Praxis (5236) - Biology > 2A1 Structures and Properties of Major Biomolecules > Flashcards

2A1 Structures and Properties of Major Biomolecules Flashcards

Describe the structure of essential macromolecules (nucleic acids, proteins, lipids, carbohydrates) and water molecules. Differentiate between organic and inorganic molecules. (101 cards)

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1
Q

What is an atom?

A

The smallest unit of matter that still holds the properties of an element.

Elements are types of matter that have specific chemical and physical properties and cannot be broken down into other substances.

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2
Q

How are atoms created?

A

Atoms originate via nucleosynthesis—light elements (H, He, trace Li) formed in the Big Bang.

Heavier elements were forged in stars and supernovae/neutron-star mergers.
Nuclear fission splits heavy nuclei and is not a primary atom-creation process.

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3
Q

How many elements are there?

A

118

Most elements occur naturally, but some are synthesized in a laboratory.

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4
Q

What are the three main subatomic particles in an atom?

A
  • Protons
  • Electrons
  • Neutrons

Subatomic particles are the particles that when put together, create an atom. These are measured using Atomic Mass Units (amu).

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5
Q

What are electrons?

A

Negatively charged subatomic particles.

Found in the electron cloud of an atom.

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6
Q

What is the electron cloud?

A

The space surrounding the nucleus where electrons can be found.

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7
Q

What are neutrons?

A

Subatomic particles that have no charge.

They are found in the nucleus of an atom and have a mass of 1 amu.

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8
Q

What is a proton?

A

Positively charged subatomic particles.

Protons are found in the nucleus of an atom and have a mass of 1 amu.

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9
Q

What is the difference between intramolecular and intermolecular forces?

A
  • Intramolecular forces are bonds holding a molecule together.
  • Intermolecular forces are forces of attraction between molecules.

Examples of intramolecular forces include covalent bonds, while hydrogen bonds are examples of intermolecular forces.

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10
Q

What is the atomic number?

A

The number of protons in an atom, defining it as a specific element.

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11
Q

What are atoms with a charge called?

A
  • Cations
  • Anions
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12
Q

What is the term for a charged atom?

A

Ion

An ion is an atom or molecule that has a net electric charge due to the loss or gain of electrons.

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13
Q

What is the term for a positively charged ion?

A

Cation

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14
Q

What is the term for a negatively charged ion?

A

Anion

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15
Q

What type of bond is formed when positively and negatively charged ions are brought together by their electrostatic charge?

A

Ionic bond

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16
Q

What are isotopes?

A

Atoms that have a different number of neutrons than the average number.

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17
Q

What is the purpose of the periodic table?

A

To organize elements based on their properties.

An element’s physical and chemical properties correspond directly to their atomic number (the number of protons in an atom).

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18
Q

What is the atomic mass unit a measure of?

(AMU)

A

Mass

amu measures the mass of subatomic particles.

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19
Q

Define:

element

A

A pure substance consisting of only one type of atom.

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20
Q

What are molecules made up of?

A

Atoms chemically bond together to form molecules.

The most basic units of compounds.

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21
Q

What is the difference between atoms and molecules?

A
  • Atoms are the most basic units of elements.
  • Molecules are the most basic units of compounds.

Atoms build molecules.

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22
Q

Define:

electronegativity

A

How strongly the nucleus of one atom pulls on the electrons of another atom to form a chemical bond.

Determines the type of bond formed between 2 atoms.

Atoms of different elements have different numbers of electron orbits or shells leading to different electronegativities.

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23
Q

Define:

diatomic element

A

Elements whose atoms bond to each other and bond together by sharing electrons equally.

Examples: Hydrogen, Oxygen, Nitrogen

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24
Q

What is the outermost shell of an atom referred to as?

A

Valence shell

Electrons found here are known as valence electrons.

