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Phase 1 - Lectures > P1 - IMMS > Flashcards

P1 - IMMS Flashcards

1
Q

Structure and function of Nucleus

A

Largest membrane bound organelle
Storage and transmission of genetic information
Information (coded in the DNA) synthesises the protein determining the structure and function of the cell.
Double membrane (nuclear envelope) with gaps called nuclear pores
RNA moves out via pores
DNA and proteins form chromatin – a mass of genetic material
At cell division, chromatin becomes chromosomes, condenses.

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2
Q

Structure and function of Mitochondria

A

Site of oxidative phosphorylation
Outer membrane – lipid synthesis and fatty acid metabolism
Inner membrane – respiratory chain (electron transport)
Matrix – Krebs Cycle
Intramembranous space – nucleotide synthesis (ADP – ATP)

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3
Q

Structure and function of Vesicles

A

Very small spherical membrane bound organelles which transport and store material and exchange cell membrane between compartments,
Many types: Cell surface derived, golgi-derived, ER-derived, lysosomes and peroxisomes

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4
Q

Structure and function of Nucleolus

A

In the nucleus
No membrane
Site of DNA transcription
Forms ribosomal RNA

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5
Q

Basic structure of Plasma Membrane

A

Double layer of lipids called phospholipids
Hydrophobic head, hydrophilic tail
Contain proteins (receptors/channels) and lipids (cholesterol)

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6
Q

Functions of Plasma Membrane

A 
Controls passage of various molecules 
Physical barrier
Selective permeability
Endo-/exocytosis
Cell signalling
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7
Q

Detailed components of Plasma Membrane

A

Phospholipids – lipid made of glycerol, 2 fatty acid tails and a phosphate linked head group
Cholesterol
Membrane proteins
Carbohydrate groups
These then attach to proteins to form glycoproteins or glycolipids
Sphingolipids?

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8
Q

Structure and function of Vacuole

A

Functions to hold various solutions or material.
These can have been created, stored or excreted and that have been phagocytosed or engulfed.
Chamber surrounded by a membrane – this is semi permeable and only lets certain molecules through

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9
Q

Structure and function of Smooth ER

A

Site of lipid synthesis
Proteases and store synthesized proteins
High folded, flattened membrane sheets,.

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10
Q

Structure and function of Rough ER

A

Rough due to the ribosomes on the surface
Highly folded membrane sheets which are flat
Site of protein synthesis

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11
Q

Structure and function of Golgi Apparatus

A

Parallel stacks of membrane
Processes and modifies macromolecules synthesised in the ER
Located close to the nucleus
In most cells it cant be seen – seen clearly in plasma cells.

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12
Q

Function of Cis-Golgi

A

Nuclear facing – receives from rough ER

Protein phosphorylation occurs here.

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13
Q

Function of Medial Golgi

A

Modifies producers by adding sugars

Forms complex oligosaccharides by adding sugars to lipids and peptides.

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14
Q

Function of Trans-Golgi

A

Proteolysis of peptides into active forms and sorting of molecules into vesicles which bud from the surface

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15
Q

Structure and function of Ribosomes

A

2 subunits attached to the rough ER
Acts as a large catalyst
Translates genetic code into chains of amino acids – these then fold
Deposits protein into the ER to undergo further modification
3 – 5 amino acids per second in protein production

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16
Q

Structure and function of Cytoplasm (3 components)

A

Site of glycolysis
The fluid that fills the cell, includes the cytosol and filaments, proteins, ions and macromolecular structures as well as organelles. NA the nucleus.
3 components:
Cytoskeleton with associated motor proteins
Organelles and other multi proteins complexes.
Cytoplasmic inclusions and dissolved solute

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17
Q

Structure and function of Endosomes

A

Membrane bound vesicular and tubular structures that live between golgi and membrane.

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18
Q

Structure and function of Centrosome

A

Made from 2 centrioles, which are microtubule rings
They organize microtubules and provide structure for the cell
Pull chromatids apart during cell division

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19
Q

Structure and function of Peroxisomes

A

Small membrane bound organelles containing enzymes which oxidise long chain fatty acids - they are broken down to generate ATP
Hydrogen peroxide is toxic to cells but is destroyed by peroxisomes.

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20
Q

Structure and function of Lysosomes

A

Contain digestive enzymes
Waste disposal system, and the site of breakdown for most molecules
Derived from Golgi. H+ ATPase on membrane creates low pH (pH5) to enable acid hydrolysis to function

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21
Q

Structure and function of Microtubules

A

25nm
E.g. tubulin (alpha and beta which arrange into groups of 13 to form hollow tubes)
Arise from centromere
Found in all cells, except RBC’s, so they have no nuclei, no cell division, thus structure isn’t required

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22
Q

Structure and function of Intermediate filaments

A

10nm
6 protein types
Anchored transmembrane proteins which can spread through tissues

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23
Q

Structure and function of Microfilaments

A

5nm

Actin forms a mesh (cell cortex) on the inner surface of the cell membrane

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24
Q

What is a Peptide bond?

