cellular molecules

Question 1

define proteins

Answer 1

large, complex molecules that play many critical roles in body

Question 2

describe various classes of amino acids

Answer 2

non-polar
polar
acidic
basic

Question 3

describe functions of proteins

Answer 3

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

Question 4

primary structure of proteins

Answer 4

amino acid sequence

polypeptide sequence

Question 5

secondary structure of proteins

Answer 5

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

Question 6

tertiary structure of proteins

Answer 6

overall 3D arrangement of its polypeptide chain in space

Question 7

quaternary structure of proteins

Answer 7

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

Question 8

what properties may quaternary structure confer on proteins?

Answer 8

two or more identical or different polypeptide chains

Question 9

globular v fibrous proteins

Answer 9

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

Question 10

examples of globular

Answer 10

haemoglobin,
insulin,
myoglobin, immunoglobulins
and many enzymes

Question 11

examples of fibrous

Answer 11

keratin
collagen
elastin
fibroin

Question 12

explain denaturation

Answer 12

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

Question 13

glycoprotein - what molecules

Answer 13

carbohydrate and protein

Question 14

lipoprotein - what molecules

Answer 14

lipid (fat) and protein

Question 15

elastins

Answer 15

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

Question 16

keratins

Answer 16

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

Question 17

define enzymes

Answer 17

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

Question 18

how do enzymes catalyse reactions

Answer 18

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

Question 19

discuss rate of an enzyme-catalysed reaction - factors etc

Answer 19

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

Question 20

define Michaelis constant and explain

Question 21

describe molecular nature of competitive inhibition

Answer 21

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

Question 22

describe molecular nature of non-competitive inhibition

Answer 22

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

Question 23

why is enzyme activity measured in clinical settings

Answer 23

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

Question 24

what factors can influence enzyme activity in samples

Answer 24

temperature
pH
substrate and enzyme conc

Question 25

discuss use of enzyme assays in clinical diagnosis

Answer 25

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

Question 26

define enzyme assays

Answer 26

lab methods for measuring enzymatic activity within a sample

Question 27

define cofactor and coenzyme

Answer 27

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

Question 28

allosteric proteins

Answer 28

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

Question 29

define major CHOs in diet

Answer 29

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

Question 30

describe CHOs digestion

Answer 30

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

Question 31

describe and contrast actions/functions of hexokinase and glucokinase

Answer 31

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

Question 32

describe synthesis and degradation of glycogen

Answer 32

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

Question 33

glycogen functions in skeletal muscle v liver

Answer 33

skeletal muscle - energy storage maintain a physiological blood glucose conc

Question 34

function of glycolysis

Answer 34

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

Question 35

functions of lactate dehydrogenase-catalysed reactions

Answer 35

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

Question 36

fate of blood lactate

Answer 36

in skeletal muscle = oxidation and glyconeogenesis (glycogen synthesis)

Question 37

define precursors

Answer 37

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

Question 38

describe precursors for, functions of and process of gluconeogenesis

Answer 38

precursors = lactate, glycerol, amino acids | synthesis of glucose from noncarbohydrate precursors, provides glucose when dietary intake is insufficient

Question 39

fates of absorbed galactose and fructose

Answer 39

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

Question 40

define major lipid classes

Answer 40

triglycerides phospholipids steroids

Question 41

describe processes of lipid digestion and absorption

Answer 41

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

Question 42

describe how lipids are transported in body

Answer 42

lipoproteins in the blood

Question 43

role of lipoproteins in process of transportation

Answer 43

transport lipids as chylomicrons to most tissues for oxidation and to adipose tissue for storage and from liver as very low density lipoproteins (VLDL)

Question 44

synthesis of free fatty acids

Answer 44

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

Question 45

define 'essential fatty acid'

Answer 45

polyunsaturated fatty acids provided by foods as they cannot be synthesised in the body necessary for health 2 families: omega-3 and omega-6

Question 46

describe catabolism of fatty acids by beta-oxidation

Answer 46

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

Question 47

describe structure and functions of cholesterol

Answer 47

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

Question 48

structures and functions of eicosanoids and steroid lipids

Answer 48

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

Question 49

what are ketone bodies

Answer 49

produced by liver | alternative source of energy if glucose levels are too low in body

Question 50

define phospholipid

Answer 50

``` 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 ```

Question 51

define prostaglandins

Answer 51

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

Question 52

5 absorption mechanisms

Answer 52

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

Question 53

describe CHOs absorption

Answer 53

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

Question 54

functions of pyruvate dehydrogenase-catalysed reactions

Answer 54

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

Question 55

role of triglycerides in health and disease

Answer 55

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

Question 56

role of phospholipids in health and disease

Answer 56

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

Question 57

role of steroids in health and disease

Answer 57

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)