Biology 🧪 🔬🧬🧫

How does water enter the cell membrane?

* Some water molecules don’t need proteins to enter the cell but they may need help due to the huge amount of water trying to enter the cells
* The water gets this help due to a specific type of transport protein known as aquaporin

What is the fluid mosaic model?

model used to describe a membrane’s structure(diverse protein molecules suspended in fluid phospholipid bilayer)

* in other words it describes the fluidity of the cel membrane

What does the plasma membrane allow?

selective permeability(lets certain things in and out of the cell)

What molecules have an easier time going through the cell membrane?

* Smaller not charged molecules easily travel through the membrane
* Meanwhile, bigger,charged molecules have a hard time to pass through membrane and need special protein to pass through

What do transport molecules do?

allow specific ions/molecules to enter or exit the cell

What is a channel transport protein?

This protein is one that allows the solute molecule into the cell and requires no energy to do so as it is “down hill/going with the gradient”

What is an active transport protein?

This protein is one that allows solute molecules to enter the cell by going “uphill/against the gradient” by requiring energy (ATP)

What is an enzyme?

* certain membrane proteins that carry out sequential reactions as well as modify one molecule through an interaction and create a new product

What are attachment proteins?

* attach to the extracellular matrix and cytoskeleton
* help support the membrane(attach from outer side of the membrane with the ECM to the inner side of the membrane with the cytoskeleton)
* can coordinate external and internal changes

Receptor Proteins

* signaling molecules bind to receptor proteins
* these receptor proteins then relay the message by activating other molecules inside the cell

Junction Proteins

* form intercellular junctions that attach adjacent cells
* in other words they attach together to form tissue

Glycoprotein

* serve as ID tags (recognize self from non-self)
* may be recognize by membrane proteins of other cells

What is the overview of cell signaling?

Give an overview for signal transduction pathways.

What does the cell membrane of cells look like and what are the different parts that compose them?

What is the general term “transport” in cells mean?

allows passage of substances across cell membranes

What does passive transport generally mean?

Transporting molecules into the cell by going “with the gradient” and not using energy

What does active transport generally mean?

the use of transporting molecules out of the cell by going against the gradient and using energy

What are the gradients movement ways for active and passive transport?

Active: Low to High

Passive: High to Low

What are the different types of passive transport

1) Diffusion: molecules go from high to low concentration

2) Facilitated Diffusion: molecules go from high to low concentration with the help of certain proteins

3) Osmosis: diffusion of water from higher to lower concentrations across a selectively permeable membrane

What is diffusion and its goal?

* tendency of particles to spread out evenly in an available space
* its goal is to find equilibrium among the same type of molecules

Describe the U-tube experiment and what is signifies.

* In this experiment the amount of solute is uneven on both sides of the tube as a membrane is permeable to water but not the solute
* Due to this the water will cross the membrane and move down its own concentration gradient until the solute concentration on both sides is equal

What is tonicity?

term that describes the agility of a surrounding solution to cause a cell to gain or lose water in order to reach equilibrium

What is a hypertonic solution and what is its effect on cells?

* causes cells to shrink and is a solution with high solute levels

What is a hypotonic solution and what is its effect on cells?

* Plant cells= Turgid(normal)
* Animal Cells=swelling till burst
* Solution with low solute levels

What is an isotonic solution and what is its effect on cells?

* animal cells=normal
* plant cells=flaccid
* solution with equal solute levels

What types of substances early diffuse across a cell membrane?

hydrophobic/nonpolar

What types of substances need help moving across membranes?

* hydrophillic/polar substances need help moving across the membrane with specific transport proteins
* this is known as **facilitated diffusion**

What is the general rule of thumb for transport proteins?

greater the number of transport proteins for a particular solute in a membrane, the faster the solute’s rate of diffusion

What is the importance of aquaporin?

* allows for the rapid diffusion of water into and out of certain cells as it is a channel protein

What happens in active transport?

a cell must expend ATP energy to move solutes against concentration gradient

What are the two mechanisms to move large molecules across membranes?

