Extra IMMS Flashcards
What are the net products of Glycolysis?
2 PYRUVATE, 2ATP AND 2NADH
What does a kinase enzyme do?
- enzyme that adds/removes phosphate group to things from/to an ATP
What are the basic steps of Glycolysis?
Gross - Glucose Guys - Glucose 6 phosphate Favour - Fructose 6 phosphate Big Butts - Fructose 1-6 Biphosphate Good - Glyceraldehyde 3 Phosphate (G3P) Boys - 1-3 Bisphosphate Prefer - 3 Phosphoglycerate PrettyGirlsIn - 2 Phosphoglycerate Pink - Phosphoenolpyruvate Pyjammas - Pyruvate
What is the enzyme to catalyse the first reaction of glycolysis?
Hexose Kinase in the rest of the body, but Glucose Kinase in the Liver!
What are the two energy consuming steps of Glycolysis
The first step:
Glucose ==> Glucose 6 Phosphate (Hexose Kinase in the rest of the body, but Glucose Kinase in the Liver!) ATP => ADP +Pi
And the third step:
Fructose 6 phosphate ==> Fructose 1,6 Bisphosphate (Phosphofructokinase 1 /PFK1) ATP => ADP +Pi
What is the 3rd step of glycolysis? What is the significance of it?
- Fructose 6 phosphate ==> Fructose 1,6 Bisphosphate (Phosphofructokinase 1 /PFK1) ATP => ADP +Pi
This also irreversible = it is the rate limiting step - the rate at which this happens determines the rate of Glycolysis
What are the regulators of glycolysis?
Insulin
Glucagon
Glucose 6 phosphate (the first product)
Phosphofructoskinase-1
Define Allosteric
modifies the active site of the enzyme, changing its affinity for the substrate
What are to two energy generating steps of glycolysis?
The 6th step:
1-3 Biphosphoglycerate ==> 3 Phosphoglycerate (Phosphoglycerate Kinase) THIS STEP GENERATES 2 ATP
The last (9th) step: Phosphoenolpyruvate ==> Pyruvate (Pyruvate Kinase) THIS STEP GENERATES 2 ATP
How does Insulin effect Glycolysis?
increases the rate of Glycolysis, by increasing PFK 1
How does Glucagon effect Glycolysis?
Decreases levels of PFK 1
How does Glucose 6 Phosphate affect Hexose Kinase enzyme (the enzyme in the 1st step) effect Glycolysis?
- The Higher the concentration of Glucose 6 Phosphate (its product), the lesser the activity of the enzyme Hexokinase to make more of it!
- so more glucose (makes sense)
- –> this is the minor regulator
How can phosphofructokinase be affected, and how does this affect glycolysis? (enzyme in the 3rd step)
Energy/phospate
a. Allosterically effected (stimulated) by AMP ==> More AMP = More PFK action
b. Allosterically Inhibited by ATP, and Citrate==> More ATP and citrate = Less PFK action
How does AMP effect PFK-1?
It Allosterically effects/stimulates PFK-1, so more AMP = More PFK action
How does ATP effect PFK-1?
It allosterically inhibits PFK-1, so more ATP = Less PFK action
What is the irreversible step of Glycolysis?
Step 1, 3, 9
hexokinase; phosphofructokinase;
pyruvate kinase.
(New enzymes are needed to catalyze new reactions in the opposite direction for gluconeogenesis.)
How does Citrate effect PFK-1?
It allosterically inhibits PFK-1, so more citrate = Less PFK action
If in anaerobic conditions, and the NADH and pyruvate can’t enter the Krebs cycle, what will happen to them?
They will form Lactate and NAD+, as well as little more ATP. This needs to happen so Glycolysis can continue, so NAD+ can go back to accepting H+
In Glycolysis, What step generates NADH?
