Physiology chapter 2 (a and b)

Molecules and cells

Describe the Structures of the Cell membrane

The cell membrane consits of a phospholipid bilayer and embedded proteins. The phospholipids contain hydrophilic polar heads that face the water and hydrophobic nonpolar tails that face inward toward each other. Integral proteins are embedded in the membrane while peripheral proteins are associated with its surface but can be removed

Understand the improtance of Membrane Fluidity

Membranes need to maintain fluidity. Cold temps make the membrane too stiff, so species adapted to colder environments by having unsaturated phospholipids. Unsaturated phospholipids contain double bonds to create bends in in phospholipid tails, preventing them from packing tightly when cold.

Name the 5 types of membrane Proteins

Channel protei, transporter protein, enzyme, receptor protein, structural protein

Channel Protein

Opens a pathway through the membrane for water and solutes to diffuse and pass through

Transporter Protein

Binds specific molecules and moves them across the membrane

Enzyme

Cataylzes chemical reaction to make or break bonds. Helps chemical reaction occur

Receptor Protein

binds to specific molecules and causes change in membrane permeability meaning receptor responds to chemical signals outside the cell membrane

Structural Protein

attaches to molecules and helps establish structural relationships

Understand the basic components of an Epithelial Cell

Epithelal cell is a sheet of cells that cover the bodies surface/organs and creates a boundary. The Apical surface faces the top side of the epithelial cell and the basal surface faces the bottom side of the epithelial cell. Under the basal surface lies the basement membrane which is a thin nonliving layer that supports the epithelial cell underneath.

What is a Junction

Connecting point between cells

Compare and Contrast Tight Junction and Septate Junction

Tight and septate junctions are occluding junctions that seal/restrict the space between adjacent cells. Tight junctions are common in vertebrates; septate junctions are mostly in invertebrates.

Desmosome

A junction that attaches neighboring cells together using glyprotein filaments from adjecent cells and there is space between the cells.

Gap Junction

Junction that allows small molecules/ions to pass between adjacent cells which is important in electrophysiology

Compare and Contrast an Enzyme and Catalyst

A Catalyst is a molecule that accelerates a reaction without altering itself. An Enzyme is a type of Catalyst for protein that speeds up and regulates the reaction

Explain how an Enzyme affects a Reaction

An Enzyme accelerates a reaction by lowering the needed activation energy to reach the transitional state.

Understand the Characteristics of Hyperbolic reactions Kinetic

As substrate concentration increases, reaction velocity increases and then levels off when enzymes become saturated

Reaction Velocity

How fast enzyme catalyst reaction is occurring

How is Maximum Velocity Determined (Vmax)

Vmax is determined by two properties. HOW MANY enzymes you have and HOW EFFECTIVE each enzyme is(kcat).

What does Affinity mean

How likely an enzyme will bind to a substrate. High affinity means enzyme will highly likely bind to substrate

How does Km relate to enzyme-substrate affinity?

Km is the substrate concentration needed to reach ½ Vmax. Lower Km = higher affinity because less substrate is needed to reach ½ Vmax.

Explain how Sub-Maximum Reaction Velocity is Determined

It is determined by the number of active enzymes, catalytic effectiveness, and enzyme-substrate affinity, which is how likely the enzyme is to bind to the substrate.

What are protein structure and denaturation?

Proteins have primary, secondary, tertiary, and quaternary structure. Denaturation disrupts protein structure and can occur with increased temperature.

What reaction does lactate dehydrogenase (LDH) catalyze?

LDH catalyzes the reversible reaction between pyruvic acid and lactic acid.

what is Enzyme Comformation

Enzyme conformation is the 3-D shape of an enzyme and will determine where and what kind of substrate will bind to the enzyme

Cooperativity

Substrate binding to one site affects how another site will bind. If substrate binds to site 1, site 2 maybe be more likely to bind (+ cooperativity) or less likely to bind (- cooperativiity)

Homotropic Cooperativity vs Heterortropic Cooperativity

Homotropic Cooperativity is when two of the same type of substrates bind to two sites. Heterotrpic Cooperativity is when two different substrates bind to two different sites

Allosertic Modulation

A nonsubstrate molecule binds to an enzymes allosertic site and changes the enzymes catyltic acitvity, causing activation or inhibition

what is an Isozyyme

Different molecular forms of an enyzme that cataylzes the same reaction in one species.

