Unit 2: Cells Flashcards
Why can’t we have massive cells?
Cells need to exchange things between the outside and inside to maintian homeostasis. As the volume of a cell increases, more exchanges need to occour. However, SA increases slower than volume, meaning that as volume increases there is less SA to perform exchanges. This is why SA: Volume ratio is important.
What is the Fluid Mosaic model?
It is a model of the cell membrane that states it is made out of a phospholipid bilayer that is able to change shape, and the bilayer has many proteins littered around it.
What is the role of cholestrol in the cell memberane?
Cholestrol appears between phospholipids and makes sure the molecules don’t get two close under cold temperatures and don’t go too far away under high temperatures.
What are the 3 types of structures found within cell membranes?
Transmembrane proteins: Span the entire membrane. Often acts as channels for molecules to flow through, and can also be a recepter for cell signaling.
Integral Proteins: Don’t span the entire membrane and stop through the membrane
Periphiral proteins: On the outside of the plasma membrane. Thye are used for structure, such as by conencting to the cytoskeleton, for cell recognition, and also cell signaling.
What happens when there are unsaturated fatty acids in the cell membrane?
These unsaturated fatty acids are usually kinked, which decreases membrane rigidity by increasing the space between phospholipids.
What molecules can go through the membrane?
Small hydrophobic molecules
What’s the difference between a channel and a carrier protein?
Channel proteins are just hydrophillic channels, carrier proteins undergo changes to transport a molecule into the cell.
What kind of protein lets water into the cell?
channel proteins called aquoporins.
What are the different types of molecular movement in an out of cells?
Passive Transport
Simple Diffusion: Along the concentration gradient throught the bilayer
Facilitated diffusion: requires channel/carrier protein
Osmosis: The movement of water instead of soluted
Active Transport
Requires ATP
The Sodium Potassium pump goes against the concentration gradient and is used in nerve cells to allow a signal to pass.
Endocytosis
This is when the cell membrane folds around a molecule and engulfs it, creating a vessicle or vacuole.
Exocytosis
Opposite of endo
Explain the difference between hypotonic, isotonic, and hypertonic?
Hypotonic means the body your refering to has less solute
Isotonic means equal solute
Hypertonic means more solute
How does watter flow in hypertonic, isotonic, and hypotonic solutions?
Hypertonic: Out of the cell
Iso: Nowhere
Hypotonic: Into the cell
How does water flow in terms of water pressure and solute concentration?
Water flows from low to high solute concentration. It flows from high to low water pressure
What are the types of endocytosis?
Pinocytosis: Liquid ingested
Phagocytosis: Solids
Receptor-Mediated: Cell Surface receptors detect a compound causing the folding of the membrane.
What are the parts of a prokaryotic cell?
- The cytoplasm contains all the insides of the cell
- It has one, circular DNA molecule located in the nucleoid
- Most prokaryotes have a cell wall that surrounds their cell membrane
- Robocomes are scattered across the cytoplasm for protein production
- Some bacteria have an extra capsule around the sell wall
- bacteria often have a flagella for motillity
What do carbohydrate side chains do?
They can help with cell recognition and cell-cell adhesion. They are found outside the cell
What is the nucleus?
- Largest organelle in the cell
- Contains DNA which is organized into chromosomes.
What is the nucleolus?
- A part of the nucleus where rRNA is made and ribosomes assembled
What are ribosomes?
- They are the sites of protein synthesis
- They have a large and small subunit
- They are either free-floating or attatched to the ER
What is the Endoplasmic Reticulum? What are the two parts?
- A network of tubules and sacs extending from the nucleus that provides support and facillitates intracellular transport
- The rough ER has ribosomes attatched and produces proteins
- The smooth ER has no ribosomes and produces makes lipids and breaks down toxin
What is the Golgi Complex?
- Stacks fo flattened sacs that modify, process, and sorts proteins creaated by the ribosomes
- It packages them into little sacs called vesicles which are then carrier to the cell membrane
- They also produce lysosomes
What is the mitochondria?
- Produces energy for the cell
- Consists of an inner matric, and an innter and outer membrane
What are Lysosomes?
- Small membrane-enclosed structures that contain and digest the cells waste using enzymes
- They are useful in cell apoptosis, or cell death
What are centrioles?
- Found mosltly in animal cells
- Cylindrical structures that produces microtubules that pull chromosomes apart
What are vacuoles?
Store stuff in the cell
What are peroxisomes?
Organelles that detocify substances using enzymes and produce H2O2 as a byproduct. Commonly found in liver and kidney cells.
What is the difference between plant and animal vacuoles?
Plants have one, large central vacuole that contains many things and helps maintain turgor pressure. Animals have many small vacuoles
What is the difference between a cilia and flagella?
A flagella is one large tail, a cilia is many small tails
What does the cytoskeleton do and composed of?
It is a netowrk of protein fibers that provides structure to the cell.
It uses microtubles for cell division and movement, and microfilaments
Microfilaments are useful for movement by expanding or contracting the cell, which is used for the muscle contraction.