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25
What determines the **stability** of an atom's outer electron shell?
The **number of electrons** in the outer shell. ## Footnote The outer electron shell typically needs 8 electrons to be stable. This need to have 8 electrons in the outer shell is known as the octet rule.
26
How do atoms with **incomplete valence levels** deal with instability?
* Share electrons * Take or donate electrons
27
What are **chemical bonds** and how do they occur in molecules?
* They are a force that **creates** molecules * Occur through the **sharing or exchanging of electrons**
28
When can an atom form **multiple bonds** with the same partner?
If that atom has enough valence electrons. ## Footnote Double Bond: 2 sets of electrons are shared between 2 atoms. Triple Bond: 3 sets of electrons are shared between 2 atoms.
29
What are electrons in the outermost shell **not involved in bond formation** called?
Lone pairs
30
What are the two main types of bonding between atoms in molecules?
* **Covalent bonds** where atoms **share** an electron pair. * **Ionic bonds** when atoms with **opposite charges are attracted** to each other.
31
What are **ionic bonds**?
Electrostatic interactions between two **oppositely charged** ions. ## Footnote Generally stable bonds. Occurs when the difference in electronegativity between atoms is greater than 2.0. Example: Sodium Chloride (NaCl)
32
What type of bonds occur when atoms **share an electron pair**?
Covalent bonds ## Footnote Atoms share electrons to try to achieve the octet rule. Generally very strong and very stable. Examples: Oxygen (O2), Water (H2O), Methane (CH4)
33
How are the bonds between atoms in a **covalent** bond often represented?
With a line. ## Footnote Instead of a dot representation, the bond between atoms in a covalent bond is often abbreviated with a line.
34
What are the unique properties of **covalent bond** molecules?
Covalent molecular compounds generally have low melting/boiling points, are poor conductors, and often dissolve in organic solvents if nonpolar, or in water if polar. Density varies depending on the specific compound.
35
What are **double and triple** covalent bonds collectively known as?
Multiple bonds
36
What is a **nonpolar** covalent bond?
A bond that occurs between atoms in which electrons are shared **equally**. ## Footnote A bond that occurs between atoms with an electronegativity difference between 0.2 - 0.5. Compounds formed from these types of bonds have a neutral charge.
37
What is a **polar** covalent bond?
A bond that occurs between atoms where electrons are shared **unequally**. ## Footnote Different sides of the molecule will exhibit positive and negative charges Occurs with an electronegativity difference between 0.6 - 1.6. The more electronegative atom will be slightly negative, and the less electronegative atom will be slightly positive.
38
What is the term used to describe the **difference in charge** within a polar covalent bond?
Polarity
39
# Define: dipole
An electrically asymmetrical molecule that is oppositely charged at two points. ## Footnote Formed due to the presence of a polar bond and the shape or geometry of the molecule.
40
What does the lowercase Greek letter **Delta** followed by a plus or minus sign represent in terms of charges?
The **slightly positive and slightly negative** charges on atoms in a polar covalent bond.
41
How do chemists know what a molecule **looks like**?
Using **noncontact atomic force microscopy** and **computational models** to predict their shape.
42
How does **noncontact atomic force microscopy** work?
It uses a carbon-oxygen molecular tip to hover over molecules and generate actual images of individual molecules.
43
What are the **models** used for studying the molecular structure of molecules?
* Ball-and-stick model * Space-filling model * Line-angle model * Blob or ribbon model
44
What is the **ball-and-stick model** used for in chemistry?
To represent **atoms** and the **bonds** between them in molecules. ## Footnote Used to study the exact shape of the molecule and how the atoms connect to each other. Best for modeling small to medium molecules.
45
What does the **space-filling model** represent in molecules?
The **amount of space** occupied by an atom's electron cloud. ## Footnote Looks like blobs and are used to understand how molecules interact. Best for modeling small to medium molecules.
46
When is a **line-angle model** used in chemistry?
To show the **structure** of a molecule, minus the details. ## Footnote Best when modeling small and medium molecules in two dimensions.
