Microbio Exam 2

How many covalent bonds can a carbon atom typically form and why?

How many covalent bonds can a carbon atom typically form and why?

4 bonds - carbon only has 4 valence electrons in its outermost shell

How can you determine whether a molecule is organic/inorganic when given a molecular formula?

organic molecules contain both hydrogen and carbon

What are the principal functional groups of organic molecules?

How can you tell whether an organic molecule is hydrophilic/hydrophobic when given a diagram and why?

polar/charged functional groups make a molecule hydrophilic, absence of partial/full charges make a molecule hydrophobic

How can you tell whether two molecules are isomers of each other?

if they both have the same chemical formula but different structures

What is the relationship between macromolecules, monomers, dimers, and polymers?

macromolecules - large organic molecules that make up living organisms

monomers - similar small components that assemble large macromolecules

dimers - two monomers joined together

polymers - assembled chain of >3 monomers

What are the similarities/differences between dehydration synthesis and hydrolysis?

dehydration synthesis (requires energy) - removing an OH group from one subunit and an H from another to form a covalent bond (removing water molecules to link two monomers together)

hydrolysis (releases energy) - adding an OH group to one subunit and an H to another to break the covalent bond (adding water molecules to break apart polymers)

What is a monosaccharide?

carbohydrate monomers with up to 7 carbon atoms

What are the structures/functions of the glucose, fructose, galactose, ribose, and deoxyribose monosaccharides?

What is a disaccharide?

two monosaccharides joined together by a covalent bond through dehydration synthesis

What are the structures/functions of the sucrose, lactose, and maltose disaccharides?

What is a polysaccharide?

many monosaccharides joined together

What are the structures/functions of the glycogen, starch, cellulose, and chitin polysaccharides?

What are the 5 major categories of lipids? What major physical characteristics do they share?

fats, oils, waxes, steroids, phospholipids (lots of C and H - very few O, hydrophobic)

-high-density long term energy storage

-absorption of fat-soluble nutrients

-padding, insulation, membranes, protection

-hormones, structure, water-proofing

What is the function of fats and oils?

fat - high-density long term energy storage in animals within fat cells of adipose tissue, insulate (keep body temp constant) and provide cushioning for organs

oils - high-density long term energy storage in plants

What is the function of waxes?

sticky rather than oily, solid at room temp due to high melting point, provide a protective layer that prevents water loss in plants and guards our eardrums from dust, dirt, and insects

What is the function of steroids?

4-carbon ring structure with different functional groups attached to carbon backbone for different functions (cholesterol, testosterone, estrogen, aldosterone)

What is the function of phospholipids?

lipids with phosphate groups, main components of cellular, plasma, and organelle membranes (keep them fluid-like)

What is the structure of fats and oils?

triglycerides - one glycerol molecule (3 carbon and 3 hydroxyl groups) and 3 fatty acids (1 acidic carboxyl group and hydrocarbon chain)

3 dehydration synthesis reactions bind each fatty acid to the glycerol molecule, 3 hydrolysis reactions release each fatty acid from the glycerol

What are the chemical and physical properties of saturated/unsaturated fats?

saturated fats - no C=C bonds, more hydrogens, solid at room temp

unsaturated fats - at least one C=C bond, less hydrogens, liquid at room temp (cis/trans)

How does hydrogenation occur?

converts fluid, unsaturated oils to solid, saturated fats by adding hydrogen atoms to the oil’s double bonds

increases shelf life and decreases spoiling of food, can be headed repeatedly without breaking down

What are the major functions of proteins?

enzymes - speed up chemical reactions, shape defines function

structural proteins - fibrous proteins that give support and shape to different tissues (collagen, keratin)

regulatory proteins - transported through the body as chemical messengers that tell specific cells to carry out certain functions (hormones, insulin)

transport proteins - transport things in/out of the cell, carry molecules throughout the body (hemoglobin)

How are amino acids structured and how do they join to form polypeptides?

amino acids have a central carbon bound to an amino group, carboxyl group, a hydrogen, and a unique R group (side chain) that gives the amino acid its properties, joined through dehydration synthesis

What are the 4 structural levels of proteins?

primary- straight chain and order of amino acids before any folding takes place, joined through covalent peptide bonds (amino acids must be in correct sequence and order for its proper function)

secondary- transitional 3D shape, once a polypeptide has been made on the ribosome, amino acids in the chain start interacting with each other to form hydrogen bonds (alpha helix or beta pleated sheets)

tertiary- determines final globular shape, involves 3D folding of a protein due to interactions (ionic/acid-base bonds, hydrogen bonds, hydrophobic interactions, covalent/disulfide bonds) of amino side chains (what gives a protein its function), hydrophobic amino acids hide on the inside while hydrophilic amino acids interact with the environment

quaternary- two or more polypeptides (chains) join together to make a mature protein

How are proteins denatured? How does temp and pH affect protein functions?

when a protein unfolds (3D structure breaks down) due to encountering an unideal environment (lose shape = lose function), increased temp or pH change affects hydrogen bonding which is involved in the folding process

What are the parts of a nucleotide?

deoxyribose - 5-carbon sugar (1’ = where base is attached, 2’ = where DNA (H attached) and RNA (hydroxyl group attached) differ, 3’ = holds a hydroxyl group where next nucleotide is attached, 5’ = where phosphate group is attached)

phosphate group

nitrogenous base

What is the difference between deoxyribose and ribose?

deoxyribose - has a hydrogen attached to the 2’ carbon

ribose - has a hydroxyl group attached to the 2’ carbon

What are the 4 nitrogenous bases?

adenine - purine (double ring), pairs with T

thymine - pyrimidine (single ring), pairs with A

guanine - purine (double ring), pairs with C

cytosine - pyrimidine (single ring), pairs with G

How are nucleotides joined into strands?

phosphodiester bonds join nucleotides together through dehydration synthesis

What is the basic structure of DNA? (sugar-phosphate backbone, antiparallel strands, complementary base pair binding, double helix)

DNA is made of two strands of nucleotides running anti-parallel (opposite) to each other, forming a double helix or twisted ladder shape. Complementary base pair binding holds the 2 strands together with hydrogen bonds (2 for A/T, 3 for G/C). The bases are located in the inside of the helix, so the sugars and phosphate groups stay on the outside to form the sugar-phosphate backbone.

How do you create the complementary strand of DNA when given the base strand?

Adenine binds with Thymine via 2 hydrogen bonds

Guanine binds with Cytosine via 3 hydrogen bonds

The 5’ end of one must be paired with 3’ end of the other (anti-parralel/opposite)

What is semi-conservative DNA replication?

when each “old” strand of DNA acts as a template against which a new strand is synthesized so several parts of the DNA can be replicated simultaneously

What is the process and results of DNA replication? (gyrase, topoisomerase, helicase, DNA polymerase, ligase)

1) Relaxing: the topoisomerase and gyrase enzymes relax the supercoiled bacterial DNA to prepare for replication

2) Unwinding: old strands of the parent DNA molecule are unwound as weak hydrogen bonds between the paired bases are “unzipped” and broken by the enzyme helicase

3) Complementary base pairing: the enzyme DNA polymerase binds free nucleotides present in the nucleus with complementary bases on unzipped portions of the 2 DNA strands

4) Joining: DNA polymerase bonds complementary nucleotides to each other to form new strands, gaps in DNA phosphate backbone are sealed by the enzyme DNA ligase

How are the leading and lagging strands formed during DNA replication?

leading strand - synthesized continuously

lagging strand - synthesized in pieces that are then joined together (ligase fills the gaps), always occurs 5’ to 3’ direction