Chapter 3 (Exam One) Flashcards
What are trans-fats? (5)
(a type of fat, or lipid)
- Are made by adding hydrogen to unsaturated fats, a process called hydrogenation.
- Are used to increase food shelf life and flavor/texture.
- May cause worse health effects than saturated fat in an individual’s diet.
- FDA now requires trans-fat labeling on foods and in foods in restaurants.
What are organic molecules? What’s another name for them?
molecules that contain both carbon and hydrogen atoms; biomolecules
What four classes of organic molecules exist in living organisms?
Carbohydrates
Lipids
Proteins
Nucleic Acids
Describe the carbon atom. How many covalent bonds can it form?
The carbon atom is small with only 6 electrons,
two in the first shell and four in the outer shell.
Carbon can form four covalent bonds.
Describe the carbon atom’s covalent bonds
- Bonds with carbon, nitrogen, hydrogen, oxygen,
phosphorus and sulfur. - The C-C bond is very stable.
- Long carbon chains, hydrocarbons, can be formed.
- Besides single bonds, double bonds, triple bonds and
ring structures (cylic) are also possible. (carbon, nitrogen) - Branches at any carbon make carbon chains more
complex.
The carbon chain of an organic molecule is called
its skeleton or backbone
What are functional groups? What do they do? Examples (6)
clusters of specific atoms bonded to the carbon skeleton with characteristic structures and functions.
What are isomers? Examples
organic molecules that have identical molecular formulas but different arrangements of atoms. Isomers have different chemical properties and react differently with other molecules.
glyceraldehyde and dihydroxyacetone
What do biomolecules usually consist of?
repeating units
What are the repeating units in a biomolecule called?
Each repeating unit is called a monomer.
What is a polymer? Name an example
A molecule composed of monomers is called a polymer (many parts).
Example: amino acids (monomer) are
joined together to form a protein
(polymer)
What biomolecule is not a polymer and why?
Lipids are not polymers because they contain two different types of subunits.
What are the subunits (monomers) and polymer of carbohydrates?
monomers: Monosaccharide
polymer: Polysaccharide
What are the subunits (monomers) and polymer of lipids?
monomers: Glycerol and fatty acids
polymer: fat
What are the subunits (monomers) and polymer of proteins?
monomers: amino acids
polymer: polypeptide
What is organic chemistry?
It deals with carbon and hydrogen
inorganic organic
Inorganic: is what you find it in
Organic: groups
What are the subunits (monomers) and polymer of nucleic acids?
monomers: nucleotide
polymer: DNA, RNA
What is a dehydration reaction? What does it do?
a chemical reaction in which subunits are joined together by the formation of a covalent bond and water is produced during the reaction.
Used to connect monomers together to make
polymers
a hydroxyl (— OH) group is removed from one monomer and a hydrogen (— H) is removed from the other.
What is hydrolysis? What does it do?
'"water breaking" A hydrolysis reaction is a chemical reaction in which a water molecule is added to break a covalent bond. Used to break down polymers into monomers A hydroxyl (— OH) group from water attaches to one monomer and hydrogen (— H) attaches to the other.
These special molecules are required for cells to carry out dehydration synthesis and hydrolysis reactions.
enzymes
What are enzymes? What are their characteristics?
a molecule that speeds up a chemical reaction.
Enzymes are not consumed in the reaction.
Enzymes are not changed by the reaction.
Enzymes are catalysts.
What are the functions of carbohydrates?
Energy source
Provide building material (structural role)
What do carbohydrates contain?
carbon, hydrogen and oxygen atoms in a 1:2:1 ratio
What are the varieties of carbohydrates? (3)
monosaccharides, disaccharides, and polysaccharides
What is a monosaccharide? Describe it
a single sugar molecule.
It is also called a simple sugar.
It has a backbone of 3 to 7 carbon atoms.
