What is the function of the cell membrane
acting as a boundary that separates the cell’s interior from its external environment. Composed primarily of a phospholipid bilayer, it controls the transport of substances entering and exiting the cell and helps maintain the cell’s internal structure and function
What is the basic structure of the cell membrane
The cell membrane is made up of phospholipids.
Be able to draw a simple (but accurate) example of the lipid bilayer.
cell membrane mostly made up of phospholipids and protein channels for molecules go get in and out of cell.
Be able to draw and label the parts of a phospholipid while including the terms hydrophobic and hydrophilic
hydraulic head( phosphate top and glycerol bottom), hydrophobic tails (saturated fatty acid and broken part is unsaturated fatty acid part)
How does the structure of the membrane impact its function? As in, what particles/molecules can freely pass through the lipid bilayer?
hydrophobic interior that prevents charged and polar molecules from passing through easily, but allows small, nonpolar molecules like oxygen (O₂) and carbon dioxide (CO₂) to diffuse freely. Hydrophilic substances, including glucose, amino acids, and ions, cannot readily cross the lipid bilayer
What does it mean to be selectively permeable
selectively permeable-some substances can pass across them and others cannot, also called “semi permeable” membranes
What is meant by the term concentration in relation to solutions
amount of a dissolved substance, the solute, present in a given amount of the substance it’s dissolved in, the solvent or the entire solution.
What is a concentration gradient?
concentration gradient is the difference in concentration of a substance between two regions, causing those substances to naturally move from an area of high concentration to an area of low concentration until equilibrium is reached
What is equilibrium?
diffused equally
What is the difference between active and passive transport
active transport requires energy (ATP) while passive transport requires connection granite the difference in the concentration across the cell membrane
What is the difference between simple and facilitated diffusion?
facilitated diffusion requires protein channels, simple diffusion does not require protein channels the molecules cross though the phospholipids.
Compare and contrast the 3 different types of transport across the cell membrane.
-What is needed for this transport? (protein channel or pump? energy?)
-Does it go with/against the concentration gradient?
-What molecules are typically transported in each process?
Simple and facilitated diffusion are passive, using no cellular energy , hight-low, facilitated diffusion requires protein channels for substances, Active transport requires cellular energy (ATP) to move substances low to high often using protein pumps to achieve this
What is osmosis? What kind of protein channel does this process use?
example of facilitated diffusion, movement of water from low solute conc. to high solute conc. through aquaporin
Explain the difference between isotonic, hypotonic, and hypertonic solutions.
Predict what will happen to cells in different solutions/environments.
-Hypertonic: when comparing two solutions, the solution with greater concentration of solutes “above strength”
-Hypotonic: when comparing two solutions, the solution with lower concentration of solutes “below strength”
-isotonic: when the concentration of two solutions are the same; “same strength”
What are the processes of exocytosis and endocytosis?
-Exocytosis: this is an EXAMPLE of active transport and is referred to as Bulk Transport. Molecules are expelled out of the cell.
-Endocytosis: this is an EXAMPLE of active transport and is referred to as Bulk Transport. Molecules are engulfed into the cell
Explain why cells are so small. (hint: surface area to volume ratio video)
The cell size is limited by its’ surface area to volume ratio.
The larger the cell, the higher the volume, the greater need to diffuse materials
What is homeostasis?
the state of relatively constant and stable internal physical and chemical conditions.
What are the two types of feedback loops? How are they different and be able to identify what type is being presented when given an example scenario.
are positive and negative feedback. Negative feedback loops stabilize a system by reducing or counteracting changes to maintain a set point or equilibrium, like body temperature regulation. In contrast, positive feedback loops amplify changes, leading to instability and self-reinforcing cycles of growth or decline, such as blood clotting.
SA/ Cell size. Why are humans made of many small cells instead of one big cell? (Cell surface area vs volume video)
Humans are made of many small cells to maintain a high surface area-to-volume ratio, which allows for efficient nutrient and gas exchange necessary for survival. A small cell has more surface area relative to its volume, enabling faster intake of oxygen and nutrients and quicker removal of waste products than a single large cell could achieve
SA/ What happens to cells when placed in pure, distilled water?
cell is placed in pure, distilled water, it swells and may burst due to a process called osmosis. Distilled water is a hypotonic solution, meaning it has a lower solute (salt, mineral)
SA/ Positive vs negative feedback loops
-negative feedback loops-Primary way to maintain homeostasis; a mechanism that counteracts or opposes a change in an organism
-positive feedback loops- Usually occurring when something is wrong in the body; a feedback loop that amplifies a condition
SA/ Osmosis and homeostasis: how can fish in saltwater and freshwater regulate their internal salt/water balance and why would they need to?
-homeostasis- For fish, this includes keeping their body’s salt and water levels within a narrow range, regardless of the surrounding water’s salinity(maintain stable internal environment)
-osmosis- Since fish have different salt concentrations in their bodies compared to freshwater and saltwater, water naturally tries to move in or out of their cells. (water moves from high to low concentration across membrane)
you got this
encouragement
