IMMS Flashcards
(193 cards)
1
Q
How many chromosomes are found in humans?
A
46 chromosomes, 22 pairs of autosomes and 1 pair of sex chromosomes
2
Q
Define Karyotype
A
number and appearance of chromosomes in a cell. Spreads are arranged
in size order, biggest is pair 1 and smallest is pair 22, sex pair is pair 23
3
Q
Which phase in the cell cycle is the longest?
A
Interphase
4
Q
Which events occur in Interphase
A
G1 - rapid growth, New organelles produced, protein synthesis
S - DNA replication, Histones replicate, Centrosomes replicate
G2 - Energy stores accumulate and mitochondria duplicate
5
Q
What occurs in Prophase?
A
Chromatin condenses into chromosomes
Centrosomes nucleate microtubules and move to opposite poles
6
Q
What occurs in Prometaphase?
A
Nuclear membrane breaks down
Microtubules invade nuclear space
Chromatids attach to microtubules
7
Q
What occurs in Metaphase
A
Chromosomes line up on the equator of the cell
8
Q
What happens in Anaphase
A
Sister chromatids separate and are pushed to opposite poles of the cells, centromere
first, as spindle fibres contract
9
Q
What happens in telophase?
A
- Nuclear membrane reforms
- Chromosomes unfold into chromatin
10
Q
What happens in cytokinesis?
A
Cytokinesis is where the cell divides into two genetically identical daughter cells
11
Q
Which genetic disease arises from trisomy 21?
A
Down Syndrome
12
Q
What is meiosis used for and what does it produce?
A
Used to produce gametes
4 haploid cells are produced (genetically different)
13
Q
Name two ways in which genetic diversity arises in meiosis and when do they occur?
A
Independent assortment - a random assortment of the chromosomes, new combinations - METAPHASE 1
Crossing over - Between non-sister chromatids, alleles are exchanged - PROPHASE 1
14
Q
What occurs in meiosis 2?
A
Sister chromatids separate and haploid cells are produced
15
Q
Briefly describe gametogenesis in males
A
- Primordial germ cell
- lots of mitoses
- Spermatogonia produced
- Begins at puberty
- Cytoplasm divides equally
- process takes 60-65 days
16
Q
Briefly describe gametogenesis in females?
A
- Primordial germ cell
- 30 mitotic divisions
- oogonia produced
- oogonia enter prophase 1 (8th month if intrauterine life)
- process suspended
- enter ovulation, the cytoplasm divides unequally
- 1 egg , 3 polar bodies
- Meiosis 1 completed at ovulation
- Meiosis 2 completed at fertilisation
17
Q
Describe Non-Disjunction
A
Failure of chromosome pairs to separate in Meiosis 1 or sister
chromatids to separate properly in meiosis 2.
- can result in monosomy, trisomy
18
Q
Describe Gonadal Mosaicism
A
• Occurs when precursor germline cells to ova or spermatozoa are a mixture of two or
more genetically different cell lines (due to errors in mitosis)
• One cell line is normal, the other is mutated
• Incidence increases with advancing paternal age
- Most common in males
19
Q
Define Genotype
A
the genetic constitution of an individual
20
Q
Define Phenotype
A
The appearance of individual results from the interaction of the
environment and the genotype
21
Q
Define Allele
A
One of several alternative forms of a gene at a specific locus;
22
Q
What is polymorphism
A
frequent hereditary variations at a locus. Doesn’t cause problems
(thats mutations). Polymorphisms can be you more/less efficient or make you more/
less susceptible to disease.
23
Q
define consanguinity
A
the reproductive union between two relatives
24
Q
Define Homozygous and heterozygous
A
- Homozygous: both alleles are the same at a locus
* Heterozygous: alleles at a locus are different
25
Define penetrance
Proportion of people with a gene/genotype who show the expected
phenotype
26
Define variable expression
Variation in clinical features (type and severity) of a genetic
disorder between individuals with the same gene alteration
27
Define sex limitation
Expression of a particular characteristic limited to one of the sexes
28
What is a multifactorial condition?
Diseases due to a combination of genetic and
| environmental factors.
29
Summarise autosomal dominant inheritance.
