genes and health

Question 1

components of phospholipids

Answer 1

polar/ hydrophilic phosphate head
on outside cos attracted to water

non polar/ hydrophobic fatty acid tail
on inside cos repelled by water

Question 2

function of cholesterol in the plasma membrane

Answer 2

restricts lateral movement of other molecules in the membrane

makes membrane less fluid at high temps so water and dissolved ions dont leak out

Question 3

function of peripheral proteins in the plasma membrane

Answer 3

do not extend across whole membrane
mechanical support
or connected to carbs/ lipids to form glycoproteins for cell recognition

Question 4

function of integral proteins in the plasma membrane

Answer 4

span across from one side of bilayer to the other
carrier/ channel proteins

Question 5

what molecules cant pass thru the phospholipid bilayer

Answer 5

large
polar

Question 6

how do carrier proteins work

Answer 6

bind to complementary molecule
protein changes shape
allowing molecule to be released to other side of membrane

Question 7

how do channel proteins work

Answer 7

form tubes filled w water
allows water soluble ions to pass
only open in presence of certain ions when they bind to it

Question 8

what is an isotonic solution

Answer 8

water potential same inside and outside cell

Question 9

what is a hypotonic cell

Answer 9

water potential of solution higher than cell

Question 10

what is a hypertonic cell

Answer 10

water potential of solution lower than cell

Question 11

what is active transport

Answer 11

against conc grad
using ATP from aerobic respiration
using carrier proteins

Question 12

endocytosis

Answer 12

cell membrane folds inwards to form a cavity around particles

membrane completely encircles particles to form a vesicle

pinches off inside cell

Question 13

exocytosis

Answer 13

Golgi vesicles w substances inside move to cell surface membrane

fuse w it

substances secreted

Question 14

what are endo/ exocytosis used for

Answer 14

move substances in bulk across membranes

move molecules too large eg enzymes, antibodies

Question 15

what is carrier testing

Answer 15

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

Question 16

what is PGD

Answer 16

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

Question 17

pros of prenatal testing

Answer 17

allows parents to make informed decisions- abortion?

prepare for child’s future care

Question 18

what is amniocentesis

Answer 18

15- 20 weeks
removing and testing cells from amniotic fluid which contain foetal DNA
low risk of miscarriage

Question 19

what is chorionic villus sampling

Answer 19

11- 14 weeks
removing and testing cells from placenta which contain foetal DNA
higher risk of miscarriage

Question 20

what is the trachea

Answer 20

tube that allows air to travel to lungs

Question 21

what are the C shaped rings of cartilage in the trachea for

Answer 21

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

Question 22

what is the structure of bronchi compared to the trachea

Answer 22

thinner walls
smaller diameter
cartilage rings full circle rather than c

Question 23

what are bronchioles

Question 24

what are the walls of alveoli

Answer 24

single layer of squamous epithelium
thin, permeable for easy diffusion

Question 25

where are alveoli

Answer 25

at ends of bronchioles in groups

Question 26

why are alveoli surrounded by elastic fibres

Answer 26

so they can stretch during inhalation

Question 27

why does a layer of moisture line the alveoli

Answer 27

facilitates gas diffusion
O2 and CO2 can dissolve in moisture layer

Question 28

what is the secondary structure of proteins

Answer 28

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

Question 29

when does quaternary structure occur

Answer 29

when a protein is made from more than 1 polypeptide chain

Question 30

why are globular proteins roughly spherical

Answer 30

tertiary structure
non polar R groups oriented to centre of protein
polar to outside

Question 31

structure of haemoglobin

Answer 31

globular protein
4 polypeptide chains
has quaternary structure
each subunit has a prosthetic hem group
4 globin subunits held together by disulphide bonds

Question 32

why are globular proteins soluble in water

Answer 32

water molecules surround polar r groups so then
easily transported
involved in metabolic reactions

Question 33

features of globular proteins

Answer 33

roughly spherical
compact
water soluble
some r conjugated proteins that contain a prosthetic group

Question 34

features of fibrous proteins

Answer 34

long strands of polypeptide chains
have cross linkages cos of H bonds
little/ no tertiary structure
insoluble in water
strong

Question 35

examples of fibrous proteins

Answer 35

keratin- hair, nails
elastin- bone., connective tissue
collagen- skin, ligaments

Question 36

structure of collagen

Answer 36

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