IMMS Flashcards
1
Q
How many chromosomes are there in a normal somatic cell?
A
46
2
Q
Male genotype
A
XY
3
Q
How many H bonds between A and T
A
2
4
Q
How many H bonds between C and G?
A
3
5
Q
How is a chromosome condensed?
A
Coils around nucleosides, coils again to suprcoil
6
Q
What is an ideogram?
A
Diagrammatic form chromosome bands
7
Q
What are the 4 centromere locations
A
Metacentric, sub-metacentric, Acrocentric, telocentric
8
Q
What happens in G1
A
rapid growth, cell organelles produced, proteins in spindle formation made, normal metabolic function
9
Q
how many genes are there in humans
A
22000
10
Q
what happens in S phase of cell cycle
A
DNA replicated to 4n, centrosome replication, histone production
11
Q
what happens in G2
A
growth, chromosomes condense, energy stores accumulate, mitochondria and centrioles double
12
Q
what happens to cells in G0
A
dont undergo mitosis
13
Q
whats the purpose of mitosis
A
turn 1 parent cell to 2 daughter cells
14
Q
whats the lifespan of RBC
A
120 days
15
Q
what happens in prometaphase
A
nuclear membrane breaks down, microtubules invade nuclear space, chromatids attach to microtubules
16
Q
what is a microtubule
A
largest cytoskeleton fibres found in cell made of tubulin
17
Q
what is a chromatid
A
2 identical chromsomes joined by centromere
18
Q
what happens in metaphase
A
chromosomes line up along metaphase plate
19
Q
what happens in anaphase
A
sister chromatids separate and are pulled to opposite poles of cell, microtubules condense
20
Q
what happens in telophase
A
nuclear membrane reforms, chromosome unfolds to chromatin, cytokinesis begins
21
Q
what happens in cytokinesis
A
cell splits and 2 daughter cells made
22
Q
what is the general principle of chemotherapy
A
blocks different phases of cell cycle
23
Q
how can you tell a cell is undergoing mitosis histologically
A
dark nucleus as chromatin condensed to chromosomes and nuclei are different sizes
24
Q
how can you distinguish a malignancy histologically
A
too many mitotic figures i.e. lots of dark nuclei of different sizes
25
where does meiosis occur
gametes
26
when does crossing over occur
prophase 1
27
what happens in meisosis 1
Chromosome number halved
28
what happens in prophase 1
crossing over occurs at chiasma; between non-sister chromatids diversity
29
what happens in metaphase 1
independent assortment
30
what is Mendel's 2nd law of independent assortment
alleles of 1 gene sort into gametes independently of the alleles of another gene
31
what happens in meiosis 2
sister chromatids separate, haploid cells produced
32
sperm production basic pathway
Primordial germ cells -> lots of mitoses -> spermatogonia
33
what are spermatogonia
basic gametes
34
how are primary spermatocytes made
mitosis in embryonic stages
35
when do meiotic divisions in sperm production start
puberty
36
what happens in puberty in sperm production
cytoplasm divides evenly to form 4 equal gametes after meiosis II
37
how long does it take to make mature sperm
60-65 days
38
what is the basic pathway for egg production
primordial germ cell forms 30 mitoses forms oogonia
39
what is an oogonia
basic gamete
40
what happens to oogonia
enter prophase of meiosis I by 8th month of intrauterine life
41
what happens to oogonia in ovulation
cytoplasm divides unequally to form 1 egg and 3 polar bodies
42
what happens to polar bodies from egg production
apoptose
43
when is meiosis I completed in egg production
ovulation
44
when is meiosis II completed in egg production
if fertilisation occurs
45
what is non-disjuncture
Failure of chromosome pairs to separate in meiosis 1 or sister chromatids to separate properly in meiosis II
46
what is Down's syndrome
regular trisomy 21
47
what is Turners syndrome
loss of 1 x chromosome
48
what is the general name for loss of 1 chromosome
monosomy
49
what is reciprocal translocation
swapped between 2 different chromosomes
50
what is Robertsonian translocation
2 chromosomes join
51
what is gonadal mosaicism
When precursors germline cells to ova/ spermatozoa are a mix of 2 or more genetically different cell lines
52
what increases risk of gonadal mosaicism
advancing paternal age
53
what genetic patterns are most commonly associated with gonadal mosaicism
autosomal dominant and X linked disorders
54
genotype
genetic constitution of an individual
55
Phenotype
appearance of individual which results from the interaction of environment and phenotype
56
multifactorial condition
disease that are due to combination of genetic and environmental factors
57
allele
one of several alternative forms of a gene at a specific locus
58
functional type allele
