Cell Exam 1

What is cell theory?

all organisms consist of cells, the cell is the basic unit of life, all cells come from preexsisting cells

Important properties of carbon for biology

it has 4 valence elections so it can make 4 bonds, most likeley to form covalent bonds with C, O, N, S, H, takes a lot of energy to break covalent bonds, can form stereoisomers due to tetrahedral structure, hydrocarbons can be insoluble in water

ionic bonds

giving elections (to more electrons), not really a bond more association, strong not in water, dissociate easily in water

covalent bonds

sharing electrons, either polar (O-H, slight difference in electronegativity) or nonpolar (C-C no difference in sharing electrons)

hydrogen bonds

O-H between water molecules, weak alone but strong when many are together

CH3

methyl, nonpolar, hydrophobic

OH

hydroxyl, polar, hydrophilic, neutral, alcohols

C=O

carbonyl, either ketone (in between two C groups) or aldehyde (in between H and C group), slightly polar, hydrophilic, polar, sugars

COOH, C=O, C-OH

carboxyl, negative charge, polar, hydrophilic, acid (releases H protons)

NH2

amino/amine, positive charge in aqueous, polar, hydrophilic, base because takes up H+

PO4

phosphate, negative charge, polar, hydrophilic

S-H

sulfhydral, slightly polar, neutral, can be hydrophilic or hydrophobic

What properties make water essential for life?

cohesiveness/high surface tension, high boiling point, high specific heat because hydrogen bonds make water stick together when there is a lot of them

What does it mean if something is polar or nonpolar?

polar molecules have unequal distribution of electron charge, which makes positive/negative sides, nonpolar share electrons equall

properties of phospholipids for membrane

highly polar head and 2 long nonpolar tails that face each other and make it amphipathic, they have proteins for regulation of material into and out of the cell

What does selectively permeable entail?

small nonolar molecules can easily pass through such as uncharged small polar, charged ions./large polar moelcules can’t pass through on their own

What are the overall principles for synthesis of macromolecules?

they are made up of subunits usually via dehydration synthesis

solvent

fluid in which another substance called a solute can be dissolved

What are proteins?

polymers of amino acids which have a carboxyl group, an amine group, an H and an R group, also called polypeptides

What determines if an amino acid is nonpolar, polar, charged, or neutral?

their R group

How can nonpolar vs polar amino acids impact protein structure?

hydrophobic/nonpolar amino acids (9) are usually found in the interior of proteins if the proteins are in aqueous environments, hydrophilic (11) or charged tend to be on the surface of protein to maximize interactions with water

How are proteins assembled?

The OH of a carboxyl group (right side C terminus) and an H on an amine group (left side N terminus) are taken away, connecting the C and N and making water in dehydration synthesis

What do disulfide bonds do in proteins?

they are between S on cystene (covalent), removes 2 H’s, stable, can bond proteins together or to the same protein

What do H bonds do to proteins?

many R groups can do this, folding allows this to happen, important in stabilizing helical and sheet structures (secondary structure)

What do ionic bonds do in proteins?

R groups can repel the same force and attract to oppisite, charges are strong and this bond doesn’t need strict angles

Why does pH denature proteins (mainly)?

loss of ionic bonds, when low or high pH because these changes can cause charge loss

What do van der waals attractions do in proteins?

brief attraction of 2 nonpolar molecules, there is a short time where there is unequal partial charges between molecules, they have to be very close for this to happen but a lot of interactions can be strong together

What do hydrophobic interactions do in proteins?

not a bond, the fact that hydrophobic molecules usually dont interact with molecules (inside of proteins)

What do the different bonds do in terms of protein structure (levels)?

primary (amino acid sequence, covalent peptide bonds), secondary (a-helix/b-sheet, H bonds between NH and CO groups of pepetide bonds in backbone), tertiary (3 dimensional folding of single polypeptide chain, disulfide, H, ionic, VDW, hydrophobic), quaternary same for tertiary

What are nucleic acids and their structure?

store, transmit, express genetic info, polymer of nucleotides which has a sugar, a phosphate base, and a nitrogen containing aromatic base

What is the structure of DNA?

it has deoxyribose, phosphate base and nitrogen containing aromatic base, the four nitrogenous bases are adenine, guanine, thymine, and cytosine

What is the structure of RNA?

ribose, phosphate base and nitrogen containing aromatic base, the four nitrogenous bases are adenine, guanine, uracil, cytosine

What bases pair with what? (DNA/RNA)

Adenine pairs with Thymine in DNA and Uracil in RNA, cytosine always pairs with Guanine

How does DNA have directionality?

the phosphate group is joined by phosphoester bond to 5’ C of sugar, base is attached to 1’, the phosphate group of 1 nucleotide will join to a second nucleotide (with a phosphoester bond) to the 3’, DNA always written 5’ to 3’

What is the basic structure of polysaccharides?

long chains of sugar/sugar deriviative, usually single repeating or 2 alternating units

What is the purpose of polysaccharides?

energy storage and cell structures

What are the basic properties of lipids (and function)?

not formed by linear polymerazation, energy storage, membrane structure, biological functions (transmission of chemical signals)

What are the major classes of lipids?

fatty acids, triacylglycerols, phospholipids, phosphoglycerides, sphingolipids

What is the structure of fatty acids?

long unbranched hydrocarbon chain with a caqrboxyl group at one end, the chain is nonpolar/hydrophobic, head is polar/hydrophilic

What distinguishes unsaturated and saturated fatty acids?

unsaturated is 1 or more double bond, saturated is no presence of double bonds

What is the basic structure of phospholipids?

they are amphipathic and key component in bilayer structure, fatty acids are part of phospholipids so they have 2 tails and a head

triacylglycerol

glycerol with 3 fatty acids, stores energy

phosphoglycerides

predominant phospholipid in most membranes

sphingosine

important in membrane structure and cell signaling, not based on glycerol but amine acid sphingosine (actual word is sphingolipid)