genes and health

Question 1

describe the role of tRNA

Answer 1

tRNA molecules transport amino acids to the ribosome. tRNA molecule has a complimenteray anticodon that binds to a codon on the mRNA. each tRNA carries a particular amino acid. tRNA binds to ribosome

Question 2

compare and contrast the process of endocytosis and exotycosis

Answer 2

• both processes involve vesicles and both involve energy/ATP
• exocytosis involves substances leaving the cell whereas endocytosis involves substances entering the cell. exocytosis involve vesicles fusing with cell surface membrane whereas endocytosis involves the formation of vesicles

Question 3

function of glycoprotein

Answer 3

cell recognition/receptors/antigens

Question 4

explain how the structure of a phospholipid molecule contributes to the partial permeability of the membrane

Answer 4

contains hydrophilic phosphate head and hydrophobic fatty acid chains. it allows non-polar molecules to pass through the membrane. polar molecules cannot pass through the phospholipid bilayer

Question 5

how do phopsholipids form bilayer

Answer 5

hydrophilic parts associate with water. hydrophobic parts repel with water. a bilayer forms with hydrophobic parts pointing towards the centre of the bilayer

Question 6

why are phospholipids arranged into two layers in a membrane

Answer 6

hydrophilic region orientated towards water and hydrophobic regions away from the water. solution either side of the cell membrane

Question 7

function of carrier proteins

Answer 7

involved in facilitated diffusion. movement of large molecules from a high to low concentration. involved in active transport.

Question 8

describe the structure of the cell surface membrane

Answer 8

it is phospholipids and protein. phospholipids form a bilayer. proteins float in the phospholipids

Question 9

how does primary sturcture of leptin allow it to be soluble

Answer 9

primary structure determines the folding of the polypeptide forming a globular structure. hydrophobic r groups are located in the centre of the protein. water forms hydrogen bonds with protein

Question 10

how does substitution base affect fucntion of molecule

Answer 10

different triplet is produced which changes the codons in mRNA resulting in a different amino acid. but this may code for the same amino acid. due to the degenerate nature of the genetic code

Question 11

why can enzymes that arent correctly folded not carry out its function

Answer 11

teriary structure would be different so active site of enzyme wouldn’t bind with the enzyme/wouldn’t be able to form enzyme susbtratwe complex. therefore, it wouldnot be able to catalyse the reaction

Question 12

compare and contrast globular and fibrous proteins

Answer 12

both are chains of amino acids joined by peptide bonds. both contain hydrogen and ionic bonds, disulfide bridges.
globular proteins have hydophilic groups on the outside whereas fibrous proteins have little or no tertiary structure.
globular are folded into compact shapes whereas fibrous have long chains

Question 13

how is a peptide bpnd formed

Answer 13

condensation reaction between amine group and carboxyl group of adjacent amino acids

Question 14

products when several amino acids are joined toegther

Answer 14

water and polypeptide

Question 15

compare transcription and DNA replication

Answer 15

both involve formation of polynucleotide. both involve DNA helicase. transcription uses RNA nucleotides and RNA polymerase whereas replication uses DNA nucleotides and DNA polymerase. transcription produces single strand of mRNA whereas replication produces double stranded DNA

Question 16

what deos a frameshift do

Answer 16

changes triplet code so introduces a new coodn which codes for a shorter sequence of amino acids. more likely to affect the position of a start/stop coodn

Question 17

describe how mRNA is synthesised at a template strand

Answer 17

RNA nucleotides align with complementary bases. RNA nuclepotides joined together by RNA polymerase/phosphodiester bonds

Question 18

compare RNA and DNA

Answer 18

DNA is double stranded whereas RNA is single stranded. DNA contains deoxyribose while RNA contains ribose. DNA contains thymine whereas RNA contains uracil

Question 19

which type of bond holds strands of dna together

Answer 19

hydorgen

Question 20

describe how nucleotides join together to form dna

Answer 20

condensation reaction. phosphodiester bonds. DNA polymerase

Question 21

why did they accept one of the dna replication models and not the otger

Answer 21

semi-conservatvie model was accepted because generation 1 has a single band which is halfway between 15N and one 14N. the dna has one strand containing 15N and one strand containing 14N. further generations would have a band halfway between 15N and 14N