normal allele/ wild type
59
pathogenic allele
disease allele carrying pathogenic variant
60
polymorphism
frequent hereditary variation at a locus
61
polyploidy
the state in which an organism/ cell has more than 2 paired (homologous) sets of chromosomes
62
penetrance
proportion of individuals with a specific genotype showing the expected phenotype
63
complete penetrance
gene/ genes for trait are expressed in all the population
64
incomplete penetrance
genetic trait is only expressed in parts of population
65
expressivity
range of phenotypes expressed by a specific genotype
66
variable expression
variation in clinical features (type and severity) of genetic disorder between individuals with the same gene alteration
67
sex linked/ limited
condition inherited in autosomal dominant pattern that seems to affect 1 sex more than the other e.g. BRCA
68
somatic mosaicism
genetic fault present in only some tissues in the body
69
gonadal mosaicism
genetic fault present in gonadal tissue - not detected in genetic test
70
consanguinity
reproductive union beyween 2 relatives
71
Autozygosity
homozygous by descent i.e. inheritance of the same mutant allele through 2 branches of the same family
72
sex-limitation
expression of a characteristic limited to one of the sexes
73
karyotype
number and appearance of chromosomes in a cell
74
aneuploidy
presence of abnormal number of chromosomes in a cell
75
autosome
any chromosome other than sex chromosome
76
allelic hetrogeneity
where different mutations within the same gene result in the same clinical condition
77
locus hetrogeneity
variants in different genes give the same clinical condition
78
anticipation
whereby genetic disorders affect successive generations earlier or more severely - usually due to expansion of unstable triplet repeat series
79
predictive testing
testing for a condition in pre-symptomatic individual to predict their chance of developing the condition
80
imprinting
epigenetic phenomenon that causes genes to be expressed in parent-of-origin manner; non-mendelian - each gene has 2 alleles, requires equal contribution for most alleles but some only require contribution from specific parent e.g. Prader Willi = deletion of paternal gene
81
late-onset
condition not manifested at birth
82
congenital
disease manifested at birth
83
heritability
proportion of the aetiology that can be ascribed to genetic factors as opposed to environmental factors
84
prevalence
total number in population who have the disease
85
incidence
number of new cases per year in population who don’t have the disease
86
genetic counselling
process by which patients/ relatives at risk of a disorder that may be hereditary are advised of the consequences of the disorder, the probability of developing/ transmitting it and the wats it may be prevented or ameliorated
87
methods of genetic testing in pregnancy
chorionic villus sampling or amniocentesis
88
types of mendelian inheritance
autosomal dominant, autosomal recessive, x-linked
89
non-traditional inheritance
mitochondrial, imprinting, mosaicism
90
autosomal dominant definition and example
disease manifests in heterozygous state, Huntington's
91
autosomal recessive definition and example
disease manifests in homozygous state e.g. CF, sickle cell
92
x linked definition and example
caused by pathogenic variants in genes on X chromosomes, Duchenne's and haemophilia
93
what shape is male on family tree
square
94
what shape is female on family tree
circle
95
what does a diamond on a family tree mean
unspecified gender
96
what does a half shaded shape on a family tree mean
autosomal carrier
97
what does a circle with a dot in it mean on a family tree
x linked carrier
98
what does a double line between 2 people on a family tree mean
consanguineous marriage
99
what does a dotted line on a family tree mean
extramarital union
100
what do square brackets around someone mean on a family tree
adopted
101
what does a downwards line connecting to a black circle mean on a family tree
still birth or abortion
102
what does an arrow pointing to the bottom left of a shape mean on a family tree
person of reference
103
what do diagonal lines connecting 2 children with a single point of origin mean on a family tree
dizygotic (fraternal) twins
104
what do diagonal lines connecting 2 children with a single point of origin and with a line between the 2 children (making a triangle) mean on a family tree
monozygotic (identical) twins
105
autosomal recessive characteristics
- Males and females equally affected
- Affected individuals in single generation
- Parents can be related i.e. consanguineous
