Genes & Health

Question 1

What are the Symptoms of Cystic fibrosis?

Answer 1

Very salty-tasting skin.
Persistent coughing, at times with phlegm.
Frequent lung infections including pneumonia or bronchitis.
Wheezing or shortness of breath.
Poor growth or weight gain in spite of a good appetite.

Question 2

Possible treatments of cystic fibrosis?

Answer 2

antibiotics to prevent and treat chest infections.
medicines to make the mucus in the lungs thinner and easier to cough up.
medicines to widen the airways and reduce inflammation.
special techniques and devices to help clear mucus from the lungs.
medicines that help the person absorb food better.

Question 3

Effects for cystic fibrosis

Answer 3

CF causes thick mucus that clogs certain organs, such as the lungs, pancreas, and intestines. This may cause malnutrition, poor growth, frequent respiratory infections, breathing problems, and chronic lung disease.

Question 4

What is a gene and what is a gene mutation

Answer 4

Genes are sections of DNA nucleotides located on chromosomes that contain the instructions for production of a specific protein.

A change in the DNA nucleotides in the gene so either no protein or an incorrect protein is made.

Question 5

Identify the parts of the respiratory that provide the following features:

• Large surface area
• Very thin permeable membrane, for a short diffusion
pathway
• Maintaining diffusion gradients

Answer 5

LSA= alveoli & capillaries
Maintaining diffusion = blood flow & gasses
Short diffusion distance = alveoli epithelial& capillary endothelium .

Question 6

There are three layers between the blood and the air in the alveoli: the capillary wall, a layer of extracellular matrix and the alveolar wall. This is called the blood-gas barrier.
Explain how the blood-gas barrier of the chicken is adapted to give more efficient gas exchange than the blood-gas barrier of the dog. (3)

Answer 6

• Thinner blood-gas barrier
• Because of thinner alveoli walls/capillary walls
• Therefor a reduced diffusion distance
• Faster rate of diffusion/gas exchange

Question 7

Emphysema is another lung disease associated with cigarette smoking. One symptom of emphysema is shortness of breath. This is due to the damage to the alveoli and destruction of capillaries surrounding the alveoli. Use your knowledge of the structure of the lung and its adaptations for gas exchange to explain why a person with emphysema has problems with gas exchange.

Answer 7

-reduced diffusion of gases
-due to decrease in surface area of alveoli / gas exchange surface
-and capillaries due to the destruction
-less blood flow and therefore less o2 being carried
-meaning lower concentration gradient.

Question 8

What is fick’s law ?

Answer 8

Rate of diffusion = (surface area x concentration gradient) / diffusion distance

Question 9

Fick’s law can be used to calculate the rate of diffusion across gas exchange surfaces. Use fick’s law to explain the adaptations of mammalian gas exchange surfaces

Answer 9

Rate of diffusion is proportional to surface area - alveoli have large surface area so rate of diffusion increases.
Rate of diffusion is proportional to difference in concentration blood flow maintains a difference in gas concentrations.
Rate of diffusion is inversely proportional to diffusion distance. Walls of alveoli and capillaries are one cell thick
Diffusion distance is reduced due to flattened cells forming alveoli and capillary walls.

Question 10

State 3 things needed for efficient diffusion of gases across the gas exchange surface

Answer 10

• short dif pathway
• large SA
• steep conc gradient

Question 11

What provides the large SA in the GE system

Answer 11

Alveoli + capillaries

Question 12

What maintains a steep conc gradient in GE system?

Answer 12

Blood circulation + breathing

Question 13

What provides short dif pathway in GE system?

Answer 13

Alveoli + capillary walls = 1 cell thick

Question 14

Define breathing and respiration

Answer 14

Respiration = the process, which occurs in mitochondria , that releases energy stored in organic molecules( food) such as glucose. energy released during respiration is used to synthesise molecules of ATP, which can be used as an immediate source of energy.

