Biology Chapter 4

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Chapter 4 notes, campbell biology

What are living organisms on Earth mainly made up of?


How does carbon enter the biosphere?

Via plants. They use solar energy to transfer atmospheric CO2 into the molecules of life

What is organic chemistry? How did it come about?

Organic chemistry is the study of carbon compounds, regardless of origin.
-In the early 1800s, Berzelius made distinction between compounds from living things and not. He called it organic (he was heavily influenced by vitalism).
-Eventually, chemists began to synthesize organic compounds. urea was the first one.
In the 1950s Miller tested whether complex organimc molecules could arise abiotically and spontaneously in early Earth conditions. They did.

What is vitalism? What is mechanism?

Vitalism was the belief that a life force existed outside the jurisdiction of physical and chemical laws. This is why only organic molecules were from organisms only. Mechanism is the opposite - it is the belief that physical and chemical laws govern all natural phenomena, including the process of life. In the 1950s, this helped to push the idea that organic molecules could spontaneously and abiotically be created from inorganic molecules.

Why is carbon very verstile?

Carbon creates inexhaustible variety because:
1) it can form 4 bonds, hence able to form large and complex molecules. It's valence shell has 4 atoms in different orbitals, so it can covalently bond with four other atoms Each carbon acts as an intersection point from which a molecle can branch off. This is why biological molecule sare so diverse.
2) There are actually only 5 main major elements of life, C,H,O,N,S,P - but carbon is the key for diversity.

What is tetravalence?

Tetravalence is when a molecule like carbon has the ability to create four covalent bonds with other atoms and can therefore branch off in as many as four directions.

what shape does carbon universally have?

A carbon with a group of four has a tetrahderal shape.

What are hydrocarbons? Why are they important?

The hydrocarbons are long chains of hydrogens covalently bonded to carbon skeleton. They are the major components of fossil fuels. In living being, organic molecules have regions of hydrocarbons, like fatty acids. When in reactions, they release a TON of energy.

What is the forumula for hydrocarbon?


What are carbon isomers?

compounds that have the same number of atoms of the same elements but different structures.

What are the three types of isomers we learned about in class?

Structural - same molecular formula, different structure of bonding
geometric - different arrangement about a double bond
enantiomers - mirror images

What happens to the possibility of structural isomers as carbon skeletons increase in size?

Possible isomers increase tremendously.

Geometric isomers

Single bonds allow atoms they join to rotate freely. With double bonds, it is more rigid.


Four groups arranged in space around asymmetric carbon in two different ways. They are mirror images of each other. One is viologically acive and the other is in active.

What is the chiral carbon?

It is the middle carbon atached to four different atoms or group of atoms.

Example of geometric isomers

Example of enantiomers

What type of isomers are these?

1) structural
2) structural
3) same molecule
4) enantiomer
5) geometric
6) structural

What type of isomers are these?

7) not isomers, different formula
8) enantiomers
9) geometric
10) structural
11) not isomers, different formula
12) not isomers, same

What are functional groups?

Functional groups are chemical groups attached to the carbon atom and gives the molecule specific properties.
They are CASHCaMP.

What are they? (CASHCaMP)

Carboxyl - COOH
Amino - NH2
Sulfhydryl - SH
Hydroxyl - OH
CArbonyl - CO
methyl - CH3
Phosphate - -PO4

What does a carboxyl often dissociate to?

H+ + O-C=O-

What are carboxyls called?

Carboxylic acids

Which functional group is a weak acid?

Carboxyls. The H tends to dissociate from the OH.

Is carboxyl polar or non polar?


Where are carboxyls in?

Fatty acids AND amino acids.

what are molecules with amino group called?


Which functional group imparts basic properties to molecule?

Amines, -NH2. They can absorb an H to become NH3.

Where are amines found?

Amino acids, nucleic acid, proteins.

What is the building block of protines?

Amino acids.

What does an amino acid look like?

Amino acids have amino on one side and a carboxyl on the other. there is an R attached to the chiral carbon.

What imparts the properties in an amino acid?

The R group.

Why are amino acids natural buffers?

