genes and health Flashcards
components of phospholipids
polar/ hydrophilic phosphate head
on outside cos attracted to water
non polar/ hydrophobic fatty acid tail
on inside cos repelled by water
function of cholesterol in the plasma membrane
restricts lateral movement of other molecules in the membrane
makes membrane less fluid at high temps so water and dissolved ions dont leak out
function of peripheral proteins in the plasma membrane
do not extend across whole membrane
mechanical support
or connected to carbs/ lipids to form glycoproteins for cell recognition
function of integral proteins in the plasma membrane
span across from one side of bilayer to the other
carrier/ channel proteins
what molecules cant pass thru the phospholipid bilayer
large
polar
how do carrier proteins work
bind to complementary molecule
protein changes shape
allowing molecule to be released to other side of membrane
how do channel proteins work
form tubes filled w water
allows water soluble ions to pass
only open in presence of certain ions when they bind to it
what is an isotonic solution
water potential same inside and outside cell
what is a hypotonic cell
water potential of solution higher than cell
what is a hypertonic cell
water potential of solution lower than cell
what is active transport
against conc grad
using ATP from aerobic respiration
using carrier proteins
endocytosis
cell membrane folds inwards to form a cavity around particles
membrane completely encircles particles to form a vesicle
pinches off inside cell
exocytosis
Golgi vesicles w substances inside move to cell surface membrane
fuse w it
substances secreted
what are endo/ exocytosis used for
move substances in bulk across membranes
move molecules too large eg enzymes, antibodies
what is carrier testing
tested before having kids
couples w fam history of genetic disorders
tested for recessive alleles
determine probability of kids inheriting disorder
can make informed decisions before having kids
what is PGD
analysis of DNA from IVF embryo before implantation
offered to parents that are both carriers
avoids abortion, decreases risk of baby having genetic disorder cos implant embryos without condition
pros of prenatal testing
allows parents to make informed decisions- abortion?
prepare for child’s future care
what is amniocentesis
15- 20 weeks
removing and testing cells from amniotic fluid which contain foetal DNA
low risk of miscarriage
what is chorionic villus sampling
11- 14 weeks
removing and testing cells from placenta which contain foetal DNA
higher risk of miscarriage
what is the trachea
tube that allows air to travel to lungs
what are the C shaped rings of cartilage in the trachea for
ensure tube stays open at all times and does not collapse
prevents friction from rubbing w aesophagus
provides increased flexibility when food is being swallowed
what is the structure of bronchi compared to the trachea
thinner walls
smaller diameter
cartilage rings full circle rather than c
what are bronchioles
what are the walls of alveoli
single layer of squamous epithelium
thin, permeable for easy diffusion
where are alveoli
at ends of bronchioles in groups
why are alveoli surrounded by elastic fibres
so they can stretch during inhalation
why does a layer of moisture line the alveoli
facilitates gas diffusion
O2 and CO2 can dissolve in moisture layer
what is the secondary structure of proteins
sequence of amino acids causes parts of a protein to bend into alpha helix or fold into beta pleated sheets
held together by H bonds between O and H from NH2
when does quaternary structure occur
when a protein is made from more than 1 polypeptide chain
why are globular proteins roughly spherical
tertiary structure
non polar R groups oriented to centre of protein
polar to outside
structure of haemoglobin
globular protein
4 polypeptide chains
has quaternary structure
each subunit has a prosthetic hem group
4 globin subunits held together by disulphide bonds
why are globular proteins soluble in water
water molecules surround polar r groups so then
easily transported
involved in metabolic reactions
features of globular proteins
roughly spherical
compact
water soluble
some r conjugated proteins that contain a prosthetic group
features of fibrous proteins
long strands of polypeptide chains
have cross linkages cos of H bonds
little/ no tertiary structure
insoluble in water
strong
examples of fibrous proteins
keratin- hair, nails
elastin- bone., connective tissue
collagen- skin, ligaments
structure of collagen
fibrous protein
3 polypeptide chains held by h bonds
each subunit is a helix shape
covalent bonds form cross links between r groups
cross links hold collagen molecules together to form fibrils
