---
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