- Manifests in the heterozygous state.
- Male to Male transmission is seen.
- Both males and females are affected equally.
- The disease is present in several generations.
- There is a 50% chance of offspring having the disease.
30
Summarise autosomal recessive inheritance.
- Manifests in the homozygous state.
- The disease is often not seen in every generation.
- 25% chance of offspring having the disease.
- 50% chance of offspring being carriers.
- Healthy siblings have a 2/3 chance of being carriers.
31
Give an example of an autosomal dominant condition.
Huntington's disease
32
Give an example of an autosomal recessive condition
Cystic fibrosis
33
Give two examples of X-linked conditions
- Haemophilia
| - Duchenne muscular dystrophy
34
Summarise X-linked inheritance
- No Male-Male transmission
- all daughters from an affected male are carriers
- sons unaffected
- Males can never be carriers
35
Define lyonisation.
One of the female X chromosomes becomes inactivated early in embryogenesis.
36
What is imprinting?
some genes have only one of the two alleles active, either maternal or paternal
37
Which symbol on a pedigree chart shows a termination of pregnancy
triangle with a line through it
38
Which symbol on a pedigree chart shows a miscarriage?
triangle
39
which symbol on a pedigree chart shows a stillborn - sex unknown
Diamond
40
What process occurs on the outer membrane of mitochondrion?
Lipid synthesis
41
Where in a cell does the Krebs cycle take place?
Matrix
42
Name 2 places DNA can be found.
1. Nucleus of a cell.
| 2. Mitochondria (purely maternal DNA).
43
What process occurs on the inner membrane of mitochondrion?
Electron transport chain - oxidative phosphorylation
44
What is the role of the RER
Protein synthesis
45
Describe the role of the SER?
Lipid synthesis
46
What is the function of the golgi apparatus?
Processes and modifies ER products.
47
What is the cis face of the golgi apparatus?
The cis face is nearest the nucleus and receives ER vesicles.
48
What does the medial Golgi do?
It modifies products by adding sugars forming oligosaccharides
49
What does the trans face of the golgi do?
It sorts molecules into vesicles.
50
What are the functions of vesicles?
Transports and stores materials. These are membrane-bound organelles.
51
What are lysosomes?
- Derived from golgi
- H+/ATPase on surface
- enables acid hydrolases to work
- breakdown debris and bacteria and cell organelles
52
What is the role of peroxisomes?
Oxidise long-chain fatty acids - involved in fatty acid beta oxidation
53
How do HbS sub-units cause sickling?
They bind to the cytoskeleton which causes sickling.
54
What the smallest type of filamentous protein found in cells?
Microfilaments - actin forms a bracing mesh
55
What the largest type of filamentous protein found in cells?
Microtubules - tubulin - arise from centrosomes - in all cells apart from erythrocytes
56
Give an example of an intermediate filament
Desmin
57
What is the role of intermediate filaments?
Spread the tensile forces through the tissues - reduces cell damage
58
What is lipofuscin?
Orange-brown pigment - peroxidation of lipids - found in older people - wear and tear pigment
59
Describe the primary structure of proteins?
The sequence of the amino acids - held together by covalent bonds
60
Describe the secondary structure of proteins
Formation of beta-pleated sheets and alpha helixes due to H-bonds
61
Describe the tertiary structure of proteins
- Overall 3D shape of a protein
| - ionic bonds, disulphide bridges, van der Waals and hydrophobic forces
62
Describe the quaternary structure of a protein
Two or more polypeptide chains joined together - e.g haemoglobin
63
What is an isoenzyme?
enzymes that have a different structure and sequence but catalyse the
same reaction
64
What is a Coenzyme?
they cannot in themself catalyse a reaction but can help enzymes to
do so. They can bind with the enzyme protein molecule to form the active enzyme
65
Which part of an immunoglobulin does the antigen bind to?
variable domain
66
What is the function of topoisomerase?
it unwinds the DNA double helix by relieving the supercoils.
67
In what direction does DNA polymerase read?
3' to 5' (but replication occurs in the 5' to 3' direction).
68
What is a promoter sequence?