Glyceraldehyde 3 Phosphate (G3P) => 1,3 Bisphoglycerate,
By enzyme G3P Dehydrogenase
In order to undergo beta oxidation, what do Fatty acids get converted to in the cytoplasm?
Fatty acids ==> Acyl Adenylate ==> Acyl CoA (by acyl CoA synthase)
In order to cross the outer membrane of the mitochondria to get into the intermembrane space, what happens to Acyl coA? What enzyme catalyses this?
becomes acyl carnitine (by carnitine acyltransferase 1 –CAT1), as part of the CARTNITINE SHUTTLE
what happens once acyl carnitine has crossed into the intermembrane space?
- Acyl carnitine is reformed to acyl coA (by carnitine acyltransferase 2 – CAT2)
- On the interior side of the membrane, in the matrix
the carnitine is recycled
What happens to Acyl coA once it is now in the intermembrane space?
Once acyl coA has crossed the membrane it can now be oxidised
This involves the sequential removal of 2 carbon units by oxidation – the second (hence beta) carbon is cleaved
What does one round of beta oxidation produce?
Each round of beta oxidation produces 1NADH, 1FADH2 and 1 acetyl coA
Define Nucleotide
What is an Nucleoside?
a compound consisting of a nucleoside linked to a phosphate group. Nucleotides form the basic structural unit of nucleic acids such as DNA.
A nucleoside is a Pentose Sugar and a BASE
Define a single nucleotide polymorphism
SNP= DNA sequence variation that occurs at a single nucleotide
What cells produce elastin?
Fibroblasts
Where is renin produced?
Juxtaglomerular (grannular cells) cells in the kidney
Where is ADH produced?
Where is it secreted?
The Hypothalamus
The Posterior Pituitary gland
What does Renin do?
Renin converts angiotensinogen into angiotensin I
Which 2 proteins are involved in the generation of ciliary movement
Tubulin and dynein are involved in the generation of ciliary movement
Tubulin is a microtubule (25nm)
What is a gene sequence coded in?
A gene sequence is coded in single strand DNA
What is a promoter sequence? What is it coded in?
This area of DNA indicates the starting point of transcription, and there may be multiple promoter sequences within a DNA molecule. It is what mRNA recognises and where it starts.
It is coded in single strand DNA
What is the transcriptome composed of?
The transcriptome is composed of all the RNA present in the cell
During transcription, what do specific amino acids bind to?
Amino acids bind to tRNA
What is the structure of Haemoglobin?
2 alpha and 2 beta polypeptide chains
What type of inheritance pattern is seen with sickle cell disease?
Autosomal recessive.
A mutation in what gene results in HbS production?
what chain is involved?
HBB gene.
The beta globin chain
What does the Sickle cell disease single nucleotide polymorphism result in?
an amino acid replacement at position 6 in the beta-globin chain from glutamic acid to valine. This results in sickled haemoglobin (HbS).
Under physiological stress, what happens to sickled haemoglobin?
eg hypoxia, cold temperature, dehydration, acidosis
sickled haemoglobin (HbSS) polymerises and causes erythrocytes to deform into a sickled shape, and crystallises
Define non disjunction
occurs when homologous chromosomes fail to separate in M1 OR
sister chromatids fail to separate in M2.
Define gondal mosaicism
occurs when precursor
germline cells to ova or spermatozoa involve a mixture of 2 or more genetically
different cell lines- this may occur due to random mutation in the germline cells that
undergo mitosis leading to mutated gametes, or due to errors in mitosis during
gametogenesis; the result is such that one cell line is normal and the other is
mutated.
By which process is ATP formed during glycolysis?
In glycolysis, ATP is formed by substrate level phosphorylation
what are the 3 types of Cytoskeletons? What are their respective sizes?
