Chapter 1: Cells from Cells - Biology Flashcards
(20 cards)
Cell Reproduction
Asexual Reproduction:
- Body organisms, and other single-celled organisms
- One parent cell divides to create two daughter cells which are identical to one another, and the parent cell
Sexual Reproduction:
- Two parents mate and produce an offspring having one chromosome from the father, and the other from the mother (a person has in total 46 chromosomes meaning 23 from the father, and 23 from the mother)
- Offspring share genetic material and may look alike but not exactly the same
Cell Divison (Prokaryotes)
Single celled organisms - Individuals that go through the process of cell division
Prokaryotes - Undergo a process known as binary fission (the parent cell splitting into two daughter cells)
Cell Division (Eukaryotes)
Multicellular Organisms (Eukaryotes):
* The fertilized egg (zygote) splits to create two new cells (undergoes cell division) which creates a new individual
* Damaged cells are replaced through cell division
Diffusion
- The movement of molecules from an area of high concentration to an area of low concentration (eg. Oxygen can easily pass through the cell membrane from an area of higher concentration outside the cell to an area of lower concentration inside the cell)
- Water molecule pass through the process of Osmosis
Cell membrane
- It is a barrier where everything must pass into or out of the cell through diffusion
- Only lets select materials in an out (semipermeable), and by doing so it keeps things inside the cell stable (Homeostatis)
Hypertonic, Hypotonic, and Isotonic solutions
- Hypertonic is when there is a higher concentration of solute compared to another solution, meaning water will flow into it
- Hypotonic is when there is a lower concetration of solute compared to another solution meaning water will flow out of it
- Isotonic solution is when there is the same concentration of solute compared to another solution meaning water flow will reach equilibrium
Explain how hyper, hypo, and isotonic solutions affect animal cells
Animal Cell:
* When it is in a hypotonic solution, due to it having a lower solute concentration, the water flows out of it into the cell making the cell contain too much water, and due to too much water, the cell may burst (LYSED)
* In an Isotonic solution, the concentration is balanced outside, and inside the plant, meaning that the water reached equilibrium (NORMAL)
* In an hypertonic solution, due to the higher solute concentration, water will flow out of the cell into the higher solute concentration solute outside making the cell deform (SHRIVELED)
Explain how hyper, hypo, and isotonic solutions affect plant cells
Plant Cell:
* When it is in a hypotonic solution (lower solute concentration), there is a higher solvent concentration, meaning more water outside the cell meaning that water will flow out of it into the cell, and due to the pressure, it helps the plant cell maintain structure, and be rigid (TURGID/NORMAL)
* In an Isotonic solution, the water, and solute concentration is balanced outside, and inside the plant, and so there is no necessary water movement which could cause the pressure for the cell to maintain structure, and get rigid (Flaccid)
* In an hypertonic solution (higher solute concentration), the water flows out of the cell, making the cell shrink, and get deformed (PLASMOLYZED)
Limiting Cell Size
- Cells are limited in size due to the RATIO between the outer surface area, and their volume
(As a cell’s size increases, its volume increases at a faster pace in relative to its surface area, which is why a large cell has less surface area in relative to its volume. A small cell has more surface area than a large cell for a given volume of the cytoplasm making it easier for nutrients to be carried inside, and out of the cell) - The cell’s nucleus can only control a certain amount of living, active cytoplasm
DNA Replication
The process by which the chromosomes are copied creating sister chromotids joined at the centromere
- During replication, each chromosomes are copied, which leads to 2 sister chromotids attached at the centromere
The Cell Cycle
The phases of a cell is known as the cell cycle (It consists of 3 phases):
1. Interphase
2. Mitosis
3. Cytokinesis
(Cell Division is a part of the cell cycle and it consists of mitosis and cytokinesis)
Interphase
The portion of the cell cycle between divisions, and it is the longest phase of the cell cycle.
Consists of:
1. Cell Growth
2. DNA is copied
3. Growth and preparation for cell division
Mitosis
A series of 4 phases in cell division which only occurs in Eukaryotes. During this phase, the nucleus divides into two nuclei with identical genetic material.
The four phases are:
1. Prophase
2. Metaphase
3. Anaphase
4. Telophase
Prophase
- The sister chromatids condense, and the chromosones are visible, making it easier to pull them apart in a later phase
- Two organelles known as centrosomes extend the mitotic spindle which is a structure made of microtubules (fibers that are part of the cell’s skeleton). The spindle fibers continue to form and extend away from the centrosomes towards the centromeres on each chromosomes.
- The nucleolus disappears, and the nucleus breaks down.
Metaphase
- Longest phase in mitosis
- The centrosomes arrive at the opposite of the cells
- The chromosomes line up in the middle of the cell with the spindle fibre from the centrosome connecting to the centromere of all the chromosome. Each centromere is connected to two spindle fibres each from the centrosome located at opposite sides.
Anaphase
- One of the shortest phase
- The protein holding the two chromatids together breaks apart
- Spindle fibre is formed between the two chromatids, and each chromatids is being pulled to the end of the cell by the spindle fibre
- Now the chromatids are their own chromosones, and the cell has double the amount of chromosomes needed
Telophase
- The spindle fibers start to disappear
- Membrane is formed around the two new daughter nuclei, which each is located at the end of the cell
- Within each nucleus, a nucleolus appears
- Chromosomes are less coiled, and are harder to notice
- The division of one nucleus into two daughter nuclei is complete
Cytokinesis (Animal Cell)
Animal cells:
* A ring of specialized protein surrounding the middle of the cell starts to contract spliting the parent cell into two daughter cell
Cytokinesis (Plant Cell)
Plant cells:
* Rigid cell wall makes cytokinesis having to differ from animal cells
* The golgi apparatus makes small vesicles where each of the sacs carry materials necessary to make the cell wall
* The vesicles lines up between the two daughter nuclei making a cell plate which then extends, and connects to the cell wall
* The cytoplasm is split into two, and new cell membranes form within the cell wall
Telophase vs Cytokinesis
Telophase primarily focusses on the genetic material spliting into two whereas cytokinesis focusses on the cytoplasm splitting and forming the two new daughter cells. In simpler terms, telophase focusses on creating two new daughter nuclei whereas cytokinesis focusses on making two new daughter cells.