What are some examples of monosaccharides? (2)
- Glucose (blood sugar), fructose (fruit sugar), and galactose: Hexoses – six carbon atoms
- Ribose and deoxyribose (sugars contained in
nucleotides, the monomer of DNA): Pentoses – five carbon atoms
What are disaccharides?
A disaccharide contains two monosaccharides joined together by dehydration synthesis.
Name examples of disaccharides and what they are contained of. (4)
- Lactose (milk sugar) is composed of galactose and
glucose. - Sucrose (table sugar) is composed of glucose and
fructose. - Maltose is composed of two glucose molecules.
- Lactose-intolerant individuals lack the enzyme
lactose which breaks down lactose into galactose
and glucose.
What is a polysaccharide?
A polysaccharide is a polymer of monosaccharides.
Name examples of polysaccharides and what they do. (5)
- Starch provides energy storage in plants.
- Glycogen provides energy storage in animals.
- Cellulose is found in the cell walls of plants.
- Most abundant organic molecule on earth.
- Animals are unable to digest cellulose. - Chitin is found in the cell walls of fungi and exoskeleton of some animals.
- Peptidoglycan is found in the cell walls of bacteria.
- its monomers contain an amino acid chain
Describe lipids and name their functions (5)
Varied in structure Large, nonpolar molecules that are insoluble in water Functions: 1. Long-term energy storage 2. Structural components 3. Heat retention 4. Cell communication and regulation 5. Protection
What are the varieties of lipids?
fats, oils, phospholipids, steroids, waxes
What are the functions and human uses of fats?
Functions: Long-term energy storage and insulation in animals
Human uses: Butter, lard
What are the functions and human uses of oils?
Functions: Long-term energy storage in plants and their seeds
Human uses: Cooking oils
What are the functions and human uses of phospholipids?
Functions: Component of plasma membrane
Human uses: Food additive
What are the functions and human uses of steroids?
Functions: Component of plasma membrane (cholesterol), Sex hormones
Human uses: medicines
What are the functions and human uses of waxes?
Functions: Protection, prevention of water loss (cuticle of plant surfaces), beeswax earwax
Human uses: candles, polishes
What are triglycerides? Describe them (3)
- Also called fats and oils
- Functions: long-term energy storage and insulation
- Consist of one glycerol molecule linked to three fatty acids by dehydration synthesis
Fatty acids may be either
unsaturated or saturated
Describe unsaturated fatty acids (3) and give an example
- one or more double bonds between carbons
- Tend to be liquid at room temperature
- Can have chemical groups on the same (cis) or opposite (trans) side of the double bond
Example: plant oils
What is trans?
a triglyceride with at least one bond in a trans configuration
Describe the structure of phospholipids (4)
- membrane components
- The structure is similar to triglycerides.
- It consists of one glycerol molecule linked to two fatty acids and a modified phosphate group.
- The fatty acids (tails) are nonpolar and hydrophobic. The modified phosphate group (head) is polar and hydrophilic.
What is the function of phospholipids?
forms plasma membrane of cells
What do phospholipids do in water? (5)
- In water, phospholipids aggregate to form a lipid
bilayer (double layer). - Polar phosphate heads are oriented towards the water.
- Nonpolar fatty acid tails are oriented away from water.
- Nonpolar fatty acid tails form a hydrophobic core.
- Kinks in the tails keep the plasma membrane fluid across a range of temperatures.
Describe the structure of steroids
They are composed of four fused carbon rings.
Various functional groups attached to the carbon skeleton
What are the functions of steroids? (2)
component of animal cell membrane, regulation
name and describe examples of steroids
Examples: cholesterol, testosterone, estrogen
Testosterone and estrogen are sex hormones differing only in the functional groups attached to the same carbon
skeleton.
Cholesterol is the precursor molecule for several other steroids.
Cholesterol can also contribute to circulatory disorders.
