Cells and Organelles Flashcards
1
Q
Prokaryotic Cells
A
- do not enclose genetic information in a nucleus
- organelles are not membrane bound
- always unicellular
- DNA is circular
- generally smaller and less complex than eukaryotic cells
note: all cells have a cell-membrane, cytoplasm, ribosomes, and genetic material
2
Q
Eukaryotic Cells
A
- genetic information is enclosed in the nucleus
- organelles are enclosed by a plasma membrane
- mostly multicellular, but it is sometimes unicellular
- DNA is linear
- generally larger and more complex
note: all cells have a cell-membrane, cytoplasm, ribosomes, and genetic material
3
Q
Differences Between Plant and Animal Cells
A
- plant cells have a cell wall and chloroplasts
- plant cells have one large central vacuole for water while animal cells have many, smaller vacuoles
4
Q
Cell Wall
A
- Provide support and protection for the cell
- Much like a very strong wire mesh net, not like a completely rigid wall.
- The cell wall itself doesn’t have color, but the chloroplasts are pushed up against the cell wall causing them to be green.
- Plant cells are made up of cellulose (complex carbohydrates)
5
Q
Cell Membrane
A
- a selectively permeable, fragile, transparent barrier that surrounds the cell
- Selective permeable: it can choose what goes through it
- Also protects the cell
- Composed of a phospholipid bilayer with embedded proteins
- The phospholipids are lined up tail to tail; the hydrophilic heads interact with water: the hydrophobic tails do not (makes it impermeable to water-soluble molecules)
- The proteins can be enzymes, can be binding sites for chemical messengers, can be carriers, or act as passageways through which water and ions can move.
6
Q
Cytoskeleton
A
- A web of protein filaments that help the cell maintain its shape.
- Just protein fibers that helps hold thing in place but still have wiggle room.
- Made of microtubules and filaments
7
Q
Cytoplasm
A
- Jelly-like substance inside cells; contains structures that perform specific functions called organelles.
- holds the organelles together and protects them from damage
- responsible for the cell’s shape
- makes up the entire region of the cell between the nucleus and the plasma membrane
8
Q
Nucleus
A
- the control center
- membrane-enclosed organelle that contains DNA (technically)
- consists of the nuclear membrane, nucleolus, and chromatin
9
Q
Nuclear Membrane
A
- A double membrane barrier filled with fluid and nuclear pores where the two membranes fuse.
- Proteins (the pores) in between the membranes which allows things to enter and leave the nucleus.
10
Q
Nucleolus
A
- One or more dark round bodies where ribosomal subunits are assembled (some chromosomes code for ribosomal RNA)
- Transported out through nuclear pores into cytoplasm
11
Q
Chromatin
A
- DNA wrapped around proteins forming a network of loose bumpy threads.
- When a cell is getting ready to divide this chromatin coils into Chromosomes
- The chromosomes are coiled a lot, so you don’t have access to the information, thus as soon as the cell is split it is released back into chromatin.
12
Q
Ribosomes
A
- Assemble amino acids into proteins (protein synthesis)
- They are just two RNAs combined, which is why they are so small.
- Found floating free in the cytoplasm; these ribosomes assemble proteins that will stay inside the cell.
- Found attached to the endoplasmic reticulum; these ribosomes assemble proteins that are meant to leave to the cell.
13
Q
Endoplasmic Reticulum
A
- A system of fluid-filled tubules that coil and twist through the cytoplasm, carrying substances from one part of the cell to another
- The Rough ER is studded with ribosomes to produce proteins and to then transport them by making vesicles
- The Smooth ER functions in cholesterol synthesis and breakdown, detoxification of drugs, and fat metabolism. It also produces lipids, cholesterol, and hormones
14
Q
Golgi Apparatus
Golgi Body
A
- Appears as a stack of flattened sacs with swarms of tiny vesicles; packages proteins that are meant to leave the cell
- Rough ER takes the proteins made to the Golgi and the Golgi packages it.
- The membrane of the Golgi bulges out and forms a pouch for the insulin particles.
- The small pouch then pinches off. This forms a vesicle filled with the protein.
- The vesicle then goes and fuses with the cell membrane and the sac opens allowing only the insulin to leave
- i.e. the golgi body receives the vesicles from the rough ER and modifies the proteins (folding them, but also sometimes adding lipids and carbs), and then ships them out
15
Q
Vacuoles/Vesicles
A
- membrane bound sacs that function in storage and transport
- Storage sites for water, sugars, ions, etc
- A plant has a single vacuole that holds a bunch of water (far bigger than a vesicle) and breaks down macromolecules
- Vacuoles also have a lot of water which puts pressure on the cell wall, this makes the cell rigid and allows them to stand up, maintaining their structure (Turgor Pressure)