The promoter region controls when and where the RNA polymerase will attach to DNA so transcription can commence.
69
what is the role of single-stranded binding protein (SSB) in DNA replication?
keeps two strands of
| DNA apart whilst synthesis of new DNA occurs
70
What is the role of DNA ligase
joins the short DNA pieces (Okazaki fragments) together into one
continuous strand.
71
What is the role of a primer?
Short strand of DNA that is the start point for DNA synthesis
72
Briefly describe translation.
A tRNA with a complementary anticodon to the codon on mRNA binds. Peptide bonds from between amino acids = polypeptide chain.
73
What is splicing?
Removal of introns
74
Which part of the gene contains coding sequences
Exons
75
List 3 features of the genetic code.
1. Non-overlapping
2. Universal
3. Degenerate
76
What is a mis-sense mutation?
A single nucleotide change results in a codon coding for a different amino acid. This can result in a non-functional protein or can have no effect (degenerative nature of the genetic code).
77
What is a non-sense mutation?
A single nucleotide change that produces a premature stop codon. This results in an incomplete/non-functional protein.
78
What is an in-frame deletion?
- Complete codon removed
- less catastrophic
- reading frame not altered
79
What is an out of frame deletion?
- reading frame is altered
| - can be catastrophic
80
What is it called when a child shows a phenotype for a disease younger than their father/mother does? e.g. in huntington's disease.
Anticipation.
81
What is anticipation?
repeats get bigger when they are
| transmitted to the next generation resulting in earlier symptoms of greater severity
82
Describe autocrine communication
Chemical is released from cell into the
extracellular fluid and then acts upon the very cell that
secreted it
83
Describe paracrine secretions
Chemical messengers involved in the
communication between cells, released into extracellular
fluid - travel short distances, local communication. E.g
Acetylcholine at neuromuscular junction
84
Describe endocrine secretions?
- Secrete into blood
- travel long distances
- can affect the whole body
- organs involved
85
Describe exocrine secretions?
Secretions into ducts and then into organs
86
compare paracrine and endocrine secretions
- Paracrine travel in extracellular fluid
- endocrine travels in the blood
- endocrine affects organs and more things
- paracrine short distance and endocrine long distance
87
Define hormone
A molecule that acts as a chemical messenger
88
Name the three types of hormones
1) Peptide
2) Steroid
3) amino-acid derivative
89
Give a brief description of peptide hormones
- made from short chains of amino acids
- large hydrophilic charged molecules
- cannot diffuse across the membrane - receptors on the membrane
- Pre-made and stored in vesicles
- dissolves in blood
- quick response
e. g - insulin, TSH, ADH
90
Give a brief description of steroid hormones
- Synthesised from cholesterol
- Water-insoluble, lipid-soluble
- Requires transport in blood
- intracellular receptor
- no storage
- slow response
- directly affects the DNA
91
Give a brief description of amino acid hormones
Synthesised from tyrosine, acts in same way to peptide. Examples;
adrenaline, thyroid hormones (thyroxine (T4) and triiodothyronine (T3))
92
What is the predominant electrolyte in ICF?
K+
93
What is the predominant electrolytes in ECF?
sodium, chloride, bicarbonate and calcium
94
what is interstitial fluid?
The fluid which surrounds the cells, does not circulate
95
Water distribution: how much water is there in:
a) the ECF?
b) the ICF?
a) 14L
| b) 28L
96
Water distribution: how much water is there in the (ECF):
a) interstitial fluid
b) plasma
a) interstitial - 11L
| b) plasma - 3L
97
Water distribution: How much water is there in the ICF?
28L
98
Define insensible loss
Water loss that we are unaware of. It is comprised only of solvent and can not be measured.
99
Name 3 hormones involved in water homeostasis.
1. Aldosterone.
2. ADH - antidiuretic hormone.
3. ANP - atrial natriuretic peptide.
100
If a patient has diabetes insipidus and is not producing any ADH what is her blood and urine osmolality after 3 hours of water deprivation going to look like?
Blood osmolality would be high.
| Urine osmolality would be low - very dilute urine.
101
How much water does a typical person have
42L (roughly 60% of bodyweight)
102
What are the osmotically active solutes in the ICF
K+
103
What are the osmotically active solutes in the ECF?
