Biochemistry Flashcards
1
Q
what are the main components of a cell membrane?
A
lipids and proteins.
2
Q
what are the components of a phospholipid?
A
- alcohol
- phosphate
- glycerol
- 2x fatty acids.
3
Q
for a D-glucose where would you expect to find the OH?
A
on the right
4
Q
for a L-glucose where would you expect to find the OH?
A
on the left.
5
Q
on a carbohydrate - you number the carbon atoms, how can you tell which carbon in number 1?
A
it is the one that is a carbonyl group. so is connected by a double bond with O and also bonded to a hydrogen.
6
Q
if a carbohydrate has a carbon atom with a double bond to an oxygen and a single bond to a hydrogen what are they classed as?
A
aldose.
7
Q
if a carbohydrate has a carbon atom with a double bond to an oxygen and no bond to a single hydrogen what are they classed as?
A
ketose.
8
Q
in a haworth projection of glucose if the OH is at the bottom on the right hand side what time of sugar are they?
A
alpha glucose.
9
Q
in a haworth projection of glucose if the OH is at the top on the right hand side what time of sugar are they?
A
beta glucose.
10
Q
what is meant by the term mutariotation carbohydrate?
A
that is can spontaneously change between alpha and beta.
11
Q
what is a 5 membered ring monosaccharide called?
A
furanose.
12
Q
what is a 6 membered ring monosaccharide called?
A
pyranose.
13
Q
what is the bond between 2 monosaccharides called?
A
glycosidic bond.
14
Q
what 2 monosaccharides makes up sucrose?
A
glucose + fructose.
15
Q
what 2 monosaccharides makes up lactose?
A
glucose + galactose.
16
Q
what 2 monosaccharides makes up maltose?
A
glucose and glucose.
17
Q
where is lactose found?
A
milk of mammals.
18
Q
where is sucrose found?
A
in sugar cane and sugar beets.
19
Q
what is meant by the term homopolysaccharide?
A
polysaccharide make up from the same monosaccharide.
20
Q
what are 2 examples of homopolysaccharide?
A
- glycogen.
- starch.
21
Q
what is the purpose of glycogen in humans?
A
stored carbs.
22
Q
what is glycogen made up from?
A
many glucose.
a-(1,4) linkages with a a(1,6)branched linkage every 8-10.
23
Q
what is the main difference it the structure between glycogen and starch?
A
glycogen is very compact - large amount of carbon energy in small volume.
24
Q
what is the purpose of starch in plants?
A
stored carbs.
25
what is unbranched starch called?
amylose.
26
what is branched starch called?
amylopectin.
27
how is cellulose different from amylose?
humans don't contain enzymes to break down cellulose - so we are unable to digest it.
28
what is a carb joined with a lipid called?
glycolipid.
29
what is a carb joined with a protein called?
glycoprotein.
30
what are Glycosaminoglycans (GAGs)?
long unbranched polysaccharide containing a repeating disaccharide unit.
31
what are 3 examples of Glycosaminoglycans in the human body?
- Dermatan sulphates (in skin/blood vessels/ heart valves)
- Chonaritin 4 + 6 sulphates (in cartilage, bone, and heart valves)
- Heparan sulphates (in basement membranes and components of cell structure.
32
what are the majority of GAGs in the body linked to?
proteins creating proteoglycans.
33
what are glycoproteins?
GAGS links to core proteins that are then cell-surface antigens, virus coat proteins and cell receptors.
34
what are the components of DNA?
- phosphate group
- pentose sugar (either ribose or deoxyribose)
- nitrogenous base
35
what are the 5 bases found in cells?
- adenine
- guanine
- thymine
- cytosine
- uracil.
36
what 2 bases are the derivatives of purine?
- adenine
| - guanine
37
what 3 bases are the derivatives of pyrimidine?
- thymine
- cytosine
- uracil.
38
what is the structure of an amino acid?
a central carbon connected to:
- hydrogen,
- carboxyl group
- R-group
- amino group.
39
what part of the amino acid base structure changes for each amino acid?
R-group.
40
what bond is formed between amino acids?
peptide bonds.
41
what are the roles of lipids within the body?
- structural component of biological membrane.s
- provide energy reserves.
- serve as vitamins and minerals
- lipohilic bile acids aid in lipid solubilisation.
42
what are the 3 groups lipids are classified into?
- fatty acids
- cholesterol
- lipoproteins.
43
what is the structure of a fatty acid?
carboxylic aid end with a long-chain hydrocarbon tail.