106
risk to offspring with carrier parents autosomal recessive
1 in 4 risk
107
odds of healthy children being carriers for autosomal recessive disorder if parents are carriers
2 in 3
108
prevelance of CF
1 in 2500
109
odds of being a CF carrier
1 in 25
110
cause of CF
CFTR gene on 7q31.2
111
autosomal dominant inheritance main characteristic
- Disease manifests in heterozygous state
- Males and females equally affected
- Affected individuals in multiple generations
- Transmission by individuals of both sexes to both sexes
- ONLY WAY TO HAVE MALE TO MALE INHERITANCE
112
examples of autosomal dominant inheritance
Huntington’s, Marfan’s, Polycystic kidney disease
113
3 reasons for unaffected parents having affected children with autosomal dominant condition
1. Don’t have gene for it (mutation in child)
2. Gonadal mosaicism
3. Mother has reduced penetrance or variable expression
114
x linked inheritance characteristics
- Usually only males affected
- Transmitted through unaffected females
- No male-to-male transmission
- Affected male cannot have affected son, but all his daughters will be carriers
115
outcome for carrier female and unaffected male with x linked conditions
¼ having affected son
| ¼ having carrier daughter
116
outcomes for affected male and homozygous normal female with x linked condition inheritance
all daughters are carriers, sons not at risk
117
what is lyonization
inactivation of an x chromosome
118
when does deactivation of x chromosome occur in lyonization
early embryonic development
119
why does lyonization occur
prevent females having twice as many gene products from X chromosomes as male
120
what is a barrbody
inactive X chromosome since package in heterochromatin and so can't be transcribed
121
what causes mitochondrial disease
mtDNA inherited from mother
122
what processes do mitochondrial diseases affect
energy heavy processes e.g. muscle, nervous, vision
123
what is homoplasmy
eukaryotic cells whose copies of mtDNA are all identical
124
what is heteroplasmy
multiple copies of mtDNA in each cell
| o Level of Heteroplasmy can vary between cells in same tissue/ organ/ person/ individuals
125
trisomy 21 name
Downs
126
trisomy 18 name
Edwards
127
trisomy 13 name
Patau
128
47, XXY name
Kleinfelter
129
Downs cause
trisomy 21
130
Edwards syndrome
trisomy 18
131
Patau syndrome casuse
trisomy 13
132
Kleinfelters karyotype
47, XXY
133
when do constitutional abnormalities occur and what do they affect
gametogenesis, affect all cells of body so heritable
134
when do acquired abnormalities occur and what do they affet
during life, restricted to malignant tissue and non heritable
135
gain of function mutations
1 mutation
136
loss of function mutation
2 mutations; inheritance of 2 copies - to loose function both copies must be defective
137
Knudson's 2 hit hypothesis
- Gene mutations may be either inherited or acquired during a person’s life
- Sporadic cancers = 2 acquired mutations
- Hereditary cancers = 1 inherited mutation and 1 acquired mutation
138
3 causes of disease
genetic, multifactorial, environmental
139
F.I.S.H.
- Fluorescence in situ hybridisation
- Use DNA probes labelled with fluorophores – target specific regions of DNA
- Are hybridised directly to the chromosome
140
Relative risk
risk of having disease compared to someone who doesn’t have the genotype
141
relative risk of 1
no increased risk
142
nucleotide definition
building block to make new DNA
| o Free phosphate groups provide energy for reaction
143
DNA structure
- Double helix; due to v.d.w. forces
- DNA coils around histones (chromatin complex) and forms nucleosomes supercoils chromosomes
- Double stranded, phosphodiester bonds
- Anti-parallel strands with H bonds between complementary bp
144
functions of DNA
emplate and regulator for transcription/ protein synthesis
| o Genetic material; structural basis of hereditary and genetic disease
145
describe the DNA code
degenerate but unambiguous, universal, non-overlapping without punctuation
146
describe RNA structure
single strand, uracil not thymine
147
describe mRNA function and structure
Accumulates following cell stimulation
Prints a long linear transcript; processing removes introns
o Has 5’CAP and 3’ PolyA tail
148
what does Poly-A tail on RNA do
stops RNA being broken down by stopping enzyme degradation
| • Added to mRNA which facilitates nuclear export of RNA and translation
149
what does rRNA do
combines with proteins -> 80S ribosomes; abundant in cytoplasm
150
what does tRNA do
carries AA to ribosomes; checks incorporated in correct position
151
start codons
AUG
152
stop codons
UAG, UGA, UAA
