Organelles

The Nucleus (Brain)

- Surrounded by nuclear envelope

- Protects genetic information

- Has 2 membranes: outer and inner

- DNA codes for the production of RNA, starting the process of protein synthesis

Note: The nucleus is often called the "brain" of the cell because it controls cellular activities and stores genetic information.

Mitochondria

- Create energy for specific cell

- Double membrane-bound organelle

- Inner membrane is folded into compartments called cristae

- Cristae increases surface area and allows greater production of energy

- More folds = more energy

- Main organelle responsible for cellular respiration

- Cellular respiration: process where all organisms use glucose to produce ATP

- Has its own DNA

Fun fact: Mitochondria are often referred to as the "powerhouses" of the cell due to their crucial role in energy production.

Endoplasmic Reticulum (ER)

- Buds off nucleus

- Close to the Golgi apparatus

- Smooth ER:

- Detoxifies toxins

- Metabolizes carbohydrates

- Produces hormones and steroids

- Performs lipid synthesis

- Rough ER:

- Exports proteins and lipids

- Has ribosomes attached to it

Remember: The rough ER gets its name from the ribosomes attached to its surface, giving it a "rough" appearance under a microscope.

Protein Synthesis and Transport

Protein synthesis starts in the cytoplasm, then moves to the rough ER for modification, which then goes to the Golgi apparatus that further modifies and sorts proteins into designated areas. Finally, some proteins may end up in the lysosome, which contains digestive enzymes.

Key point: This process demonstrates the interconnected nature of cellular organelles in protein production and distribution.

Vacuoles and Lysosomes (Storage)

- Lysosomes: small organelles that work as a cellular stomach, containing enzymes

- Vacuoles: mostly used for storage, primarily stores water

Interesting fact: Plant cells typically have larger vacuoles than animal cells, often taking up most of the cell's volume.

Chloroplast

- Site of photosynthesis: process where plants make their own food

- Has inner and outer membranes

- Calvin cycle takes place in stroma

- Contains thylakoids arranged in stacks called grana

Note: Chloroplasts are found in plant cells and some protists, but not in animal cells.

Ribosomes

- Composed of two different subunits

- Made of rRNA and various proteins

- Subunits: large and small

- Site of translation (tRNA and mRNA work together inside the ribosome to link amino acids together to form polypeptides/proteins)

- Present in all cells

Important: Ribosomes are the only organelles found in both prokaryotic and eukaryotic cells.

Golgi Apparatus

- Present in eukaryotic cells

- One of the largest organelles

- Complex series of compartments of flattened membranes called cisternae

- Functions:

- Modifies, sorts, and packages proteins for transport

- Removes proteins for secretion or transport to other organelles

- Often compared to a post office for its sorting and distribution functions

Analogy: Think of the Golgi apparatus as the cell's "shipping and packaging department".