Genes and Health

Question 1

Explain the anatomical adaptations in organisms with respiratory systems that maximise gas exchange

Answer 1

High surface area on gas exchange surfaces increases the rate of diffusion, obtained with many alveoli in the lungs.
Short diffusion pathway so gas can travel from one medium to another quickly, obtained through having thin walls between alveoli and capillaries.
High concentration gradient to increase rate of diffusion, obtained via breathing fresh air and constant flow of deoxygenated blood.

Question 2

What is the formula for ficks law.

Answer 2

rate of diffusion = surface area x difference in concentration / thickness of gas exchange surface

Question 3

Explain how an Increased thickness of gas exchange surface due to thicker mucus would affect the rate of gas exchange

Answer 3

it would decrease it as in ficks law a higher thickness would divide the rate of diffusion.

Question 4

Explain how a Reduction in the concentration gradient between the alveolar space and capillaries would affect the rate of gas exchange

Answer 4

It would decrease the rate of gas exchange as in the ficks law equation the concentration gradient is a multiplier.

Question 5

Explain how Damage to alveoli resulting in a reduction in their number would affect the rate of gas exchange

Answer 5

It would decrease the rate of gas exchange as in the ficks law equation surface area is a multiplier.

Question 6

Explain the role of goblet cells in the respiratory system

Answer 6

Produces mucus

Question 7

Explain the role of ciliated epithelial cells in the respiratory system

Answer 7

used to transport mucus to remove pathogens from the lungs.

Question 8

Describe how amino acids react together to form a polypeptide

Answer 8

Condensation reaction where amine group joins to carboxyl group to form a peptide bond.

Question 9

Give a definition of the primary structure of a protein

Answer 9

The number of amino acids and the order they are arranged in a polypeptide chain

Question 10

Describe how the secondary structure of a protein forms from the primary structure

Answer 10

The secondary structure of a protein is created by hydrogen bonds in the polypeptide chain causing the chain to form alpha helix shapes or beta pleat shapes.

Question 11

Describe how the tertiary structure of a protein forms from the secondary structure

Answer 11

Tertiary structure is formed by R group bonds (hydrogen bonds, ionic bonds etc.) between alpha helixes and beta pleats causing them to fold over one another into more complex shapes

Question 12

Explain how the primary structure of a protein determines the functional shape of the protein

Answer 12

The primary structure of a protein (the sequence of amino acids in the chain) determines how the protein will fold. The sequence of variable groups and how they interact with each other through hydrogen and sulfide bonds will determine the secondary structure (of alpha helices and beta pleated sheets), which will help determine the tertiary structure (the overall shape of that individual protein), and thus its function.

Question 13

Describe the structure of a globular protein

Answer 13

Polypeptide chain that has folded into a spherical shape. Polar R groups face outwards.

Question 14

Explain how the structure of a globular protein determines its function and properties

Answer 14

Globular proteins have polar R groups on the outside of the spherical molecule, which means it will have hydrophilic properties which means it is soluble in water.

Question 15

Describe the structure of a fibrous protein (incl. specific reference to collagen)

Answer 15

Fibrous proteins do not have a tertiary structure, and instead wrap around each other to form long, thin structures where polar R groups face inwards, such as collagen which is made up of 3 alpha helix polypeptide chains wound together in a helical structure

Question 16

Explain how the structure of a fibrous protein determines its function and properties

Answer 16

Fibrous protein has no outward facing polar R groups so it is insoluble in water, and due to their closely linked polypeptide chains, they have a high tensile strength.

Question 17

Describe the structure of a phospholipid

Answer 17

Glycerol base with 2 fatty acid chains and a phosphate group. Has a polar side (hydrophilic) and a non polar side (hydrophobic).

Question 18

Describe the structure and properties of phospholipids

Answer 18

phospholipids are composed of a phosphate group, two alcohols, and one or two fatty acids. On one end of the molecule are the phosphate group and one alcohol; this end is polar, i.e., has an electric charge, and is attracted to water (hydrophilic).

Question 19

Explain why phospholipids form a bilayer in cell membranes

Answer 19

Because their fatty acid tails are poorly soluble in water, phospholipids spontaneously form bilayers in aqueous solutions, with the hydrophobic tails buried in the interior of the membrane and the polar head groups exposed on both sides, in contact with water

Question 20

List the components of cell membranes and give a function for each

Answer 20

Proteins:
play a role in many other functions, such as cell signaling, cell recognition, and enzyme activity.
Phospholipids:
Interactions between polar heads and non polar tails create a bilayer which forms the basis of a plasma membrane
Carbohydrates:
Carbohydrates combine with protein molecules to form a glycoprotein,
Glycoproteins play a role in the interactions between cells, including cell adhesion, the process by which cells attach to each other.

