PCS 1

Question 1

Explain the importance of ATP
(chemistry of life)

Answer 1

ATP is used as energy within the body. Organisms require energy for work and heat, mechanical work, active transport and macromolecule synthesis.

Question 2

Explain how reaction coupling (bioenergetics) is used in the body
(chemistry of life)

Answer 2

Reaction coupling is when energy transferred from one side of the reaction to the other involving a common intermediate in the chemical chain, meaning that a product of one reaction is used as a reactant in the second reaction.

When two reactions are coupled, they can be added together to give an overall reaction, and the ΔG of this reaction will be the sum of the ΔG values of the individual reactions. As long as the overall ΔG is negative, both reactions can take place.

When reaction coupling involves ATP, the shared intermediate is often a phosphorylated molecule.

Question 3

explain how metabolic reactions are regulated using allosteric regulation, covalent modification, competitive inhibition and the concentration of substrate, product and enzyme.
(chemistry of life)

Answer 3

Allosteric regulation - any form of regulation where the regulatory molecule (an activator or inhibitor) binds to an enzyme someplace other than the active site. The place where the regulator binds is called the allosteric site.

Covalent modification - enzymes can be regulated by transfer of a molecule or atom which causes the tertiary structure to change shape.

Competitive inhibition - it will decrease the reaction rate when there’s not much substrate so can be outcompeted. They bind to the active site of enzymes to block the active site therefore preventing substrates binding to the enzyme.

• synthesis vs breakdown of enzyme
• accessibility of substrate
  
  • beta oxidation vs FA synthesis
• regulation of catalytic activity
  
  • allosteric and covalent modification
  • energy charge and adenylate control

Question 4

define a rate-limiting step in a pathway using glycolysis as an example
(chemistry of life)

Answer 4

The rate limiting step in a pathway is the slowest step in a pathway, which determines how fast the whole pathway can be carried out.

In glycolysis the rate limiting enzyme is phosphofructokinase which speeds up glycolysis.

Question 5

recognise the following key reaction types in metabolic pathways (redox, condensation/ligation, hydrolysis, isomerization, group transfer, group transfer and lyase reactions)
(chemistry of life)

Answer 5

Hydrolysis - breaking a bond of a molecule using water

Condensation - formation of a bond releasing water

Redox - reversible reaction

isomerisation - the chemical process by which a compound is transformed into any of its isomeric forms.

group transfer - where one or more groups of atoms is transferred from one molecule to another.

lyase reaction - lyases are the enzymes responsible for catalysing addition and elimination reactions. Lyase-catalyzed reactions break the bond between a carbon atom and another atom such as oxygen, sulfur, or another carbon atom.

Question 6

recognise catabolic and anabolic pathways
(chemistry of life)

Answer 6

Catabolic - break down complex structures to simpler ones
- energy yielding
- ADP, NADP+

Anabolic - building larger molecules from smaller ones
- energy requiring
- ATP, NADPH

Question 7

explain ATP synthesis and utilisation
(chemistry of life)

Question 8

Outline the structure and function of the mitochondrion
(chemistry of life)

Answer 8

function - oxidative phosphorylation, which generates ATP.

• membrane bound organelle containing matrix.

Question 9

Outline the primary, secondary, tertiary and quaternary structure of proteins.
(biological macromolecule structure)

Answer 9

Primary - the sequence of amino acids bonded together by peptide bond

Secondary - the folding of the amino acid chain to form alpha helices and beta-pleated sheets

Tertiary - the further 3D folding of the alpha helices and beta-pleated sheets due to hydrogen, ionic and disulfide bondings

Quaternary - multiple amino acid chains (polypeptide)

Question 10

Name the different classes of lipids, define saturate and unsaturated and cis trans forms of fatty acids.
(biological macromolecule structure)

Answer 10

two classes : fatty acids and steroids.
(fatty acids form more classes such as triglycerides and phospholipids)