47
What kind of models are used for **macromolecules** and very large molecules like proteins or DNA?
Blob or ribbon models ## Footnote These models are especially useful for visualizing secondary and tertiary structures in proteins or DNA.
48
Why is learning about molecular structures important?
* To **predict** chemical reaction outcomes * **Create** useful substances like drugs * **Determine** the composition of unknown substances
49
What **elements** commonly make up biological atoms and molecules?
Organic molecules made with **carbon**, often bonded to other common elements like oxygen, nitrogen, and hydrogen.
50
Is the molecule pictured organic or inorganic?
Organic ## Footnote The molecule contains carbon.
51
Is the molecule pictured organic or inorganic?
Inorganic ## Footnote There is no carbon present in the molecule.
52
How many **valence electrons** does carbon have and how many **covalent bonds** can it form?
* Four valence electrons * Four covalent bonds
53
# Define: inorganic molecules
Compounds that lack carbon-hydrogen (C-H) bonds. They may contain carbon or hydrogen individually but not both in a C-H bond. ## Footnote Examples include water (H₂O), salts, and carbon dioxide (CO₂).
54
What is predictable about the structure of a molecule?
The **bond length** and **bond angle**.
55
# Define: hydrogen bond
An intermolecular force between a hydrogen atom in one polar molecule and a small and very electronegative atom of another polar molecule.
56
How are hydrogen bonds **formed**?
Between polar molecules with one molecule serving as a **hydrogen bond donor** and the other as a **hydrogen bond acceptor**. ## Footnote Molecule with a relatively large positive charge at one end (donor). Molecule with an atom containing a lone pair of electrons (acceptor).
57
What is the strength of a **hydrogen bond** compared to **covalent bonds**?
A hydrogen bond is usually only **2-5%** as strong as a typical covalent bond. ## Footnote Despite being weak compared to covalent bonds, hydrogen bonds play important roles in various applications such as the formation of liquids like water and surface tension.
58
Give an example of a daily application of hydrogen bonds.
* Hydrogen bonds form liquids like water * Provide surface tension for water striders to move across * Important for the formation of paper products ## Footnote Hydrogen bonds are crucial in various everyday applications, despite being weaker than covalent bonds.
59
What are **macromolecules**?
**Large molecules** that contain key nutrients necessary for survival that are obtained from other organisms. ## Footnote Macromolecules are composed of carbon, hydrogen or oxygen in different arrangements.
60
Name the **four classes** of macromolecules.
* Carbohydrates * Proteins * Lipids * Nucleic acids
61
What are **monomers**?
**Smaller molecules** or subunits that compose macromolecules. ## Footnote 'Mono-' means 1. Monomers are individual pieces that are put together to create polymers.
62
# Define: polymerization
The process of chemically **linking monomers together** to form polymers. ## Footnote 'Poly-' means many.
63
What are **polymers**?
Chains of monomers
64
# Define: catabolism
The **chemical breakdown** of molecules, such as macromolecules, through hydrolysis.
65
# Define: anabolism
The process of **building molecules**, particularly macromolecules, through dehydration synthesis.
66
What are **carbohydrates** primarily used for?
For quick energy ## Footnote Examples: Sugar, starches
67
What are the **monomers** of carbohydrates?
Monosaccharides ## Footnote Monosaccharides are simple sugars.
68
What are **polysaccharides**?
Macromolecules made up of many monosaccharides.
69
What are some **healthy carbohydrate** choices you can introduce to your students?
* Brown rice * Carrots * Broccoli * Whole grain bread
70
What are **lipids** used for in the body?
**Store** energy for future use and **protect** internal organs. ## Footnote Examples: fats, waxes, steroids and phospholipids used in membranes. Lipids are utilized when carbohydrates are low or the body's energy demands exceed those provided by carbohydrates.
71
What is a common choice for healthy lipids you can introduce to your students?
* Salmon * Nuts * Avocados
72
Why are lipids **not** considered polymers?
The monomer **is not repeated**.
73
What is the combination that **creates** a lipid?
A glycerol backbone and hydrocarbon tails. ## Footnote This combination creates a nonpolar, hydrophobic structure, meaning that lipids will not dissolve in water.
74