44
what is understood by the term saturated?
most hydrogens possible
45
what is understood by the term unsaturated?
at least one double bond between 2 carbon molecules.
46
what is the basic structure of a triacylglyceride?
glycerol with 3 fatty acids chains of it.
47
what is the structure of cholesterol?
4 rigidly fused carbon ring forming the steroid nucleus with a hydroxyl (OH) group attaching to one end and a steroid to the other.
48
what is the importance of cholesterol to a cell membrane?
it adds rigidity and strength against mechanical rupture.
49
what are 2 vitamins derived from steroids?
- ergosterol
| - vitamin D
50
what is the phospholipid found in membranes that doesn't include glycerol?
-sphingomyelin.
51
is cholesterol found in prokaryotes?
no- it is absent.
52
what is meant by the term amphipathic?
contains hydrophilic and hydrophobic properties.
53
what is meant by the term integral membrane protein?
protein that is interact extensively with the bilayer.
54
what is meant by the term peripheral proteins?
bind to surface of integral proteins - they can span the membrane with alpha helices.
55
what is meant by the term bacteriorhodopsin?
alpha spanning helices in contact with hydrocarbon core (aka the tails) or with other alpha spanning helices.
56
what type of he helices fold in such a way to form a hollow cylinders through the phospholipid bilayer of cell membranes?
beta helices that found bacterial porin.
57
what type of environment are amino acids showing a more negative value most likely to be found?
- aqueous environments.
58
what is membrane movement/fluidity controlled by in the phospholipid bilayer?
fatty acid composition (more unsaturated- not as tightly packed)and cholesterol content (.
59
how can the differences between cell membranes in prokaryotes be identified?
using gram stain.
60
how can molecules transport across the plasma membrane?
- diffusion
- transporter proteins
- channel proteins.
61
what are prokaryote?
bacterial small single-cell organisms.
62
what is the difference between prokaryotes and eukaryotes?
prokaryotes don't contain organised membranous internal structures and transcription and translation can occur simultaneously.
63
what are Eukaryotes?
all plant and animal cells
| swell as algae, fungi and protozoa.
64
what is the endosymbiosis theory?
how different organelles came into the cell - evolution.
65
what is the purpose of the cytoskeleton in eukaryotes?
gives the cell structural integrity and allows for locomotion, transport and cell division.
66
what does the cytoskeleton in eukaryotes consist of?
- actin filaments
- intermediale filaments
- tubules filaments.
67
what are the stages of mitosis?
1) prophase (present)
2) metaphase (middle)
3) anaphase (appart)
4) telophase (two)
68
what is meiosis?
making of a daughter cells with half the number of chromosomes. (making a haploid daughter cell)
69
how do viruses multiply?
hijack other cells 'machinery' and get them to replicate. /
70
what is an example of a DNA virus?
poxvirus
71
what are examples of a RNA virus?
- HIv
- mumps
- influenza
- common cold.
72
how is Lysogeny (budding) carried out by viruses?
- viruses injects DNA into host cell
- virus DNA integrates with host cell DNA
- cell goes through mitosis replicating infected DNA
- phase induction happens with host immune system is down.
- viral DNA comes away from host DNA, destroys the host DNA, hijacks the cells functions replicating itself until the cell explodes with many viruses.
73
what are prions?
proteins in the brain converted leading to brain lesions.
74
what kind of disease can prions cause?
- BSE (mad cow disease)
| - New variant CJD (human form of BSE)
75
what is different about prions when compared to other cells?
- very heart and UV-irradiation resistant.
| - cannot be autoclaved.
76
how many different types of amino acid are there?
20
77
what is an example of a polar molecule? and what type of molecule do they tend to bond with?
Water is a polar molecule.
| - tends to form hydrogen bonds with other water molecules or other polar molecules.
78
what is mean by the term polar molecule?
more electro charged at the top.
79
what is meant by theorem apolar molecule?
electo distribution is equal.
80
what is an example of an apolar molecule?
methane.
81
where are many essential amino acids humans need found?
in meat.
82
why is diet so important regarding amino acids?
as humans cannot synthesis 9 essential amino acids so they need to be provided by diet.
83
how are proteins primarily folded?
nonpolar sidedchains in the centre as they are hydrophobic.
| polar side chains o the outside as they can form hydrogen bonds to water.
84
what do most polypeptide chains start with?
methionine (AUG)
85
what are the 4 folded polypeptide chain structures?
- alpha helices
- beta sheets
- turns
- loops.
86
what causes the alpha helices folding in polypeptide chain structures?
hydrogen bonds to ensure that the hydrophobic non polar side chains are the the centre.