Saturated - has no double bonds in its carbon chain

unsaturated - has double bonds in its carbon chain

CIS - priority group is on the same side
TRANS - priority group is on the opposite side

Question 11

describe the basic structure of metabolically important carbohydrates
(biological macromolecule structure)

Answer 11

Starch, glycogen - many 1,4 glycosidic bonds so highly branched structure and cellulose

Simple (monosaccharides and disacchrides) and complex (polysaccharides)

Glucose + glucose → maltose + water

glucose + fructose → sucrose + water

glucose + galactose → lactose + water

Question 12

give examples of these biological molecules in cells and tissues
(biological macromolecule structure)

Answer 12

catalysis - enzymes
defence - antibodies
transportation - haemoglobin
support - collagen
motion - actin and myosin
regulation - hormones
storage - ferritin (primary form of stored iron)

Question 13

explain roles of the cytoskeleton: microtubles, myosin and actin, microtubule associated proteins.
(biological macromolecule structure)

Answer 13

Microtubules are the scaffolding by which vesicles and some molecules are transported around the cell using the molecular motors dynein and kinesin - form spindles required for cell division

Myosin and actin - work together to allow muscle contraction and relaxation.

• Tubulin - the protein component of microtubules
• Actin - the means by which cells change shape and move, supports and strengthens the cell membrane
• Lamins - the protein component of intermediate filaments

Question 14

Outline the evolution of eukaryotic and prokaryotic cell structures (intro to cell structure)

Answer 14

Prokaryotes (bacteria) (small) and eukaryotes (animal, plant, fungi)(big) are fundamental

Question 15

Outline major milestones in the evolution of the cell
(intro to cell structure)

Answer 15

They hypothesise that spontaneous formation of organic molecules occurs CH4 + NH3 + H20 gives organic molecules, such as nucleic acids, lipids and proteins

If combine early earth’s gases we eventually get protenoid material

RNA - early genetic material capable of catalysing its own replication

Question 16

outline the structural complexity of mammalian tissue
(intro to cell structure)

Answer 16

grouped into four basic types: connective, muscle, nervous and epithelial. Connections of tissues joined in structural units to serve a common function compose organs.

Question 17

classify bones according to their shape and relate this to their function and clinical significance.

Answer 17

• long - have a tubular structures that act as leavers and transmit longitudinal forces i.e. femur
• short - cuboidal/ roughly equal in length and width to provide strength to structure they are contained in. i.e. only found in the wrist/ ankle such as the capitate bone
• flat - usually serve protective functions and are broad and sheet-like. Provides large surface area for muscles and tendons attach to i.e. ribs and scapula
• irregular - groups of bones that don’t fit in the other categories i.e. T6 Thoracic Vertebra
• sesamoid - precious group of bones found in certain tendons (i.e. patella and kneecap). These bones protect the tendons from excessive wear and often change the angle of the tendons as they pass to their attachments.

Question 18

describe the characteristic internal and external features of bones and explain that they are responsive to mechanical loading.

Answer 18

(Internal)
Compact bone - within the shaft it is thick but gets thinner towards the metaphysis and at the epiphysis there are spongy bone (useful as it makes it strong but minimizes the weight)

• Osteoblasts are bone-forming cell
• osteoclasts resorb or break down bone
• osteocytes are mature bone cells.

Wolff’s law - the bone adapts to the experiences it is experiencing

Question 19

identify and describe the different components of musculoskeletal system.

Answer 19

bones - providing support

cartilage - designed to resist compressive forces which are experienced by joint.

ligaments - fibrous connective tissue that connects two bones and provide stability to joints ensuring that they stay aligned during movement.

tendons - a band of fibrous connective tissue that connects muscle to bone. The function is to transfer the muscle force to bone to facilitate joint movement.

Question 20

describe the structure and function of the axial and appendicular skeleton

Answer 20

Axial - Made up of the skull (cranium), hyoid bone, neck (cervical vertebrae), and trunk (ribs, sternum, vertebrae, and sacrum)
The principle function is to protect the spinal cord, heart and lungs. It provides a large surface area for the attachment of muscles which move the skeleton.