What can the body **reuse** lipid monomer components for?
Energy and cell membranes
75
What are **phospholipids** major constituents of?
Cellular membrane ## Footnote Phospholipids are created by replacing one hydrocarbon tail with a phosphate group. A small modification to the shape of a lipid, leads to additional functions as cell membrane components.
76
What are **proteins** used for in the body?
* Movement * Cellular protection * Structural components * Signaling ## Footnote Can also be used as an energy source in the body when the body has depleted its stores of carbohydrates and lipids.
77
What are proteins made of?
Amino acids
78
What determines the **function** of a protein?
Its final three-dimensional shape. ## Footnote The way the protein is folded determines the function.
79
What do proteins provide **instructions** for in all organisms?
Growth, repair of structures within the body.
80
What are some **examples** of foods rich in proteins?
* Meat * Seafood * Eggs * Dairy
81
What are **nucleic acids** responsible for?
Contain genetic information and direct the production of proteins. ## Footnote Commonly known as DNA or RNA.
82
What is the **difference** between DNA and RNA in terms of sugar content?
* DNA has **deoxyribose** sugar * RNA has **ribose** sugar ## Footnote DNA is double-stranded. RNA is single-stranded.
83
What is the function of **RNA** in cells?
To carry the genetic information from DNA to build proteins.
84
What is the function of **DNA** in cells?
To carry the genetic information that is responsible for inheritable traits.
85
What are the **monomers** of nucleic acids?
Nucleotides ## Footnote The nucleotides found in nucleic acids are: * Adenine * Thymine * Cytosine * Guanine * Uracil (in RNA)
86
What are the three **subcomponents** of a **nucleotide**?
* Sugar * Phosphate * Base
87
What is the **chemical formula** of a **water molecule**?
H₂O
88
How many **hydrogen** atoms are in a water molecule?
Two
89
What causes the **bent structure** of a water molecule?
The **two lone pairs of electrons** on the oxygen atom. ## Footnote The unpaired electrons cause water to be polar, and have slightly different charges on each side of the molecule. The molecule is bent at about 105°.
90
What properties of water are attributed to **hydrogen bonds**?
* Cohesion and adhesion * Solubility * Low density when frozen * Surface tension
91
What are the **cohesive and adhesive** properties of water?
* **Cohesion**: attraction between water molecules due to hydrogen bonds. * **Adhesion**: attraction of water molecules to molecules of other substances. ## Footnote Cohesion and adhesion are essential for transporting water and nutrients in plants.
92
What property of water allows ice to **float**?
Ice is less dense than liquid water. ## Footnote When water freezes, crystalline structures form within the ice leaving space between the molecules.
93
Why is water considered one of the **essential requirements** for Earth to be habitable?
* Helps regulate Earth's temperature * Allows for the hydration and survival of plants and animals
94
Why can bodies of water help **cool** the surrounding area?
Water has a **high specific heat** and requires extra energy to heat, creating a more temperate climate.
95
What is the **specific heat capacity** of water?
1 cal/g°C | (4186 J/kg°C) ## Footnote Water's high specific heat capacity makes it challenging to heat or cool. 1 calorie of energy must be added to 1 gram of water in order to increase the temperature of the water 1°C.
96
What is the **heat of vaporization** of water?
540 cal/g | (41 kJ/mol) ## Footnote The high heat of vaporization enables water to have a significant cooling effect on the environment.
97
What is **surface tension** in water?
Water's ability to **resist being stretched or broken**. ## Footnote Surface tension in water enables small objects to float and insects to walk on its surface.
98
What property of water allows it to move up a narrow plastic tube against gravity?
Capillary action ## Footnote Water's cohesive and adhesive properties contribute to capillary action. * Cohesion: Water molecules want to bond to other water molecules. * Adhesion: Water molecules want to bond to other substances.
99
What property of water is described as water being attracted to other water molecules?
Cohesion
100
What property of water is used to describe water being attracted to other substances?
Adhesion
101
What is **density** a measure of?
Mass of an object per unit volume. ## Footnote Density indicates how much matter occupies a given volume.
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