Question 21

Explain why the cell membrane is called a fluid mosaic

Answer 21

Because it is made up of many different components which can move freely around each-other, giving it the appearance of a mosaic that moves like a fluid.

Question 22

Explain how the level of cholesterol affects membrane fluidity

Answer 22

higher cholesterol levels increase membrane fluidity by increasing distances between phospholipids allowing them to slide around one another

Question 23

Explain how saturated and unsaturated phospholipid tails affects membrane fluidity

Answer 23

Saturated tails will decrease membrane fluidity as the tails will pack closely together preventing movement, whereas unsaturated tails will increase membrane fluidity as they do not pack closely together and so can move freely around eachother

Question 24

Give reasons why the three-layer protein lipid sandwich theory of membrane structure was rejected as a model

Answer 24

It did not account for the permeability of certain substances,
as it did not explain the transport mechanism to allow certain substances across the membrane.

Question 25

Give a definition of osmosis

Answer 25

The movement of water from an area of low solute concentration to an area of high solute concentration, through a partially permeable membrane.

Question 26

Under what conditions would water move into a cell via osmosis?

Answer 26

When there is a higher concentration of water outside the cell than inside.

Question 27

Under what conditions would water move out of a cell via osmosis?

Answer 27

When there is a higher concentration of water inside the cell than outside.

Question 28

Explain why plant cells store glucose in the form of amylose/amylopectin and animal cells store glucose in the form of glycogen

Answer 28

Plants store glucose as starch because it can be broken down quickly and it is insoluble which means it does not disrupt osmotic balance, Animals store glucose as glycogen as it can be broken down quickly and it is insoluble which means it does not disrupt osmotic balance

Question 29

Explain how and why the hydrolysis of amylopectin/glycogen stored in a cell would impact the movement of water via osmosis

Answer 29

It would impact the movement of water via osmosis as water would be used up in a hydrolysis reaction, causing the concentration of water in that area to decrease, which would cause water to move towards the area of lower water concentration.

Question 30

Explain the role of the CFTR protein

Answer 30

Acts as a medium to allow chloride ions to transport across a cell membrane

Question 31

Explain how a faulty CFTR protein results in thicker, stickier mucus in CF sufferers

Answer 31

Faulty CFTR - Always open - Cl- Ions transport from mucus into cell - Travel across cell membrane into tissue fluid via diffusion - Na+ ions travel along electrochemical gradient from mucus to tissue fluid between cells - Water potential within the cell is higher than tissue fluid, water travels via osmosis from cell to tissue fluid, Water potential within mucus higher than cell, water gtravels via osmosis from mucus to cell, causing it to be thicker and stickier and more viscous

Question 32

Explain the effects of CF on the respiratory system

Answer 32

Cf means no cftr protein in membrane, which means water is constantly removed from mucus which results in thicker stickier mucus. This mucus cannot be moved by cilia cells which means there is a longer diffusion pathway as the mucus builds up a thick layer, which reduces rate of diffusion. Also, dirt and pathogens trapped inside the mucus cannot be moved out of the lungs so pathogens will cause infections inside the lungs.

Question 33

Explain the effects of CF on the reproductive system, incl. both males and females

Answer 33

female: thick mucus creates a mucus plug in the cervix which can block sperm from reaching the egg during reproduction Male: thick Mucus gathers inside the vas deferens canal as it cannot be moved by cilia, which means sperm is blocked from reaching the urethra as the sperm canal is blocked.

Question 34

Explain the effects of CF on the digestive system

Answer 34

Thick mucus is produced in the pancreas, mucus cannot be removed which means it eventually builds up and blocks the pancreatic duct. this means enzymes produced in the pancreas cannot reach the intestines, so food cannot be digested in the intestines and the enzymes will instead cause damage to the pancreas by breaking it down

Question 35

Describe and explain the effect temperature has on membrane permeability

Answer 35

Higher temperature increases membrane permeability as the phospholipids have more kinetic energy which means they move around eachother more, creating more gaps for small molecules to pass through the membrane.