Macromolecules, Monomers, and Membranes

Unit 4

What are the 4 major macromolecules?

• carbohydrates

• proteins

• nucleic acids

• fat/lipids

Describe carbohydrates

• contain carbons, hydrogens, and oxygens

• polymers include: starch, cellulose, glycogen (varies depending on organism)

• monomers: glucose, fructose

• Dimer: sucrose, maltose

• enzymes: amylase, lactose

What carbohydrate polymer is used by humans?

glycogen 

Describe nucleic acids

• made of phosphate/sugar backbone and a nitrogenous base

• basic monomer is a nucleotide

• polymer is RNA and DNA

Describe fat (lipids)

• made of fatty acids (hydrocarbon chains are monomers; they are also non polar, which is ideal)

• sometimes made of a sugar or phosphate (also potential monomers)

• main types of lipids: phospholipids, triglycerides, steroids, and waxes

Which has more potential energy (calories): saturated or unsaturated fats?

saturated fats

Which has a higher melting point: saturated or unsaturated fats?

saturated fats ( more solid at room temp. bc of this)

Describe why saturated fats are solid at room temp

they have straight hydrocarbon chains; they’re packed in tightly, making them solid at room temp. 

Describe why unsaturated fats are NOT solid at room temp

In unsaturated fats, there is a kink in the hydrocarbon chains, so they cannot pack in as tightly; results in them being less solid at room temp

Describe proteins

• monomer = amino acids

• polar

Describe what we learned about polar bonds in the MSH unit

• electrons are not shared evenly; happens when the atoms have significantly different electronegativities (pull)

• results in partial negative and partial positive charges

Describe what we learned about non-polar bonds in the MSH unit

• occur when the atoms involved have roughly the same electronegativity (they can be a little different and we still call them nonpolar)

Describe what we learned thus far about molecular polarity in this unit

• molecular polarity has big implications on how molecules behave and move in our bodies

• solubility: “like dissolves like”

• transport: only some of these molecules can pass through a cell membrane and only some can dissolve in the blood

Describe polar molecules 

• have charged regions 

• interact well (dissolve) in water

Describe non-polar molecules

• mostly non-polar bonds

• do NOT dissolve well in water

• often have long strings of CH’s

• Rule of 5

• not black and white (variation exists)

What does the Rule of 5 state?

• at least 5 carbons in a row with no partial charge will make a molecule ACT nonpolar (almost always CH bonds)

When do polar bonds containing carbon occur?

when C is bound to O or N (highly electronegative)

what is true of proteins, from polymers to monomers, regarding R groups and amino acids?

While some amino acids have non-polar R groups, we usually refer to them as polar molecules

What is true about carbohydrates, from polymers to monomers, regarding polarity and composition?

• contain lots of carbons, hydrogens, and oxygens

• always polar

How do we get monomers into our bodies? 

• first, they need to cross into the cells that make up our intestinal lining

• small intestine → lots of surface areas → long → villi

• intestinal cells = microvilli (structure=function) and surface area = absorption 

True or false: the cell membrane of the intestine is similar to other cell membranes?

true

where are the gut and cytoplasm located in relation to the intestinal cell?

• gut = outside intestinal cell

• cytoplasm = inside intestinal cell

What are the other features of the intestinal cell membrane structure?

• selectively permeable phospholipid bilayers

• phospholipid has a hydrophilic head and a hydrophobic tail

True or false: the phrases phospholipid bilayer, phospholipid membrane, and cell membrane are all referring to the same thing? 

true

Describe the makeup of the phospholipid

• phosphate (PO4 - very polar)

• glycerol - sugar (slightly polar)

• fatty acid - 2 tails (non-polar)

• polar head - hydrophilic → loves water

• nonpolar tails - hydrophobic → hates water

• polar is attracted to polar and nonpolar is attracted to nonpolar