153
what does topoisomerase do
relives supercoiling by breaking phosphodiester bonds and re joining them
154
what does helicase do
breaks H bonds
155
what do SSB proteins do
hold strands open and prevents reannealing so remain single stranded
156
where is new DNA made
behind the replication fork
157
describe the process of DNA replication
Topoisomerase, helicase, ssb proteins open DNA, primer binds, base sequence copied into complimentary daughter strand
158
what is primase
RNA polymerase that synthesis short RNA primers needed to start replication process
159
what does RNAs H do
removes the RNA primers that previously began DNA synthesis
160
what direction does DNA polymerase print
5 to 3
161
what direction does dna polymerase read
3 to 5
162
why does dna polymerase print 5 to 3
phosphate at 5 acts as energy source
163
what is the substrate for dna polymerase
deoxyribonucleoside triphosphates
164
what does DNA primase do
Joins adjacent nucleotides together via a phosphodiester bond in 5’ 3’ direction
o Enzyme remains on strand and at same time extends and proof reads
o Starts at primer
165
what is a primer
short strand of DNA that is the start point for DNA synthesis
166
what do ligase enzymes do
joins short DNA pieces (Okazaki fragments) to form 1 continuous strand
167
what are Okazaki fragments
short DNA pieces
168
where do TF bind
specific sequence on 5’ of 1st exon (promoter region)
169
what are transcription factors
proteins which bind to promoter regions
170
describe transcription
- TF bind to promoter region
- Transcription complexes form (around TATA box)
- Topoisomerase relieves supercoiling
- DNA helicase breaks H bonds DNA separates
- SSB’s coat single strand to prevent re-annealing
- Free mRNA nucleotides line up next to complementary bases on template/ antisense strand
- RNA polymerase 2 binds to DNA at specific sites adjacent to promoter sequence
- Forms pre-mRNA; attaches free ribonucleotides bases together
171
describe the journey of mRNA
moves through pores to cytoplasm to ribosome and attaches to 80s ribosome
172
how are AAs attached to tRNA
covalent bonds at 3' end
173
what enzyme attaches AA to tRNA
aminoacyl-tRNA synthetase
174
how does translation occur
- tRNA molecule anticodon is complementary to specific codon on mRNA
- Initiation; methionine (AUG) starts polypeptide chain
- Elongated by successive addition of AA forming peptide bonds; condensation reaction
- Terminates at sequence (UGA, UAG, UAA)
175
what is nonsense mediated decay
- Surveillance mechanism; eliminates mRNA transcripts that contain premature stop codons
176
how are genes silenced
genes are in heterochromatin (H for hiding) so no transcription can occur
177
what state do genes need to be to be transcribed
euchromatin
178
mis sense variant
SNP changes AA in portein
179
sickle cell gene change
SNP CAG to CTG
180
non-sense variant
SNP creates premature stop codon
181
what does SNP stand for
single nucleotide polymorphism
182
types of deletion mutations
in frame and out of frame
183
what is an in frame mutation and what does it do
deletes multiples of 3 and doesn't alter gene sequence so may or may not affect protein
184
what is an out of frame mutation and what does it do
non-multiple of 3; causes frameshift so more likely to cause damage
185
what can happen in a splice site mutation
o Can cause disease as mutation at splice junction mean section isn’t spliced out
Introns not accurately removed non-functioning protein
186
give an example of a disease caused by expansion of tri-nucleotide repeat
Huntingtons, CAG
187
gene for Huntington's
> 36 CAG repeats
188
anticipation definition
tri nucleotide repeats get bigger when transmitted to next generation earlier symptoms of greater severity
189
aim of PCR
synthesise DNA fragments; basis for forensic testing
190
respiration definition
oxidation of fuels to generate ATP
191
fed state definition
period in which digestion and absorption of nutrients occurs
192
metabolism definition
sequence of chemical reactions: a particular molecule is converted into some other molecule(s) in a defined fashion
193
anabolic definition and use
synthesis of large molecules from smaller components
| o Storage and biosynthesis
194
catabolic definition and use
break larger molecules into smaller ones
| o Usually with release of energy
195
4 main pathways of dietary metabolism
biosynthesis, fuel storage, waste disposal, oxidative process
196
anabolic metabolic processes example
biosynthesis and fuel storage
197
catabolic metabolic process example
oxidative process
198
example of a process that can be both anabolic and catabolic