Exocytosis

Endocytosis

What is exocytosis?

used to export bulky molecules such as proteins or polysaccharides

What is endocytosis?

used to take in large molecules

What happens in both endocytosis and exocytosis?

material is transported after it is packaged within a vesicle that fuses with the membrane

What are the three kinds of endocytosis?

Phagocytosis

Receptor-mediated endocytosis

Pinocytosis

Phagocytosis

engulfment of a food practice by the cell wrapping cell membrane around it and forming a vacuole

Receptor-mediated endocytosis

uses membrane receptors for specific solutes

Pinocytosis

engulfment of small particles suspended in extracellular fluid

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Energy

Ability to do work

Kinetic Energy

Energy of motion

What does kinetic energy require?

Requires ATP via cellular respiration made via mitochondria

What are the two forms of kinetic energy?

thermal(heat) energy and light energy

What is potential energy?

Energy stored in the location or structure of matter

Chemical Energy

Type of potential energy that is available for release in a chemical reaction

What is an example of chemical energy?

The process of breaking down glucose to make ATP via cellular respiration

What can light be used to do?

Harness the power of photosynthesis

What is thermodynamics?

Study of energy transformations

What is system in terms of thermodynamics?

Matter under study

What is surroundings in terms of thermodynamics?

Everything outside of the study

What is a closed system?

Isolated from its surroundings like a liquid in a thermos

What is an open system?

Energy and matter can be transferred between system and surroundings

What type of system are organisms?

Open systems since they absorb light in organic molecules and release heat and metabolic waste

What is the first law of thermodynamics?

states that energy can be transferred and transformed, in other words “Energy is neither created nor destroyed”

What is the second law of thermodynamics?

states that every energy transformation must make the universe more disordered or entropy (quantity used as a measure of disorder, or randomness)

What is an exergonic reaction?

Releases energy

Exergonic Reactions

Huge amount of reactions into small amount of products with a side product of ATP

What are examples of exergonic reactions?

Hydrolysis(breaks down polymers to monomers and release energy) and Cellular Respiration

What are endergonic reactions ?

require energy and yield products rich in potential energy

What is an example of an endergonic reaction?

Photosynthesis

What does motabolism do?

encompasses all of a cell’s chemical reactions- a mix of both exergonic and endergonic.

How does ATP power cellular work?

transfer of a phosphate group from ATP forming ADP and P is involved in chemical, transport, and mechanical work

How exactly does the hydrolysis process work?

The process breaks down the bond between the second and third phosphates and releases energy therefore it is exergonic/ endergonic

What are the three kinds of work does a cell do?

1)Chemical: driving endergonic reactions such as the synthesis of polymers from monomers.

2) Transport: pumping substances across membranes against the direction of spontaneous movement

3) Mechanical: beating of cilia, contraction of muscle cells, and movement of chromosomes

What is dephosphorelation and phosphorylation?

Removing phosphate and adding phosphate

Describe the ATP to ADP+P cycle

What are enzymes?

protein catalysts that decrease the activation energy needed to begin a reaction

What must a substrate do?

Fit specifically into an enzyme’s active site

What is activation energy?

amount of energy necessary to push the reactants over an energy barrier

What is the transition state

summit the molecules are at an unstable point

What is delta G?

The difference between free energy of the products and the free energy of the reactants

How do enzymes work?

Speed reactions by lowering activation energy and can be reached even at moderate temperatures

Describe the catalactic cycle of an enzyme

What is a competitive inhibitor?

competes with the substrate for the active site.

What is a non competitive inhibitor?

alters an enzyme’s function by changing its shape

What is feedback inhibition?

* helps regulate metabolism
* Product of reaction is the inhibitor

What are some uses for enzyme inhibitors?

Enzyme inhibitors have also been developed as

pesticides, deadly poisons for chemical warfare, and Beneficiary drugs

What are cofactors?

* non protein helpers for catalytic activities
* They may be organic or inorganic
* They bind to the enzyme permanently or reversibly
* Some inorganic cofactors include zinc, iron, and copper

What are coenzymes?

Are organic cofactors that include vitamins or molecules derived from vitamins