The Cell Flashcards
Define Cell
The smallest unit of life
Describe the structure and function of the Mitochondria
Function: Provide most of the ATP for the cell
Structure: Enclosed by 2 membranes. Outer membrane is smooth while inner membrane is folded inward forming cristae. Space within is called the matrix. The more of them in a cell, the more active this cell is.
Describe the function and structure of the plasma membrane
Function: They are an external barrier. Selectively permeable. Contain Transmembrane proteins
Structure: Has a Phospholipid bilayer (Fluid mosaic structure). Made up of lots of Proteins, Carbohydrates and Cholesterol.
Where is Cholesterol Produced?
SER
What is the structure of a Phospholipid?
Polar head- Due to phosphate group. It is hydrophilic (water-loving)
2 fatty acid tails- Hydrophobic
What proteins carry out facilitated diffusion and what do they transport?
Carrier proteins- Sugars and amino acids. Sugar enters carrier protein which causes change in shape of the carrier protein so it can pass across the cell membrane.
Channel proteins- For movement of ions. Have a specific structure based on what ion can pass through.
Ligand gated proteins- Ligand will bind to protein on extracellular membrane which allows molecules to pass into cell
Voltage gated protein channels- Will open/close based on the membrane potential in the cell.
Aquaporins- Move Water
Why is Endocytosis and Exocytosis required and what is it?
To move larger molecules through the cell membrane using ATP.
Endocytosis- Molecules going into the cell. Molecule binds to receptor on extracellular membrane and is engulfed into a vesicle and enters the cell
Exocytosis- Molecules leaving the cell. Packed into vesicles and move to the membrane and fuse with it and contents released out of the cell.
How can the cell membrane be specialized?
Contain Microvilli- Increases surface area of the cell membrane so increases rate of diffusion
What are the three types of membrane juction?
Gap Junction- Connected via connexins that allows ions to pass directly between cells and also allows cells to rapidly communicate with each other
Adherens Junction- Anchors cells together and prevents separation in cells that are under a lot of force
Tight Junction- Seals 2 plasma membranes of adjacent cells together. Selectively prevents water, small proteins and bacteria from passing in between
What is the cystol?
The fluid in which cell organelles are suspended in within a cell. Mainly water but also dissolved proteins, salts etc.
What is the Cytoskeleton?
Supports cell structures and generates cell movements. It is found in the cystol and contains no membrane.
What are the three types of rod in the cytoskeleton? Explain each?
Microfilaments- Made up of actin (a protein). Involved in cell motility (cell movement).
Intermediate filaments- Permanently in the cell. Act as internal cables in a cell to resit pulling forces exerted on the cell
Microtubules- Determine overall cell shape. Distribute organelles in a cell.
What can microfilaments do in non-moving cells?
Maintain shape and distribute tension throughout the cell
What is the cytoplasm made up of?
The cystol, organelles and inclusions (chemicals such as glycogen, melanin and lipids)
Why are most cells not usually perfectly spherical?
Because they are constricted by their external environment. They are squished together or held in place by bone or stretched along a surface.
