IMMS Flashcards
(189 cards)
1
Q
What is the structure of a chromosome? How many do humans usually have? How are they arranged?
A
- Each have a long arm (q) and a short arm (p),
separated by the centromere. - 46 chromosomes, arranged in 23 pairs.
2
Q
What is the name of the staining and technique used to identify and analyse chromosomes?
A
Giemsa staining, G banding.
3
Q
What are the two purposes of mitosis?
A
- Producing 2 daughter cells that are genetically identical to the parent cell.
- Growth and replacing dead cells.
4
Q
What are the phases of the cell cycle?
A
G1, synthesis phase, G2, mitosis.
5
Q
What are labile cells?
A
Cells that are constantly dividing.
6
Q
Why do the daughter cells of stem cells do majority of divisions?
A
To protect the genetic material of the stem cells.
7
Q
Where are the ‘checkpoints’ in the cell cycle?
A
End of G1, in G2 and in mitosis.
8
Q
What are the purposes of the ‘checkpoints’ in the cell cycle?
A
End of G1: sends a signal to tell cells to divide.
G2: can stop the cycle and even kill the cell if damage is detected.
Mitosis: check chromosomes have aligned properly.
9
Q
What are the five stages of mitosis?
A
Prophase, prometaphase, metaphase, anaphase, and telophase.
10
Q
What happens in prophase?
A
- Chromatin condenses -> chromosomes.
- Centrosomes nucleate microtubules.
- Centrosomes move to opposite poles of
nucleus.
11
Q
What happens in prometaphase?
A
- Nuclear membrane breaks down.
- Microtubules invade nuclear space.
- Chromatids attach to microtubules.
12
Q
What happens in metaphase?
A
- Chromosomes line up along equatorial plane.
13
Q
What happens in anaphase?
A
- Sister chromatids separate and are pulled to
opposite poles of the cell.
14
Q
What happens in telophase?
A
- Nuclear membranes reform.
- Chromosomes unfold into chromatin.
- Cytokinesis begins.
15
Q
How can mitosis be used to categorise tumours as benign or malignant?
A
- Shouldn’t be able to see mitotic figures as mitosis is
so fast. - Mitotic figures if visible should only be in particular
areas. - Many mitotic figures in many places = likely
malignant.
16
Q
How can mitosis be used to grade malignant tumours?
A
- Counting mitotic figures in a specified area.
- More figures = more aggressive tumour.
17
Q
What are three methods of stopping/attacking mitosis? What do each target?
A
- Taxol and vinca alkaloids: target mitotic spindle.
- Ispinesib: targets spindle poles.
- Colchicine-like drugs: target anaphase.
18
Q
What are the key differences in meiosis to mitosis?
A
- Two cell divisions.
- Four daughter cells rather than two.
- Not genetically identical, creating genetic diversity.
- Only in gametes.
19
Q
How is meiosis involved in sperm production? When does this occur?
A
- Meiotic divisions commence at puberty.
- After meiosis II: four equal gametes that can be
genetically different.
20
Q
How is meiosis involved in ova production? When does this occur?
A
- Meiosis I is completed at ovulation.
- Meiosis II only completed if fertilisation occurs.
21
Q
Describe the structure of DNA.
A
DNA molecule consists of two strands wound around each other to form a double helix structure, with each strand held together by bonds between the four bases.
22
Q
What are the four bases of DNA? Which are the pairs?
A
Ademine (A) with Thymine (T)
Guanine (G) with Cytosine (C)
23
Q
Roughly what percentage of DNA is coding DNA? Which part of DNA is coding DNA?
A
1.5%
Exons.
24
Q
What parts of DNA are non-coding?
A
Introns and promoters.
25
Which is the longest chromosome? Which is the shortest?
Longest = 1
Shortest = 22
26
Which chromosomes are Robertsonian?
13, 14, 15, 21, and 22.
27
What does it mean if a chromosome is Robertsonian?
They lack a short (p) arm.
28
What are the five types of chromosomal abnormalities?
- Deletion
- Duplication
- Extra chromosome
- Missing chromosome
- Translocation
29
What does it mean if a gene is 'dosage sensitive'?
An imbalance caused by deletion or duplication would cause human disease.
30
What is the difference between balanced and unbalanced translocation? Do either cause disease?
Balanced -> no loss of genetic material -> healthy.