A

Bond Formed by condensation

reaction (water released)

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25
Q

Properties of amino acids

A

Very stable
Cleaved by proteolytic enzymes – proteases or peptidases
Can have partial double bonds
Flexibility around C atoms not involved in bond thus allows multiple conformations
Usually one preferred conformation, determined mainly by types of side chains and amino acid sequence

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26
Q

Describe the charge of amino acids

A

Charge is determined by all three components and on the pH of the environment
Side chain often determines polarity (and thus solubility and permeability)
Carboxyl groups = negative
Amino groups = positive

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27
Q

Structure and no. of amino acids

Which form is most common?

A

Building blocks of proteins - 20 in total
Carbon with amino group, carboxyl group and a specific side chain
Most natural amino acids are in the L form, in contrast to that of sugar whose natural form is D.

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28
Q

Structure/function of enzymes

A

Catalysts = Provide an alternative reaction pathway with a lower activation energy
Enable reactions to occur that otherwise would not be able to occur at physiological (body) temperatures and conditions.
Bind to the reactants and convert them to products – then release the products and return to their original form
Speed up reactions and provide a way to regulate the rate of reactions

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29
Q

Describe regulation by enzymes

A

Altering concentration of substrates, products, inhibitors or activators, can also be regulated by modifying the enzyme itself by phosphorylation

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30
Q

Define isoenzyme

A

enzymes that have a different structure and sequence but catalyse the same reaction

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31
Q

Define coenzyme

A

cannot in themselves catalyse a reaction but can help enzymes to do so. Bind with the enzyme protein molecules to form active enzymes.

32
Q

Basic structure of proteins

A

Amino acids linked together by peptide bonds
Protein is a large polypeptide –from 10s to 1000s amino acids
Function is totally dependent on structure

33
Q

Difference between proteins and peptides

A 
Protein = if it is functional and synthesized by a cell
Peptide = bit of protein broken off
34
Q

Describe folding of proteins

A

Linear chains fold in different shapes to form 3D structures –
Determined by charged interactions, flexibility, amino acid sequence, and physical dimensions

35
Q

Primary structure of proteins

A

linear sequence of amino acids

36
Q

Secondary structure of proteins

A

alpha helix or beta pleated sheets formation due to H+ bonds between amino acids – determined by local interactions between side chains and sequence of amino acids
peptide backbone - repeating pattern

37
Q

Tertiary structure of proteins

A

Overall 3D conformation of a protein due to side chain interactions
Confirmation can change with temperature or pH

38
Q

Quaternary structure of proteins

A

3D structure of protein with multiple subunits.

More than 1 AA chain

39
Q

Van der Waals forces in proteins

A

Weak attractive/repulsive force between all atoms due to fluctuating electrical charge

40
Q

Hydrogen bonds in proteins

A

Interaction between polar groups.

41
Q

Hydrophobic forces in proteins

A

as uncharged and non-polar side chain are repelled by water, hydrophobic side chains form tightly packed cores in the interior of proteins, excluding water molecules

42
Q

Ionic bonds in proteins

A

between fully/partially charged groups.

43
Q

Disulphide bonds

A

very strong covalent bonds between sulphur atoms

44
Q

Describe Monosaccharides

A

One hydroxyl group
An aldose has an aldehyde
An ketose has a ketone
Generally exist as ring structures (cyclized)

45
Q

Describe a Glyosidic bond

A

The hydroxyl group of a monosaccharide can react with an OH or an NH group to form a glycosidic bond.
O-glycosidic bonds form disaccharides, oligosaccharides and polysaccharides.
N-glycosidic bonds are found in nucleotides in DNA

46
Q

Describe a disaccharide bond

A

Contain two monosaccharides joined by an o-glycosidc bond

47
Q

Describe Oligosaccharides

A

Contain 3 – 12 monosaccharides.

Product of digestion of polysaccharides, or part of a complex protein or lipid.

48
Q

Describe Polysaccharides

A

Formed by thousands of MS joined by glycosidic bond.

Glycogen – branched polysaccharide formed of glucose residues

49
Q

Describe Nucleotides

A

Building blocks of DNA.
Made from nitrogenous base + sugar + phosphate.
Bonds between bases are hydrogen bonds
Bonds between phosphate and sugar are phosphodiester
Phosphate bonds in nucleotides are a source of energy

50
Q

Describe lipids (+ triglycerides and unsat fatty acids)

A

Triglyceride = 3 fatty acids bound to glycerol
Straight carbon chains with a methyl group and a carboxyl group at ends
Tend to be hydrophobic and contain no oxygen in main chain
In unsaturated fatty acids - double bonds are commonly cis, spaced at 3C intervals

51
Q

Describe Autocrine cell signalling with examples

A

messenger molecules bind with receptors in the cell where they are produced
E.g. chemical/secondary messengers

52
Q

Describe Direct cell signalling with examples

A

messenger molecules travel between cells via gap junction (protein channel)
eg. passage of AA and ions

53
Q

Describe Paracrine cell signalling with examples

A

messengers in extracellular fluid

E.g. clotting factors, prostaglandins in childbirth, inflammatory mediators

54
Q

Describe Endocrine cell signalling with examples

A

secretions into blood

E.g. insulin

55
Q

Define osmosis

A

net movement of solvent molecules through a semipermeable membrane to higher solute concentration (i.e lower water conc.)

