College Biology Test 2, Fall 2025

What do organic Molecules Consist of?

Organic molecules are molecules that contain Carbon and hydrogen atoms 

They often also contain oxygen, phosphorus, sulfur and nitrogen atoms.

What is the covalent bonding capacity of carbon?

Carbon has a covalent bonding capacity of four, meaning it can form up to four covalent bonds with other atoms to achieve a stable octet of eight valence electrons.

If organic molecules are so stable, what part of them is able to react?

their reactive parts are called functional groups

What are the 4 common types of organic Molecules in living organisms?

carbohydrates, lipids, proteins, and nucleic acids

What is the purpose of the functional groups of organic Molecules?

Functional groups are the key to an organic molecule's chemical properties, defining its reactivity and behavior by providing distinct sites for chemical reactions, enabling the classification of compounds, and allowing for the synthesis of more complex molecules.

structure and function of carbohydrates

Carbohydrates are biomolecules composed of carbon, hydrogen, and oxygen

sugars that provide most living creatures with energy

Classes of carbohydrates-structure

Monosaccharide, Disaccharide, and polysaccharide

What is Carbohydrates proper sub-unit?

Monosaccharide

Monosaccharide

simple sugars 

The carbon backbones consist of 3-7 carbons 

used as an energy source in the cell

ex) glucose-6 carbon sugar

Disaccharide

Sugar made of 2 monosaccharide units

Often sugars found in natural sources are disaccharides

ex) sucrose-table sugar (glucose+fructose) Lactose-milk sugar (Glucose+galactose) 

Polysaccharide

Sugars made of many monosaccharide (complex carbs)

Structure and function of cellulose

Cellulose is a polysaccharide made of glucose units that provide structural support to plant cell walls.

Structure and function of Chitin 

Structural complex carbs (polysaccharide)

Exoskeleton of invertebrate 

ex)insects 

Structure and function of starch

Starch is a branched polysaccharide made of glucose units

the primary energy storage in plants

Structure and function of glycogen

Glucose storage in animal cells

made in the liber, persist in bloodstream for 18-36 hours

Lipids structure and function

function as long-term energy storage, cell membrane components, and signaling molecules.

Their basic structure involves nonpolar fatty acid chains

do lipids have a proper subunit?

no, the closest thing is triglyceride

what are the 4 common groups of Lipids?

1. Phospholipid

2. Steroids

3. Waxes

4. Fat

Phospholipid function

Found in the cell’s outer plasma membrane

the nature of fat Vs. water causes the cell to be separated from the outside of the cell.

Steroids function 

Ringed lipids 

Act as hormonal messenger (testosterone or estrogen) molecules in animals 

found in the cell membrane 

Waxes function

Sticky lipids that protect living things. They conserve water loss

Plants: cover the surface of leaves to prevent water loss (cuticle)

In general all lipids contain long hydrocarbon chains with many bonds

Fat function

Very common lipid

Role in animals: Energy storage and foring the shape of the body, insulation for warmth, and cushioning within our bodies.

Plant oils: stored for long term energy storage in seeds/fruit

Most common plant energy storage is starches

What is the difference between an unsaturated and saturated fat? 

Saturated Fat: refers to the C-H backbone. If the carbon backbones has a full amount of hydrogen on it, then it is saturated. Spaces within the backbone and unsaturated 

Contain any single bonds and are solid at room temp 

EX) butter, hydrogenated vegetable oil

Unsaturated Fat: Contain double bonds and are oils. Liquid at room temp

EX) olive oil, vegetable oils, other oils 

What is fatty acid?

A fatty acid is a long chain of carbon atoms with a carboxylic acid group at one end, serving as a fundamental building block of fats, oils, and other lipids.

What is glycerol?

Glycerol is naturally found in fats and oils, such as triglycerides.

What is the advantage and disadvantage of animal fat?

The main advantage of animal fat is its rich nutritional content and beneficial effect on flavor and cooking stability

the main disadvantage is the high amount of saturated fat, which has been associated with an increased risk of heart disease when consumed excessively. 

Protein structure and function

polypeptide

Function: structure our bodies

Protein subunit 

Amino-acid 

what is the difference between the terms amino acid and polypeptide?

An amino acid is the fundamental monomer, or single building block

while a polypeptide is a polymer, or long chain, of many amino acids linked together by peptide bonds.

Amino acids are individual units that link in a specific sequence to form polypeptides, which are the primary structures of proteins. 

Is there a difference between the terms polypeptide and protein?

Yes, there is a difference: a polypeptide is a long chain of amino acids linked by peptide bonds

while a protein is a functional molecule made of one or more polypeptides that have folded into a specific three-dimensional structure.

All proteins are technically polypeptides, but not all polypeptides are proteins, as some remain unfolded or incomplete.  

Shape of proteins

Primary structure

Secondary structure

Tertiary structure

Quaternary structure

Primary structure

Simple sequence of amino acids: Alanine, cysteine, phenylalanine, and tryptophan

Secondary structure 

3-D shape a protein assumes in nature. refers to the local folding of a polypeptide chain into stable, repeating shapes, most commonly the alpha helix and the beta sheet

Tertiary structure

The polypeptide sequence (Linear amino acid strand) interact more fully via hydrogen, covalent, and ionic bonding to assume a 3-D shape, like a globular protein 

Quaternary structure

4th degree

some proteins are made of more than 1 polypeptide strand, this happens when 2 different polypeptide strands with their own 3-D shape interact with each other to form the structural protein that is functionally active.

What does alpha helix mean?

An alpha helix is a common secondary structure in proteins where the polypeptide chain forms a right-handed spiral or coiled shape

What does beta pleated sheet mean?