Unbalanced -> loss/gain of genetical material -> human disease.
31
What is trisomy? Give an example of a condition caused by it, and which chromosome causes this condition?
- Trisomy is the presence of an extra chromosome.
- Caused by failure of chromosome pairs to separate
in meiosis I, or failure of sister chromatids to
separate in meiosis II.
- If chromosome 21 is affected, this causes down
syndrome.
32
What are some key signs of down syndrome?
- Learning problems.
- Short stature.
- Congenital heart disease.
- Characteristic facial appearance.
33
How many genomes does the human body have? What are these called?
3. Germline, somatic, and mitochondrial.
34
Which genomes in the human body are heritable? Which is not?
Germline and mitochondrial are heritable.
Somatic is not heritable.
35
Where are germline cells found?
In the sperm/eggs.
36
Where are somatic cells found?
Connective tissue, skin, blood, bones and internal organs
37
Where are mitochondrial cells found?
In the mitochondria.
38
What is mutagenesis?
An alteration to the genomic code by exposure to a substance e.g. carcinogenesis.
39
What is teratogenesis?
A damaging effect on embryonic/fetal development by exposure to a substance.
Some teratogens are also mutagens.
40
Describe malformation.
Intrinsic issue with development of an organ/tissue, commonly genetic.
41
Describe deformation.
Extrinsic factors implying upon development, less commonly genetic.
42
In what state does autosomal dominant inheritance cause disease?
Heterozygous state - one gene with variant, one 'normal' gene.
43
Is autosomal dominant inheritance gain of function or loss of function?
Gain of function.
44
Who is affected by autosomal dominant diseases? (Genders and generations).
- Males and females, transmitted by both sexes to both sexes.
- Affects multiple generations.
45
What is the recurrence risk for autosomal dominant inheritance?
1/2
46
Define pentrance.
% of individuals who have a variant of a certain gene and develop a medical condition because of it.
47
Define age related penetrance.
% of individuals who have a variant of a certain gene and develop a medical condition at a given age.
48
Describe variable expressivity. Give an example of a condition.
- People with the same gene variant can have a range
of symptoms.
- Neurofibromatosis type 1: most only have skin
signs, small % have epilepsy and learning problems.
49
What is anticipation?
The condition manifests in successive generations earlier or with more severe symptoms.
50
What is a De Novo Mutation?
The genetic variant occurs in the sperm or egg, therefore an unaffected parent has a child with a condition.
51
In what state does autosomal recessive inheritance cause disease?
Homozygous state - genetic variant in both copies of a gene.
52
Is autosomal recessive inheritance gain of function or loss of function?
Loss of function.
53
Who is affected by autosomal recessive diseases? (Genders and generations).
- Males and females, parents can be related.
- Affects a single generation.
54
What is the recurrence risk for autosomal recessive inheritance?
1/4
55
What is the probability of a healthy sibling of an affected child being a carrier?
2/3
56
What is the most common recessive condition affecting the Northern European population? What is the carrier frequency?
Cystic fibrosis.
1/25
57
Who is affected by X-linked recessive inheritance?
Males are affected, females are unaffected carriers.
58
Who is affected by X-linked dominant inheritance?
Both males and females.
Females generally less severely.
59
What is it called if an affected man has an affected son?
Male-male transmission.
60
What does male-male transmission in a family tree rule out in terms of inheritance?
The condition cannot be X-linked.
61
If a father has an X-linked condition and the mother is unaffected, what will this mean for his children?
All his sons will be unaffected - Y chromosome.
All his daughters will be carriers.
62
If a father is unaffected and the mother is a carrier of an X-linked condition, what will this mean for her children?
50% of sons will be affected.
50% of daughters will be carriers.
63
What causes duchenne muscular dystrophy, what is it, and who does it affect?
- Mutation in the dystrophin gene on the X-
chromosome.
- Absence of dystrophin protein in skeletal
muscle.
- Causes limb weakness in males.
64
What part does gonadal mosaicism play in duchenne muscular dystrophy?
Dystrophin mutation only found in the ovary, not in blood DNA of mother.
65
What is lyonization and how does it cause disease?
Random X-inactivation, happens in females.
If the 'healthy' X is inactivated more than the mutated X -> disease.
66
What happens if a female with the dystrophin gene has skewed X-inactivation?