56
Q

Define osmolarity

A

concentration of solutes in plasma per kg of solution

57
Q

Define osmolality

A

concentration of solutes in plasma per kg of solvent

58
Q

Define osmotic pressure

A

pressure applied to a solution, by a pure solvent, required to prevent inward osmosis, through a semipermeable membrane.

59
Q

Define oncotic pressure

A

form of osmotic pressure exerted by protein that tends to pull fluid into its solution – water moves from ISF into plasma.

60
Q

Define hydrostatic pressure

A

pressure difference between capillary blood (plasma) and interstitial fluid – water and solutes move from plasma into ISF

61
Q

Total volume of water in adult male? Splits into which 2 types of fluid (give most predominant electrolytes)?

A

60% of body weight, 42L splits into:
Extracellular fluid - 14L (Na+, Cl-, urea, glucose)
Intracellular fluid - 28L (K+)

62
Q

Water in ECF splits into which 2 fluids (give volumes)?

A 
Intravascular fluid (plasma which circulates EC component of blood) - 3L
Extravascular fluid - 11L
63
Q

Extravascular fluid splits into which 2 types of fluid (give volume of water and relevance)?

A 
Interstitial fluid (surrounds cells but does not circulate) - 10.5L
Transcellular (makes up cerebrospinal fluid, digestive juices, mucus)  0.5L
64
Q

Describe osmotic position of Fluid compartments in the body, and what causes osmotic gradients across CSM

A

Fluid compartments in the body are in osmotic equilibrium
Osmotically active substances (solutes) in the ICF (potassium) and ECF (sodium, chloride, glucose and urea) create an osmotic gradient across cell membranes

65
Q

Define positive feedback with examples

A

amplification of signal

E.g. clotting cascade, oxytocin, and labour

66
Q

Define negative feedback with examples

A

the basis for homeostasis

E.g. the majority of endocrine hormones

67
Q

Names for high/low Na+/K+/Ca+ levels

A

Hypernatremia: High sodium
Hyponatremia: Low sodium

Hyperkalaemia: high potassium
Hypokalaemia: low potassium

Hypercalcemia: high calcium
Hypocalcaemia: low calcium

68
Q

Describe process of Peptide hormones

A

Made from short chain amino acids.
Stored in cell and released when needed/signalled
Binds to receptor on membrane
Produces a quick response via a secondary messenger cascade
Examples: Insulin, growth hormone, TSH and ADH.

69
Q

Describe process of Amino acid derivative hormones

A

Synthesised from tyrosine
Stored in cell and released when needed/signalled
Binds to receptor on membrane
Produces a quick response via a secondary messenger cascade
Examples: adrenaline, thyroid hormones (T4 and T3)

70
Q

Describe process of steroid hormones

A

Synthesised from cholesterol, water insoluble and lipid soluble – can cross membranes but requires transport proteins in blood
Intracellular receptor target
Steroid hormone is made by the cell and diffuses out once made (not stored)
Directly affects DNA and alters transcription/translation – this is a slow response as proteins have to be made
Examples: testosterones, oestrogen and cortisol

71
Q

Sources of water intake and water loss

A

Water intake: drink, diet and IV fluid.
Water loss: kidneys
insensible losses: sweat, breath, vomiting and faeces

72
Q

Name the regulating hormones for water balance

A

ADH, Aldosterone and atrial natriuretic peptide (ANP)

73
Q

Causes and consequences of dehydration

A

Causes: water deprivation, vomiting, diarrhoea, burns, heavy sweating, diabetes insipidus, diabetes mellitus and drugs
Consequences: thirst, inelastic skin, sunken eyes, raised haematocrit (viscosity of blood), weight loss, and hypotension.

74
Q

Causes and consequences of water excess

A

Causes: high intake/ decreased loss of water, excess ADH
Consequences: Hyponatremia (low sodium levels), cerebral over perfusion (due to high blood volume and thus pressure) – causes headaches, confusion and convulsions.

75
Q

What is serous effusion (water balance)?

A

excess water in body cavity

76
Q

What is Oedema (water balance)?

A

excess water in the intercellular tissue space

77
Q

What causes inflammatory leakage (water balance)?

A

proteins leak out due to increased vascular permeability
they bring in water, thereby diluting the toxins
fibrinogen polymerises to form a fibrin mesh and immunoglobulins collect

Phase 1 - Lectures (4 decks)

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