Microtubules - 25nm
Intermediate Filaments - 10nm
Microfilaments - 5-7nm
Give an example of each of the 3 types of cytoskeletons
Microtubules - eg Tubulin, used in Mitosis, found in cilia along with Dynein
Intermediate Filaments - help remain Cell integrity and cell to cell contact - seen in Desmosomes eg Nuclear laminin - in nuclei of all cells
Microfilament - eg Actin seen in Adheren junctions,
ACTIN forms a bracing mesh (cell cortex) on the inner
surface of the cell membrane
Where does the Krebs cycle occur?
The Mitochondrial matrix
Why is glycolysis inhibited in acidic conditions?
Because PFK-1 enzyme is inhibited by acidic conditions
Why can the krebs cycle only take place in aerobic conditions?
since oxidative
phosphorylation is required to covert NADH & FADH2 back to NAD+ and FAD to be used in the conversion of isocitrate to a-ketoglutarate
Outline the link reaction
Pyruvate ==> Acetyl CoA + CO2, and NADH
Briefly outline the Krebs cycle
Acetly CoA enters, becomes Citrate Isocitrate A-ketoglutarate Succinyl CoA Succinate Fumarate Malate Oxaloacetate Citrate again
What are the rate limiting substances in the krebs cycle?
Citrate Synthase
Citrate
a-ketoglutarate dehydrogenase
Calcium
How can citrate synthase be inhibited?
○ can be Allosterically inhibited By ATP and NADH
Can be competitively inhibited by Succinyl CoA
Slows Down
What affect does Citrate have on the krebs cycle?
Inhibits PFK1 , a key enzyme in Glycolysis, which would therefore reduce production of Pyruvate
Slows Down
What affect does a-ketoglutarate dehydrogenase have on the krebs cycle?
Its products - (Succinyl CoA and NADH) will inhibit this enzyme
What affect does Calcium have on the Krebs cycle?
Stimulates the Link reaction, so accelerates the TCA
Speeds up
What effects will high levels of ATP, NADH and FADH2 have on the Krebs cycle?
What about ADP?
High levels inhibit the Krebs Cycle
Conversely, it is activated by high ADP levels
What happens if the krebs cycle is inhibited?
there is a build up of acetyl coA and this undergoes fatty acid synthesis
Where does CO2 and NADH first get produced during a turn of the krebs cycle?
When isocitrate becomes a-ketoglutarate
Under action of isocitrate dehydrogenase enzyme
Explain DENA, DENA , A, FA, WA NA
CO2 and NADH (off Isocitrate)
CO2 and NADH (off a-ketoglutarate)
ATP(/GTP) off Succinyl CoA
FADH2 (off Succinate)
Water IN (to convert Fumarate to malate)
NADH (off Malate) when going to Oxaloacetate
What are the products of one turn of the Krebs cycle
3 NADH (3ATP each) 1 FADH2 (2ATP) 1 GTP (1ATP)
= 12 ATP
Where does Oxidative phosphorylation take place?
the inner membrane of the mitochondria
How many complexes are there?
Which one removes electrons from NADH and Which from FADH2
4 complexes
Complex I – removes electron from NADH
Complex II – removes electrons from FADH2 in the presence of co enzyme Q (ubiquinone)
What is needed in order to remove electrons from FADH2?
co enzyme Q (ubiquinone), at complex 2
What are the electrons finally transferred to? What does this form?
electrons are finally transferred to molecular oxygen, which then combines with hydrogen ions (protons) to form water.
What does the energy generated from ETC do?
cytochromes to pump hydrogen ions
from the matrix into the intermembranal space - the compartment between the inner
and outer mitochondrial membranes
• This creates a source of potential energy in the form of a hydrogen-ion-
concentration gradient across the membrane.
hydrogen ion to flow back
into the matrix via chemiosmosis, generating energy for ATP to be formed from ATP and ADP and Pi
Pedigree interpreting:
How do you show
a Healthy Male
b Healthy Female
Male is an empty Square
Female is an empty circle
Pedigree interpreting:
How do you show
a Affected Male
b Affected Female
Male is an coloured in Square
Female is an coloured in circle
Pedigree interpreting: How do you show an an unborn, or sex unknown
How would you show a still birth?
empty diamond
Put an SB by the diamond if they are a still birth
Pedigree interpreting:
How would you show
a) a pregnancy
b) a termination
a) an empty triangle
b) an empty triangle with a cross over it
How do you show consanguinity?