If the healthy X-chromosome is inactivated more than the mutated X-chromosome, the female could show limb weakness.
67
What is multifactorial inheritance?
Genetic risk and environmental exposure combine to increase chance of disease.
This combination can be called liability, which can be used to form a normal distribution.
68
Who has the highest risk of multifactorial inheritance?
Family members > general population.
First degree relatives > other relatives.
69
Give three examples of conditions that are caused by multifactorial inheritance?
- Schizophrenia.
- Diabetes.
- Neural tube defects e.g. spina bifida.
70
Compare gonadal/germline mosaicism with somatic mosaicism.
- Gonadal mosaic: some gametes have a
genetic variant, some do not.
- Somatic mosaicism: some tissues have a
genetic variant and some do not.
71
What causes symptoms of mitochondrial disease?
Mitochondria produce ATP, a lack of ATP = a lack of drive for cellular functions = symptoms.
72
What is the different between homoplasmy and heteroplasmy?
- Homoplasmy - all mitochondria in a cell
have the same genetic code.
- Heteroplasmy - a proportion of
mitochondria in a cell has a genetic
variant.
73
What increases the chance of a mitochondrial disease?
Greater proportion of mutant mitochondria.
74
Who can/cannot transmit mitochondrial diseases to their children? Why?
- Only affected mothers can transmit
mitochondrial diseases to their children,
as all our mitochondria are derived from
our mother.
- Therefore, affected males cannot have an
affected child.
75
What causes leber's optic neuropathy, what are the affects, and who is affected?
- Caused by mutations in mitochondrial
DNA which encode complex 1 (ATP
production).
- Thins the optic nerve -> gradual onset of
painless visual loss.
- Males more likely to be affected.
76
What is imprinting? How can it cause disease?
- When the maternal or paternal copy of a
gene is 'switched-off' it is an imprinted
gene.
- Deletion of copies alongside imprinting
causes disease as there is no functioning
gene.
77
Give two example of imprinting disorders, their symptoms, and which copy of gene at which chromsome has been deleted?
Prader-willi syndrome:
- Floppy baby, learning problems, obesity.
- Paternal gene at chromosome 15p.
Angelman syndrome
- Below average size, epilepsy, learning
problems.
- Maternal gene at chromosome 15p.
78
What is a SNP? What is the difference between a synonymous and non-synonymous SNP?
- SNP = single nucleotide variant. A genomic
variant at a single nucleotide in DNA.
- Synonymous = no alteration to the protein.
- Non-synonymous = alters protein.
79
What is a missense mutation? What effects can this have? Give an example.
Altering of one amino acid, if this has very different chemical properties to normal amino acid, there can be a significant change in the proteins function.
E.g. haemoglobin, glutamate -> valine, changed shape and strength of haemoglobin.
80
What is an in-frame insertion/deletion? What is an out-of-frame insertion/deletion?
In-frame: multiple of 3 nucleotides inserted/deleted, loss/gain of a single amino acid.
Out-of-frame: not a multiple of 3 nucleotides inserted/deleted, leads to premature formation of STOP codon.
81
What is trinucleotide repeat expansion? What does it cause? Give an example of a disease caused by this.
- Abnormal repetition of a set of 3 nucleotides.
- Forms an elongated, toxic mRNA which resists
degradation.
- E.g. Huntington's disease: CAG repeat unit
82
What are copy number variants? Which type is more harmful?
- Deletion or duplication of a segment of a
chromosome, ranging from affecting a single
exon to hundreds of genes.
- Deletions are more harmful.
83
What can comparative genomic hybridisation detect?
Copy number variants involving single exons.
84
What is the difference between exome and genome sequencing?
Exome: exons and some splice sites.
- Misses non-coding variants and trinucleotide
repeats.
- Cover ~1% of genome.
Genome: exons, promotors/enhancers, splice sites, trinucleotide repeats: EVERYTHING.
- Can detect copy number variants.
- Covers ~95% of genome.
85
What suggests a variant is pathogenic?
- De novo mutation in the affected offspring.
- Variant found in several people in the family
who have the disease.
- Absence of single nucleotide variant from
‘healthy’ population.
- Computational tools predict damaging effect.
86
What suggests a variant is benign?
- Variant is found in an unaffected parent.
- Variant is found commonly in healthy
populations.