One side can accept a proton (NH2) but the other side can donate (COOH).

Amino acids always have which isomer?

They always have enantiomers. Living organisms only make the L enantiomer amino acids. If not living, the process creates equal amounts of L and R.

What are molecules with sulfhydryls called?


where are they?

They are in proteins. Two of them create a disulfide bridge. They stabilize protein's tertiary structure. It actually exists cisteines.

Are sulfhydryls polar or non polar?


What are hydroxyls called?


are hydroxyls polar or non polar


where are hydroxyls found?

Sugars and alcohols

Sugars always have which two functional groups?

carbonyl and hydroxyl

Carbonyl groups are


If the carbonyl group is in the middle of a hydrocarbon chain, it is called

a ketone

if the carbonyl group is at the end of a hydrocarbon chain, it is called an


What is a popular aldehyde?


Fully ringed form of glucose does not have a free carbonyl group

ketones and aldehydes may be

Structural isomers. They have differen tproperties because they have different structures.

What is an aldose?

Sugars that have the aldehyde groups.

What is a ketose?

Sugars that have ketone groups.

Is carbonyl polar?


Which group is the only non polar molecule?

Methyl group. It is the only hydrophobic group.

Which group is the only hydrophobic funtional group?

Methyl group.

what are methyls called?

Methylated compounds.

Where are methyl groups located?

They are non reactive and change shape They are everywhere that needs to be hydrophobic.

What group is ionized 2+?


Which group is a strong acidic?

Phosphate group

Which group can donate two protons?

Phosphate group

Where is the phosphate group located?


Point out the functional groups

This functional group is polar because the electronegative oxygen has a strong attraction for electrons. Water is attracted to this group, and therefore molecules that have this group (such as sugars) tend to dissolve in water. Alcohols are characterized by this functional group. What is this?

Hydroxyl groups "-OH"

This group is polar because oxygen has a strong attraction for electrons. If this group is at the end of a carbon skeleton, the molecule is called an aldehyde; otherwise it is called a ketone.

Carbonyl group "-CO"

The two electronegative oxygens of this group pull electrons away from the hydrogen atom. This weakens the bond between oxygen and hydrogen, and the hydrogen atom tends to dissociate from the molecule as a hydrogen (H+) ion. Because it donates hydrogen ions, this group is acidic, and molecules that contain these groups are known as carboxylic acids.

carboxyl group "-COOH"

The slightly electronegative nitrogen atom in this group tends to pick up hydrogen ions from the surrounding solution, and thus this functional group acts as a base. Because of the added hydrogen ion, this group usually has a +1 charge in the cell. This group is characteristic of organic molecules called amines.

amino group "-NH2"

Molecules termed thiols are characterized by this group, which resembles a hydroxyl group. These groups interact to help stabilize the structure of many proteins.

sulfhydryl "-SH"

The electronegative oxygens of this functional group draw electrons, and as a result the group acts as an acid, losing hydrogen ions to the surrounding solution. This dissociation leaves the group with a negative charge. This group is important in ATP and the transfer of energy between organic molecules.

phosphate group "-OPO3^2-"

Which group is most likely for an organic molecule behaving as a base?

amino group

The first organic molecule to be synthesized from in organic susbstances is

Acetic acid.

A straight chain carbon compound constructed from ___ must contain at least one arbon carbon double bond.

six hydrogen, three carbon. (draw it out)

what are properties of hydrocarbons?

-good source of stored energy

Glucose and hexanoic acid each contains six cabon atoms but they have completely different properties. Glucose is a nutrient found in food; hexanoic gas is poinsonous. Their differences must be due to

Different functional groups

Although the structures of the functional groups that are most important to life vary, they all share one thing in common. They:

are all hydrophilic and increase the organic compounds water solubility. The only exception to this is the methyl group.

Which group's OH tends to dissociate?


Is an -SH alone a thiol?

no. It needs an R group attached

What is ATP's importance in the cell?

ATP stores the potential to react with water, thereby removing a phosphate group and releasing energy for cellular processes.

The two compounds are related to each other by:
-organic compounds
-double-bonded compounds
-All of the listed responses are correct.

all of the above

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