Describe waxes and name examples (6)
- Long-chain fatty acids connected to carbon chains containing alcohol functional groups
- Solid at room temperature
- Waterproof
- Resistant to degradation
- Function: protection
- Examples: earwax (contains cerumin), plant cuticle, beeswax
Describe the structure of proteins (this is beatin long I’m sorry) (7)
- Proteins are polymers of amino acids linked together by ?.
- A peptide bond is a ? between amino acids.
- As much as ? of the dry weight of most cells consists of proteins.
- Several hundred thousand have been identified.
- Two or more amino acids joined together are called ?
- Long chains of amino acids joined together are called ?
- A protein is a polypeptide that has ?
- Proteins are polymers of amino acids linked together by peptide bonds.
- A peptide bond is a covalent bond between amino acids.
- As much as 50% of the dry weight of most cells consists of proteins.
- Several hundred thousand have been identified.
- Two or more amino acids joined together are called peptides.
- Long chains of amino acids joined together are
called polypeptides. - A protein is a polypeptide that has folded into a particular shape, which is essential for its proper functioning.
Describe the functions of proteins (ANOTHER beatin long one I apologize) (6)
- Metabolism: Most enzymes are proteins that act as catalysts to accelerate chemical reactions within cells.
- Support: Some proteins have a structural function, for example, keratin and collagen.
- Transport: Membrane channel and carrier proteins regulate what substances enter and exit cells. Hemoglobin protein transports oxygen to tissues and cells.
- Defense: Antibodies are proteins of our immune system that bind to antigens and prevent them from destroying cells.
- Regulation: Hormones are regulatory proteins that influence the metabolism of cells.
- Motion: Microtubules move cell components to different locations. Actin and myosin contractile proteins allow muscles to contract.
There are how many common amino acids? How do they differ?
There are 20 different common amino acids.
Amino acids differ by their R or variable, groups,
which range in complexity. Amino acids contain an acidic group (— COOH) and an amino group (—NH 2 ).
The R group of the amino acid cystine ends with a sulfhydryl (— SH) that serves to connect one chain of
amino acids to another by a disulfide bond (— S— S—).
A protein can’t function properly unless what?
Proteins cannot function properly unless they fold into their proper shape.
What is a denatured protein? How does a protein become denatured?
When a protein loses it proper shape, it said to be denatured. Exposure of proteins to certain chemicals, a
change in pH, or high temperature can disrupt protein structure.
Proteins can have up to how many levels of structure? What are they?
Proteins can have up to four levels of structure: Primary Secondary Tertiary Quaternary
Describe the primary level of protein structure (4)
- Primary level is the linear sequence of amino acids.
- Hundreds of thousands of different polypeptides can be
built from just 20 amino acids. - Changing the sequence of amino acids can produce different proteins.
- 20 amino acids can join to form a huge variety of
“words.”
Describe the secondary level of protein structure (3)
Secondary level is characterized by the presence of alpha helices and beta (pleated) sheets held in place with hydrogen bonds.
Describe the tertiary level of protein structure (3)
- Tertiary level is the overall three-dimensional shape of a
polypeptide. - It is stabilized by the presence of hydrophobic interactions, hydrogen, ionic, and covalent bonding.
- Enzymes are globular proteins and have specific conditions for optimal functionality.
Describe the quaternary level of protein structure. example
Quaternary level consists of more than one polypeptide.
Hemoglobin is a globular protein with a quaternary structure of four polypeptides; each polypeptide has a primary, secondary, and tertiary structure.
What are chaperone proteins? What happens if they are defected?
- Chaperone proteins help proteins fold into their normal shapes and may also correct misfolding of new proteins.
- Defects in chaperone proteins may play a role in several human diseases such as Alzheimer’s disease and cystic fibrosis.
What are prions (name an example)? What do they do?
Prions are misfolded proteins that have been
implicated in a group of fatal brain diseases
known as TSEs.
Mad cow disease is one example of a TSE.
Prions are believed to cause other proteins to misfold.