Appendicular skeleton - Contains the bones that make up the upper and lower limbs, including those forming the pectoral (shoulder) and pelvic girdles.
- upper limb for dexterity
- lower limb or support or movement

Question 21

explain the basic principles of muscle anatomy and the movements they produce.

Answer 21

A muscle will have a central fleshy part (the belly)

During muscle contraction the muscle will move one bone relative to another.

A muscle tendon unit will pass from one bone to another across a joint to facilitate movement.

The end of the muscle which remains stationary is the origin.

The movable end is known as the insertion

The proximal end is usually the staionary

The distal end is usually the movable end

Muscles work in antagonistic paris:

• The prime mover (agonist) generates the basic movement
• The antagonist controls the movement
• e.g. when tensing the bicep brachii is the prime mover, the triceps brachii is the agonist and vice versa.

The fixator ensures that there isn’t any unwanted bone movement at intermediate joints which may be crossed or influenced by the prime mover.

Question 22

describe the varying shapes of skeletal muscle and relate muscle fiber organisation to the strength and range of force produced.

Answer 22

Parallel fibred
- running parallel to the direction of movement
- can shorten a lot
- large range of movement
- weak contractile force

Oblique fibred
- at an angle to the direction of movement
- shorter range of movement as cant shorten much
- being at an angle you can pack more muscle fibres in so increasing the contractile force = stronger contractile force

Pennate (Oblique fibred) muscles - feather like in the arrangement of their fascicles (fiber bundles)

(weakest) parallel, unipennate, bipennate, multipennate (strongest)

Question 23

explain the significance of fascia in the body and the importance of muscle compartments.

Answer 23

It is a sheath of connective tissue that surrounds every structure in your body. It provides support to your organs, muscles, tendons, ligaments, tissues, nerves, joints and bones. it is a continuous layer, so its flexible and moves with your body.

Question 24

outline the four basic tissue types with reference to structure and function

Answer 24

Epithelial - simple (one layer) or stratified (many layers thick)
The characterisitcs of epithelial cells are:
- Cellularity
- Specialised contacts
- Polarity
- (free upper (apical surface))
- Lower (basal) surface contributing basal lamina to basement membrane
- Supported by connective tissue
- Avascular, but innervated (without vessels and nerve endings)
- regenerative
Some epithelial cells are non-stick so other cells don’t sick to them when they clot.

• Muscle
• Nerve

Connective tissue - arises from embryonic mesenchyme and differentiates to form our skeleton, cartilage, blood and much of the tissue.

Question 25

name the main groups of connective tissues and describe their composition.

Answer 25

loose connective tissue - mucosa and submucosa

dense connective tissue - tendons and ligaments

reticular connective tissue - lymph nodes, liver and spleen.

elastic connective tissue - ligaments in vertebral column or sheets in the wall of the aorta

specialised connective tissue - cartilage and bone

Question 26

describe general characteristics of connective tissues and apply these to their functional roles

Answer 26

All connective tissues are a 3d matrix that connect or interface one anatomical feature to another.

All tissues are made of supporting physical structures (collagen, cartilage, fibrins) in which cells reside. The gel-like substance is known as ground substance and all structural features and cells reside in it.

Functions:
- provides an environment where the exchange of nutrients and gases can take place.
- stores reserve energy and acts as protective padding for internal structures
- surrounds internal organs and provides support
- connects skeletal muscle to bones

Question 27

name and describe the characteristics, distribution and functions of bone and cartilage, loose and dense connective tissue and fat.

Answer 27

loose connective tissue - contains variety of resident cells and loose arrangement of all three fibers (collagen, reticular, elastic) and a large amount of ground substance.
This tissue supports and cushions features that may change shape and size.

Question 28

to provide examples of when histology is a suitable imaging resource in medicine

Question 29

to appreciate the appearance of 2d slices through 3d objects

Question 30

to identify cells and matrices in histological sections