M2 chapter 3: Biological molecules Flashcards
(110 cards)
1
Q
what are the four key elements?
A
Hydrogen
Carbon
Nitrogen
Oxygen
2
Q
what is a bond?
A
2 or more atoms joining together
3
Q
what is a covalent bond?
A
bond where a pair of electrons are shared
4
Q
carbon bond rules?
A
makes 4 bonds
5
Q
nitrogen bond rules?
A
makes 3 bonds
6
Q
oxygen bond rules?
A
makes 2 bonds
7
Q
hydrogen bond rules?
A
makes 1 bond only
8
Q
what is a ion?
A
where the number of electrons in an atom don’t equal the number of protons, so the atom becomes positively or negatively charged
9
Q
what is the difference between an cation and an anion?
A
cation has a positive charge and is formed when an atom on loses an electron. whereas an anion has a negative charge as it is formed when an atom gains an electron.
10
Q
cations: what does ammonia do?
A
production of nitrate ions by bacteria
11
Q
cations:what does calcium do?
A
needed for nerve impulse transmissions and muscle contractions
12
Q
cations: what does sodium do?
A
needed for nerve impulse transmissions and kidney function
13
Q
cations: what does potassium do?
A
needed for stomata opening in plants and pH determination
14
Q
cations: what does hydrogen do?
A
needed for the catalysis of reactions and pH determination
15
Q
anions: what does nitrate do?
A
supplies nitrate to plants for amino acid and protein formations
16
Q
anions: what does hydrocarbonate do?
A
maintains blood pH
17
Q
anions: what does chloride do?
A
balances the charges of sodium and potassium ions
18
Q
anions:what does phosphate do?
A
membrane formation
bone formation
nucleic acid and ATP formation
19
Q
anions: what does hydroxide do?
A
catalysis of reactions and pH determination
20
Q
what are biological molecules made up of?
A
polymers
(long chain of monomers)
21
Q
what happens to electrons in covalent bonds?
A
they spend more time to one of the atoms than the other so one atom in the bond is more positive whereas the other atom is more negative
22
Q
what is a key fact about the share of electrons between oxygen and hydrogen?
A
oxygen always has the greater share of electrons compared to hydrogen
23
Q
what is a key feature of a water molecule?
A
it is a POLAR molecule
24
Q
what is a polar molecule?
A
a molecule which has areas of positivity and negativity as the electrons are attracted to one atom more strongly than the other (eg water)
25
what are some characteristics of water?
high boiling point due to hydrogen bonding
when it is a solid it is less dense due to hydrogen bonds fixing their positions slightly further then in a liquid
cohesive
adhesive
26
what does cohesive mean?
a molecule that moves as one mass due to attraction
27
what does adhesive mean?
molecules that are attracted to other molecules
28
why is water so important?
acts as a solvent
is a medium for chemical reactions.
transports dissolved compounds in and out of cells
is a coolant to buffer temp changes in cells as cells need a constant temperature
stable doesn't change state easily
surface tension is strong
29
what do carbohydrates contain?
carbon, hydrogen and oxygen
30
what are carbohydrates also known as?
saccharides or sugars
31
what is a single sugar unit known as?
a monosaccharide
32
what is a disaccharide?
when 2 monosaccharides join together
33
what is it called when more than 2 monosaccharides join together?
a polysaccharide
34
what is the glucose formula?
c6h12o6
35
is glucose a monosaccharide?
yes it is a hexose monosaccharide as it is composed of 6 carbons
36
what are the types of glucose and how are they different?
alpha ajnd beta glucose
the OH (hydroxyl group) is in opposite positions on carbon 1
37
characteristics of glucose?
polar and soluble in water due to hydrogen bonds between hydroxyl groups and water molecules. this allows glucose to be dissolved in the cytosol of the cell
38
what happens in condensation reactions between 2 alpha glucoses?
the two hydroxyl groups interact
2 hydrogen atoms and an oxygen atom are removed forming water
a glycosidic bond is formed between the molecules
39
what is starch composed of?
many alpha glucose molecules joined together by glycosidic binds.