waste disposal
199
energy from carbohydrate
4kcal/ g
200
energy storage of carbohydrate
glycogen;
200g in liver
150g in muscles
201
energy from lipids
9kcal/ g
202
energy storage of lipids
TG in adipose tissue; 15kg
203
energy from proteins
4kcal/ g
204
AA need
0.8g/kg/day
205
energy storage of protein
6kg in muscles
206
energy from alcohol
7kcal/ g
207
BMR meaning
basal metabolic rate
208
BMR definition
- Measure if energy required to maintain non-exercise bodily functions
- Energy needed to stay alive at rest
209
BMR equation
- 1kcal/kg body mass/ hour
210
factors that cause decreased BMR
age, gender, dieting/ starvation, hypothyroidism, decreased muscle mass
211
factors that increase BMR
weight, hyperthyroidism, low ambient temperature, fever/ infection/ chronic disease, caffeine/ stimulant, exercise
212
DEE meaning
daily energy expenditure
213
DEE definition
- Energy to support BMR and physical activity and diet induced thermogenesis
214
diet induced thermogenesis definition
energy required to process the food we eat
215
how much glucose does the brain require per day
150g
216
how much glucose is eft in the liver after an overnight fast
80g
217
what mechanism does the body rely on during an overnight fast
glycogenolysis
218
what happens in a fast lasting 2-4 days
o Insulin decreases, cortisol increases – lipolysis and proteolysis
Gluconeogenesis uses Lactate, amino acids (muscle, intestine, skin), glycerol (fat breakdown)
219
what happens in a fast lasting more than 4 days
liver produces ketones from fatty acids
220
malnutrition definition
state of nutrition with a deficiency, excess or imbalance of energy, protein or other nutrients causing measurable adverse effects
221
what happens in re-feeding syndrome
insulin secretion decreases in food deprivation
insulin secretion increases when shifts back from fat to carbohydrate metabolism; phosphate and potassium needed to convert glucose to energy
re distribution of ions and electrolytes can be fatal
222
how much sodium is allowed per day in prudent diet
2.4g = 6g
223
what enzyme is used in the ATP/ ADP cycle
ATPase
224
what happens when adenine attaches to ribose
forms adenosine
225
how is amp formed
when 2nd phosphohydride bond in ATP (i.e. ADP) is hydrolysed
226
nucleoside definition
sugar + base
227
nucleotide definition
sugar + base + phosphate
228
methods of ATP regeneration
glycolysis, krebs, oxidative phosphorylation, substrate level phosphorylation, electron transport cjain
229
where is glucose oxidised
cytosol of cell
230
equation for glycolysis
Glucose + 2ADP +2Pi +2NAD+ 2 pyruvate + 2ATP + 2NADH + 2H+ + 2H20
231
what regulates glycolysis rate
[ATP]/ [AMP] and insulin/ glucagon
232
what does AMP stand for
adenosine monophosphate
233
what is the rate limiting enzyme in glycolysis
phosphofructokinase-1 (PFK-1)
234
what does phosphofructokinase-1 do
Converts fructose-6-phosphate fructose-1, 6-biphosphate
235
what are the functions of glycolysis
```
o Provides ATP
o Generates precursor for biosynthesis
Pyruvate transaminated to alanine
Pyruvate substrate for FA synthesis
Glycerol-3-P (G3P) = backbone of triglycerides
```
236
what are the intermediates from glycolysis converted to
Ribose 5-P (nucleotides)
| AA; serine, glycine, valine
237
what happens to pyruvate in aerobic conditions
enters Krebs cycle
238
what happens to pyruvate in anaerobic conditions
converted to lactate then back to pyruvate or precursor for gluconeogenesis
239
what enzyme is used for conversion of glucose to lactatw
lactate dehydrogenase
240
equation for conversion of glucose to lactate
Glucose + 2ADP + 2Pi 2 lactate + 2ATP + 2H20 + 2H+
241
what happens if [H+] and [lactate] increase
pH decreases and ACIDOSIS occurs
242
equation that PFK-1 catalyses
Fructose -6-phosphate + ATP fructose-1, 6-biphosphate + ADP
243
what does fructose-2, 6 bisphosphate do
allosterically activates PF1! and increases rate of glycolysis and thus fructose-1, 6 bisphosphate production
244
what happens in fed state (regarding PFK1)
high insulin levels mean more fructose-2, 6-bisphosphate produced so increased PFKa activation so higher rate of glycolysis so glucose sequestered from blood more efficiently so prevents hyperglycaemia
245
what happens in fasting state (regarding PFK1)
high glucagon levels so decreased fructose2, 6-bisphosphate production so less PFK1 production so glycolysis pathway less efficient so blood glucose concentration maintained
246
what allosterically inhibits PFK1
citrate/ other ions
247
what is AMP regarding PFK1
allosteric activator so increases PFK1 affinity for fructose-6-phosphate
