building blocks of bio

Question 1

water accounts of __% of a cell’s weight

Answer 1

70%

Question 2

name the four building blocks of every cell

Answer 2

sugars
fatty acids
amino acids
nucleotides

Question 3

polymers made from the four building blocks

Answer 3

sugars –> polysaccharides
fatty acids –> fats / lipids / membranes
amino acids –> proteins
nucleotides –> nucleic acids

Question 4

basic structure of a nucleotide

Answer 4

N-containing base
5-C sugar
phosphate group(s)

Question 5

name five types of N-containing bases

Answer 5

adenine
guanine
cytosine
thymine
uracil

Question 6

how many rings do each of the N-containing bases have?

Answer 6

A and G = 2
T and C = 1
so that all base pairs have 3 rings in total

Question 7

nucleoside vs nucleotide

Answer 7

nucleoside = sugar + base
nucleoTide = sugar + base + phosphaTe (eg. ATP, dAMP)

Question 8

biological polymerisation is driven by___

Answer 8

ATP
w/ loss of H2O (condensation polymerisation)

Question 9

general bonding in DNA

Answer 9

covalent - phosphate backbone
H-bonds between bases

Question 10

DNA structure main features

Answer 10

double helix, major + minor groove
phosphate backbone = POLAR due to -vs charge on phosphate
planar bases
stacking of bases influences stability

Question 11

how many H-bonds form between A-T and C-G?

Answer 11

A=T
C-G 3 bonds

Question 12

RNA vs DNA nucleotides differences

Answer 12

additional hydroxyl group in ribose sugar of RNA (ribose, not deoxyribose)
Uracil rather than thymine

Question 13

describe RNA secondary structure

Answer 13

does not form a double helix like DNA
moves in space until it finds the lowest energy folding combination
held together by H-bonds

Question 14

general amino acid structure

Answer 14

NH2 amino group
COOH carboxyl group
R functional group (side chain) attached to alpha C chiral centre

Question 15

at pH7, what happens to amino acids?

Answer 15

both amino and carboxyl groups ionised –> zwitterionic

Question 16

formation / breaking of peptide bond

Answer 16

N and C terminus of two amino acids
condensation reaction –> peptide bond
hydrolysis reaction (+H2O) to break

Question 17

describe the four levels of protein structure

Answer 17

primary = amino acid residues
secondary = local folding (determined by interactions between amino acids)
tertiary = global folding, combination of secondary structures –> polypeptide chain
quaternary = assembled subunits

Question 18

describe the bonding in an alpha-helix protein secondary structure

Answer 18

N-H of every peptide bond is H-bonded to the C=O four amino acids away
Left or right handed

Question 19

bonding in beta-sheets of protein

Answer 19

H-bonding between adjacent strands of polypeptide chains
can run parallel / antiparallel

Question 20

simple monosaccharide general formula

Answer 20

(CH2O)n
eg. glucose C6H12O6

Question 21

how are disaccharides formed

Answer 21

C w/ ald/ket can react w any hydroxyl group on a second sugar
glycosidic bond formed
eg. sucrose = glucose + fructose

Question 22

what is a glycosaminoglycan

Answer 22

GAGs = unbranched polysaccharide chains made of repeating disaccharide units

Question 23

name 5 GAGs

Answer 23

hyaluronic acid
chondroitin sulfate
dermatan sulfate
heparin sulfate
keratan sulfate

Question 24

describe the properties of GAGs

Answer 24

polysacc chains are stiff + strongly hydrophilic
–> GAGs occupy huge volume relative to mass + negative charge density attracts could go cations, esp Na+ which is osmotically active sucking up lots of water
hence GAGs fill extracellular space

Question 25

phospholipid molecule structure

Answer 25

hydrophilic head (glycerol+phosphate+polar functional group)
two hydrophobic fatty acid tails which can be saturated or unsaturated

Question 26

lipid micelles are formed from…

Answer 26

phospholipids w a single tail, form a ball

Question 27

cholesterol structure

Answer 27

rigid steroid ring + polar head group = hydrophilic
non polar hydrocarbon tail
amphipathic

Question 28

cholesterol function

Answer 28

stiffer than phospholipids, can pack into membranes –> controls stiffness
important in cell signalling