40
what is starch?
a chemical energy store and the main energy store in plants , excess glucose from photosynthesis is stored as starch. it is insoluble which is good for storage as it doesnt allow water to enter via osnosis
41
what is amylose?
long unbranched chains of alpha glucose
angles of the glycosidic bonds give it a coiled structure which makes it compact, ideal for storage
42
what is amylopectin?
long branched chain of alpha glucose. side branches allow the enzymes that break down the molecule reach the bonds easily meaning glucose to be released quickly
43
what is the structure of glycogen?
has many more branches than amylopectin making it more compact and less space needed to be stored
44
why is glycogen so efficient at releasing glucose in animals?
excess glucose is stored as glycogen in animal's
the structure has many free ends so glucose molecules can be added or removed, so easily accessible for quick release of energy
45
what is the structure of cellulose?
long unbranched chains of beta glucose linked together by glycosidic bonds to form strong fibres called microfibrils
46
what is the function of cellulose?
is main component of cell walls in plants
the fibres made by the cellulose molecules joining together are strong and insoluble providing structure to the cell.
47
what molecules do lipids contain?
carbon, hydrogen and oxygen
48
are lipids polar?
no, this means they aren't soluble in water
49
what type of molecule is a lipid?
a macromolecule
50
what is a triglyceride?
a glycerol molecule joined to 3 fatty acids by an ester bond
51
what is glycerol?
an alcohol molecule
52
what are fatty acids?
carboxylic acids (carboxyl group with a hydrocarbon chain attached). they have long tails of hydrocarbons which make them insoluble in water and hydrophobic
53
what breaks triglycerides down?
a hydrolysis reaction, as 3 water molecules are needed to reverser the esterfication (condensation reaction)
54
describe an saturated fatty acid chain?
it has NO double bonds present between the carbon atoms
55
what is the difference between mono and poly unsaturated fatty acids?
mono = just one double bond between carbon atoms
poly= two or more double bonds between carbon atoms
56
what effect does the double bond in unsaturated fats have on the structure of the molecule?
the double bond gives it a kink/ bend therefore it cannot pack closely together, making them liquid at room temp and described as oils rather than fats.
57
what are phospholipids?
a phosphate molecule - which is negatively charged so soluble and hydrophillic
2 fatty acids attached to the phosphate molecule- these are hyydrophobic
58
what is the structure of cholesterol?
lipid with a hydrocarbon ring attached to a hydrocarbon tail, polar hydroxyl group attached to the hydrocarbon ring
59
functions of triglycerides?
-triglycerides are used as an energy storage molecule
-bacteria use them to store both energy and hydrocarbon tails contain lots of chemical energy when broken down, 2x more than carbohydrates
-insoluble so stops water from entering the cell
60
functions of phospholipids?
make up phospholipid bilayer so controls what enters and leaves the cell
61
functions of cholesterol?
regulate fluidity of cell membrane as it fits between the phospholipid molecules to either pack them together or spread them apart
62
how to test for lipids?
use the emulsion test
mix sample with ethanol
mix this solution with water and shake
if white layer forms on top lipids are present
clear= negative result
63
what are proteins made of?
amino acids are the monomer which make the polymer protein
64
what is a dipeptide ?
former when 2 amino acids are joined together
65
what is a polypeptide?
when 2 or more polypeptides join together
66
what is the structure of an amino acids?
a carboxyl group and an amino group
67
how are dipeptides and polypeptides formed?
amino acids join together by peptide bonds, this process releases a molecule of water as it it a condensation reaction
68
what is a primary protein?
amino acids held together by peptide bonds
69
what are secondary proteins?
hydrogen bonds form between the NH and CO groups of the amino acids which causes it to coil or fold
70
what are tertiary proteins?
coiled chain of amino acids coil further more bonds are formed
71
what bonds can be formed in tertiary proteins?
ionic
disulfide
hydrogen
hydrophilic r groups pushed to the outside
hydrophobic r groups clump together
72
what is a quaternary protein?
made up of several types of polypeptide chains held together by bonds
73
what is a globular protein?
round and compact
they have a hydrophilic r groups which is pushed to the outside of the protein making them soluble
74
what is a fibrous protein?
tough and rope shaped
insoluble and strong
unreactive
75
what is a nucleotide?
a molecule made up of a pentose sugar, a nitrogen containing base and a phosphate group
76
what elements does a nucleotide contain?
carbon, oxygen, hydrogen, nitrogen and phosphate
77
what structures do nucleotides create?