Sodium, chloride, glucose and urea
104
Define osmosis
net movement of solvent molecules through a semipermeable membrane
to a higher solute concentration (i.e. lower water conc.)
105
Define osmolality
the measure of the number of dissolved particles per kg of fluid
106
Define osmolarity
measure of the number of dissolved particles per L of fluid
107
Define osmotic pressure
pressure applied to a solution, by a pure solvent, required to
prevent inward osmosis, through a semipermeable membrane
108
Define oncotic pressure
form of osmotic pressure exerted by protein that tends to pull fluid
into its solution - water moves from interstitial fluid into plasma
109
What is hydrostatic pressure?
Pressure difference between capillary blood(plasma) and
| interstitial fluid - water and solutes move from plasma into interstitial fluid
110
What happens when water is lost from ECF?
increase in osmolality in ECF
111
Name the 4 types of oedema.
1. Lymphatic.
2. Venous.
3. Hypoalbuminaemic.
4. Inflammatory.
112
Electrolyte homeostasis: what is the cause(s) of hypernatremia? And what are the risks?
Cause - water deficit (poor intake, diabetes insipidus etc).
Risks - Dehydration.
(High sodium = low H2O which dehydrates the brain).
113
Electrolyte homeostasis: What is the cause(s) of hyponatremia and what are its risks?
Causes: Excess water due to IV fluids, diuretics.
Risks: Overhydration - headache, confusion
114
Electrolyte homeostasis: What is the cause(s) of hyperkalemia and what are its risks?
Causes: renal failure, acidosis, diuretic inhibitors.
Risks: Cardiac arrest.
115
Electrolyte homeostasis: What is the cause(s) of hypokalemia and what are its risks?
Causes: D+V, alkalosis, diuretics.
Risks: weakness and dysrhythmia.
116
Electrolyte homeostasis: What is the cause(s) of hypercalcemia and what are its risks?
Causes: hyperparathyroidism, Vit D toxicity, malignancy.
Risks: renal stones and metastatic calcification.
117
Electrolyte homeostasis: What is the cause(s) of hypocalcemia and what are its risks?
Causes: renal disease, Vit D deficiency, intestinal malabsorption.
Risks: tetany (spasms).
118
List 4 functions of a plasma membrane.
1. Physical boundary for the cell.
2. Regulates the movement of substances.
3. Has receptors for cell to cell signalling.
4. Attaches the cell to the external environment.
119
Name 4 molecules you'd find in a plasma membrane.
1. Cholesterol
2. Glycoproteins
3. Glycolipids
4. Integral proteins
120
What are tight junctions?
Binds cells together to prevent leakage of molecules in between them.
121
What are adherens junctions
Join actin bundle in one cell to a similar bundle in the other cell
- keeps cells to together
122
What are desmosomes
Attach cells via the intermediate filaments.
| - resists shearing forces
123
What are hemidesmosomes?
anchor intermediate filaments in a cell to the basal
| lamina
124
What is the function of gap junctions?
allows the passage of small water-soluble ions and
molecules
- electrical conduction
125
Name 3 mechanisms by which a molecule can move across a plasma membrane.
1. Diffusion - movement down a concentration gradient.
2. Facilitated diffusion.
3. Active transport - uses ATP, against a concentration gradient.
126
Describe the process of exocytosis?
Vesicle from the golgi apparatus, fuse with the plasma cell membrane, resulting in the
expulsion of waste or the secretion of enzyme/hormones
127
Which dietary energy source provides the most energy?
lipid (9kcal/g - gives the most energy per gram)
128
Define basal metabolic rate?
- amount of energy needed to keep the body alive in the
rest state.
- typically (24kcal/kg/day)
- requirement 0.8g/kg ideal body weight protein per day
129
What factors increase BMR?
Being overweight, pregnancy, low temperature, exercise, hyperthyroidism
130
What factors decrease BMR?
Increasing age, being female, starvation, hypothyroidism
131
How much energy is stored as triglycerides?
15kg
132
How much energy is stored as glycogen? And where is it stored?