A beta-pleated sheet is a type of protein secondary structure where two or more polypeptide strands (beta strands) run side-by-side, connected by hydrogen bonds between their backbones, creating a zig-zag, pleated, and stable sheet-like arrangement.

What does peptide bond mean?

A peptide bond is the covalent bond that connects two amino acids to form a longer chain, called a polypeptide or protein.

What is the function of proteins?

acting as enzymes to catalyze reactions, transporting molecules like oxygen across, and enabling immune responses with antibodies. They also act as hormones to regulate processes, maintain pH and fluid balance, and can be a source of energy if other nutrient intake is insufficient

structure and function of Nucleic acids

Function: store and express genetic information.

Structure: consists of a phosphate-sugar backbone with nitrogenous bases(adenine, thymine, guanine, cytosine) arranged in specific sequences

does the nucleic acid group have a proper subunit?

Yes, the subunits of nucleic acids are called nucleotides

Purpose of DNA and RNA

DNA: long-term genetic instructions for operating an organism

RNA: a temporary messenger and copier that processes these instructions to direct the synthesis of proteins

How are DNA and RNA different?

Different:

sugar (deoxyribose for DNA, ribose for RNA)

structure (double helix for DNA, single-stranded for RNA)

nitrogenous bases (thymine in DNA, uracil in RNA).

Parts of the cell theory

1. All living creatures are made of cells

2. Every cell is derived from a parent cell (where did the first cell come from)

3. Each cell is able to carry out all necessary function to support life

Structure and function of the nucleus

-dark staining center of the cell

contains genetic information of the cell (Chromosomes are located here)

Produce ribosomes

Name and describe 3 features that allow you to distinguish a prokaryotic cell from a eukaryotic cell?

Nucleus

Eukaryotic Cells:

Contain a membrane-bound nucleus that houses DNA

Prokaryotic Cells:

Lack a membrane-bound nucleus; their DNA is located in the nucleoid

Membrane-Bound Organelles

Eukaryotic Cells:

Possess numerous membrane-bound organelles, such as mitochondria, endoplasmic reticulum, and Golgi apparatus

Prokaryotic Cells:

Do not have membrane-bound organelles, making their internal structure simpler

DNA Structure

• Eukaryotic Cells: Have their DNA organized into long, linear chromosomes. 

• Prokaryotic Cells: have a single, circular chromosome located in the cytoplasm within the nucleoid region. 

characteristics of bacteria (prokaryote cell)

1. size 1/10 to 1/100 of the size of a eukaryotic cell. ranges from 1-10 micrometers in length

2. no organelles Have ribosomes

3. circular chromosome. no linear chromosome. DNA is found in a circular structure directly attached to the cell membrane.

4. cells grow and divide much faster than eukaryotic cells. mainly Asexual.

5. has a cell wall this helps maintain shape of the cell

Ribosomes

protein building

Crucial for all cells to survive.

Endoplasmic Reticulum (ER)

Forms an extensive network of membranous routes throughout the cell that connects the nucleus with different regions of the cell

Location of most protein synthesis

Transport of materials from one part of the cell to another region

making phospholipids, steroids, and fats

2 types: smooth and rough

Smooth ER

makes lipids

looks smooth

Rough ER

Studded with ribosomes, making proteins

when referring to the cell membrane, what does the term selective permeability mean?

Provide examples

Selective permeability in a cell membrane means its ability to allow some substances to pass through while preventing others, thereby controlling the flow of materials in and out of the cell

examples

oxygen, carbon dioxide, water, small lipid soluble molecules like cholesterol can move across the membrane freely

Proteins, carbs, lipids, charged ions and charged molecules are restricted across the membrane

functional groups: what are they and why is their inclusion within organic molecules important?

Functional groups are specific, recurring arrangements of atoms in organic molecules that determine the molecule's chemical properties and reactivity.

Their inclusion is crucial because they provide a relatively small set of characteristic behaviors that explain the vast diversity of organic compounds

What is the purpose and function of nucleic acids?

Nucleic acids, DNA and RNA, store, transmit, and express genetic information to control cell functions and inherited traits

how does the function of nucleic acids compare to the function of proteins?

nucleic acids are the information carriers

proteins carry out cellular processes based on that information

Reducing sugar-benedict's: between what does this test distinguish and what color change is observed?

The Benedict's test distinguishes between reducing sugars and non-reducing sugars

the original blue to green, yellow, orange, and to a red/brown precipitate

indicating an increasing concentration of reducing sugar present in the sample when heated.  

Protein-biuret: What does this test indicate and what color does it change?

used to detect the presence of proteins in a solution. 

starts as blue and changes to purple in the presence of proteins.

characteristics of the Eukaryotic cell

Domain: Eukarya

Kingdoms: Plant, animal, protist, and fungal

Cells contain nucleus and Organelles

Many eukaryotic cells form tissues

Primary found in multi-celled organisms. Except protists (contains single celled eukaryotes)

Mitochondria structure and function

Function

site of cellular respiration (Glucose to ATP)

Able to reproduce independently from the cell and does contain its own DNA and some of its own proteins

Naming molecules

Number of carbons+the type of bonds in the backbone

Number of carbons

Meth 1 eth 2 prop 3 but 4 pent 5 hex 6

hept 7 oct 8 non 9 Dec 10

Suffix

ane- all single bonds

ene- at least one double bonds

yne- at least one triple bond

Golgi

This organelle is like a factory

Processes, sorts, modifies, and packages proteins and lipids

often proteins and lipids will be modified by the addition of a sugar group (this happens in the golgi)

Vesicles move between the compartments of the golgi carrying proteins or lipids from one region to the next.

plant cells make cell wall cellulose here

who created the cell theory?

Schleiden: botanist; all plants are made of cells

Schwann: zoologist; all animals are made of cells

Virchow: Physician; each cell is a citizen of the body