Breathing = the process of inhaling oxygen and exhaling carbon dioxide

Question 15

Draw and Label an amino acid into the 3 groups

Answer 15

Carboxyl group = COOH

amine group = NH2

Variable group = R

+ oxygen

Question 16

What is the reaction that causes 2 amino acids to join and what to they create. Draw and name the product of the reaction

Answer 16

Use notes to mark drawing .
Condensation reaction
Dipeptide + water

Question 17

Summarise diffusion

Answer 17

Diffusion is the net movement of particles form a high a lower concentration. Molecules with diffuse both ways but the net movement will be to the area of lower concentration until particles are evenly distributed throughout the liquid or gas.

the concentration gradient is the path from an area of high concentration to an area of lower concentration. Particles diffuse down this.

Diffusion is a passive process- no energy needed for it to happen

Question 18

How are gas exchange surfaces adapted for efficient diffusion?

Answer 18

Most gas exchange surfaces have to things in common:
- they give gas exchange organs (like the lungs)a large SA:VOL ratio
- they’re thin (often just one layer of epithelial cells). This provides a short diffusion pathway across the gas exchange surface.

The organism also maintains a steep concentration gradient of gases across the exchange surface

Question 19

Explain surface area to volume ratios & how to calculate them.

Answer 19

-large objects have smaller SA:VOL ratios than small objects
-the smaller the SA:VOL ratio the slower the rate of exchange e.g a substance would diffuse more slowly out of a bigger cube than a smaller cube

SA equation = n x n x 6
Vol equation = n x n x n
Then put both answers into a ratio

Question 20

How are the lungs adapted for efficient gaseous exchange?

Answer 20

In mammals the gas exchange surface is the alveolar epithelium in the lungs:
- oxygen diffuses out of the alveoli across the alveolar epithelium (layer of thin flat cells) and the capillary endothelium ( a type of epithelium that forms the capillary wall) and into the blood

The mammalian lungs have the following features which all help to + rate of gaseous exchange.

1) Having lots of alveoli means there is a large surface area for diffusion to occur across.
2) The alveolar epithelium and capillary endothelium are each only one cell thick, giving a short diffusion pathway.
3) All the alveoli have a good blood supply from capillaries - they constantly take away oxygen and bring more carbon dioxide, maintaining the concentration gradient.
4) Breathing in and out refreshes the air in the alveoli, keeping the concentration gradients high.

Question 21

What are the different forms of amino acids?

Answer 21

1) The monomers of proteins are amino acids.
2) A dipeptide is formed when two amino acids join together.
3) A polypeptide is formed when more than two amino acids join together.
4) Proteins are made up of one or more polypeptides.

Question 22

How are polypeptides formed?(explain and show diagram)

Answer 22

Amino acids are linked together by condensation reactions to form polypeptides.
A molecule of water is released during the reaction. The bonds formed between amino acids are called peptide bonds. The reverse reaction happens during digestion.

Question 23

Explain the 4 structural levels of proteins

Answer 23

Primary Structure - this is the sequence of amino acids in the polypeptide chain.

Secondary Structure - the polypeptide chain doesn’t remain flat and straight.
Hydrogen bonds form between the amino acids in the chain.
This makes it automatically coil into an alpha (a) helix or fold into a beta (B) pleated sheet - this is the secondary structure.

Tertiary Structure - the coiled or folded chain of amino acids is often coiled and folded further. More bonds form between different parts of the polypeptide chain, including hydrogen bonds and ionic bonds (see next page).
Disulfide bonds can also form (see next page). For proteins made from a single polypeptide chain, the tertiary structure forms their final 3D structure.

Quaternary Structure - some proteins are made of several different polypeptide chains held together by bonds. The quaternary structure is the way these polypeptide chains are assembled together. For proteins made from more than one polypeptide chain (e.g. haemoglobin, insulin, collagen), the quaternary structure is the protein’s final 3D structure.

Question 24

What are the different bonds that hold the 4 structural levels of proteins together?

