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FOM > cellular molecules > Flashcards

cellular molecules Flashcards

1
Q

define proteins

A

large, complex molecules that play many critical roles in body

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2
Q

describe various classes of amino acids

A

non-polar
polar
acidic
basic

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3
Q

describe functions of proteins

A

repair and build body’s tissues
allows metabolic reactions to take place
coordinates bodily functions

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4
Q

primary structure of proteins

A

amino acid sequence

polypeptide sequence

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5
Q

secondary structure of proteins

A

formed by H bonds between carbonyl and amino groups that make up the polypeptide backbone
alpha helices, beta sheets and random coil

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6
Q

tertiary structure of proteins

A

overall 3D arrangement of its polypeptide chain in space

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7
Q

quaternary structure of proteins

A

association of several protein chains or subunits into a closely packed arrangement
subunits held together by H bonds and van der Waals forces between nonpolar side chains

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8
Q

what properties may quaternary structure confer on proteins?

A

two or more identical or different polypeptide chains

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9
Q

globular v fibrous proteins

A 
fibrous = long, narrow strands , helical like structure, generally structural roles - only soluble in strong acids 
globular = compact, rounded shape, folded ball like structure, functional roles - soluble in water, acids and bases
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10
Q

examples of globular

A

haemoglobin,
insulin,
myoglobin, immunoglobulins
and many enzymes

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11
Q

examples of fibrous

A

keratin
collagen
elastin
fibroin

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12
Q

explain denaturation

A

primary structure is unaffected, however, shape of protein can be altered so much that the protein becomes dysfunctional = therefore protein considered denatured

this can happen when protein is subject to changes in temp, pH, chemical exposure etc outside optimal range

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13
Q

glycoprotein - what molecules

A

carbohydrate and protein

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14
Q

lipoprotein - what molecules

A

lipid (fat) and protein

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15
Q

elastins

A 
ECM protein , fibrous protein
function - extensibility and elastic recoil of many vertebrate tissues eg arteries, valves, skin etc
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16
Q

keratins

A

fibrous structural proteins
main constituents of hair, nails etc
produced by keratinocytes (stratum corneum layer, outermost layer of skin - regenerative)

functions - protect epithelial cells, strengthen internal organs, control growth of epithelial cells, maintain elasticity

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17
Q

define enzymes

A

biological catalysts, proteins which help speed up metabolism or the chemical reactions in our bodies
naturally produced but can be manufactured

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18
Q

how do enzymes catalyse reactions

A

enzyme binds to substrate(s) on the active site, substrate molecule changed -> product formed
lowering activation energy necessary for a reaction to occur

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19
Q

discuss rate of an enzyme-catalysed reaction - factors etc

A

temperature - ^temp, ^rate - however extreme temps can cause denaturation
pH - optimum range, extreme values cause denaturation
enzyme conc - ^conc, ^rate
substrate conc - ^conc, ^rate

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20
Q

define Michaelis constant and explain

A
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21
Q

describe molecular nature of competitive inhibition

A

competitive inhibitors bind to enzyme, often at active site, which prevents real substrate from binding , therefore , inhibitor and substrate compete for enzyme

decreases no. of enzyme molecules available to bind to substrate

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22
Q

describe molecular nature of non-competitive inhibition

A

inhibitor doesn’t prevent substrate from binding , inhibitor and substrate do not affect each other’s binding
however, when inhibitor is bound, enzyme cannot catalyse its reaction to produce a product

decreases no. of functional enzyme molecules that can carry out reaction

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23
Q

why is enzyme activity measured in clinical settings

A

valuable for clinical diagnosis of several diseases - due to their high sensitivity, specificity and rapid response

24
Q

what factors can influence enzyme activity in samples

A

temperature
pH
substrate and enzyme conc

25
Q

discuss use of enzyme assays in clinical diagnosis

A

understanding how well a key enzyme functions in a physiological process reveals early signs of disease that has a long latency period

26
Q

define enzyme assays

A

lab methods for measuring enzymatic activity within a sample

27
Q

define cofactor and coenzyme

A

cofactor - “helper molecules” , can be inorganic or organic , do not bind to enzyme
eg metal ions,

coenzyme - organic, bind loosely to active site of enzyme and aid in substrate recruitment

28
Q

allosteric proteins

A

one with an effector which regulates its activity by acting on a site physically distant from protein’s ligand-binding site

29
Q

define major CHOs in diet

A

sugars - simple
starch - complex , made of lots of sugars
fiber - complex

30
Q

describe CHOs digestion

A

chemical digestion begins in mouth
in the small intestine, pancreatic amylase does the brunt of starch and CHO digestion
after amylases breaks down starch into smaller fragments, brush border enzyme alpha-dextrinase starts working on alpha-dextrin, breaking off 1 glucose at a time

31
Q

describe and contrast actions/functions of hexokinase and glucokinase

A

hexokinase - present in all cells, high affinity toward glucose, converts glucose at a faster rate
phosphorylation of glucose to form glucose-6-phosphate, by ATP

glucokinase - only present in liver, low affinity toward glucose

32
Q

describe synthesis and degradation of glycogen

A

glycogenesis = synthesis of glycogen from glucose
glucose-6-p converted to glucose-1-p and then converted to uridine diphosphate (UDP)-glucose - inserted into glycogen by either enzyme, glycogen synthase or branching enzyme at the branch points

glycogenolysis = process of liberating glucose from glycogen
glycogen phosphorylase is involved
glucose-1-p is cleaved from glycogen by enzyme which can then be converted to glucose-6-p

