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Structure of a Plant Cell: A Visual Guide

Updated on May 13, 2013
This hub will teach you how to identify all of these organelles, and explain each of their functions
This hub will teach you how to identify all of these organelles, and explain each of their functions | Source

What Are the Organelles of a Plant Cell?

One of the first things I teach my students at A-level Biology (16-18yrs) is the structure of the cell. After going over the structure of the animal cell, we turn our attention to the plant cell. These cells contain many more 'parts' than an animal cell, and a classic exam question is to compare animal and plant cells.

All plants are eukaryotic - they have a nucleus and other membrane bound organelles. Plant cells contain almost all of the organelles found in animal cells but have several new ones to help them survive. Compared to drawings of cells from earlier in education, the diagrams below look very crowded!

To learn all this complexity use the same tricks as when learning the animal cell. Start by matching cut out keywords to different parts, then try naming parts from memory. Once you have mastered this try drawing your own diagrams. To show understanding of the functions, start off using one or two sentences and then try to use metaphors to describe the job of each organelle.

Diagram of a Plant Cell

Plant cells contain almost everything that animal cells do, and then several unique organelles.
Plant cells contain almost everything that animal cells do, and then several unique organelles. | Source

Plant Cell Definitions

  • Chlorophyll - a green pigment that captures the Sun's energy for photosynthesis
  • Eukaryotic - a cell that contains a nucleus and other membrane-bound organelles (e.g. mitochondria)
  • Osmotic Pressure - outward pressure exerted by water (think filling a water balloon)

Function of a Plant Cell

There are lots of different types of plant cell that must all work together to keep the plant alive. Unlike animals, however, plants are usually rooted to one place - they cannot move around if things get tough. This is why plants have all the extra 'bits' when compared to animal cells.

Remember, each plant cell will actually do everything that we do:

  • Move
  • Respire
  • Sense
  • Grow
  • Reproduce
  • Excrete
  • Nutrients

Always remember - plants are living things!

Parts of a Plant Cell

Every organelle found in an animal cell (with the exception of centrioles) is found in the plant cell. They even do the same jobs!
Every organelle found in an animal cell (with the exception of centrioles) is found in the plant cell. They even do the same jobs! | Source

Eukaryotic Plant Organelles

Plants have almost all of the same parts as an animal cell, namely:

  • Cell Membrane
  • Cytoplasm
  • Nucleus (separated into nucleolus, nuclear membrane and nuclear pores)
  • Endoplasmic Reticulum (rough and smooth)
  • Ribosomes
  • Mitochondria
  • Cytoskeleton
  • Golgi Body
  • Lysosomes and Peroxisomes

All of these organelles perform the same tasks in plant cells as they do in animal cells. However, because animals do not make their own food, and have a skeleton to help them move, plant cells need a few extra organelles to help them survive

Photograph of a Chloroplast

Chloroplasts are easily recognisable - They look like stacks of coins inside an outer membrane
Chloroplasts are easily recognisable - They look like stacks of coins inside an outer membrane | Source

Chloroplasts

Chloroplasts are probably the most important organelle on Earth. Not only do they help plants make food (and so put plants at the base of almost all food chains) but they also release most of the oxygen we breathe.

Chloroplasts are the engines for photosynthesis. They contain a green pigment called chlorophyll that uses sunlight to combine carbon dioxide and water into sugar. The oxygen from the water isn't needed to make this sugar and so the plant releases it through pores in the leaf called stomata.

Chloroplasts are easy to identify in electron micrographs. They are cylindrical in shape and appear to have stacks of coins inside them. Evidence suggests that, like mitochondria, chloroplasts were originally a type of ancient prokaryote was eaten by another, larger prokaryote. Instead of being digested, the smaller prokaryote survived and struck up a symbiotic relationship with its would-be killer. The rest is history.

Starch Granule

A simple storage organelle, these are numerous in the cells of tubers like potatoes! They store glucose in the form of starch for when times are tougher.

Cell Wall Diagram

Cellulose is arguably the most abundant biomolecule on the planet - it is this chemical that makes up most of the plant cell wall
Cellulose is arguably the most abundant biomolecule on the planet - it is this chemical that makes up most of the plant cell wall | Source

Cell Wall

Without a skeleton, plants need a different strategy to allow themselves to reach for the sky: the cell wall.

The cell wall is made of cellulose - perhaps the most common natural polymer on Earth . There are many forms of cellulose, each with a different function. The cell wall is made of layers of different celluloses - along with other molecules (e.g peptidoglycans and pectins) - to increase the strength of the cell wall.

The main function of the cell wall is to allow turgor pressure to be built up. Turgor pressure is caused by the contents of the cell pressing firmly against the solid cell wall. Without this pressure, plants could not stand up. When plants lose water, there are less contents to push against the cell wall, turgor pressure drops, and the plant starts to wilt.

Central Vacuole

Vacuoles are large storage organelles. This is where the 'sap' of the plant is stored. There is a membrane that surrounds the vacuole called the tonoplast that controls what enters and leaves the vacuole.

