Unit 2 Part 1: Organelles Flashcards
Why are Cells so small?
The higher the difference between SA:V ratio, the more amount of diffusion takes place
What could a cell do in response to a shrinking SA/V ratio?
the cell could slow down its processes in response to shrinking SA:V because a smaller ratio of Sa:V could mean more space available inside the cell. The cell could also start to divide or evolve.
Justify “Numerous small cells are evolutionarily advantageous in regard to maintaining homeostasis in multicellular organisms”
This is true because having smaller cells maximize the surface are to volume ration, helping the diffusion rate go up.
As the mitochondria metabolize the glucose, they produce carbon dioxide waste. Would the CO2 be able to leave the cell faster if the cell had a smaller volume or larger volume?
CO2 would be able to leave the cell with a smaller volume faster than a cell with a larger volume due to there being less surface area to journey.
Is bigger always better for a cell
Bigger is not always better for the cell because cells with a larger surface area would have waste and other unwanted objects in their cell for a longer time. This additional time traveling could also create more time objects to travel that a cell might need immediately.
Is it more desirable for a cell to have a small SA:V ratio or a large SA:V function of a cell
It would not be desirable for cells to have a small SA:V because a lower SA:V ratio would guarantee a larger cell that has more processes occurring and a lower rate of diffusion (so water would leave the cell slower)
What might be some reasons why these unicellular organisms have larger cells than cells with similar traits (heterotrophic, lacking cell walls) that are found in multicellular organisms?
Unicellular organisms have larger cells because they depend on only themselves for protection and nutrients. That one cell has to be specialized in different jobs, unlike multicellular cells that can work with each other.
How are phospholipids arranged in the cell membrane?
Heads facing out toward the water and the tail face each other.
Remembering the characteristics of a lipid, why must one of the fatty acid chains be replaced with a phosphate group?
So the lipid can become hydrophilic. Lipids are naturally hydrophobic, so adding a phosphate group will change the lipid and give it a hydrophilic part.
What do you have to put into the membrane to help stabilize it?
Cholesterol will help stabilize the membrane.
What does Cholesterol do for the membrane?
Cholesterol acts as a Buffer for the membrane, it will dampen the effects of temperature
What is selectively permeable?
That the membrane allows some substance to pass through, but not others.
What 2 molecules easily pass through the membrane?
Simple Diffusion - O2 moves high concentration (outside the cell) to lower concentration (inside the cell) and Simple Diffusion - CO2 moves high concentration (outside the cell) to lower concentration (inside the cell
What does polar mean?
Molecules that have areas where there is a partial positive or negative charge.
Why are CHANNEL PROTEINS part of the cell membrane?
TO help transportation of substances that couldn’t pass easily through the membrane
Compare and contrast diffusion and facilitated diffusion.
DIffusion happens naturally, but facilitated diffusion happens with help from channel proteins. Both do not require energy.
Why is energy (ATP) sometimes required for the transport of materials?
ATP is needed for active transport, this is when the substance needs to go against its concentration gradient. This type of transport is called active transport. What type of materials are moved via this transport mechanism? Negative charges substances
What do Carbohydrates do in plasma membranes?
Carbohydrates are like identification badges. Cells that have different membrane carbohydrates do different jobs/functions. The immune system uses the carbohydrates to recognize that your cells belong to you and are not viruses, bacteria, or other foreign cells.
What is dynamic equilibrium?
Dynamic equilibrium is a state where no change is occurring but individual molecules still react continuously.
Why can’t sugar diffuse across the membrane?
Because it is polar and too large.
Why did diffusion stop after a certain period of time? .
Because there was nothing left to diffuse
What is Osmosis?
Water moves into and out of the cell by osmosis. This is when the diffusion of water across the membrane from an area of high concentration to an area of low concentration.
What are solutes?
Solutes are the substances that are dissolved in water.
What is Hypotonic?
When there is a low amount of solutes in water.
What is Hypertonic?
When there is a high amount of solutes in water.
What is Isotonic?
When there is an equal amount of solutes in water
What is Water potential?
This measures the concentration of free water molecules. It is a measure of the tendency of these molecules to diffuse to another area. The more free water molecules, the higher the Water Potential.
Define Tonicity
The ability of an extracellular solution to make water move into or out of a cell by osmosis
What will happen when a cell is placed in a hypertonic solution?
There will be a net flow of water out of the cell, and the cell will lose volume. A plasmolyzed plant cell has gaps between the cell wall and the cell membrane. This occurs when a plant cell is placed in a hypotonic solution. Water molecules move out of the cell resulting in the loss of turgor pressure
What will happen when a cell is placed in a hypotonic solution?
