Cell and Molec Bio (Exam 1)

What is the hierarchy of organizational levels? (5)

• cell

• multicellular

• community

• ecosystem

• biosphere

Cell

an organized chemical system that includes many specialized molecules and subcellular structures

Multicellular Organism

an organism made up of many cells

Population

a group of organisms of the same kind that live together in the same place

Community

all of the populations of different organisms that live in the same place

Ecosystem

includes the community and the nonliving environmental factors with which it interacts

Biosphere

encompasses all the ecosystems of the Earth’s waters, crust, and atmosphere

Emergent Properties

new properties and rules emerge that cannot be predicted by full knowledge of a lower level

What is an example for an emergent property for a cell? (2)

• a cell is alive if it is organized as a cell

• as its individual components it is no longer alive and functional

Element

pure substance that cannot be broken down into simpler substances by normal chemical and physical processes

Atom

unit of an element

Protons (3)

• subatomic particle with a positive charge

• the number of protons in the core of an atom uniquely identifies the element

• aka atomic number

Neutrons (2)

• subatomic particle with no charge

• exist in equal number to protons

How do you calculate the atomic mass?

proton # + neutron #

Electrons (2)

• negatively charged subatomic particles

• occupy 99% of the atom’s space, but accounts for little mass

Shells

orbit followed by electrons around an atom’s nucleus

Valence Electrons (2)

• in the outer shell

• determines an elements reactivity

Chemical Bonds

describe the chemical linkages between atoms that lead to formation of higher order structures containing more than one atom

How are chemicals formed and broken?

by chemical reactions

How are chemical reactions assisted in biological systems?

enzymes

Electronegativity (2)

• value that describes the relative tendency of an atom to attract electron towards itself

• determines an atom’s reactivity and type of bond formed between two atoms

What will an atom with 1 or 2 electrons in its valence shell want?

to lose them

What will an atom missing 1 or 2 electrons in their valence shell?

it will want to gain them

How can atoms get closer to having a full valence shell?

by sharing electrons

Ionic Bond

a bond between two atoms in which one has given some electrons to another atom

Covalent Bond

a bond formed when atoms share electrons

Molecule

entity with two or more atoms joined by covalent bonds

What are the two types of covalent bonds? (2)

• nonpolar

• polar

Nonpolar

equal electron sharing

Polar

unequal electron sharing

Intermolecular Forces

electrostatic attractions or repulsions between separate molecules

What are the important intermolecular forces for this class? (2)

• dipole-dipole

• hydrogen bonding

Dipole-dipole

force between polar molecules, where the partially positive end of one molecule attracts the partially negative end of another

Hydrogen Bond

hydrogen can be involved in such polarized covalent bond that it resembles an exposed proton and therefore a very positive surface

Water

a polar molecule with a number of emergent properties

What are the organizational properties of water? (4)

• forms lattice of H-bonded molecules

• can tolerate large changes in energy without huge temperatures

• polar solvent

• can dissociate into ions

pH

a measure of H⁺ ions relative to OH^- ions

Why do we have buffers?

changes in pH can have dramatic consequences for living systems

Buffers

substances that compensate for changes in pH by absorbing H⁺ or OH^- ions

Organic Molecules

those that include carbon

Hydrocarbons

molecules containing only carbon and hydrogen

Functional Groups

add specific properties to a molecule

What common reactions occur with water and functional groups? (2)

• Condensation

• Hydrolysis

Condensation

the components of a water molecule are removed as subunits to join into a larger molecule

Hydrolysis

the components of a water molecule are added as molecules are split into smaller subunits

What are the types of macromolecules? (4)

• carbohydrates

• lipids

• proteins

• nucleic acids

Macromolecules (2)

• made of atoms connected by covalent bonds

• can interact with themselves and other molecules using intermolecular forces

Which macromolecules are polymer based? (3)

• carbohydrates

• proteins

• nucleic acids

Polymer

a macromolecule assembled from smaller subunits through polymerization

Monomers

subunits of macromolecules

Monosaccharides (2)

• monomer of carbohydrates

• can exist in linear or ring form

What are carbohydrates used as? (3)

• structural components

• energy storage molecules

• biochemical intermediates in making other molecules

Isomers

molecules with the same chemical formula, but different structure

Structural Isomers

same chemical formula, but atoms are connected in a different order

Aldehydes

carbonyl with a C and H

Ketone

carbonyl with two Cs

Stereoisomers (3)

• same chemical formula and connectivity, but atoms are arranged differently in space around the central carbon

• two molecules that are stereoisomers are mirror images

• they have important biological implications

What kind of isomer is glucose?

stereoisomer

How is glucose a sterioisomer?

the OH on C₁ can either be up or down

Is this an α or β glucose?

