Structure of Animal and Plant Cells

Cells are what make up all living things.  They are the building blocks of life.  Plant and animal are built up of cells that are stuck together.

Nucleus - Contains all the genetic information to produce new cells and controls all chemical processes that take place in the cell.

Cytoplasm - Jelly like substance where chemical reactions take place to keep the cell alive. The reactions are controlled by enzymes.

Mitochondria - Where respiration takes place, glucose and oxygen are changed into energy.

Cell Membrane - This is the thin skin around the cell. It gives the cell its shape and controls what passes in and out of the cell.

Chloroplast - These contain a green pigment called chlorophyll which absorbs sunlight so the plant can carry out photosynthesis.

Nucleus - Contains all the genetic information to produce new cells and controls all the chemical processes that take place in the cell.

Vacuole - Plant cells have a large permanent vacuole which is filled with a weak solution of salt and sugar called sap. It also gives cell support.

Mitochondria - Where respiration takes place, glucose and oxygen are changed into energy.

Cytoplasm - Jelly like substance where chemical reactions take place to keep the cell alive. These reactions are controlled by enzymes.

Cell Wall - Covers the thin membrane and is made of tough cellulose which gives the plant cell strength and support.

Cell Membrane - This is the thin skin around the cell. It gives the cell shape and controls what passes in and out of the cell.

Similarities 

• Have a nucleus
  
• Have a cytoplasm
• Have a cell membrane
• Contain Mitochondria
• Contain Ribosomes

Differences 

• Plant Cells have a cellulose cell wall
• Plant cells have a vacuole containing cell sap
• Plant cells have chloroplast
• Many plant cells have a box-like shape whilst animal cell shape varies
• Plant cells have the nucleus to the side of the cell, animal cells have a nucleus in the middle

Now we have established the general features of both animal and plant cells we must also remember that many cells do look different and this is because they have their own special jobs to do. These cells display specialised features that make them suited to carry out their specific function.

Specific Function: 

Contain haemoglobin which transports oxygen to other cells and around the body.

Specialised Feature: 

• Have biconcave shape for maximum surface area to allow more oxygen to be absorbed efficiently.
• The biconcave shape also allows for a flexible framework which means cells can squeeze through the thinnest of capillaries.
• Cells have a thin outer membrane allowing oxygen to diffuse through easily.
• Have no nucleus so there is more room for oxygen to be carried in the cell and hence around the body.

Specific Function:

To fertilise the ovum (female egg cell).

Specialised Feature:

• The tail of the sperm cell enables it to swim to the ovum and fertilise it.
• The head is streamlined also to aid swimming
• The head contains genetic information and a nucleus and has an enzyme to help penetrate the egg cell membrane to allow fertilisation.
• The middle section immediately behind the head is packed with mitochondria to provide energy.

Specific Function:

Transmit electrical nerve impulses and so carry information from one part of the body to another ie from receptor to an effector.

Specialised Feature:

• Dendrites extend from the cell body to make connections with other neurones.
• Have a long axon (nerve fibre) to carry the impulse to the target organ.
• End plate forms a synapse with an effector (a muscle or a gland).

Specific Function: 

Small tubes that carry water from the roots to the leaves.

Specialised Feature:

• Long and tube-like hollow vessels to carry the water.
• Cells have no end walls between them so they form a 'pipeline' to carry the water.
• Spirals and rings of lignin in the cell walls strengthen them to withstand the pressure of water.

Specific Function: 

Absorb water and mineral ions from the soil.

Specialised Feature:

• Located in the root epidermis and in direct contact with the soil
• Thin walls make uptake of water easier.
• Wall nearest the soil has a long 'finger-like' projection with very thin walls into the soil. This projection increases the surface area for more efficient uptake of water and ions.

Specific Function: 

Carries out photosynthesis.

Specialised Feature:

• Packed with chloroplasts which contain the light absorbing pigment chlorophyll.
• Regular shaped closely packed cells forming a continuous layer for efficient and maximum absorption of sunlight.

Some living organisms are made up of one cell only, these are called unicellular. These organisms have a large surface area to volume ratio and rely on simple diffusion to meet their needs. An example of a unicellular animal is Amoeba.

All seven life processes take place inside this one cell. Amoebas are found in ponds and ditches. They move by changing their shape, they push out pseudopodia in the direction they want to move and the rest of the cell flows after them. Amoeba feed on smaller organisms such as bacteria. The pseudopodia flow around the food engulfing it, the food is then taken into the cytoplasm in a food vacuole. Enzymes further break down the food. Useful substances that the amoeba requires like Oxygen pass into to the amoeba from the water around by diffusion and waste substances such as carbon dioxide pass out into the water also via diffusion.

Multicellular organisms are those which are made up of many cells. Humans are multicellular. Multicellular organisms can be much larger and more complex. This is because the cells of the organism have specialised into many different types of cells such as nerve cells, blood cells, muscle cells all performing different functions.

When we have a group of similar cells working together this is called a tissue, for example, muscle tissue is made up of lots of muscle cells. All the cells in a tissue look the same and perform the same job. 

A group of different tissue working together to do a specific job is known as an organ, our heart, stomach, lungs are all organs.

Different organs working together form an organ system, our heart and blood vessels work together as part of our circulatory system.

All of our organ systems put together make up a living organism.