350g
- 200g in the liver
- 150g in muscle
133
How much energy is stored as protein?
6kg
134
What are the products of glycolysis?
2 ATP, 2 NADH, 2 Pyruvate
135
What is the rate-limiting enzyme in glycolysis?
Phosphofructokinase-1
136
Where in a cell does glycolysis take place?
Cytoplasm
137
Describe the full process of glycolysis
-
138
Briefly describe what happens in anaerobic respiration.
NAD is regenerated from NADH. Pyruvate, from glycolysis, forms lactate. Lactate dehydrogenase catalyses this reaction. NAD goes back to glycolysis so ATP can be produced.
139
Name 3 allosteric inhibitors of PFK-1.
1. Acidosis.
2. ATP.
3. Citrate.
140
Name an allosteric activator of PFK-1
AMP
141
Where in a cell does the Krebs cycle take place?
The matrix of the mitochondria
142
Draw the Krebs cycle
-
143
Name 3 regulators of citrate synthase - Krebs cycle
- ATP Allosteric inhibitor
- NADH Allosteric inhibitor
- Succinyl CoA competitive inhibitor
- Increased citrate, increased inhibition
144
How does isocitrate dehydrogenase affect the rate of reaction
- Key rate-limiting step
- ICDH reduces concentration of citrate
- speeds up citrate synthase
145
Name 5 regulators of alpha-ketoglutarate dehydrogenase
- inhibited by its products
- NADH
- Succinyl CoA
- GTP
- ATP
- ROS
146
What is thought to activate alpha-ketoglutarate dehydrogenase?
Ca2+
147
What is the product of fatty acid beta-oxidation?
Acetyl CoA.
148
Where does oxidation of fatty acids occur
Inside the mitochondria
149
What is the importance of acylcarnitine?
It is required to transport fatty acids longer than 12 carbons into the mitochondria for beta-oxidation.
150
What occurs during the fatty acid beta-oxidation process?
sequential removal of 2-carbon units by oxidation at the
| beta-carbon position of the fatty Acyl-CoA molecule.
151
What is produced after each round of beta-oxidation?
1 mol of NADH, 1 mol of FADH2 & 1 mol of
Acetyl CoA.
- Acetyl CoA used in Krebs
- NADH/FADH2 used in oxidative phosphorylation
152
What is the difference in the fatty acid yield from 1 mol of glucose and 1 mol of fatty acid?
Fatty acid oxidation yields significantly more energy per carbon than the oxidation of glucose.
1 mol of glucose - 38 moles of ATP
1 mol of fatty acid - 146 moles of ATP
153
Why don't fatty acids act as a fuel source for the central nervous system
Fatty acids cannot get through the blood-brain barrier
154
Where does oxidative phosphorylation occur
At the inner membrane of the mitochondria
155
What is the role of the cytochrome-C oxidase complex in oxidative phosphorylation?
It transports H+ out of the mitochondrial matrix.
156
What transports H+ out of the mitochondrial matrix?
Cytochrome-C oxidase complex.
157
Name 4 ways in which ATP can be produced?
- Krebs cycle.
- Glycolysis.
- Oxidative phosphorylation.
- Substrate level phosphorylation.
158
Oxidative phosphorylation: What enzyme transports protons into the mitochondrial matrix?
ATP synthase.
159
Where does ketogenesis usually occur?
In the liver
160
Why does ketogenesis occur?
- high rates of fatty acid beta oxidation
- exceed the capacity of krebs cycle
- results in ketogenesis
161
When would ketogenesis occur?
During high rates of fatty acid oxidation, too much acetyl CoA is produced; this overwhelms the Krebs cycle and so you get ketone body formation
162
Briefly describe how diabetic ketoacidosis occurs?
- reduced supply of glucose
- leads to decline in insulin circulation
- increase fatty acid oxidation
- increased Acetyl-CoA leads to ketone body formation
- exceeds ability for tissues to oxidise them
- ketones are strong acids - lowers pH
163
List 3 causes of metabolic acidosis?
Renal failure, loss of HCO3-, excess H+ production.
164
List 2 causes of metabolic alkalosis.
Vomiting (loss of H+), increased reabsorption of HCO3-.
