Unit 2 Flashcards
What do lungs allow gas exchange between?
They allow rapid gas exchange between the atmosphere and the blood
What is the job of the basement membrane and what is it made from?
It holds the cell in position and is made of protein fibres in a jelly like protein-carbohydrate matrix
Where are the ciliated epithelial cells found?
They line the airways
What do goblet cells produce and where is that released into?
They produce mucus which is released into the airway
What is the structure and function of cilia?
They are hair like structures that beat and move mucus up and out the lungs
What is the difference in mucus between people with and without cf?
People with cf have less water in their mucus so it’s sticker
What is the problem with stickier mucus in people with cf?
It is more difficult for the cilia to move which increases the chance of lung infection and makes gas exchange less efficient
Name 3 features of the alveoli
- Large SA due to many alveoli
- good blood supply
- a short diffusion distance due to thin walls of the alveoli and capillaries
What is the equation for Fick’s law?
Rate of diffusion=SA X difference in conc/ thickness of surface
Fill the blank: Surface area is ——– to the rate of diffusion
Directly proportional
Is concentration gradient directly or inversely proportional to the rate of diffusion?
Directly proportional
True or false: thickness of the gas exchange surface is directly proportional to the rate of diffusion
False. Thickness of the gas exchange surface is inversely proportional to the rate of diffusion
How many different amino acids are there?
20
Draw an amino acid
Amine group = -on the left
N bonded to 2 H's
Hydrogen above the carbon
R group below the carbon
Carboxylic group = -on the right
C bonded to OH double bondName the reaction that joins 2 amino acids
A condensation reaction
What does the cell surface membrane contain?
- phospholipid bilayer
- proteins
- cholesterol
- glycoproteins
- glycolipids
Describe the primary structure of a protein
a chain of amino acids
Describe the secondary structure of a protein
alpha helix or beta pleated sheet
Describe the tertiary structure of a protein
The polypeptide chain folds to produce a 3D shape and is held together by ionic bonds
Describe the quaternary structure of a protein
when 4 a-heix come together, they form a globular protein
Compare and contrast globular and fibrous proteins
- Globular proteins are in a compact spherical shape whereas fibrous proteins are long chains
- Globular proteins are soluble whereas fibrous proteins are insoluble
- Globular proteins are important in metabolic reactions whereas fibrous proteins are important in keratin in hair and collagen in skin
Give an example of a globular and fibrous protein
globular = Enzymes
fibrous =cartilage
How can the phospholipid bilayer be seen?
Using an electron microscope as it is about 7nm wide
What are the 2 parts of the phospholipid bilayer?
The hydrophilic head and hydrophobic tail. The head is polar and the tail is non-polar
What is the fluid mosaic model?
Some proteins are fixed upon the membrane of a cell but others can move around, creating fluidity
What was the cell membrane thought of as up to 1972?
it was thought that the cell membrane was a 3 layer protein-lipid sandwich
Evidence for the fluid mosaic model
In 1972, Singer and Nicholson came up with the fluid mosaic model, with evidence coming from the freeze fracture electron microscopy studies. The first model was created by Grendel and Gonter
Describe how water is regulated in mucus with too much water (non CF lungs)
- Excess water detected by epithelial cells
- Na+ is actively pumped into tissue fluid through basal membrane
- Na+ channel opens and Na diffuses in which creates an electrical gradient
- Cl- diffuses through gaps from mucus into tissue fluid
- Osmosis due to increase in Na+ and Cl- moves water from mucus to tissue fluid
Describe how water is regulated in mucus with not enough water (non CF lungs)
- Cl- transported to epithelial cells which causes conc. gradient
- Conc. gradient causes CFTR channel ( a gated protein channel) to open
- Build up of Cl- in mucus creates electrical gradient between mucus and tissue fluid
- Na+ diffuses through gaps from tissue fluid into mucus
- Higher salt conc in mucus means osmosis draws water out of cells into mucus
Effect of CF on the digestive system
- Problems with digestion and absorption of nutrients resulting in low body mass
- People may need to take supplements that contain digestive enzymes
Why may a CF sufferer may need to take digestive enzymes?
