Life Science 7A Midterm 1 Topics

Forming a bond requires/releases energy

Releases energy

Breaking a bond requires/releases energy

Requires energy

Hypertonic

High solute concentration

Hypotonic

Low solute concentration

Isotonic

Equal solute concentration inside and outside of the cell

Increases membrane fluidity (without cholesterol)

• Adding heat to the system

• Shorter phospholipid tails

Decreases membrane fluidity (without cholesterol)

• Removing heat from the system

• Longer phospholipid tails

Ionic bond

Formed between two oppositely charged ions

Covalent bond

Valence electrons shared between atoms

Hydrogen bond

When a hydrogen with a partial positive charge interacts with an O or N atom with a partial negative charge of another molecule

van der Waals’ forces

Electrostatic interactions between atoms that have temporary partial charges

Lower potential energy

The stronger the bond

Higher potential energy

The weaker the bond

Strength of bonds in water (strongest to weakest)

Covalent

Ionic

Hydrogen bond

van der Waals’

Nucleus

Stores DNA

Mitochondria

Converts sugar into ATP to power the cell

Endoplasmic Reticulum

Produces, synthesizes, and transports proteins and produces lipids that make up cell membranes

Golgi

Modify, sort, and package proteins and lipids received from the endoplasmic reticulum for delivery to specific locations inside or outside the cell

Lysosome

Waste management; gets rid of damaged or unnecessary macromolecules

Simple Diffusion Definition

• Does not require a protein in the lipid bilayer

• Movement of molecules from high to low concentration

• No input of energy is required

• Passive Transport

• Small, uncharged, hydrophobic molecules use this method

Facilitated Diffusion Definition

• Requires a protein in the lipid bilayer

• Movement of molecules from high to low concentration

• No input of energy is required

• Passive Transport

• Uses channel proteins, carrier proteins, and aquaporins

• Osmosis uses this method

Primary Active Transport Definition

• Requires a protein in the lipid bilayer

• Movement of molecules from low to high concentration

• Input of energy is required (ATP)

• Uses proteins such as ion pumps, antiporters, and symporters

Secondary Active Transport Definition

• Requires a protein in the lipid bilayer

• Movement of molecules from low to high concentration

• Requires indirect input of energy (uses the energy of an electrochemical gradient to drive the movement of ions or molecules)

  • Powered by an electrochemical gradient created through primary active transport)

Free Energy

Total amount of energy available to do work

Diffusion is exergonic/endergonic? Why?

Exergonic because no net input of energy is required

When is a reaction spontaneous?

∆G < 0

Anabolic pathways

One part of metabolism; set of chemical reactions that builds molecules from smaller units and requires energy (usually ATP)

Catabolic pathways

One part of metabolism; set of chemical reactions that breaks down molecules into smaller units and produces ATP in the process

Are anabolic pathways endergonic/exergonic?

Endergonic

Are catabolic pathways endergonic/exergonic?

Exergonic

Metabolism

Set of chemical reactions that convert one molecule into another and transfer energy in living organisms

Enthalpy

Potential energy of bonds

Entropy

Disorder

Diffusion Definition

Random movement of molecules from high to low concentration; membrane is not required

Enzyme function

Lower the activation energy of a reaction

Enzyme Activators

Increase enzyme activity

Enzyme Inhibitors

Decrease the activity of an enzyme

1st law of thermodynamics

No energy can be created or destroyed, it can only change form

2nd law of thermodynamics

When energy is converted into a different form, there is an increase in entropy

Movement of molecules from high to low concentration requires/releases energy

Releases energy

Movement of molecules from low to high concentration requires/releases energy

Requires energy

What force do nonpolar tails of phospholipids use to interact with each other?

van der Waals’ forces

Permeability of molecules in the phospholipid bilayer (greatest to least)