165
What enzyme of glycolysis is inhibited in acidosis?
Phosphofructosekinase-1 (PFK-1 is pH dependent).
166
Name 3 allosteric inhibitors of PFK-1.
1. Acidosis.
2. ATP.
3. Citrate.
167
Lipids have hydrophobic and hydrophilic parts. What is this called?
Amphipathic.
168
State the ideal pH with ranges of blood
ideal pH 7.4 ( 7.35-7.45)
169
What occurs in the first week of embryonic life?
Fertilisation and formation of the blastocyst [F for first =
| fertilisation]
170
What occurs in the second week of embryonic life?
Implantation and formation of bilaminar embryonic disc [2nd
| week = 2 = bilaminar]
171
What occurs in the third week of embryonic life?
Further development of the embryo and formation of trilaminar
embryonic disc [3rd week = 3 = trilaminar]
172
What occurs in the fourth week of embryonic life?
Folding of the embryo [F for 4th = F for folding]
| - from flat disk to cylinder
173
What occurs in weeks 5-8 of embryonic life?
Development of all the organs
174
What occurs at the end of the 8th week?
all organs have developed and the embryo looks like an
| adult and is called a foetus
175
What is the Morula?
Morula is a 16 cell structure arising from the fertilised ovum through mitosis
- floats freely in uterus, no nutrition as not implanted
176
When does the Morula enter the uterus?
3-4th day after fertilisation
177
When does implantation of the blastocyst occur?
end of the first week after fertilisation
178
What is the blastocyst composed of?
Inner cell mass - becomes the embryo
Trophoblast - becomes the placenta
179
What are the two spaces called that are present inside the blastocyst?
Amniotic cavity and yolk sac
180
as the embryo grows there is a slight folding on the caudal ectoderm what is this called?
primitive streak
181
What happens at the primitive streak?
The ectoderm cells break away and spill into the primitive streak under the ectoderm
182
Where are the two areas where the ectoderm and the endoderm are not separated by the mesoderm.
- - the oropharyngeal membrane - forms the opening of mouth
| - - The cloacal membrane - anus opening
183
What does the ectoderm form?
- PNS
- CNS
- Sweat glands
- Posterior pituitary
- Skin
- Hair
- Nails
- enamel of teeth
- lens of eyes
- sensory epithelium of nose, ear and eye
184
What does the endoderm form?
- Epithelial lining of the GI tract, respiratory tract and urinary bladder
- parenchyma of the thyroid gland parathyroid and liver and pancreas
- epithelial lining of the tympanic cavity and auditory tube
185
Name the three different components of the mesoderm?
- Paraxial plate mesoderm
- intermediate plate mesoderm
- lateral plate mesoderm
186
What does the paraxial plate mesoderm form?
- Somites which give rise to:
A. Myotome (muscle tissue)
B. Sclerotome (cartilage and bone)
C. Dermatome (dermis of the skin)
187
What does the intermediate plate mesoderm form?
Urogenital system
- gonads and respective duct systems
- kidneys
188
What does the lateral plate mesoderm form?
Two layers
1. Somatic (parietal) layer: forms the future body wall
2. Splanchnic (visceral) layer forms:
- Circulatory system
- Connective tissue for the glands
- Muscle, connective tissue and peritoneal components of the
way of the gut
189
Describe Cranial flexion
Brings the oropharyngeal membrane, the cardiogenic area and septum transversum ventrally and brings heart into thoracic position and septum transversum to the diaphragm
190
Describe caudal flexion
brings the
cloacal membrane onto the ventral
surface of the embryo
191
What occurs during lateral folding
```
- incorporation
of a portion of the yolk sac
(which is lined with
ENDODERM) into the embryo
to form the primitive gut
- It also leads to the formation of
body cavities
```
192
Describe the boundaries of the primitive foregut, midgut and hindgut
- Foregut: Extends from oropharyngeal membrane to the liver bud
- Midgut: from liver bud to the end of the right 2/3 of transverse colon
- Hindgut: from beginning left 1/3 of transverse colon to the cloacal
membrane
193
What is the name of the temporary connection between the yolk sac and the midgut?
Vitelline duct