33
Q

glycogen functions in skeletal muscle v liver

A

skeletal muscle - energy storage

maintain a physiological blood glucose conc

34
Q

function of glycolysis

A

breaks down glucose into two pyruvate molecules (3C compounds) and generates energy , NADH and water

35
Q

functions of lactate dehydrogenase-catalysed reactions

A

catalyses interconversion of pyruvate and lactate with associated interconversion of NADH and NAD+

36
Q

fate of blood lactate

A

in skeletal muscle = oxidation and glyconeogenesis (glycogen synthesis)

37
Q

define precursors

A

inactive substance converted to an active one , derived from an available source

38
Q

describe precursors for, functions of and process of gluconeogenesis

A

precursors = lactate, glycerol, amino acids

synthesis of glucose from noncarbohydrate precursors, provides glucose when dietary intake is insufficient

39
Q

fates of absorbed galactose and fructose

A

removed from blood once in the liver and converted into other metabolites eg glucose, glycogen and lactate

40
Q

define major lipid classes

A

triglycerides
phospholipids
steroids

41
Q

describe processes of lipid digestion and absorption

A

begins in the mouth
physical action of chewing paired with the action of emulsifiers enables digestive enzymes to do tasks - lingual lipase (and phospholipids) initiates digestion - fats separate from watery components , more accessible to digestive enzymes
within 2-4hrs , roughly 30% of triacylglycerols are converted to diglycerides and fatty acids

bile salts and micelles

42
Q

describe how lipids are transported in body

A

lipoproteins in the blood

43
Q

role of lipoproteins in process of transportation

A

transport lipids as chylomicrons to most tissues for oxidation and to adipose tissue for storage

and from liver as very low density lipoproteins (VLDL)

44
Q

synthesis of free fatty acids

A

from acetyl-CoA and NADPH through action of enzymes called fatty acid synthases - cytoplasm of cell

45
Q

define ‘essential fatty acid’

A

polyunsaturated fatty acids provided by foods as they cannot be synthesised in the body
necessary for health

2 families:
omega-3 and omega-6

46
Q

describe catabolism of fatty acids by beta-oxidation

A

occurs in mitochondrial membrane
carnitine helps shuttle long-chain fatty acids into mitochondria

2C units are cleaved off at beta-C position (2nd C from acid end) of an activated fatty acid , this forms acetyl-CoA and produces an activated fatty acid (acyl-CoA) with 2 fewer carbons, acetyl-CoA, NADH and FADH2

47
Q

describe structure and functions of cholesterol

A

structural component of cell membranes provides stability and fluidity
regulates cell function
building block for synthesising various steroid hormones, vit D and bile acids

27C compound , hydrocarbon tail, central sterol nucleus (feature of all steroid hormones) made of 4 HCO rings and a OH group

48
Q

structures and functions of eicosanoids and steroid lipids

A

role in inflammation
reproduction
gastric secretion
regulation of BP

derived from 20C polyunsaturated fatty acids, most frequently arachidonic acid

include prostaglandins, thromboxanes, leukotrienes and lipoxins

49
Q

what are ketone bodies

A

produced by liver

alternative source of energy if glucose levels are too low in body

50
Q

define phospholipid

A 
class of lipids with hydrophilic head - contains phosphate group and 2 hydrophobic tails derived from fatty acids, joined by alcohol residue (usually glycerol molecule) 
comprise cellular membranes, regulate cellular processes, possess stabilising and dynamic qualities aiding in drug delivery
51
Q

define prostaglandins

A

group of lipids made at sites of tissue damage or infection - involved in dealing with injury and illness
control processes such as inflammation, blood flow, formation of blood clots and induction of labour

derived from arachidonic acid

52
Q

5 absorption mechanisms

A 
1, active transport
2, passive diffusion
3, facilitated diffusion
4, co-transport (or secondary active transport)
5, endocytosis
53
Q

describe CHOs absorption

A

all CHOs absorbed in form of monosaccharides , small intestine highly efficient

glucose and galactose are transported into epithelial cells by common protein carriers via co-transport (with Na ions) then leave cells via facilitated diffusion and enter capillaries through intercellular clefts

fructose absorbed and transported by facilitated diffusion alone

monosaccharides combine with transport proteins immediately after disaccharides are broken down

54
Q

functions of pyruvate dehydrogenase-catalysed reactions

A

catalysed oxidative decarboxylation of pyruvate with the formation of acetyl-CoA, CO2 and NADH

55
Q

role of triglycerides in health and disease

A

high may contribute to hardening of arteries or thickening of arterial walls, increasing risk of stroke, heart attack and heart disease, also cause pancreatitis

56
Q

role of phospholipids in health and disease

A

imbalances implicated with many neurological disorders, including bipolar, schizophrenia, and neurodegenerative diseases such as Alzheimer’s, Parkinsons’

57
Q

role of steroids in health and disease

A

regulate no. of hormonal events during pregnancy, sex, differentiation, development, reproduction
also exert equally important functions in non-reproductive tissues eg heart, kidney, pancreas, brain

also reduce redness and swelling (inflammation)

FOM (35 decks)

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