Answer 24

1) Primary structure - held together by the peptide bonds between amino acids

2) Secondary structure - held together by hydrogen bonds.
positively-charged hydrogen
3) Tertiary structure - this is affected by a few different kinds of bonds:
• lonic bonds. These are attractions between negative and positive charges on different parts of the molecule.
Disulfide bonds. Whenever two molecules of the amino acid cysteine come close together, the sulfur atom in one cysteine bonds to the sulfur in the other cysteine, forming a disulfide bond.
Hydrophobic and hydrophilic interactions. When hydrophobic (water-repelling) groups are close together in the protein, they tend to clump together. This means that hydrophilic (water-attracting) groups are more likely to be pushed to the outside, which affects how the protein folds up into its final structure.
• Hydrogen bonds.
4)Quaternary structure - this tends to be determined by the tertiary structure of the individual polypeptide chains being bonded together. Because of this, it can be influenced by all the bonds mentioned above.

Question 25

How does a proteins primary structure determine its 3D structure & properties?

Answer 25

1) The amino acid sequence of a protein determines what bonds will form and how the protein will fold up into its 3D structure. E.g. if there are many cysteines, these will form disulfide bonds with each other, so the protein folds up in a certain way.
2) The 3D structure of a protein determines its properties. Its properties relate to its function in the body.

Question 26

What are globular proteins?

Answer 26

1) Globular proteins are round, compact proteins made up of multiple polypeptide chains.
2) The chains are coiled up so that hydrophilic (water-attracting) parts of chains are on the outside of the molecule and hydrophobic (water-repelling) parts of chains face inwards.
3) This makes the proteins soluble, so they’re easily transported in fluids.
4) E.g. haemoglobin is a globular protein made of four polypeptide chains. It carries oxygen around the body in the blood. It’s soluble, so it can be easily transported in the blood. It also has iron-containing hem groups that bind to oxygen.

Question 27

What are fibrous proteins?

Answer 27

1) Fibrous proteins are made up of long, insoluble polypeptide chains that are tightly coiled round each other to form a rope shape.
2) The chains are held together by lots of bonds (e.g. disulfide and hydrogen bonds), which make the proteins strong.
3) Because they’re strong, fibrous proteins are often found in supportive tissue.
4) E.g. collagen is a strong, fibrous protein that forms connective tissue in animals.

Question 28

A change in the primary structure of a protein can lead to a change in the tertiary structure which will change the overall function of the protein, describe and explain how.

Answer 28

Dif amino acids in dif order leads if different r groups (side chains)dif bonds then form in dif places leading to dif final quaternary shape meaning dif structure

Question 29

Compare and contrast the structure of a triglyceride and a phospholipid

Answer 29

Similarities= glycerol n fatty acids
Differences=
trig = 3 fatty acids no phosphate non polar
Phospho= 2 fatty acids, polar head , 1 phosphate

Question 30

What is the ‘fluid mosaic model’ And what does it contain?

Answer 30

A model that describes the arrangement of molecules in the membrane.

1)phospholipids form bilayer ( hydrophilic head, phosphate group, faces outside of cell. Hydrophobic tail, fatty acid chain faces inside of cell)

2)proteins are scattered through bilayer ( bcz bilayer is fluid ,constantly moving, proteins move w it)

3) some proteins have a polysaccharide(carbohydrate) chain attached. These are glycoproteins.

4)some lipids also have a polysaccharide chain attached making glycolipids.

5)cholesterol ( type of lipid) fits in between phospholipids forming bonds w them. Makes membrane more rigid but at low temp can cause membrane to be more fluid.

Question 31

Give the definition of osmosis

Answer 31

Osmosis is the definition of free water molecules across a partially permeable membrane from an area of high concentration to an area of low concentration. Water moles diffuse both ways through membrane but net movement will be to the side with lower concentration of water molecules.

Question 32

Give the definition of diffusion

Answer 32

Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration. This continues till particles are evenly distributed through liquid or gas.
Particles diffuse down the concentration gradient and it is a passive process ( no energy required.)

Question 33

Explain facilitated diffusion

Answer 33

Movement of larger molecules and charged molecules that do not diffuse directly thought to the phospholipid bilayer by carrier and channel proteins.

Method: carrier proteins

1) large mol attached to a carrier protein in the membrane

2) protein changed shape

3) this releases the mol on the opposite side of the membrane

Method:channel proteins

Channel proteins form pores in the membrane for charged particles to diffuse through (down conc Grad). Different channel proteins facilitate diffusion of dif charged particles.