248
what does ATP do regarding PFK1
allosteric inhibitor so glycolysis inhibited
249
what does acidosis do to glycolysis
inhibits it
250
where does TCA cycle occur
mitochondrial matrix
251
what is the rate limiting enzyme of the TCA cycle
isocitrate dehydrogenase
252
what does ADP do to ICDH
allosteric activator
253
what does NADH do to ICDH
allosteric inhibitor
254
where does oxidative phosphorylation occur
inner membrane of mitochondria
255
total ATP made from 1 glucose molecule
34-38
256
how many ATP does NADH produce
2.5
257
how many ATP does FADH2 produce
1.5
258
what are essential fatty acids
FA that can't be synthesised de novo; need to be consumed in diet
259
what is acyl adenylate composed of
fatty acid and adenosine
260
where are FA activated and then what happens
activated in cytoplasm before oxidised in mitochondrion
261
what is the largest acyl-CoA carbon chain that can diffuse through mitochondrial membrane
12C
262
what happens if acyl-coa is >14C
taken through mitochondrial membrane through carnitine shuttle
263
is fatty acid b oxidation aerobic or anaerobic
aerobic
264
is fatty acid b oxidation anabolic or catabolic
catabolic
265
what enzyme oxidises acyl coa
acyl coa dehydrogenase
266
what is produced in 1 round of FA B oxidation
1 NADH, 1 FADH2, 1 Acetyl CoA
267
what happens if acetyl coa produced exceeds limit of TCA cycle
used in ketogenesis in the liver
268
where is acetyl coa from FA B oxidation used
krebs cycle
269
where are NADH/ FADH2 from FA B oxidation used
oxidative phosphorylation
270
why can't FA act as energy source for nervous system
can't cross BBB
271
what are ketones
molecules produced by liver from acetyl coa
272
where are ketone bodies synthesised
mitochondrial matrix
273
what are ketone bodies synthesised from
acetyl coa generated in b oxidation
274
what enzyme converts acetyl coa to Acetoacetyl coa
thiolase enzyme
275
who gets ketoacidosis
insulin dependent diabetics whose dose is inadequate/ have increased insulin requirements
276
why do diabetics get ketoacidosis
o Insulin down-regulates ketone production
277
what is the presentation of ketoacidosis
hyperventilation and vomiting
278
what happens in ketoacidosis
excessive ketones lower the pH of blood
279
aliphatic definition
carbon structures that don't contain ring
280
aromatic definition
carbon compounds that contain benzene ring/ similar
281
what does 'native conformation' mean
every molecule of the same protein folds into the same stable 3D structure
282
disaccharide definition
2 MS joined by glycosidic bond
283
oligosaccharide definition and production
3-12 MS joined by glycosidic bond;
| o Products of digestion of polysaccharides
284
polysaccharides definition
multiple MS joined by glycosidic bond
285
what do spingolipids form
cell membrane of brain and nervous system
286
what shape are steroids and what are they derived from
cylindrical, cholesterol
287
what are eicosanoids derived from and what are they metabolised to
derived from eicosanoid acid, metabolised to prostaglandins
288
which is 'good' cholesterol
HDLP
289
what is 'bad' cholesterol
LDLP
290
why is LDLP bad
o Risk to CVD and atherosclerosis; can transport content into artery walls and attract macrophages
291
what affects the charge of an amino acid
r group
292
what affects the polarity of an aa
r group
293
what charge does the carboxyl group on an aa have
negative
294
what charge does the amino group on an aa have
positive
295
what form are most natural aa found in
l form
296
how are peptide bonds formed
condensation reaction
297
what enzyme cleaves peptide bonds
proteolytic enzymes
298
what determines folding in aa
charged interactions, flexibility, physical dimensions
299
Supersecondary structure examples
Helix-turn-helix
β- barrel
Leucine zipper
Zinc zipper
300
isoenzyme definition
have different structure/ sequence but catalyse the same reaction
301
allosteric site definition
location other than the active site
302
co-enzyme definition
complex nonprotein organic molecules that help maximise an enzymes active site
303
what do activation-transfer coenzymes do
form a covalent bond and are regenerated at end of reaction
304
what do oxidation-reduction coenzymes do
used in reactions where e- are transferred from 1 compound to another
305
where is myoglobin found
muscles
306
what does myoglobin do
erves as reserve supply of oxygen; also facilitates movement of O2 in muscles
307
how are haemogolobin and myoglobin related
structurally related proteins with some common elements; same tertiary structure
o Core of both molecules = porphyrin ring; holds an iron atom
308