Hydrophobic (nonpolar) molecules

Small, uncharged, polar

Large, uncharged, polar

Ions

Amphipathic

Molecules have both polar and nonpolar regions

Intramolecular forces

Covalent bonds

Intermolecular forces (noncovalent interactions)

Ionic bonds (in water), hydrogen bonds, van der Waals’ forces

Peripheral Membrane Protein

Temporarily associated with the lipid bilayer or with integral membrane proteins through weak noncovalent interactions

Integral Membrane Protein

Permanently associated with the cell membrane and cannot be separated from the membrane experimentally without destroying the membrane itself

Transmembrane Protein

Spans the entire lipid bilayer; most integral membrane proteins are transmembrane proteins

Lipids

Nonpolar hydrocarbon molecule that stores energy, acts as signaling molecules, and are a component of all cell membranes

Cholesterol function in lipid bilayer

Hydrophilic

“Water-loving,” polar

Hydrophobic

“Water-fearing,” nonpolar

Electronegativity

Affinity for electrons

How many covalent bonds can H form (lines)?

1

How many covalent bonds can C form (lines)?

4

How many covalent bonds can O form (lines)?

2

How many covalent bonds can N form (lines)?

3

Lower electronegative atoms with the same electronegativity

C & H

Higher electronegative atoms with the same electronegativity

O & N

The lower the potential energy, the stronger/weaker the bond?

Stronger

The higher the potential energy, the stronger/weaker the bond?

Weaker

Differences between prokaryotic and eukaryotic cells

Prokaryotes: No nucleus (has a nucleoid instead), no organelles, smaller

Eukaryotes: Have a nucleus and organelles, larger

Organelle

A compartment in a eukaryote that carries out a specialized function

Cytoplasm

Everything in the cell including the cytosol, except for the nucleus

Cytosol

Jelly-like substance inside the cell that surrounds the organelles

Chloroplast

Capture the energy of sunlight to synthesize simple sugars through photosynthesis, resulting in the release of oxygen as a waste product

Vacuole

Water storage

Structure of triglycerides

Structure of fatty acids

Structure of phospholipids

Structure of cholesterol

Unsaturated fatty acid

Contain double bond(s), kinks in chain because of double bonds —> Cannot be tightly packed

Saturated fatty acid

Only contain single bonds, “saturated” with H atoms, straight chain —> can be tightly packed

Raising temperature increases/decreases membrane fluidity

Increases

Lowering temperature increases/decreases membrane fluidity

Decreases

Longer phospholipid chains increase/decrease membrane fluidity

Decrease

Shorter phospholipid chains increase/decrease membrane fluidity

Increase

More phospholipid saturation increases/decreases membrane fluidity

Less phospholipid saturation increases/decreases membrane fluidity

Kinetic energy

Energy of motion

Potential energy

Stored energy that depends on an object’s structure of position relative to a field and is released by a change in the object’s structure or position

Exergonic

Releases energy, negative ∆G

Endergonic

Requires an input of energy, ∆G is positive

Substrate

A molecule acted upon by an enzyme

Active site

The portion of an enzyme that binds substrate and converts it to product

Activation energy

The energy input necessary to reach the transition state

Transition state

The brief time in a chemical reaction in which chemical bonds in the reactants are broken and new bonds in the product are formed

Reaction rate

The amount of product formed or reactant consumed per unit of time

How are enzymes able to alter the rate of chemical reactions?

High H+ concentration

Low pH = acidic

Low H+ concentration

High pH = Basic

What factors affect enzymes

Temperature and pH

What happens to an enzyme when temperature is outside the enzyme’s ideal range?

What happens to an enzyme when pH is outside the enzyme’s ideal range?

Kinetics

How fast a reaction proceeds

Thermodynamics

Whether a reaction requires an input of energy or not

What happens to an enzyme after it catalyzes a reaction

It is not consumed and remains unchanged and prepared to catalyze that reaction again

∆G°

Measured in standard lab conditions

∆G

Measured in cellular conditions