A double line between the couple in question
Name some charateristics of X linked conditions
Caused by mutations carried on the X - chromone
(NO MALE-TO-MALE
TRANSMISSION
All daughters from an affected male are CARRIERS all sons are UNAFFECTED
Males can NEVER be carriers
• Usually only males are affected
Can either be dominant - Alports Syndrome or recessive -DMD
Define Lyonization
The process of X chromosome inactivation = One of the two X chromosomes in every cell in a female is randomly inactivated early in embryonic development -prevents two sets of X chromosomes being expressed (only need one)
What is the rate limiting step of the Krebs cycle?
Isocitrate ==> A ketoglutarate,
As the enzyme involved, isocitrate dehydrogenase is an allosterically controlled enzyme.
What does the nucleus contain dna in the form in?
What is it wrapped around?
Chromatin. It is wound around histone proteins
Euchromatin vs Heterochromatin: What is what?
Euchromatin = Loose coils, Expressed Heterochromatin = tight coils repressed
Mitosis - Outline what happens in the prophase.
- Nuclear Membrane begins to break down
- Chromatin condenses into Chromosomes
Centrioles (tubules) move to polar ends - forms spindle
- Chromatin condenses into Chromosomes
Mitosis - Outline what happens in the prometaphase.
- Nuclear membrane breaks down
Spindles form
Cell no longer has a nucleus
Chromosomes attach to spindle via a centromere
Tubulin, a microfilament, (25um) forms the centrioles
Mitosis - Outline what happens in the metaphase.
Chromosomes line up at the equator
Mitosis - Outline what happens in the anaphase.
Sister chromatids separate, pushed to opposite poles of the cell, as spindle fibres contract < > shaped
Mitosis - Outline what happens in the telophase.
- Chromosomes unfold into chromatin
- Nuclear membrane reforms
Mitosis - Outline what happens in the cytokinesis
- Division of the Cytoplasm, and organelles ==> 2 genetically identical daughter cells form
What happens in Prophase 1 of Meiosis?
CROSSOVER Homologous chromosomes exchange small parts of themselves, ==> so 1 chromosomes contains both maternal and paternal DNA ==> to increase genetic diversity (known as crossover)
What happens in Metaphase 1 of Meiosis?
Independent Assortment
Maternal and Paternal chromosomes line up randomly on either side of the equator = So each gamete will either Mum or Dads genetic material - leads to more genetic diversity amongst offspring.
DNA replication enzymes: What does Topoisomerase do?
Unwinds the Supercoils (double helix, makes it unconvoluted)
DNA replication enzymes: What does Helicase do?
What do SSBs do?
Breaks the H bonds
Single strand bases SSBs from the Nucleus keeps the base pairs away from each other to stop repairing
So now, free DNA nucleotides can bind
DNA replication enzymes: What does DNA polymerase do?
Catalyses the phosphodiester bonds between the Free nucleotides - (reads in the 3’5 direction, and synthesising in the 5’3’
DNA replication enzymes: what does DNA Ligase do?
joins Ozaki Fragments (Short DNA Pieces) together in one continuous strand - SEMI CONSERVATIVE REPLICATION - ONE ORIGINAL AND ONE NEW STRAND
What factors INCREASE BMR
Being Overweight, Caffeine, Temperature, Hyperthyroidism, Exercise, Pregnancy, Being Tall, Stress
What factors DECREASE BMR
Increasing Age, Being Female, Starvation, Hypothyroidism
Define BMR, and give its standard value
Basal Metabolic Rate - The rate of metabolism needed to sustain life at rest (24kcal/kg/day)