VDW force definition
o Weak electrostatic attraction between atoms due to fluctuating electrical charges
o Only important when 2 macromolecular surfaces fit closely in shape
309
what level of structure(s) are VDW forces found
all
310
H-bond definition
strongest vdw forced, Interaction between polar groups
311
what level of structure(s) are h bonds found
secondary
312
how are hydrophobic forces formed
o As uncharged and non-polar side chains are repelled by water, hydrophobic side chains tend to form tightly packed cores in the interior of proteins, EXCLUSING WATER MOLECULES
313
what level of structure(s) are hydrophobic forces found
3/4
314
what level of structure(s) are ionic bonds found
3/4
315
ionic bond formation
o Occur between fully or partially charged groups
316
what happens to ionic bonds in aqueous systems
weakened by shielding by water molecules and other ions in solution
317
what type of bond are disulphide bonds
covalent
318
where are disulphide bonds found
between cysteine residues
319
what level of structure(s) are disulphide bridges found
3/4
320
homeostasis definition
maintenance of a constant internal environment
321
autocrine definition
cell signals with itself via extracellular fluid
322
paracrine definition
cell signals with adjacent cells via extracellular fluid
323
how do paracrine signals get transmitted
o Signal diffuses across gap between cells
o Inactivated locally, so doesn’t enter bloodstream
o Immobilised by matrix structure of interstitial fluid
o Activated by enzymes in interstitial fluid
e.g. ACh at neuromuscular junction
324
endocrine definition
cell signals with cells elsewhere in body via the blood
325
exocrine definition
secreted into ducts then organs
326
endocrine v paracrine
o Endocrine; hormines travel in blood
o Paracrine; chemical messengers only travel in extracellular fluid
o Endocrine affects more things and travels further
327
features of positive feedback
signal amplification; is exponential
328
positive feedback examples
clotting cascade, oxytocin release in childbirth
329
negative feedback general mechanism
o Products inhibit production
330
pituitary thyroid axis mechanism
TSH travels through blood from anterior pituitary thyroid; produces thyroxine which travels in blood target cell
Thyroxine inhibits secretion of TSH by anterior pituitary
331
primary hyperthyroidism
problem with endocrine gland e.g. thyroid
332
secondary hyperthyroidism
problem with pituitary or hypothalamus e.g. 2ndary hypothyroidism; both TSH and thyroixine levels are low; pituitary not producing enough TSH
333
hormone definition
- Molecules that act as chemical messengers
334
peptide hormone examples
insulin, growth hormones, TSH (made in pituitary)
335
peptide hormone structure
- Made of short chain amino acids
o Size varies
o Some have COH side chains glycoproteins
336
properties of peptide hormones
Hydrophilic – so can dissolve in water;
o Large, hydrophilic, charged; can’t diffuse across a membrane
Bind to receptors on membrane
- Binds to extracellular receptors chemical reaction quick response from cell
o 2nd messenger released into cell = very fast;
o Signal transduction cascade
337
what are amino acid hormones synthesised from
tyrosine
338
examples of amino acid hormones
adrenaline and thyroid hormones
339
steroid hormone examples
testosterone, oestrogen, cortisol
340
steroid hormone response rate
slow
341
what are steroid hormones made from
cholesterol
342
properties of steroid hormones; solubility
- Can’t dissolve in water but can dissolve in lipids
| o Must bind to transport protein to move in blood
343
what do steroid hormones target
intracellular receptors; made by cell and then diffuse out - not stored
344
amount of water in average 70kg male
42L
345
weight of 'average man' used
70kg
346
intercellular fluid distribution
28L (40% of bodyweight, 66% of water)
347
extracellular fluid distribution
14L (20% bw)
348
2 components of extracellular fluid
intravascular and interstitial fluid
349
intravascular fluid distribution
3L, 6% of water
350
intravascular fluid example
plasma
351
interstitial fluid distribution
11L, 26% of water
352
what does interstitial fluid do
surrounds cells but doesn't circulate
353
permeability of water through ICF and ECF
freely permeable
354
main contributor to ECF osmolality and volumes
sodium
355
ECF osmotic contents
sodium, chloride and bicarbonate, glucose and urea, protein
356
what does protein do in ECF
colloid osmotic pressure - stays in intravascular fluid and exerts fluid pulling water into intervascular space
357
ICF cations
potassium
358