Nucleic acids are polymers of what?
nucleotides
Name and describe the two varieties of nucleic acids
- DNA (deoxyribonucleic acid): Genetic material that stores information for its own replication and for the sequence of amino acids in proteins
- RNA (ribonucleic acid): Perform a wide range of functions within cells which include protein synthesis and regulation of gene expression
Each nucleotide is composed of how many parts? Name them
three parts:
A phosphate group
A pentose sugar
A nitrogen-containing (nitrogenous) base
There are how many types of nucleotides found in nucleic
acids? name them
There are five types of nucleotides found in nucleic
acids:
DNA contains adenine, guanine, cytosine, and thymine.
RNA contains adenine, guanine, cytosine, and uracil.
Nucleotides are joined together by
a series of dehydration synthesis reactions to form a linear
molecule called a strand, which is a sequence of nucleotides.
The backbone of the nucleic acid strand is composed of?
alternating sugar-phosphate molecules.
How many strands do RNA and DNA have?
RNA is predominately a single-stranded molecule, whereas DNA is a double-stranded molecule. DNA is composed of two strands held together by hydrogen bonds between the nitrogen-containing bases. The two
strands twist around each other, forming to a double helix.
The nucleotides may be in any order within a strand but
between strands:
Adenine (purine) makes hydrogen bonds with thymine
pyrimidine). Cytosine (pyrimidine) makes hydrogen bonds with guanine (purine
What is complementary base pairing? How does it work?
The bonding between the nitrogen-containing bases in
DNA is referred to as complementary base pairing.
The number of A+G (purines) always equals the number of
T+C (pyrimidines).
DNA
- Sugar:
- Bases:
- Strands:
- Helix:
- Deoxyribose
- Adenine, guanine, thymine, cytosine
- Double stranded with base pairing
- Yes
RNA
- Sugar:
- Bases:
- Strands:
- Helix:
- Ribose
- Adenine, guanine, uracil, cytosine
- Single stranded
- No
What is ATP?
ATP (adenosine triphosphate) is a nucleotide composed of
adenine and ribose (adenosine), and three phosphates.
ATP is a high-energy molecule due to the presence of the
last two unstable phosphate bonds, which are easily broken.
In ATP, hydrolysis of the terminal phosphate bond yields:
The molecule ADP (adenosine diphosphate)
An inorganic phosphate, P
Energy to do cellular work
Describe how ATP is involved in energy to do cellular work. Name an example
The hydrolysis of the ATP molecule can be coupled with
chemically unfavorable reactions in the cell to allow the reactions to proceed.
Example, key steps in the synthesis of carbohydrates and
proteins, and muscle contraction and nerve impulse conduction.
What is ATP called?
the energy currency of the cell.
What are fibrous proteins? example
(e.g., keratin) are structural proteins with helices and/or pleated sheets that hydrogen bond to one another.
What are globular proteins?
proteins that ball up into rounded shapes.
What are coenzymes?
molecules which facilitate enzymatic reactions.
Dietary fats do what for humans?
provide energy, build and maintain cell membranes, and provide padding for internal organs.
What do saturated fats do for humans?
are from animals and solid at room temperature, stick together and have been associated with coronary heart disease (CHD).
What do unsaturated fats do for humans?
are from plants and liquid at room temperature, do not stick together and do not clog arteries
Describe the food revolution with saturated and unsaturated fats (4)
- Although unsaturated fat is thought to be healthier than saturated fat, plant oils can go bad and since they are liquid at room temperature, are difficult to use in solid food products.
- To solve this problem, food manufacturers hydrogenated unsaturated fatty acids.
- The hydrogenation process involves heating and exposing oil to hydrogen gas.
- A consequence of the hydrogenation process is the formation of trans-fats, which increase LDL (“bad”) cholesterol and lower HDL (“good”) cholesterol, and increases the risk of CHD.
Since there has been scientific evidence to support the health risks associated with intake of trans-fat,
the food service industry has clear labeling of trans-fats on food products, and many restaurants use trans-fat-free oil.