The pancreatic duct become blocked by sticky mucus, impairing digestive enzymes so less nutrients is absorbed. This causes malabsorption syndrome
Effect of CF on reproductive system
- Females have reduced chance of pregnancy as mucus plug blocks the cervix
- Males often lack the sperm duct (vas deferens) so sperm cannot leave the testes
What monomers make up DNA?
Nucleotides
Describe the structure of a DNA nucleotide
The pentose sugar ‘deoxyribose’ at the centre, with phosphate at the top and an organic base to the right
Name the 4 organic bases
- Adenine
- Cytosine
- Guanine
- Thymine
What is the difference between mRNA and DNA?
RNA is a single stranded polynucleotide made of ribonucleic acid and contains ribose rather than deoxyribose. It also contains thymine rather than uracil
Describe DNA Replication
- hydrogen bonds break between the bases and DNA unzips
- DNA nucleotides pair up with comp bases. DNA polymerase links adjacent nucleotides
- two identical daughter stands are created
How do we know DNA replication is semi conservative?
Watson and Crick used DNA from E Coli grown in the Heavy isotope of Nitrogen, N15.
The nucleotides in bacteria at the start contained heavy nitrogen, making the DNA heavier than normal. The bacteria was then put in the medium isotope of N. The DNA replicated once and was centrifuged
What type of bond holds together nucleotides?
Phosphodiester
Describe the positioning of each part of a nucleotide
The sugars and phosphates form the sugar-phosphate backbone on the outside and the bases point inwards horizontally, being held together by hydrogen bonds; the 2 nucleotides run antiparallel
Describe transcription
- RNA polymerase attached to the DNA, the hydrogen bonds break and the DNA unwinds
- The template strand is transcribed to make mRNA which has the same base sequence as DNA
- The complimentary base RNA nucleotides align themselves and phosphodiester bonds form to produce mRNA
- When transcription is complete, the mRNA leaves through a nuclear pore and the DNA ‘zips up’.
Describe translation
- mRNA attaches to the small subunit of a ribosome
- Free amino acids become attached to the correct tRNA molecules
- The first codon will always be AUG and the next codon is facing the binding site; this attracts the tRNA- amino acid complex with the complimentary anticodon
- The ribosome holds the mRNA, tRNA and amino acids in place long enough for a peptide bond to form between the two aminos
What does non-overlapping mean?
Each triplet code is adjacent
What is a triplet codon?
The code carried b the DNA contains 3 bases
What are the 4 types of genetic testing ?
- Amniocentesis
- Chronic villus sampling
- Non invasive prenatal diagnosis
- pre implantation genetic diagnosis
What is amniocentesis and when should it occur?
Involves inserting a needle into the amniotic fluid to collect cells
This should occur between 15 and 17 weeks
1% risk of miscarriage
What is Chorionic villus sampling and when should it occur?
A sample of cells is removed either through the vagina or wall of abdomen
Between 8 and 12 weeks
1-2% risk of miscarriage
What is non-invasive prenatal diagnosis and when should it occur?
Analyses DNA fragments in the mother’s blood and can detect chromosomal conditions
Occurs between 7-9 weeks
No risk of miscarriage
What is pre implantation genetic diagnosis and when should it occur?
A cell of the baby is removed and is screened to look for any conditions. The couple will have to undergo IVF for this to happen
Occurs when the baby has around 8 cells
Very low success rate
Summarise Diffusion
Down a conc grad, from high to low conc
Hydrophobic (lipid soluble) it small uncharged molecules
Through phospholipid bi-layer
No energy required
Summarise facilitated diffusion
Down a conc grad from high to low conc
Hydrophilic molecules or ions
Through channel proteins or via carrier proteins
No energy required
Summarise osmosis
Low to high conc
Movement of water
Through Phospholipid bi-layer
No energy required
Summarise active transport
Against a conc grad, from low to high conc
Through Carrier proteins that change shape
Require energy, supplied by ATP
Summarise exocytosis
Used for bulk transport out of a cell
Vesicles fuse with the cell membrane releasing their contents
Summarise endocytosis
Used for bulk transport into the cell
Vesicles are create from the cell surface membrane, bringing their contents into the cell