87
are beta sheet arranged parallel, antiparallel or both in folded polypeptide chains?
both.
88
is there any order to a proteins tertiary structure?
not at first but then tried to reduce energy when folding.
89
what is most often on the surface of proteins tertiary structures?
charged amino acid residues.
90
what is a proteins quaternary structure?
more than 1 polypeptide chain.
91
what is an example of a protein with more than 1 polypeptide chain?
Insulin.
92
what is meant by the term transcription in gene expression?
the synthesis of RNA from a DNA template.
93
what is meant by the term translation in gene expression?
the synthesis of proteins using RNA
94
what is tRNA?
transfer RNA.
95
what is the structure of tRNA?
amino acids attached to 3' end.
| anticodon is the template recognition site.
96
what are the 3 main things genetic code has to be?
- redundant
- unambiguous
- universal.
97
how is genetic code reductant?
several different triple codons sequence can encode for the same amino acid.
98
how is genetic code unambiguous?
each codon can only encode 1 specific amino acid (ora START/ STOP)
99
how is genetic code universal?
all living organisms use the same genetic code.
100
how are proteins synthesised?
by the successive addition of amino acids to the carboxyl terminal.
101
what are ribosomes?
RNA/protein hybrid structures.
102
how many tRNA binding sites do ribosomes have?
3.
103
why do ribosomes have 3 binding sites?
to bridge the 30s and 50s subunits.
104
in what part of the ribosome has a tunnel allowing the growing polypeptide chain to extrude though?
50s subunits.
105
what is the wobble hypothesis?
allows tRNA molecules to recognise more than one codon.
106
what do many antibiotics do the protein synthesis?
inhibit it.
107
what is the difference between prokaryotic mRNA and eukaryotic mRNA?
prokaryotic mRNA code for multiple proteins. where are eukaryotic mRNA only codes for one gene
108
how is translation very accurate?
have a proof-reading mechanism.
109
what makes the backbone of DNA?
sugar and phosphate.
110
what is DNA replication classed as semi-conservative?
new stand of DNA is made up go one new and one old (original) stand of DNA.
111
what does the enzyme Helices do in DNA replication?
'unzipping' - separates the 2 DNA strands.
112
what does the enzyme DNA polyerase do in DNA replication?
builds the new stand of DNA - binds to the primer to know where to start and adds bases from 5'-3'
113
what does the enzyme Primase do in DNA replication?
makes the primes - starts of the replication with some RNA fragments.
114
what does the enzyme DNA ligase do in DNA replication?
seals up the fragments creating a continuous stand.
115
how is the leading stand in DNA replicated?
- after helicase has creating a replication form
- primase makes the primer
- DNA polymerase builds the rest of the strand in the 5'-3 direction.
116
how is the lagging stand in DNA replicated?
- after helicase has creating a replication form
- primase makes the primer
- DNA polymerase builds a small strand in the 5'-3 direction. (this small stand = okazaki fragment)
- primase makes another primer further down the stand.
- DNA polymerase creates another okazaki fragment.
- this continues until the stand is complete.
- exonuclease then removes the RNA primers
- DNA polymerase then fills in the gaps left behind with DNA bases.
- finally DNA ligase seals up the fragments in both stands - creating a continuous strand.
117
what is the difference between RNA synthesis and DNA synthesis?
RNA synthesis is carried out by RNA polymerase, and it only requires a template not a primer.
118
is DNA negatively or positively charged?
negatively.
119
why do histone proteins bind to DNA?
because they are positively charged.
120
how many times can a cell divide before it dies? and what is the only exception?
50-70 times.
| but sperm cells can divide unlimited amounts.
121
why many the telomerase enzyme be needed during DNA replication of the lagging strand?
as there may not be enough primer for all amino acids so the telomerase enzyme will extend 3' end to allow extension of the 5' end.
122
when are the only times that the telomerase enzyme is used?
- foetal development - due to rapid cell division
| - cancer cells - 'immortal' cells
123
what are 3 examples of a promoter in DNA replication and what is its purpose?
examples = TATA box / CAAT box / GC box.
| recognition sequence immediately upstream of the transcription start site.
124
what is gene splicing?
DNA is cut and further DNA is added - this allows organisms to produce useful products eg insulin, allowing for diversity.
but it can result in disease.
125
what are the factors involved in regulation of gene expression?
- chromatin remodelling (unfolding of DNA)
- Enhancers (signalling sequence of nucleotide)
- modification (suppress the gene)
