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Update Unit 2: Biology.md

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Daniel Chen 2019-11-07 15:55:36 +00:00
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Grade 10/Science/SNC2DZ/Unit 2: Biology.md
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@ -51,7 +51,7 @@ A person contains roughly 100 trillion cells
- Is the control center of the cell
- Holds deoxyribonucleic acid (DNA) in form of `chromatin`
- DNA is a double helix containing genes
- `Genes`: any section of DNA that contain a full set full set of instructions make either RNA or a protein
- `Genes`: any section of DNA that contains a full set of instructions to make either RNA or a protein, **found** in nucleus
- `Chromatin`: is DNA **wrapped tightly** in protein
- `Chromosomes`: are even more tightly wrapped `chromatin` used in cell division only, formed when `DNA` **condenses** in `mitosis`
- Surrounded by a double membrane
@ -62,7 +62,7 @@ A person contains roughly 100 trillion cells
### Nucleolus
- Dense region of DNA located in the nucleus
- This area of DNA is specially for ribosomal DNA (rDNA), or DNA used to code `ribosomes`, organelles that assemble proteins
- This area of DNA is specially for ribosomal DNA (rDNA), or DNA used to code `ribosomes`, enzymes that assemble proteins
- Produce "large" and "small" subunits of `ribosomes`, which either form complete `ribosomes` in `cytosol` or mix with `endoplasmic reticulum`, forming `rough endoplasmic reticulum` (RER)
### Cytoplasm & Cytosol
@ -124,11 +124,8 @@ A person contains roughly 100 trillion cells
### Centrosomes
- Made of same protein as `cytoskeleton`
- **Create and manipulate spindle* during mitosis in animal cells
- One centrosome is a bound pair of two `centrioles`, one mother and one daughter centriole
- Centrioles are present in very few types of plant cells
- Centrioles **create** spindle during mitosis in both plant and animal cells
- Centrioles do not manipulate spindle
- Crucial to mitosis in animal cells
- **Create and manipulate spindle fibres** during mitosis in animal cells
### Lysosomes
- Explained before.
@ -207,27 +204,13 @@ A person contains roughly 100 trillion cells
- `Centromere`: Proteins sticking sister chromatids
- PMAT (prophase, metaphase, anaphase, telophase)
- Division of the nucleus
- Prophase
- Chromatin condenses into two identical `sister chromatids` which condense into `chromosomes`
- Happens to 23 pairs of chromosomes
- Nuclear membrane dissolves
- Centrosomes move to opposite ends (`poles`) of cell, creating `spindle fibres` that begin to attach to `centromeres` in animal cells
- Cell wall organises spindle in plant cell
- Metaphase
- Chromosomes line up in centre of cell to ensure they divide evenly
- Everything in prophase has completed
- Anaphase
- Centromere splits
- Sister chromatids are pulled towards opposite sides of cell via shortening spindle fibres
- Sister chromatids now called `daughter chromosomes`
- Telophase
- Effectively opposite of prophase
- Nuclear membranes form across each of the two nuclei
- Daughter chromosomes unwind into chromatin and are no longer visible
- Nucleolus forms in each nucleus
- Spindle fibres break apart
- **Cytokinesis** usually begins in telophase
- Cell starts to **cleave** (cell centre starts to pinch itself)
| Phase | Diagram | Description |
| :--- | :--- | :--- |
| Prophase | | - Chromatin condenses into two identical `sister chromatids` which condense into `chromosomes` <br> - Happens to 23 pairs of chromosomes <br> - Nuclear membrane dissolves <br> - Centrosomes move to opposite ends (`poles`) of cell, creating `spindle fibres` that begin to attach to `centromeres` in animal cells |
| Metaphase | | - Chromosomes line up in centre of cell to ensure they divide evenly <br> - Everything in prophase has completed (e.g., nuclear membrane has dissolved completely) |
| Anaphase | | - Centromeres split, separating sister chromatids <br> - Sister chromatids are pulled towards opposite sides of cell via shortening spindle fibres <br> - Sister chromatids are now called `daughter chromomsomes` |
| Telophase | | - Effectively opposite of prophase <br> - Nuclear membranes form across each of the two new nuclei <br> - Daughter chromosomes unwind into chromatin and are no longer visible <br> - Nucleolus forms in each nucleus <br> - Spindle fibres break apart <br> - **Cytokinesis** usually begins in telophase <br> - Cells starts to **cleave** (cell centre starts to pinch itself) |
### Cytokinesis
- Cell division