cell cation/ anion distribution v intracellular space
Cells have high intracellular potassium and low intracellular sodium; reverse of intracellular space
359
examples of insensible water losses
sweat, breath, vomiting, faeces
360
osmolality definition
concentration of a solution expressed as no. of solute per kg of fluid
361
osmolality of pure water and of intra/ extracellular fluid
0 and equal
362
osmolarity definition
concentration of solution expressed as no. of solute particles per L of fluid
363
osmotic pressure definition
pressure that would have been applied to a pure solvent to prevent it from passing into a given solution by osmosis
o Often used to express the concentration of the solution
364
oncotic pressure definition
orm of osmotic pressure exerted by proteins in blood vessel plasma that usually tends to pull water into the circulatory system
o Opposing force to hydrostatic pressure
365
hydrostatic pressure definition
pressure difference between capillary blood (plasma) and interstitial fluid
o Water and solutes move from plasma into interstitial fluid
366
what happens in increased ECF osmolality
o Osmoreceptors detect an increase in osmolality
o ADH released from posterior pituitary to increase water retention
Increased permeability of DCT
Small volume of highly concentrated urine produced
o Water moves from ICF ECF
o Stimulation of thirst centres in hypothalamus to increase water uptake
367
what happens in decreased ECF volume
RAAS system activation
368
where is albumin produced
liver
369
where is angiontensinogen produced
liver
370
where is angiotensin 1 produced
from angiotensinogen
371
where is angiotensin 2 produced
from angiotensin 1
372
where is renij produced
kidney; juxtaglomerular cells
373
where is aldosterone produced
adrenal cortex
374
where is ADH formed
hypothalamus but released from posterior pituitary gland
375
ADH other name
vasopressin
376
what causes the release/ production of albumin
common plasma protein
377
what causes the release/ production of angiotensinogen
always there
378
what causes the release/ production of angiostensin 1
presence of renin
379
what causes the release/ production of angiotensin 2
ACE
380
what causes the release/ production of renin
low sodium concentration and low bp in macula densa cells
381
where does albumin act
blood
382
where does angiotensin 2 act
Adrenal gland cortex, posterior lobe of the pituitary gland, arterioles, hypothalamus
383
where does renin act
released into blood
384
where does aldosterone act
collecting ducts
385
where does ADH act
collecting ducts
386
what does albumin do
generate oncotic pressure
387
what does angiotensinogen do
acts as substrate to turn into 1
388
what does angiotensin 1 do
precursor for 2
389
what does angiotensin 2 do
Increases aldosterone secretion. increased ADH secretion, constriction of arterioles activates the thirst centres, increases sympathetic activity, increased Na+ reabsorption
390
what does renin do
breaks angiotensinogen to angiotensin 1
391
what does aldosterone do
Stimulate sodium reabsorption by making more Na+/K+ pumps
392
what does ADH do
Stimulates vesicles with aquaporins
393
what happens in water excess
o Decreased ECF osmolality
Movement of water ICF
No stimulation of thirst centre in hypothalamus
Inhibition of ADH frpm [posterior pituitary so uincreased urine volume
394
what are the consequences of water excess
```
Hyponatraemia
Cerebral overhydration;
• Headache
• Confusion
• Convulsions
Volume overload
• ECF volume expansion
o Heart/ kindye failure and cirrhosis with ascites
• Renal sodium retention
• Oedema
• Serous effusion
```
395
oedema definition
excess accumulation of fluid in interstitial space
396
serous effusion definition
excess water in body cavity
397
types of serous effusion/ oedema
inflammatory, venous, lymphatic, hypoalbuminemia
398
inflammatory oedema
albumin leaves capillary and doesn’t re-enter
| Inflammation increases permeability so proteins leak into interstitial fluid
399
venous oedema
very high hydrostatic pressure at venous end
| Water not reabsorbed
400
lymphatic oedema
diseased lymph nodes leads to impaired water reabsorption to lymph nodes
Low capacity; takes time to build up
401
hypoalbuminic oedema
low albumin in plasma
| e.g. malnutrition, liver disease leads to low oncotic pressure
402
normal capacity of pleural space
10mL of fluid
403
transudate pleural effusion
= fluid pushed through capillary due to high pressure within the capillary
404
exudate pleural effusion
fluid that leaks around cells of capillaries caused by inflammation and increasing permeability of pleural capillaries to proteins