Interspecfic Homologs

Two different species make different molecular forms of an enzyme that catalyzes the same reaction

Metabolic Pathway

Sequence of enzyme-cataylzed reactions

Rate-Limiting Reaction

A reaction that sets up pace for the whole pathway

Branch-Point Reaction

One pathway reaches a point where it can go in two or more directions, allowing different final products to form

How does Allosertic Modulation Regulate Metabolic Pathways?

A modulator reversibly binds to an enzymes allostertic site and can either upregulate (speed up the process) or downregulate (slow down the process) the catlyitc activity. If rate-limiting reaction or branch-point reaction is alloserticaly regulated, the metabolic pathways can be affected.

Protein Kinase

Catalyzes Phosphorylation (adds a phosphate)

Protein Phosphatase

Cataylzes Dephosphorylation (removes phosphate)

Covalent Modulation

Regulation of an ezyme through chemical reaction that make or break a covalent bond on an enzyme. An example being phosphorylation and dephosphorylation.

What is an example of Covalent Modulation

Protein kinase adds phosphate to an inactive enzyme which changes the enzymes shape and becomes active. Enzyme can now catalyze reaction

What is the difference between Covalent Modulation and Allosertic Modulation

Allosertic modulation involves reversible, noncovalent binding of an enzyme to a allosertic site which can upregulate or downregulate the activity of an enzyme. Covalent modulation involves making or breaking covalent bonds which acts as an ON/OFF switch for enzymes.

What is the Importance of Amplification in Intracellular Pathways

Amplification allows a small extracellular signal to produce a larger intracellular response because active enzymes can produce many product molecules, amplifying the signal at multiple steps. For example, epinephrine signaling in liver cells is amplified and cause glucose release from glycogen.

Amplificatoin

A small inital signal produces a larger cellular response

How can a protein kinase cascade cause amplification?

One activated kinase can activate multiple kinases, which activate many targets, producing a much larger response.

What is the Evolutionary Relationships of multiple enzyme forms

There are two evolutionary scales. Scientists compare formation of enzymes through amino acids to determine and construct family trees over time. Scientists examine a single species change in enzyme allele frequencies to study present day evolution and natural selection

What is an example of Evolution of enzyme alleles within one species?

Killfish in the northern enviorment have allele A which helps with colder temp and killfish in southern enviorment have allele B which helps with warmer temps.

Ligand

A molecule that binds specifically and noncovalently to a receptor protein

What are the 4 Receptor Protein Types

Ligand-Gated Channel, G Protein-Coupled Receptor, Enzyme/Enzyme-Linked Receptors, and Intracellular Receptors

Ligand-Gated Channel

Functions as a receptor and a channel. Ligand binds and channel opens allowing specific ions/sollutes to cross membrane

G Protein-Coupled Receptors

Ligand binds to GPCR and activates a seperate G protein which causes intracellular effect or activtates another membrane protein. They can produce second messengers such as cAMP

Enzyme/Enzyme-Linked Receptors

The receptor is either an enzyme itself or directly interacts with enzyme when activated. They can produce to a second messenger such as cGMP

Intracellular Receptor

The ligand crosses the cell membrane and binds a receptor inside the cell which interacts with DNA and alters gene expression

Second Messenger

Intracellular molecule that helps carry signal inside the cell which often activates protein kinase that is present but incative

What are Multiple types and Relationships of Second Messengers

Major second messengers are cAMP, cGMP, IP3, DAG, and Ca3+. cAMP activates cAMP dependent protein kinases, cGMP activates cGMP dependant protein kinases, and DAG activates membrane protein kinases. IP3 opens Ca2+ channels releasing Ca2+ into the cytoplasm. Ca2+ binds to calmodulin forming a complex that activates calmdoulin dependant protein kinases and other enzymes.