DNA and CellsCell organelles

Learning objectives

Students will understand what an organelle is.

Students will know the different organelles in a cell and their functions.

Students will understand that organelles’ function are interconnected to allow a cell to carry out its job.

Organelles

Organelles mean small organs. These are compartmentalized structures that have specialized function in a cell.

Organelle: A structure or part that is enclosed within its ownmembrane inside a cell and has a particular function.

The various organelles inside an animal (eukaryotic) cell.

Animal cells are generally spherical. But there are exceptions.

Cell membrane (Plasma membrane)

A double layer of lipid that separates the contents of the cell from its environment and regulates the passage of molecules into and out of the cell.

Cell membrane (Plasma membrane)

selectively permeable membrane

- i.e., some things are able to pass through the membrane while others are not.

Nucleus

The control centre of the cell

It contains the hereditary molecule DNA

*DNA does not leave nucleus

DNA contains instructions needed to produce proteins that control all cell activities.

Nucleus

The nucleus is surrounded by a membrane (nuclear membrane/envelope)that has pores (Nuclear Pore) in it to allow materials to pass in and out.

Nucleolus

It is a specialized region in the nucleus which produces rRNA(ribosomal RNA) from DNA.

Cytosol

Cytosol is the liquid filling the cell. It is a watery solution containing a lot of proteins, salts, dissolved molecules, etc.

Cytoplasm

The term cytoplasm refers to the cytosol in addition to the organelles, but excluding the nucleus.

Ribosomes

Small granular structures that are responsible for protein synthesis.

They are made by 1 rRNA joined together with a protein complex.

Types of Ribosomes

There are two types of ribosomes depends on their location.

Free ribosomes: they are floating freely in cytosol.

Membrane bound ribosomes: they are attached to the organelle Rough ER.

Endoplasmic Reticulum (ER)

Endo (inside)-plasmic (liquid) –reticulum (ribbon)

Endoplasmic Reticulum (ER)

Two types of ER depends on their function and texture.

Smooth ER:

- do not have ribosomes on it.

- It synthesizes lipids, carbohydrates, and detoxifying molecules.

Rough ER:

- It is rough because ribosomes are embedded in it.

- It makes proteins to be transported outside of the cell.

- It synthesizes proteins and export them out of cells.

- Is an direct extension of nuclear envelope.

Vesicles

They are small membrane-closed sac that is responsible for transporting molecules within the cell.

Golgi Apparatus (Golgi body)

It is made up of several saccules (fattened vacuoles).

Look like flattened pancake.

Golgi Apparatus (Golgi body)

Molecules from ER come into the inner face of the Golgi body.

As the saccules mature, they move toward the outer face (the face points toward cell membrane).

These molecules undergo further modification as they move through Golgi body.

Mitochondria

Mitochondria turns the food into energy through a process called cellular respiration.

Glucose + oxygen carbon dioxide + water + energy

C6H12O6 + O2 CO2 + H2O + ATP

The energy produced is in the form of ATP (adenosine triphosphate).

The internal membrane is folded to increase surface area to maximize its energy production.

Mitochondria

LysosomeThey are vesicles that contain hydrolytic enzymes which can digest large nutrients compounds or worn out cell parts.

They fuse with the materials to be recycled or to be broken down by releasing its hydrolytic content into the materials.

Epic Lysosome

https://www.youtube.com/watch?v=E4e7OR43234

Microtubules

Microtubules are proteins which act as structural support for the cell. They are component of the cytoskeleton.

- Centrioles - Basal bodies

Centriole

There are two centrioles lying at right angle to each other, and they are located near the nucleus.

Centrioles are only found in animal cells.

Centriole

• Centriole are made of 9 triplets of cylindrical microtubules, and exhibit a 9 + 0 pattern.

• 9 groups of 3 microtubule bunched together.

• With zero microtubule in the centre.

Basal Body

• they are the structures that produce microtubule for cilia and flagella.

• Basal body have a 9+0 arrangement, same as centrioles.

Cilia and Flagella

• They are used for movement.

• They have a 9+2 arrangement.

• Cilia is shorter, and flagella is longer.

Vacuoles: more prominent in plant

They are large membrane-closed sac that store nutrients.

Chloroplast

• It uses energy from sunlight to turn CO2 and H2O into sugar.

• The process is called photosynthesis.

Solar energy + CO2 + H2O Glucose + O2

• Chloroplast contain chlorophyll, a type of pigment which makes the plants green. Chlorophyll absorbs solar energy and allow chloroplast to undergo photosynthesis.

Cell Wall

• A rigid structure surrounding plant cells’ cell membrane.

• It gives plant cells their shape.

• It is mainly made of cellulose.