What differentiates the living from the non-living? What do the living have that the non-living do not have? They have cells, that make up you, me, elephants, banyan tree or the bacteria.
There are two types of living beings – Plants and Animals. Both types have their own type of cells. While there are many similarities, there are some differences as well.
Plant cell
- They have a cell wall
- Cell shape is rectangular
- Nucleus is at side of cell
- They have plastids
- Have large vacuole
- Have less number of mitochondria
Animal cell
- They do not have cell wall
- Cell shape is round or irregular
- Nucleus is at the centre
- They do not have plastids
- Have more number of small vacuoles
- Have more number of mitochondria
Parts of a cell
Plasma membrane
- Outermost membrane
- Allows things to enter or leave the cell by diffusion/osmosis
- It also prevents from entering
- Made up of lipids and proteins
Cell wall
- Present only in plants
- Made up of cellulose
- Rigid, and able to withstand outside pressure
Nucleus
- Dark, dot like structure
- Plays important role in cell division
- Contain chromosomes
- Chromosomes contain DNA that have information about the organism, to be passed to the offspring
Cytoplasm
- It is the fluid inside the plasma membrane
- Contains cell organelles
Cell organelles
- They are the parts having specific functions
Cell Organelles
Endoplasmic reticulum
- There are two types – Smooth (SER), Rough (RER
- RER creates proteins
SER creates lipids (fat molecules) - Proteins and lipids act as enzymes and hormones
- ER transports materials to different parts of the cell
Golgi apparatus
- They are flattened sacs parallel to each other
- They pack the materials created by ER and supply to other parts of the cell
- Store, modify and pack the products
- Convert complex sugars to simple sugars
- Create lysosomes
Lysosomes
- Sacs filled with enzymes
- Break down bacteria, food and foreign substances
- Keep the cell clean by removing wastes
- If damaged, lysosomes digest themselves
Mitochondria
- Called the powerhouse of the cell
- Have two membranes – Outer is porous, inner has folds
- Provide energy to cell in the form of ATP molecules
- Have their own DNA and ribosomes
Plastids
- Present only in plant cells
- Two types – Chromoplasts, Leucoplasts
- Chromoplasts contain chlorophyll
- Leucoplasts store oils, proteins and starch
- Have their own DNA and ribosomes
Vacuoles
- They are sacs for storing solid and liquid contents
- Store amino acids, proteins, sugars
- They are large in plants, small in animals
Cell Division
The process of creating new cells by the parent cell dividing itself to form daughter cells is called cell division. There are two types – Mitosis and Meiosis
Mitosis
- Each mother cell divides to form two daughter cells
- They have same number of chromosomes as mother cell
- Daughter cells are exact replica as the mother cell
- For growth and repair of tissues
Meiosis
- Each mother cells divide to form four daughter cells
- They have half the number of chromosomes as mother cell
- Form gametes needed for reproduction
Movement of Components
Diffusion: Movement of gases (O2 and CO2) in and out of the cells
Osmosis: Movement of water in and out of the cells
Osmosis: Movement of water in and out of the cells
Types of solutions related to osmosis
Hypotonic
- There is more water outside the cell
- Water enters the cell
Isotonic
- Water concentration same in and out
- No movement of water
Hypertonic
- More water inside the cell
- Water leaves the cell
Basic organisms like prokaryotes do not have a proper nucleus and organelle membranes, unlike the advanced eukaryotes.
Even my textbook did not give such wonderful way of explaining. I see bio articles are less in your site. Can you please write more on this?