DNA and RNA
78
why are nucleotides important?
they make up dna and rna which are types of nucleic acid. these are used in protein synthesis and to store genetic material
79
what does DNA do?
used to store genetic information
80
what does RNA do?
used to make proteins from instructions in DNA (proteinsynthesis)
81
what other molecules are nucleotides?
ADP and ATP which are used to store and transport energy in cells
82
what are the base pairs in nucleotides?
adenine, thymine, cytosine, guanine
83
what is different about RNA compared to DNA?
it has a ribose suagr not a deoxyribose sugar
uracil replaces the base thymine
it is a single polynucleotide chain
84
what are the 2 types of bases?
purines and pyrimidines
85
what bases are purines?
adenine and guanine
86
what bases are pyrimidines?
cytosine, thymine and uracil
87
how are the 2 types of bases different?
purines contain 2 carbon-nitrogen rings whereas pyrimidines only have 1
88
how is ADP and ATP different?
ADP contains 2 phosphate groups
ATP contains 3 phosphate groups
89
how is ATP made?
it is made by adding a inorganic phosphate on to ADP and creating a phosphate bond
90
how is energy released?
energy is stored in the phosphate bond in ATP. when needed, ATP is broken back down in to ADP and inorganic phosphate. energy is released by breaking this bond
91
what is a gene?
a sequence of dna nucleotides that code for a polypeptide.
92
what are polypeptides?
a polymer of amino acids joined together by peptide bonds
these form the primary structure of proteins
93
what determines the order of amino acids in protein synthesis?
the order of nucleotide bases
94
how many bases code for an amino acid?
3 bases called a triplet/codon
95
where does protein synthesis occur?
ribosomes
96
where is dna found?
the nucleus of the cell
97
why isn't DNA moved out of the nucleus?
it is too large to move out of the nuclear pores so it is copied instead
98
what is RNA?
a single polynucleotide strand containing uracil not thymine
99
what are the 3 types of rna?
Mrna
Trna
Rrna
100
what is mRNA?
polynucleotide strand made in nucleus during transcription, carries copy of genetic code to cytoplasm.
101
what is tRNA?
clover shaped molecules that act as temporary carriers of amino acids, bringing the appropriate amino acids to the ribosome based on the mRNA sequence.
102
what is rRNA?
it is a type of non-coding RNA which forms the 2 subunits in a ribosome it helps catalyze the formation of peptide bonds between amino acids.
103
what is the genetic code?
sequence of triplets in DNA which codes for specific proteins.it is degenerate- more codons than aa. some triplets code for the cell to stop the production of proteins
104
what does DNA helicase do?
enzyme which breaks down hydrogen bonds between 2 polynucleotide strands, unzips the DNA to form 2 separate strands
105
how does the dna replicate?
each original single strand joins with free floating nucleotide bases by complementary base pairing
106
what joins the nucleotides together on the new strand of DNA?
DNA polymerase which forms the sugar phosphate backbone
107
what is a mutation?
a change in base sequence
108
what is transcription?
when a mrna copy of a gene is made in the nucleus
109
how does transcription work?
rna polymerase attaches to the DNA uncoiling the strand as it moves down
this means complementary mrna can be formed
once rna polymerase has passed by the hydrogen bonds reform and the double helix is reformed.
110
how does translation work?
sequence of mrna codons is read by ribosome trna carry amino acids to the ribosome with an anticodon. rrna in ribosome catalyzes the formation of peptide bonds between the aa
after this is done the trna move away to fetch the other aa for the polypeptide chain