- Computational tools predict the variant has no
effect on gene function.
87
Define metabolism.
The sum of the chemical reactions that place within each cell, in a sequence.
88
What are the two categories of metabolism? Which pathways belong to such?
Anabolic: synthesise larger molecules from smaller components.
- Biosynthetic.
- Fuel storage.
Catabolic: breaks down larger molecules into smaller components.
- Oxidative processes.
- Waste disposal.
89
What are the dietary components?
Fuels, essential amino acids, essential fatty acids, vitamins, minerals, water, and xenobiotics.
90
What is a healthy BMI?
18.5 -> 24.9kg/m^2
91
How do we store excess diary fuels? What can excess fuel storage cause?
Fat -> adipose tissue.
Carbohydrate -> glycogen in liver and muscle.
Protein -> muscle.
Excess fuel stored -> obesity.
92
What is basal metabolic rate? How does this differ from resting metabolic rate?
BSR is the energy needed to stay alive at complete rest, however conditions of such are unrealistic, hence RMR, which is ~30% higher.
93
Which factors lower BMR/RMR?
- Being female.
- Aging.
- Dieting/starvation.
- Decreased muscle mass.
94
Which factors raise BMR/RMR?
- Body weight.
- Hyperthyroidism.
- Low ambient temperature.
- Fever/infection/chronic disease.
95
How do you roughly calculate BMR?
~1 kcal/kg/body mass/hour.
96
Define malnutrition.
A state of nutrition with a deficiency, excess or imbalance of energy, protein or other nutrients. Causes measurable adverse effects.
97
What is the prudent diet?
- 5+ servings of fruit/vegetables.
- Meals based on starchy carbohydrates.
- No more than 5% energy from free sugars.
- 0.8g/kg/day protein.
- No more than 30g/day saturated fat for men,
and 20g/day for women.
- No more than 2.4g/day sodium (6g salt).
- No more than 14 units alcohol/week.
- Adequate calcium.
98
What are the essential vitamins?
- Vitamin C: ascorbic acid.
- Vitamin B12: cobalamin.
- Vitamin A: retinol
- Vitamin D: calciferol
- Vitamin E: tocopherol
- Vitamin K: phylloquinone, menaphthone.
- Vitamin B1: thiamin.
- Vitamin B2: riboflavin.
- Vitamin B3: niacin.
- Vitamin B5: pantothenic acid.
- Vitamin B6: pyridoxine.
- Vitamin B7: biotin.
- Vitamin B9: folate.
99
What happens due to overnight fasting?
- Insulin secretion decreases -> glycogenolysis.
- Glycogen in the liver is broken down to glucose for the brain (needs 150g/day).
100
What occurs after fasting for less than 4 days but longer than simply overnight?
-Gluconeogenesis.
- Insulin secretion decreases, cortisol secretion increases.
- Glucose produced by breakdown of lactate, amino acids, and glycerol.
101
What happens if the body is starved for >4 days?
- Liver creates ketones from fatty acids.
- Brain adapts to using ketones.
- BMR falls to accommodate.
102
What is a monosaccharide?
Carbon chain, hydroxyl group/s, and a carbonyl group.
103
What is a polysaccharide?
Formed by thousands of monosaccharides joined by glycosidic bonds.
104
What is a proteoglycan?
Long, unbranched polysaccharide radiating from a core protein, forming a matrix.
105
What are the properties of peptide bonds?
- Very stable.
- Broken up by proteolytic enzymes
(proteases or peptidases).
- Partial double bond.
- Flexibility around Cs allow multiple
conformations.
- Usually a preferred native conformation.
106
What forces hold proteins together?
- Van der Waals forces.
- Hydrogen bonds.
- Hydrophobic forces.
- Ionic bonds.
- Disulphide bonds.
107
How do we determine protein structure?
- X-ray diffraction of protein crystals.
108
Describe primary structure of proteins.
Linear sequence of amino acids in the peptide chain.
109
Describe secondary structure of proteins.
Made up of alpha-helices and beta-sheets, stabilised by non-covalent bonds.
110
Describe tertiary structure of proteins.
Total 3D structure of the polypeptide, involves a range of forces, conformations can change with pH.
111
Describe quaternary structure.
Aggregation of several polypeptides into a single structure, a multimeric protein.
112
What do chaperone proteins do?