Question 34

Describe active transport

Answer 34

Active transport uses energy to move molecules and ions across plasma membranes, against a conc grad.
The process involves carrier proteins.

1)process is similar to facilitated diffusion (mol attached to carrier protein, protein changed shape and moves molecule across the membrane,releasing it on the other side.

2) only difference is energy is used coming from ATP. ATP is produced by respiration and acts as an immediate source of energy in the cell. When ATP is hydrolysed (broken down) energy is released. This energy is used to move the molecule against its concentration gradient.

Question 35

How are polypeptides formed?

Answer 35

Amino acids are linked together by condensation reactions. A molecule of water is released during the reaction. Peptide Bonds formed between bonds. Exact opposite for polypeptides breaking down to amino acids but H2O is used

Question 36

What are the 4 structural levels of protein?

Answer 36

Primary structure - sequence of amino acids in the polypeptide chain

Secondary structure- polypeptide chain doesn’t remain flat and straightness. Hydrogen bonds form between amino acids causing it to automatically coil into an alpha helix or beta pleated sheet.

Tertiary structure- the coiled or folded chain of amino acids is often coiled and folded further. More bonds form between different parts of the polypeptide chain, including hydrogen, ionic and disulphide bonds.proteins made from a single polypeptide chain, tertiary structure is final 3D structure.

Quaternary structure- some proteins are made of several different polypeptide chains held together by bonds. Quaternary structure is the way these polypeptide chains are assembled together. Final 3D structure for proteins made from more than 1 polypeptide chain

Question 37

What is DNA & RNA ?

Answer 37

DNA: (deoxyribonucleic acid) used to store genetic info- all the instructions an organism needs to grow and develop from a fertilised egg to a fully grown adult

RNA: ribonucleic acid) similar to DNA. One of main functions is to transfer genetic information from the DNA to the ribosomes.

DNA & RNA are both polymers of mononucleotides.

Question 38

What does RNA & DNA contain?

Answer 38

DNA:
1)deoxyribose pentose sugar
2) phosphate group
3)base (A,T,C or G)

RNA:
1)ribose pentose sugar
2)phosphate group
3)base (A,T,C or G)

Question 39

What are mononucleotides and what do they form ?

Answer 39

Mononucleotides are biological molecules that contain: a pentose sugar(sugar w 5 carbon atoms), a nitrogen base, a phosphate group

Mononucleotides join together to form polynucleotides, they are joined through condensation reactions between the phosphate of one mono nucleotide and the sugar group of another. Water is a byproduct of product.

DNA = 2 polynucleotide strands
RNA= one singular strand

Question 40

Explain how the structure of DNA is formed

Answer 40

• Two DNA polynucleotide strands join together by hydrogen bonding between the bases.
• Each base can only join with one particular partner.this is called complementary base pairing (or specific base pairing).
  -Adenine always pairs with thymine (A - T) and cytosine always pairs with guanine (C - G). This means that there are always equal amounts of adenine and thymine in a DNA molecule and equal amounts of cytosine and guanine.
  -Two hydrogen bonds form between A and T, and three hydrogen bonds form between C and G.
  -Two antiparallel (running in opposite directions) polynucleotide strands twist to form the DNA double-helix.
  -DNA was first observed in the 1800s, but lots of scientists at the time doubted that it could carry the genetic code because it has a relatively simple chemical composition. Some argued that genetic information must be carried by proteins — which are much more chemically varied.
  -By 1953, experiments had shown that DNA was the carrier of the genetic code. This was also the year in which the double-helix structure, which helps DNA to carry out its function, was determined.

Question 41

how does dna replicate by semi-conservative replication?

Answer 41

1) enzyme DNA helicase breaks the hydrogen bonds between bases on the 2 polynucleotide DNA strands. This makes the helix unwind to form 2 dinghy DNA strands

2)each original single strand acts as a template for a new strand. Complimentary base pairing means that free floating dna nucleotides are attracted to their complimentary exposed bases on each original template strand

3)condensation reactions join the nucleotides if the new strands together-catalysed by the enzyme DNA polymerase. Hydrogen bonds form between the bases on the original and new strands.

4) each new DNA molecule contains one strand from the original DNA molecule and one new strand