α

Is this an α or β glucose?

β

Disaccharides (2)

• reaction between C₁ and C₄ in 2 monosaccharides yields two rings connected via covalent bonds

• used for transient energy storage

What types of glycosidic bonds are there? (4)

• 1-4 linkage (more common)

• 1-2 linkage

• 1-3 linkage

• 1-6 linkage

What type of linkage does maltose have?

α(1-4)

What are the components of maltose? (2)

• glucose

• glucose

What is type of linkage does sucrose have?

α(1-2)

What are the components of sucrose? (2)

• glucose

• fructose

What type of linkage does lactose have?

β(1-4)

What are the components of lactose? (2)

• galactose

• glucose

Polysaccharides (3)

• linear or branched polymers

• used as energy storage molecules

• important in building structures

Amylose (3)

• Plant starch

• Linear

• α(1-4) linkage

Glycogen (3)

• animal starch

• branched

• α(1-4) and (1-6) linkages

Cellulose (3)

• primary plant cell wall components

• linear

• β(1-4)

Chitin (3)

• structural component in insect exoskeleton and fungal cell walls

• linear

• β(1-4)

What is the monomer to chitin?

N-acetylglycosamine

N-acetylglycosamine

like a glucose molecule, but with N groups attached

Lipid (3)

• water insoluble

• nonpolar molecules composed of mostly hydrocarbons

• amphipathic

Amphipathic

a molecule that contains polar and non polar regions

What are lipids used for? (3)

• to form membranes

• store energy

• as biochemical intermediates

What are the types of lipids? (4)

• fatty acids

• triglycerides

• phospholipids

• sterols

Fatty Acids (2)

• hydrocarbons of various lengths ~14-22

• carboxyl group

How are fatty acids amphipathic? (2)

• they have long hydrocarbon strings and a carboxylic acid, which makes a polar and nonpolar region

• nonpolar is dominant

Saturated

all single bonds saturated with hydrogens

Unsaturated (2)

• presence of one (mono) or multiple (poly) double bonds

• a shape is imposed by double bonds

Triglycerides

three fatty acids bonded to a glycerol molecule by ester linkages

Ester Linkage

hydroxyl and carboxyl group bonded through a dehydration reaction

What are triglycerides used for? (2)

• to store energy

• triglycerides can store twice as much energy as carbs per gram

Phospholipid (2)

• glycerol bound to two fatty acids along with another functional group linked through a phosphate

• highly amphipathic

How does the phosphate change the character of this molecule? (2)

• it makes it amphipathic

• allows it to form special structures in an aqueous solution

What are the phospholipid head types? (4)

• phosphatidic acid

• phosphatidylinositol

• phosphatidylserine

• phosphatidylcholine

Steroids (3)

• groups of lipids with structure based on framework of four carbon rings

• differentiated by functional groups

• important in signaling molecules operating at the level of the organism

Cholesterol (4)

• steroid that is very important in biological membranes

• embedded in the membrane

• very rigid structure that enhances the selective barrier properties of the plasma membrea

• keeps the plasma membrane in a packed and organized state

Which hormones demonstrate the significance of small differences in structure? (2)

• estrogen and testosterone

• important for sex determination in the development of mammals

Chiral

bound to 4 different entities

What gives rise to alpha and beta forms of glucose rings?

spontaneous ring interconversion

Protein

polymer made up of amino acid subunits

What are proteins used for? (3)

• as structural molecules

• enzymes

• in biological processes

Amino Acids (3)

• monomer of proteins

• 20 found in proteins

• characterized by the different functional groups or side chains attached

How are amino acids used to form proteins?

they are polymerized into proteins by peptide bonds to form an amide bond

What does an amino acid contain? (5)

• amino group

• carboxyl group

• hydrogen

• R group

• central carbon