DENT Fun. I - Basics and Intro to Cells

Element

A substance that cannot be broken down into simpler substances

Compound

A substance made up of 2+ elements joined by chemical bonds

About ____ of the 92 elements are essential to life.

25

Chemical behavior of an atom is determined by its ____.

valence electrons

Elements with a full valence shell are chemically ____.

inert

Covalent Bond

Chemical bond that involves sharing a pair of electrons between atoms in a molecule

Noncovalent Bond

Chemical bond due to donated/accepted electrons

Electronegativity

The ability of an atom in a chemical compound to attract electrons

Electronegativity increases going ____ and ____ on the periodic table.

up/right

Nonpolar Covalent Bonds

Electrons are shared equally

Polar Covalent Bonds

- Unequal sharing of electrons

- Causes polarity: Partial Charges

What are the 3 Noncovalent Bonds?

- Hydrogen

- Ionic

- Van der Waals

Hydrogen Bonds

Weak attraction between a hydrogen atom and another electronegative atom

Ionic Bonds

Formed when one or more electrons are transferred from one atom to another

Van der Waals Interactions

Attractions between atoms with asymmetrically distributed electrons

Biological molecules recognize and interact with each other based on ____.

molecular shape

Structure = Function

Molecules that have similar shapes can have similar ____.

biological effects

Next to water, ____ and ____ are the most abundant biomolecules in the body.

proteins/triglycerides

Water is ____.

polar; has a positive and negative pole (dipole)

Cations

Positive ions

Anions

Negative ions

Properties of Water

- Solid is less dense than Liquid

- High Specific Heat

- Cohesion/Adhesion

- Solvent of Life

High Specific Heat of Water

It takes a lot of energy to heat up water due to hydrogen bonding, which allows for a stable environment

Cohesion/Adhesion of Water

Cohesion: H-Bonding between water causes a high surface tension

Adhesion: Attraction to substances other than water

Water is an excellent ____.

solvent

Water is polar covalent, therefore, it interacts with anything with a charge

What happens when water interacts with nonpolar substances?

Water cannot dissolve the substance and creates micelles or membrane bilayers

Micelles

Lipid molecules orient with polar (hydrophilic) head toward water and nonpolar (hydrophobic) tails away from water

Membrane Bilayer

Consists of two leaflets of lipid monolayers

- Hydrophilic head groups interact with water

- Hydrophobic fatty acid tails are packed inside

Water is amphoteric, which means that ____.

it can act as an acid or base

H2O + H2O <--> H3O+ + OH-

pH = ____

-log[H+]

Bronsted Acid

Proton (H+) Donor

Bronsted Base

Proton (H+) Acceptor

Dissociation Constant (Kd)

Kd = [H+][A-]/[HA]

Henderson-Hasselbalch Equation

pK + log[A-]/[HA]

The pK value represents the pH value at which the ionizable group is ____.

half-protonated

Arterial Blood pH

7.4

Venous Blood pH

7.35

More Carbonic Acid

Carbonic Acid

H2CO3

Bicarbonate Buffer System

CO2 (g)+ H2O(l)↔H2 CO3 (aq)↔H+ (aq)+HCO3- (aq)

What enzyme aids CO2 and H2O to create H2CO3?

Carbonic Anhydrase

Buffers

Substances that minimize pH change

All ____ and ____ buffer the pH of the solution at pH values close to their pK values.

weak acids/weak bases

Acidemia

pH < 7.35

Alkalemia

pH > 7.45

Respiratory Acidosis

A drop in blood pH due to hypoventilation (too little breathing) and accumulation of CO2

Respiratory Alkalosis

A rise in blood pH due to hyperventilation (excessive breathing) and loss of CO2

Metabolic Acidosis

High [H+] in the extracellular fluid caused by either an increase in [H+] or a decrease in [HCO3-]

Metabolic Alkalosis

High pH and high [HCO3-] due to loss of acids from the body (vomiting)

What are the 3 lines of defenses to attempt to restore normal Blood pH?

(1) Buffer Systems

(2) Respiration

Acidosis: Increased ventilation

Alkalosis: Decreased ventilation

(3) Kidneys

Acidosis: Remove [H+]

Alkalosis: Remove [HCO3-]

Eukaryotic

Membrane-Enclosed Organelles

Prokaryotic

No Membrane-Enclosed Organelles

Pathogens can only be prokaryotic (T/F)

False; prokaryotic, eukaryotic, or neither (viruses)

Features of All Cells

- DNA

- Cytosol

- Ribosomes

- Plasma Membrane

Features of Prokaryotes

- Cell Walls

- Flagella

- Pili

Features of Eukaryotes

- Nucleus

- Extensive Membrane System (Golgi, Smooth/Rough ER)

Plasma Membrane

Selectively-permeable phospholipid bilayer forming the boundary of cells

Also acts as a surface for biochemical reactions to occur

The prokaryotic plasma membrane is surrounded by the ____ and is folded to provide ____.

cell wall/a complex of membranes that allow for metabolic reactions to occur

Cell Wall

- Plant: Cellulose

- Fungus: Chitin

- Bacteria: Peptidoglycan

Gram Positive

- Purple

- Thick peptidoglycan layer

Gram Negative

- Pink

- Thin peptidoglycan layer

Since eukaryotic cells do not have cell walls, it allows for the formation of ____.

tissues

Organ and tissue mechanical/functional properties are determined by ____ and ____.

cytoskeletal components/intercellular junctions

What 3 filaments make up the Cytoskeleton?

- Microfilaments (Actin)

- Intermediate

- Microtubules

Extracellular Matrix (ECM)

Fluid outside the cell that interacts with the glycoproteins of the plasma membrane

Functions include...

- Support

- Adhesion to other Cells

- Movement

- Regulation

- Communication

Components of the ECM

- Collagen Fibers

- Elastic Fibers

- Proteoglycans

- Glycoproteins

ECM proteins bind to ____.

integrins

Protein receptors important in communication

Cellular Communication

(1) Reception

(2) Transduction

(3) Response

Direct Cellular Communication

- Proteins bind membrane proteins

- Cytosolic molecules through gap junctions

Indirect Cellular Communication

Communication via signal molecules

- Autocrine

- Paracrine

- Endocrine

What are the 8 possible ligands of Cellular Communication?

- Proteins

- Lipids

- Carbs/Glycoproteins/Glycolipids

- ECM Components

- Growth Factors

- Hormones

- Neurotransmitters

- Gases

Signal Transduction

A series of molecular changes that converts a signal on a target cell's surface to a specific response inside the cell

In connective tissues, where cells are not in close proximity, what is critical for cellular adhesion and communication?

Extracellular Matrix

Integrins binding fibronectin is an example of which type of communication?

direct