Assist proteins in reaching their conformation after translation.
113
How many subunits make up haemoglobin?
Four -> two alpha and two beta chains.
114
What are enzymes? What do they do?
- Biological catalysts.
- Bind to reactants, convert them into
products, release products, return to their
original form.
- Speed-up or regulate the rate of reactions.
- Can be used as disease markers.
115
What are antibodies? When are they produced?
- Protectors of our health, bind to antigens.
- Produced by specialised cells in response
to a foreign substance.
116
Define homeostasis. Give examples.
- Maintenance of a constant internal
environment.
- Temperature, blood oxygen, glucose.
117
Define hormones.
Molecules that act as chemical messengers.
118
Describe amino-acid hormones. Give an example.
- Synthesised from tyrosine.
- Produces a quick reaction.
- E.g. adrenaline.
119
Describe peptide hormones. Give an example.
- Made of amino-acid chains.
- Vary in size, some have carbohydrate side
chains.
- Hydrophilic.
- Produce a quick reaction.
- E.g. insulin.
120
Describe steroid hormones. Give an example.
- All made from cholesterol.
- Insoluble in water and lipids.
- Produces a slow reaction.
- E.g. testosterone.
121
What are the endocrine organs and glands?
- Hypothalamus.
- Pituitary.
- Thyroid.
- Adrenals.
- Pancreas.
- Ovaries.
- Testes.
122
What do positive feedback loops do? When are they used?
- Amplify a signal, moving a system away from
its starting state.
- Usually used when a process needs to be
pushed to completion e.g. childbirth.
123
What do negative feedback loops do? When are they used?
- Counteract changes to maintain a state,
opposing a stimulus.
- More common in homeostasis.
124
Describe the water distribution in a 70 kg male.
- Total body water = 42L (60%)
- Intracellular fluid = 28L (40%)
- Extracellular fluid = 14L (20%)
- Intravascular = 3L
- Interstitial = 11L
125
What happens in sickle cell disease to haemoglobin? Why does this happen? What effects does this have?
Haemoglobin changes shape from flexible discs -> rigid crescents because the protein has a mutation that changes the amino acid glutamate (hydrophilic) -> valine (hydrophobic).
This means they can't carry oxygen as well, and can also block blood vessels, this can cause sickle cell crises.
126
Describe how the information on DNA is used during transcription and translation to construct polypeptides.
- Transcription: two strands of DNA separate
temporarily, and one strand is used as a DNA
template for RNA to be synthesised from. RNA
polymerase catalyses this reaction.
- Translation: anticodon on tRNA pairs with the
complimentary codon on mRNA. Two tRNA fit
on the ribosome at one time, the peptide bond
is formed between their amino acids, requiring
ATP - provided by the mitochondria. The
ribosome moves along the mRNA ‘reading’ the
next codon (in a 5’ → 3’ direction), tRNAs are
released without their amino acid after a
peptide bond has been formed.
- mRNA carries the genetic code to the
cytoplasm controlling the type of protein
formed. tRNA binds to and transports activated
amino acids to the ribosomes to be used in
assembling the protein molecule during
translation.
- This continues until a ‘stop’ codon on the
mRNA molecule is reached - signal for
translation to stop, the amino acid chained
formed then creates the final polypeptide.
127
Describe the replication of retroviruses.
- Retrovirus enters the host cell.
- Reverse transcriptase converts the retroviral
RNA genome -> double-stranded DNA.
- This viral DNA migrates to the nucleus and
becomes integrated into the host genome.
- Viral genes are transcribed and translated.
- New virus particles assemble, exit the cell, and
can infect another cell.
128
What is PCR? What is it used for?
- It is an in-vitro method of DNA amplification.
- Used to produce large quantities of specific
DNA/RNA fragments from very small
quantities.
129
What is needed for PCR?
- Target DNA/RNA.
- Primers (forward and reverse).
- DNA polymerase.
- Free nucleotides.
- Buffer solution.
130
What are the three steps of PCR? What temperatures are needed for each?
1. Denaturing - 95 degrees C
2. Annealing - 55 degrees C
3. Elongation - 72 degrees C
131
What is recombinant DNA technology?
Transferring fragments of DNA from one organism/species -> another organism/species. Results in a GMO containing recombinant DNA.
132
What are the five steps of recombinant DNA technology?
