Grade 11 biology notes based off of 'McGraw-Hill Ryerson Biology 11' textbook and in-class lectures. Contact @samanthaguu on Instagram for a shared version on google drive with interactive links and document outline.
, 4.1 - Cell Division and Genetic Material
The Cell Theory
1. All organisms are made up of one or more cells.
2. The cell is the basic unit structure and function of all living organisms.
3. All cells arise from pre-existing cells.
Cell History
With the help of the microscope:
- Anton Van Leeuwenhoek: Discovered bacteria w/ dental scrapings
- Robert Hooke: Created the term ‘cell’
- Matthias Schleiden: Discovered that all plants are made of cells
- Theodor Schwann: Discovered that all animals are made of cells
- Virchow and Remack: Proved that the free-cell formation theory is false
Introduction to Genes
- Genes encodes molecules that make up our body
- 20 000 genes in human DNA
- Number of genes increased over time due to mutations during cell division;
these mistakes eventually take on essential functions
Genetic Terms
- Homologous Chromosomes: A pair of chromosomes that possess the genes for
the same characteristics but may vary in their alleles
2 Types of Chromosomes
1) Autosomes: Chromosomes that code for proteins and not involved in gender
determination of an organism
2) Sex Chromosomes: Chromosomes involved w/ gender determination; 2 X
Chromosomes in females, 1 X and 1 Y in males
, The Cell Cycle
- The process of growth and division of a somatic (body) cell
- 3 Functions of the cell cycle: growth, repair of damaged cells and maintenance
of dying cells
- Cycle is comprised of 2 main periods:
1) Interphase:
- G1: Period of cell growth before DNA
replication
- S (Synthesis): Chromatin duplication
- G2: Preparation for cell division
2) Mitosis (4.1)/Meiosis (4.2)
Mitosis
- Involves the division of body cells
1) Prophase:
- Chromatin condenses into chromosomes
- Nuclear membrane breaks down and nucleolus
disappears
- Centrosomes (made up of 2 centrioles)
move to the opposite poles of the cell to
form spindle fibres (m
icrotubules)
2) Metaphase:
- Spindle fibres attach to centromeres
- Chromosomes line up in the middle of the
cell
3) Anaphase:
- Spindle fibres shorten and sister chromatids
separate to both ends of the cell
4) Telophase:
- Chromosomes unwind into chromatin
- Spindle fibres break down
- Nuclear membrane and nucleolus form
5) Cytokinesis:
- Cytoplasm and organelles divide to create 2
new daughter cells
- In animal cells ONLY: microfilaments constric
forming a cleavage furrow (indentation)
- In plant cells ONLY: cell plate forms
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