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# System prepended metadata

title: Chapter 12 - Asexual Reproduction

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---
title: "Chapter 12 - Asexual Reproduction"
author: "David Reznik"
date: 3/11/2022
---

[toc]

# Cell Info

## Reasons for Asexual Reproduction

- Allows for growth and development of the organism
- Cells stay the same size, but the organism needs to grow
- Repair tissue
- Replace dead cells

## Types of Cells

| Somatic                      | Gametic/Gametes   |
| ---------------------------- | ----------------- |
| "Body Cells"                 | "Sex Cells"       |
| Liver, stomach, muscle, etc. | Sperm/Egg Cells   |
| Asexually produced           | Sexually produced |

## Types of DNA

- Chromatin
  - Uncoiled DNA
  - Easy to access
- Chromosomes
  - Supercoiled DNA
  - Densely packed
  - Single-Chromatid (S.C.C.)
    - Single curved line
  - Double-Chromatid (D.C.C.)
    - Double line, "X"
    - Two single-chromatid strands

# Stages of the Asexual Cell cycle

1. Interphase - Growth of cell + replication of organelles + DNA
    1. Substages: G$_1$, S, G$_2$
2. Mitosis - Division/Replication of the nucleus
    1. Prophase
    2. Prometaphase
    3. Metaphase
    4. Anaphase
    5. Telephase
3. Cytokinesis
    1. Physical separation of the cell

## Interphase

### **G$_1$**

G is for Gap or Growth

- Cell starts to grow
- Starts the replication of organelles
- G$_1$ checkpoint
  - Checks whether the cell is large enough to hold 2x the amount of genetic information
  - Does the cell have the materials necessary for DNA replication
  - If the cell does **not** pass, it goes into G$_0$

### **S (Synthesis)**

- Replication of DNA
- Continue with organelle replication

### **G$_2$**

- Growth (Organelles still being copied + the cell will split at the end)
- G$_2$ checkpoint
  - Is the cell big enough to split
  - Do we have all the materials necessary for mitosis
  - Cell will stay in G$_2$ until it is ready

## Mitosis

### Prohpase

- Nucleus dissapears
- Chromatin supercoils into double-chomatid chromosomes
- Centrosomes move towards opposite sides due to microtubule growth
- Nuclear envelope still intact

### Prometaphase

- Breakdown of the nuclear envelope
- Special proteins attach to a centromere forming Kinetochores
- Some microtubules will attach to the kinetochores (kinetochore microtubules)
- Spindle apparatus contains all spindles moving inwards
- Aster is the centrosome + microtubules pointing inward and outward

### Metaphase

- Kinetochore microtubules move the chromosomes to the center of the cell (Metaphasal plate)
- M-Phase checkpoint
    - Chromosomes must be lined up properly
    - All **chromatids** have a microtuble attached to it
    - Activates the Anaphase Promoting Complex (APC) breaks down the proteins holding the chromatids together, allowing them to move apart

### Anaphase

- Kinetochore microtubules shorten (Depolymerize)
    - Allow the chromosome to move to opposite sides
    - Shorten at the chromosome end, not the centrosome end
    - Dynein protein walks backwards as it breaks the end of the tubule
- Nonkinetochore microtubules continue to grow (Polymerize)
- Cell gets wider

### Telephase

- Nuclear envelope reforms and nucleoli reappear
- DNA uncoils (Chromosomes -> Chromatin)
- All microtubules are broken down
- Cytokinesis begins during telephase

#### Cytokinesis in Animals

- Ring of Actin contracts, pulling the membrane inward
- Clevage furrow appears at the metaphase plate (center)
- Cell gets physically separated in two

#### Cytokinesis in Plants

Cell cannot fold in half, so they must make a new cell wall to separate

- Golgi-derived vesicles contain cell wall materials are sent ot the center of the cell
- Vesicles fuse with one another and form a cell plate, which wil be the new cell wall
    - They will share this cell wall

## Regulatory Proteins


