Cells Structure, Physiology, Molecules And Enzymes Flashcards
What is the Golgi apparatus and where is it found?
- The Golgi apparatus is a series of cisternae (flattened curved sacs)
- Vesicles enter and leave the Golgi. Vesicles carrying protein coalesce on the convex edge, the proteins are modified, and then they are carried away by vesicles from the concave face.
They are found in all eukaryotic cells.
What are mitochondria and where are they found?
- Mitochondria are the ‘the power house of the cell’ / site of ATP synthesis during aerobic respiration.
- The mitochondria is enclosed in a double membrane, in which the inner membrane is folded into the matrix. This folds are called Cristae.
- Cristae are more numerous and deeply folded in more active cells.
Mitochondria are found in eukaryotic cells.
What is the Endoplasmic reticulum and where is it found?
- The ER is connected to the nuclear envelope and facilitates RNA transport.
- The ER can be Rough (RER) which provides scaffolding for ribosomes to make proteins, or Smooth (SER) Which synthesises cholesterol.
The ER is found in all eukaryotic cells.
What is the cell membrane and where is it found?
The cell surface membrane is found in animal cells and
is made of a phospholipid bilayer, with intrinsic and extrinsic proteins.
There are cell membranes in eukaryotic cells.
What has an affect on diffusion?
Concentration gradient
Size of molecule
Temperature
Membrane surface area
How does facilitated diffusion work?
- Facilitated diffusion can occur through carrier or channel proteins.
- Carrier proteins take in a molecule, change shape and release the molecule on the other side of the membrane.
- Channel proteins have a central pore allowing ions to pass through. Some are gated with opening and closing lids.
How does active transport work?
Molecules are transported against the diffusion gradient via pumps. This requires ATP, supplied by mitochondria.
What is cytosis and why is it important?
-Cytosis is important because it transports smaller molecules as well as large molecules that carrier proteins cannot transport.
-There are two types of cytosis: exocytosis (materials exiting cell) and endocytosis (materials entering cell).
-In exocytosis secretory vesicles move to fuse with membrane, and substances are released as secretory vesicles merged with the membrane.
-In endocytosis the cell surface membrane invaginates (encloses around) material to form vesicles. There are two types: phagocytosis (solids) and pinocytosis (liquids).
vesicles
What is osmosis?
Osmosis is the net movement of water through a selectively permeable membrane from a solution of higher water potential to a solution of lower water potential.
What is water potential?
Water potential is effectively the measure of a solution’s tendency to take in water. It is measured in kPa, or Kilopascals. Pure water has 0kPa. Water potential indicates free water molecules.
What are free water molecules?
In solutions, hydration shells form around solutes, reducing the amount of free water molecules.
What is solute potential, pressure potential and water potential?
- Water potential (Psi cell) is the potential for water to move into a cell.
- Solute potential (Psi s) is the reduction in water’s ability to move, and therefore reducing the water potential value
- Pressure potential (Psi p) is the cell pushing molecules back into the cell, increasing the water potential value.
What do the terms turgid and lysis mean?
- Turgid or turgidity is a state in an plant cell when water has effectively filled the cell, and the opposing forces of the cell wall and membrane create turgor.
- Lysis is a state in an animal cell where too much water enters the cell and causes it to burst.
What do the terms plasmolysis and crennation mean?
- Plasmolysis is a state in plant cells in which the protoplasm pulls away from the cell wall, and occurs because of an excess of water leaving the cell.
- Crennation is a state in animal cells in which the cell shrinks and shrivels up. This is because too much water has left the cell.
What do the terms incipient plasmolysis and flaccid mean?
- Incipient plasmolysis is the point at which the cell membrane just begins to pull away from the cell wall.
- Flaccid describes the state of a plant cell whenever it suffers suffers a shortage of water and loses turgidity, and therefore wilting occurs.
What is a hypertonic solution?
A hypertonic solution is a solution in which there is more water present, less hydration shells, less solute concentration and therefore a high water potential.
What is the isotonic point?
Where there is no osmosis because the water potential of the cells is exactly equal.
What is a hypotonic solution?
A solution in which there is more solute present, more hydration shells, more solute concentration and therefore a low water potential.
What is the nucleus, and where is it found?
- The nucleus is the storage container of DNA, in the form of chromatin.
- It is found in eukaryotic cells (plants, animal and fungi cells)
What is a chloroplast?
The chloroplast is the organelle responsible for photosynthesis. It is found in plant cells. It contains chlorophyll, which is stored in thykaloids. Many thykaloids form a grana.
Describe the structure of a chloroplast
There is a double membrane outer layer, with a stroma suspending grana and the intergranal lamellae.
What are ribosomes?
Ribosomes are small organelles either moving freely in the cytoplasm or attached to the RER. They are responsible for protein synthesis.
What are lysosomes?
- Tiny vesicles.
- They contain hydrolytic enzymes for internal use.
- They fuse with vesicles holding something that needs to be destroyed or digested.
- They have an important role in phagocytes, where they digest engulfed bacteria.
What are microtubules?
- Microtubules are hollow cylinders
- They occur within centrioles and form spindle fibres essential to nulcear division.