There will be a net flow of water into the cell, and the cell will gain volume. . A turgid cell is a cell that has turgor pressure. A plant cell that is placed in a hypotonic solution would cause the water to move into the cell by osmosis, resulting in large turgor pressure being exerted against the plant cell wall.
What will happen when a cell is placed in a isotonic solution?
There will be no net flow of water into or out of the cell, and the cell’s volume will remain stable. A flaccid plant cell is not swollen and the cell membrane does not press against the cell wall tightly.
Organelles that all cells have
Plasma Membrane, Cytosol, Chromosomes, Ribosomes (not organelles), and Cytoplasm
Plasma Membrane
Bound by a selective barrier that allows passage of enough O, nutrients, and wastes for the entire cell
Cytosol
Semi-fluid, jelly-like substance, where organelles are suspended
Chromosomes
Gene are carried in from the DNA
Ribosomes
Tiny complexes that make proteins according to instructions from DNA (not an organelle)
Cytoplasm
place of cytosol
Organelles in Plants
Nucleus, Plasma membrane, ribosomes, Golgi apparatus, ER, cytoskeleton, Peroxisome, Mitochondrion, Cholorplast, Central Vacuole, Plasmodesmata, Cell Wall,
Organelles in Animal
Nucleus, Plasma membrane, ribosomes, Golgi apparatus, Lysosom, ER, flagellum, centrosome, cytoskeleton, Microvilli, Peroxisome,
Nucleus (Function)
Contains most genes of eukaryotic cells
(both)
Nuclear envelope (Function)
Encloses the nucleus, separating its content from the cytoplasm. Is a double membrane made of a lipid bilayer (Both)
Nucleolus (Function)
associated with many proteins (Both)
Chromosomes (Function)
DNA’s discrete units that carry genetic information, Each one contains one long DNA molecules associate (Both)
Chromatin (Function)
complex of DNA and proteins making up chromosomes (Both)
Plasma Membrane (Function)
membrane enclosing the cell (Both)
Ribosomes (Function)
complexes that make proteins: free in cystosol or bound to rough ER or nuclear envelope (Both)
Golgi Apparatus (Function)
organelle active in synthesis, modification and secretion of cell products (Both)
Lysosome (Function)
digesive organelle where macromolecules are hydrolyzed (animal)
Endoplasmic reticulum (Function)
network of membranous sacs and tubes: active in membrane synthesis and other synthetic and metabolic processes (Both)
Rough ER (Function)
is studded with ribosomes: Involved in the synthesis of proteins and also a membrane factory for the cell (Both)
Smooth ER (Function)
not studded ribosomes: functions are the synthesis of lipids, steroid hormones, the detoxification of harmful metabolic byproducts and the storage and metabolism of calcium ions within the cell (Both)
Flagellum (Function)
motility structure composed of a cluster of microtubules w/i an extension of the plasma membrane (animals)
Centrosomes (Function)
region where the cell’s microtubules are initiated; contains a pair of centrioles (animals)
Cytoskeleton (Function)
reinfores cell’s shape: functions in a cell movement: components are made of proteins: includes microfilaments, intermediate microfilaments, and microtubules maintenance (Both)
Microfilament (Function)
made of actin protein subunits: maintennance of cell shape: changes in cell shape: muscle contradiction: cell motility: division of animal cells (Both)
Intermediate Microfilaments (Function)
maintenance of cell shape: anchorage of nucleus and certain other organelles: formation of nuclear lamina (animals)
Microtubules (Function)
maintenance of cell shape: cell motility like cilia or flagella: chromosomes movements in cell division: organelle movements (Both)
Microvilli (Function)
projections that increase the cell’s surface area (animals)
Peroxisome (Function)
organelle with various specialized metabolic functions: produces hydrogen peroxide as a by-product and then converts it to water (Both)
Mitochondrion (Function)
organelle where cellular respiration occurs and most ATP is generated (Both)
Central Vacuole (Function)
prominent organelle in older plant cells: functions include storage, breakdown of waste products, and hydrolysis of macromolecules: enlargement of the vacuole is a major mechanism of plant growth (plant)
Chloroplast (Function)
photosynthetic organelle: converts energy of sunlight to chemical energy stored in sugar molecules (plant)
Plasmodesmata (Function)
cytoplasmic channels through cell walls that connect the cytoplasms of adjacent cells plant)
Cell Wall (Function)
outer layer that maintains cell’s shape and protects cell from mechanical damage, made of cellulose, other polysaccharides, and proteins
Endomembrane System (Function)
Nuclear Envelope, ENdoplasmic Reticulum, Golgi Apparatus, Lysosomes, various vesicles and vacuoles, Plasma Membrane (not in all parts, but can occur in both animal and plant cells)
Vesicles (Function)
small sac or cyst containing fluid or gas (Both)
Vacuoles (Function)
a small cavity or space in the tissues of an organism containing air or fluid (Both)
