during division
Once replicated, each chromosome consists of two identical sister chromatids held together at the centromere

14. The Process of Cell Division
The Cell Cycle
The series of events a cell goes through as it grows and divides
growth
DNA replication
Cell division
End Result = two new daughter cells genetically identical to the parent cell

15. The Process of Cell Division
The Prokaryotic Cell Cycle
happens quickly
begins when the cell reaches a certain size
is a form of asexual reproduction
results in a new organism being formed
called binary fission

16. The Process of Cell Division
The Eukaryotic Cell Cycle
Multiple stages with checkpoints
Interphase
G1: Cell Growth
S: DNA Replication
G2: Preparation for division
Cell division (also called M phase)
Mitosis: division of the nucleus
Prophase
Metaphase
Anaphase
Telophase
Cytokinesis: division of the cytoplasm

17. The Process of Cell Division
The Eukaryotic Cell Cycle

18. The Process of Cell Division
Mitosis
PROPHASE
First phase of mitosis
Chromosomes are visible
Nucleus disintegrates
Spindle fibers form
Centrioles migrate

19. The Process of Cell Division
Mitosis
METAPHASE
Second phase of mitosis
Chromosomes line up across the center of the cell

20. The Process of Cell Division
Mitosis
ANAPHASE
Third phase of mitosis
Sister chromatids separate and move to opposite sides of the cell

21. The Process of Cell Division
Mitosis
TELOPHASE
Final phase of mitosis
Chromosomes unwind
Nucleus reforms around each new set of chromosomes
Spindles break down

22. Take a Break…QUICK CHECK
Construct 3 different sized cubes. Ask students to determine the surface area (to represent the surface at which a “cell” can exchange material) and volume (significant of cell size). Volume increases at a much faster rate than the surface area.
CLICK HERE

23. Cell Division and Reproduction
Asexual Reproduction
Cell division that results in a new organism
Reproduction by a single parent
Offspring are clones of parent
Advantages: Quick - organisms well suited for an environment can reproduce very quickly
Disadvantages: Lack of genetic diversity

24. Cell Division and Reproduction
Sexual Reproduction
Results from the joining of two different cells
Offspring have a mix of DNA from both parents
Advantages: Offspring are genetically different
Disadvantages: Slow – takes time to mature and find a mate

25. Think about this… How many chromosomes do you have in your cells?
How many of those chromosomes came from dad?
How many of those chromosomes came from mom?

26. Cell Division and Reproduction
Homologous Chromosomes
Homologous chromosomes = chromosomes that carry the same types of genes
An organism with two parents must receive a set of genes from both parent
Reproductive cells therefore can only carry a half of the chromosomes
When an organism produces reproductive cells (sperm and egg), homologous chromosomes must separate
Meiosis is the process that ensures the separation of homologous chromosomes

27. Cell Division and Reproduction
Homologous Chromosomes

28. Cell Division and Reproduction
Meiosis
Cell division that produces reproductive cells
Begins with interphase (DNA replicated)
Two rounds of division
Meiosis I – homologous chromosomes
Meiosis II – sister chromatids
Each round of division consists of prophase, metaphase, anaphase and telophase

29. Cell Division and Reproduction
Meiosis – End Result
End result of meiosis is different from mitosis
4 cells produced
Each cell contains half the # of chromosomes that are needed in the organism (haploid)
Cells that form are genetically different

30. Cell Division and Reproduction
The process of Meiosis
Begins with interphase (DNA replicated)
Two rounds of division
Meiosis I – homologous chromosomes
Meiosis II – sister chromatids
Each round of division consists of prophase, metaphase, anaphase and telophase

31. Cell Division and Reproduction
Meiosis and genetic diversity
Prophase I
Homologous chromosomes pair up
Crossing over occurs between homologous chromosomes (exchange of genetic info)
Produces new combinations of genes

33. Keystone Prep Questions
Which statement best describes the phase of the cell cycle shown?
The cell is in prophase of mitosis because the number of chromosomes has doubled.
The cell is in prophase I of meiosis because the number of chromosomes has doubles.
The cell is in telophase of mitosis because the cell is separating and contains two copies of each chromosome.
The cell is in telophase of meiosis because the cell is separating and contains two copies of each chromosomes

34. Keystone Prep Questions
2. Mitosis and Meiosis are processes by which animal and plant cells divide. Which statement best describes a difference between mitosis and meiosis?
Meiosis is a multi-step process.
Mitosis occurs only in eukaryotic cells.
Meiosis is used in the repair of an organism.
Mitosis produces genetically identical daughter cells.