- Identification of the DNA fragment.
- Isolation of the desired DNA fragment.
- Multiplication of the DNA fragment using PCR.
- Transfer into the organism using a vector e.g.
plasmids, viruses, liposomes.
- Identification of the cells with the new DNA
fragment, by using a marker, which is then cloned.
133
What is needed for recombinant DNA technology?
- Enzymes.
- Vectors.
- Markers.
134
Describe extracellular fluid (ECF).
- Sodium is main contributor to osmolality and
volume.
- Anions chloride and bicarbonate.
- Glucose and urea.
- Protein = collard osmotic pressure (oncotic).
135
Describe intracellular fluid (ICF).
Predominant cation is potassium.
136
How do you estimate plasma osmolality?
2[Na] + 2[K] + urea + glucose mmol/L.
137
What are some causes of water depletion?
- Reduced intake.
- Sweating.
- Vomiting.
- Diarrhoea.
- Diuresis/diuretics.
138
What are some symptoms of dehydration?
- Thirst.
- Dry mouth.
- Inelastic skin.
- Sunken eyes.
- Raised haematocrit.
- Weight loss.
- Confusion (brain cells).
- Hypotension.
139
What are the consequences of water excess?
- Hyponatraemia.
- Cerebral overhydration.
- Headache.
- Confusion.
- Convulsions.
140
What is hydrostatic pressure? Which direction does water move?
- Pressure difference
between plasma and
interstitial fluid.
- Water moves from
plasma -> interstitial fluid.
141
What is oncotic pressure? Which direction does water move?
- Pressure caused by
difference in protein
concentration between
the plasma and interstitial
fluid.
- Water moves from
interstitial fluid -> plasma.
142
What is osmotic pressure?
The minimum pressure that must be applied to a solution to halt the flow of solvent molecules through a semipermeable membrane (osmosis).
143
What is oedema?
Excess accumulation of fluid in an interstitial space which can cause inflammation.
144
What is serious effusion?
Excess water in a body cavity e.g. lungs.
145
What causes inflammatory oedema?
Increased capillary permeability.
146
What causes venous oedema?
Increased hydrostatic pressure.
147
What causes lymphatic oedema?
Issues with the lymphatic system and drainage.
148
What causes hypoalbuminaemic oedema?
Less plasma proteins, especially albumin.
149
How much fluid does the pleural space normally contain?
~ 10 mL.
150
Why do pleural effusions occur?
When the balance between; hydrostatic and oncotic forces in the visceral and parietal pleural vessels, and lymphatic drainage, is disrupted.
151
What are the two types of fluid that can enter the pleural cavity during pleural effusion?
- Transudate: fluid pushed
through the capillary due
to high pressure.
- Exudate: fluid that leaks
around the cells of the
capillaries due to
inflammation and
increased permeability of
capillaries.
152
How can you differentiate between exudative and transudative effusions?
- Measure the pleural fluid
protein.
- High protein = exudative.
- Low protein =
transudative.
153
Give 3 examples of conditions that cause exudative pleural effusions?
- Malignancy.
- Pneumonia.
- Tuberculosis.
154
Give 3 examples of conditions that cause transudative pleural effusions?
- Cirrhosis.
- Nephrotic syndrome.
- Congestive heart failure.
155
What is the reference range of plasma sodium?
135-145mmol/L.
156
What normally causes high/low [Na]?
Loss or gain of water.
157
Describe hypernatraemia and its symptoms?
High sodium concentration -> cerebral intracellular dehydration -> tremors, irritability, confusion
158
Describe hyponatraemia and its symptoms?
Low sodium concentration -> cerebral intracellular overhydration -> headache, confusion, convulsions.
159
What can cause hypernatraemia?
- Water deficit
- Sodium excess
160
What can cause hyponatraemia?
- Artefactual (false/pseudo)
- Sodium loss
- Excess water
161
What does the renin-angiotensin-aldosterone system do?
RAAS is a regulator of blood pressure (BP) and fluid balance.
162
What is the normal plasma osmolality?
275-295 mmol/kg.
163
How do cells obtain energy?
From nutrients or fuels.
164
What is ATP?
Adenosine triphosphate.
Currency of metabolic energy.
High-energy molecules composed of adenine, ribose, and three phosphate groups.
