Cell cycle & mitosis

• Biologie
• Middelbare school
• vwo
• Leerjaar 4

Cell cycle & Mitosis

Learning objectives

• List and describe the steps of the cell cycle
• List and describe the phases of mitosis
•  Describe changes in number of chromosomes during the steps of the cell cycle and mitosis
• Describe changes in DNA content during the steps of the cell cycle and mitosis

Cell cycle

• Interphase:
    - G1-phase: growth, forming organelles
    - S-phase: DNA replication
    - G2-phase: growth, prep M-phase
•  Cell division: M-phase
     - Mitosis or Meiosis

S-phase

• DNA replication
• Chromosomes: DNA wrapped around proteins
• Centromere: point at which two chromatids connect
• Number of chromosomes = number of centromeres 
• Chromatid: half of a replicated chromosome
• n: number of different types of chromosomes in that species, n=23 for humans. We have chromosomes in pairs (except in gametes), remember Aa from inheritance last year.

The G1, S and G2 phase together make up the:

1. Cell cycle
2. Interphase
3. Mitosis
4. Growth phase

In which phase of the cell cycle are organelles formed?

1. M phase
2. G1 Phase
3. G2 Phase
4. S phase

What is the structure called that connects the chromatids?

1. Centriole
2. Centromere
3. Controsome

Which applies?

1. 4 chromosomes, 8 chromatids
2. 8 chromosomes, 8 chromatids
3. 8 chromosomes, 4 chromatids
4. 8 chromosomes, 16 chromatids

Which applies?

1. 4 chromosomes, 8 chromatids
2. 8 chromosomes, 8 chromatids
3. 8 chromosomes, 4 chromatids
4. 8 chromosomes, 16 chromatids

M-phase

• Cell division
• Two options:
    - Mitosis: creating exact copies of the original cell for growth and repair
    - Meiosis: creating cells with half the number of chromosomes for reproduction (the gametes)

Mitosis

One cell will split in two exact copies

2n (46) --> 2n + 2n

Prophase

• Chromosomes condense: each has two chromatids
• Nuclear membrane starts breaking down
• Spindle apparatus appears 

Metaphase

• Centromeres lined up on the equator
• Each chromatid attached to a spindle fibre 

Anaphase

• Separation of the sister chromatids 
• Sister chromatids move to opposite poles, now called chromosomes

Telophase

• Chromosomes have reached poles
• Nuclear membranes start forming
• Chromosomes uncoil, become less visible 

Cytokinesis

• Actual splitting of cytoplasm 

Homework

• Watch the two video's below
• Complete the worksheet Mitosis on the Classroom and hand in before next lesson
• Study the Quizlet words
• Tip: pages 99-104

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