It is important to keep many molecules in a cell out of the way in case they affect other vital chemical reactions of the cell. But this is not the vacuole's only job; the vacuole also contains lots of water that helps keep the plant cell turgid and upright. It acts like the air bladder in a football - as you add more air the football gets firmer; as you add more water to the vacuole, the cell gets firmer. When plants wilt, they have lost water from their vacuole. There is no longer enough pressure to keep the cell rigid.

These are easily identified as large white 'gaps' in the cell - often one of the largest organelles on view.

Plasmodesmata Diagram

Plasmodesmata are gaps in the cell wall that allow molecules to pass through. This is called the Symplastic Pathway
Plasmodesmata are gaps in the cell wall that allow molecules to pass through. This is called the Symplastic Pathway | Source

Plasmodesmata

We already know that cells must co-operate and co-ordinate. To do this they must communicate! This is made difficult for plant cells thanks to the thick cell wall that surrounds every plant cell.

Think how difficult it is to text whilst wearing gloves...

An easy solution is fingerless gloves! They allow you to communicate more easily. Plasmodesmata are gaps in the cellulose cell wall that allow neighboring cells to talk to each other. This is called the 'Symplastic Pathway' and allows molecules like proteins, RNA and hormones to pass from cell to cell.

Plant Cell Model

Learning Resources Giant Magnetic Plant Cell
Learning Resources Giant Magnetic Plant Cell

A Giant magnetic poster! Great for learning about the plant and used in my Biology lessons. Comes with some basic background information and an activity guide. A useful plenary resource

 

Functions of Plant Organelles

Organelle
Function
Analogy
Cell Wall
Provides structural support to the plant cell
The Walls of a castle
Chloroplast
Contains chlorophyll and is the site of photosynthesis
Solar Panel
Starch Granule (amyloplast)
Stores excess sugar as starch
Storage warehouse
Central Vacuole
Storage for dissolved solutes. Also provides structural support
The bladder in a football
Plasmodesmata
Gaps in the cell wall to allow cells to communicate with each other
Secret tunnels in a prison
Using metaphors and analogies is a great way to learn the functions of each organelle. Just be sure you use the true function in the exam.

Nutrient Deficiency in Plants

A grape plant showing a mineral deficiency - probably phosphorus but it could be potassium deficiency.
A grape plant showing a mineral deficiency - probably phosphorus but it could be potassium deficiency. | Source

Plants and Plant Food

Plants are producers - they make their own food by combining carbon dioxide and water (and energy from the sun) to make glucose. We call this reaction 'Photosynthesis'. Photosynthesis happens entirely in the Chloroplast - a specialised organelle that gives plants their green colour.

So why do plants need Plant food? We already know that plants make their own food (by photosynthesis, which happens in the chloroplast), so why are we feeding them? Plant food contains lots of essential nutrients that the plants need to grow properly. If the plant doesn't have these, lots of problems can occur.

Plant food is basically vitamin tablets for plants.

  • Nitrogen - the main ingredient of nucleic acids (e.g. DNA), amino acids and chlorophyll. Without enough Nitrogen the leaves turn yellow because of a lack of chlorophyll.
  • Phosphorus - makes up the backbone of RNA and DNA; also used in production of ATP (energy molecule in eukaryotes). Without Phosphorus, the plant cannot grow well (cells can't make DNA so can't divide their cells so can't grow) and leaves will turn purple
  • Potassium - used in proton pumps and vital for protein synthesis. Leaf veins and edges becomes yellowed because the cells become damaged.


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    • Lord De Cross profile image

      Joseph De Cross 5 years ago

      Hi TFS,

      Nice explanation and the graphics are right on target. I was going to ask you two questions:

      -What is the relationship between this cells and inherited values.

      -Are we getting improvements in nano-technology and its use in our biological studies? Are we close to defrag the atom in favor of Nano-technology?

      Was a curiosity that came up!

      Happy Holidays TFS!

      Lord

    • TFScientist profile image
      Author

      Rhys Baker 5 years ago from Peterborough, UK

      Mendel's "inherited values" are what we now know to be genes - subsections of long strands of DNA that we call chromosomes. All aspects of a cell are controlled by DNA. Most organelles are coded for by nuclear DNA; mitochondria and chloroplasts are the exception. They have their own loops of DNA and self replicate.

      Improvements in nano technology are turning out to be a double-edged sword. Whilst they offer a tantalising prospect of personalised therapy for problems as diverse as diabetes and cancer, the use of nano particles is opening up a hitherto unexplored section of Toxicology. It is unclear, for example, the longe term of parabans and nano particles of aluminium in deodarants may have on the human genome and body.

      The field is still in its infancy and the rate of improvement is not homogenous across the field. The biological application of nano-technology will always lag behind computing or physics applications, as anything introduced into the human body must first be proven to be safe...or at least not too harmful.

    • profile image

      cool dude99 5 years ago

      thx for the info

    • ChitrangadaSharan profile image

      Chitrangada Sharan 16 months ago from New Delhi, India

      Congratulations for the HOTD!

      Great educational and informative hub with full illustrations . I feel I am back to my Botany classes in school.

      Thank you for sharing!

    • Kristen Howe profile image

      Kristen Howe 16 months ago from Northeast Ohio

      Rhys, congrats on HOTD! This was real cool and interesting to know about plant cells and the structure of it. Thanks for sharing this wealth of information.

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