165
What is ADP? How does the ATP-ADP cycle work?
Adenosine diphosphate.
ATP -> ADP + Pi = energy released with loss of a phosphate group
ADP + Pi -> ATP = requires energy
ATP -> ADP favourable due to -ve Gibbs free energy.
166
How do cells generate energy from nutrients?
1. Glycolysis
2. Krebs cycle
3. Oxidative phosphorylation
167
Where does glycolysis occur? Why does it occur?
Cytosol under anaerobic conditions.
Emergency energy producer when oxygen is limiting.
Generates precursors to biosynthesis.
168
What are the two types of regulation of glycolysis?
Allosteric and hormonal.
169
Describe allosteric regulation of glycolysis.
- Regulatory molecules binds to a non-
catalytic site.
- Conformational change.
- Increases of decreases affinity for the
substrate.
170
Describe hormonal regulation of glycolysis.
- Insulin and glucagon.
- Increases or decreases gene expression of
the enzyme.
- Indirect route through affecting regulatory
molecules.
- Increases or decreases enzyme activity.
171
Describe recovery.
Muscle produces ATP by glycolysis for rapid contraction.
Liver uses ATP in gluconeogenesis during recovery.
172
Where does the Krebs cycle occur? Why does it occur?
In the mitochondrial matrix, under aerobic conditions.
Generates lots of energy (ATP).
Final common pathway for oxidation of carbs, fat and protein via acetyl CoA.
Produces intermediates for the synthesis of amino acids, glucose, heme etc.
173
Where does oxidative phosphorylation occur? Why does it occur?
In the inner mitochondrial membranes, under aerobic conditions.
Releases majority of energy during cellular respiration.
Reduced NADH or FADH2 are oxidised, electrons -> electron transport chain (ETC) -> final electron acceptor = O2.
Energy released is trapped to generate ATP.
174
What are the sources of energy in the body?
- Carbohydrates.
- Fats.
- Protein.
175
Describe fatty acids.
Carboxylic head group (hydrophilic) and aliphatic tail (hydrophobic), can vary in length.
Saturated and unsaturated.
Most derived from triglycerides and phospholipids.
176
What type of patients suffer with ketoacidosis?
Insulin-dependant diabetics.
Chronic alcohol abusers.
Patients starving.
177
How does ketoacidosis present?
Hyperventilation and vomiting.
178
What is a consequence of ketoacidosis?
Ketones = strong acids, therefore pH of blood is lowered, impairs ability of haemoglobin to bind oxygen.
179
Describe the utilisation of acetyl-CoA.
Normally, most is used via Krebs cycle to produce glucose.
Small proportion converted into ketones.
High rate of fatty acid oxidation -> large amounts of acetyl-CoA -> too much for Krebs -> ketogenesis.
180
What can modify the phospholipid bilayer's fluidity?
- C=C bonds.
- Cholesterol.
- Temperature.
181
What is the phospholipid bilayer freely permeable to?
- Water.
- Gases (CO2, N2, O2).
- Small uncharged polar molecules (ammonia,
urea, ethanol).
182
What is the phospholipid bilayer impermeable to?
- Ions (Na+, K+, Cl-).
- Charged polar molecules (ATP, glucose-6-
phosphate).
- Large uncharged polar molecules (glucose).
183
What are the three main types of membrane protein transport carriers?
- Uniport.
- Antiport.
- Symport.
184
Describe a uniport carrier.
- Moves a single substance.
- E.g. glucose via glut-1.
- Passive.
185
Describe an antiport carrier.
- Carries two substances in opposite directions.
- E.g. 3Na+/2K+ ATPase.
- Energy from ATP hydrolysis.
186
Describe a symport carrier.
- Moves two or more
substances in the same
direction.
- Na+/Glc nutrient transport.
- Energy indirectly from ATP
hydrolysis.
- Ion gradient used.
187
Give 6 examples of membrane transport.
- Simple diffusion.
- Facilitated diffusion.
- Primary active transport.
- Secondary active transport.
- Ion channels
- Pino/phagocytosis.
188
What is a cell?
A fundamental functional unit of tissue.
189
What is a cell made up of?
Nucleus, cytosol, plasma membrane, lysosomes, mitochondria, microtubules, ribosomes, Golgi body, smooth endoplasmic reticulum, and rough endoplasmic reticulum.
