Biology - Organelles Flashcards
Organelles
A specialized compartment within a cell that carries out a specific function
Cell membrane
- Acts as a barrier between intracellular fluid + extracellular fluid
- Controls what enters/exits the cell
- “semi-permeable membrane”
Cell wall
- Made of cellulose that makes wall tough and strong
- Provides structural support + protection
Nucleus
- Surrounded by double membrane
- Controls the activities of the cell
- Contains genetic info (DNA in chromosomes)
Nuclear membrane
- Encloses the genetic info (DNA)
Cytoplasm
- Area between cell membrane + nuclear membrane
- Contains substances (enzymes, ATP) until cell needs it
- Organelles are suspended
Cytosol
Liquid that makes up cytoplasm which contains water, ions, and other small molecules
DNA
- Found in nucleus entangled as chromatin
- Makes up genetic code of cell
- Is the hereditary information
Nucleolus
- Site at which ribosomes are made
- No membrane
Ribosomes
- Small, dark, spherical organelles
- Attached to membranes of RER or float freely in cytoplasm
- Makes proteins
Endoplasmic reticulum
- Series of interconnected tubes that are formed by membranes
- Can be continuous with the nucleus membrane
RER; ribosomes attached + transports proteins that are made by ribosomes throughout cell
SER; makes lipids (fat), storage site for calcium ions
Golgi bodies
- Loosely stacked sacs of membrane
- Often interconnected with ER
- Receive, modify, and transport protein
- Secrete mucus
Vacuole
- Fluid filled spaces containing water and dissolved molecules
- Surrounded by single membrane called tonoplast
- Store food particles or waste
- In plants: provide support and storage space for water and starch
The vacuole in plant cells hold water, creating turgor pressure against the cell
Mitochondria
- Rod shaped, 1-3 micrometers long
- Has double membrane
- Inner membrane is folded projections called cristae
- Fluid inside is the matrix
- Breaks down large macromolecules to release stored energy in a process called cellular respiration (glucose + O2 = CO2 + H2O + energy) which is converted to an easily usable form (ATP)
Chloroplasts
- Oval, 5-10 micrometers long
- Has a double membrane + own DNA and ribosomes
- The # of chloroplasts vary (1-200) per cell
- Chrlorophyll (green pigment) in thylakoids trap sunlight and uses it to make glucose in photosynthesis (CO2 + H2O = glucose + O2)
Lysosomes
- Found in both plant and animal cells
- Spherical organelles that are bound by single membrane
- Contain enzymes (type of protein) derived from RER
- Digest food molecules (food to cell to vacuole which joins up with lysosome)
- Destroy harmful chemicals that enter the cell by engulfing them
- When cell is old and doesn’t function, lysosomes act as suicide bags and breakdown, releasing their digestive enzymes into cytoplasm
- Enzymes are also used to destroy old + damaged organelles
Centrioles
- Present in animal cells
- Short cylinders that occur in pairs at right angles called centrosome
- During mitosis; centrioles in centrosome travel to opposite poles of cell
- Also associated with produciton of cilia and flagella
Animal cell?
Plant Cell?
Secretory Vesicles
Once sugar and fat molecules is added to protein, they collect in sacs that pinch off from the golgi; they remain in cytoplasm or move to cell membrane to be expelled
