topic 2 Flashcards
What are adaptations of large organisms to improve gas exchange
Mammals have alveoli which increases surface area for gas exchange.
Fish have gills which have structures called lamellae and this provides a very large surface area.
Plants have a spongy mesophyll layer within which the large leaf cell surface area is exposed to air
Features of the alveoli
It has a flattened/squamous endothelium and this allows it to have a short diffusion distance.
The alveoli are surrounded by elastic fibres and allow it to stretch during inhalation.
It has a layer of moisture which facilitates diffusion of gases and this allows the oxygen and CO2 to be dissolved in that layer so exchange occurs in a solution.
The alveoli are surrounded by an extensive capillary network and this means that CO2 diffuses out the capillary and into the alveoli while oxygen from the alveoli diffuses into the capillary to be transported around the whole body
What is a phospholipid made of?
A molecule of glycerol
a phosphate group also known as a phosphate head
two fatty acids making up the lipid tail
What part of the phospholipid is polar and which part is non-polar?
The phosphate head is polar and hydrophilic and can react with other polar molecules whilst the lipid tail is hydrophobic and non polar
What are cell membranes made-up of?
Phospholipid bilayer
What do the phospholipid bilayer contain?
Proteins -
Cholesterol
Glycolipids
What bases are purines?
Adenine and guanine have a double ring structure
What bases are pyrimidines
C , T , U they all have a single ring structure
How many hydrogen bonds form between A and T
2
How many hydrogen bonds form between C and G
3
On what carbons do the phosphate group bond to the DEOXYRIBOSE sugar by phosphodiester bonds? (DNA NUCLEOTIDE)
3’ AND 5’ and on the antiparallel it goes 5’ AND 3’
what is the difference between DNA nucleotide and a RNA nucleotide
DNA nucleotide has a hydrogen bonded to carbon 2 known as deoxyribose sugar whilst RNA nucleotide has a hydroxyl bonded to the carbon 2