Question 22

why does antibiotics that binds to ribosome affect production of protein

Answer 22

mRNA is prevented from binding to the ribosome. so translation cant occur so protein can’t be synthesised

Question 23

describe the role of CFTR in ensuring that mucus produced in the lungs is the right consistency

Answer 23

chloride ions leave the cell. sodium ions leave the cell. this increases the solute concentration in the mucus. water moves out of the cells by osmosis

Question 24

describe the roles of translation and transciption

Answer 24

the gene for the protein is transcribed. complementary base pairing between RNA nucleotides and DNA. mRNA leaves the nucleus and attaches to the ribosome. pairing between codons on mRNA and anticodons kn tRNA. tRNA provides specific asmino acids. the sequence of bases determione the primary structure

Question 25

explain why different mutations in the CFTRNgene can lead to differences in the severity of the symptoms of cystic fibrosis

Answer 25

different mutations will have different effects on the protein produced chloride ion transport affected by the extent of changes varying the stickiness of mucus

Question 26

why does cystic fibrosis affect the rate of oxygen uptake in lungs

Answer 26

thick sticky mucus which cannot be moved by cilia restricting air flow trhough bronchioles reduced surface area for gas exchange in the alveoli

Question 27

how many hydrogen bonds between a-t

Answer 27

2

Question 28

how many hydrogen bonds between c-g

Answer 28

3

Question 29

why do children with cystic fibrosis need dietary supplements and digestive enzymes

Answer 29

cystic fibrosis causes the production of stuckier thicker mucus this blocks the pancreatic duct which prevents pancreas enzymes from reaching the intestine prevents enzymes elnde digesting in intestines resulting in reduced absorption of products of digestion into the blood digestive enzymes and dietary supplements would increase growth rate

Question 30

what does CFTR gene code for

Answer 30

a channel protein

Question 31

why may parents choose not to do CVS

Answer 31

Test result may be innacurate increased risk of miscarriage false positive may lead to termination of healthy fetus against values or beliefs of the parents

Question 32

definition of inherited recessive disorder

Answer 32

caused by a faulty allele only expressed in the homozygous condition

Question 33

what is it called when many different siblings are different genotype

Answer 33

incomplete dominance Both alleles expressed

Question 34

allele definitin

Answer 34

alternative form of a gene found at the same locus

Question 35

how to know if parents are heterozygous

Answer 35

if some of the children have the recessive disease

Question 36

what is cvs

Answer 36

chorionic villus sampling cells taken from placenta between 10-14 weeks of pregnancy benefit of earlier diagnosis

Question 37

amniocentesis definition

Answer 37

amniotic fluid containing cells collected betwen 14-20 weeks of pregnancy lower risk of miscarriage

Question 38

horse can be either red or white but it is orange what happened?

Answer 38

heterozygous therefore incomplete codominance occurs because both alleles are expressed

Question 39

advantage of genetic screening

Answer 39

prevents child dying late in pregnancy and parents can prepare for child. less stress for parents

Question 40

difference between substitution and addition

Answer 40

loss causes frame shift replacement only changes one codon so number of amino acids remain the same

Question 41

template

Answer 41

RNA nucleotides attach to this strand

Question 42

what is pre implantation genetic diagnosis

Answer 42

an embryo created by IVF can be screened before it is placed in the mothers uterus

Question 43

fluid mosaic meaning

Answer 43

fluid refers to the movement of the phospholipids in the plane of the membrane mosaic refers to the random association of proteins within the membrane

Question 44

properites of cells that allow them to enter cells by diffusion

Answer 44

small, non-polar, lipid soluble

Question 45

compare facilitated diffusion and active trasnsport

Answer 45

both transport molecles. hoewver active transport is against a concentration gradient while facilitated diffusion is down it. facilitated diffusion doesnt require ATP

Question 46

how is channel protein involved in passive transport

Answer 46

allows movement of large molecles by diffusion down a concentration gradient

Question 47

why do people with cf hage breathing difficulties

Answer 47

stickier thicker mucus blocking brocnhioles mucus cant move it out of lungs reduced flow of air to alveoli reduced gaseous exchange loss of surace area redyuced concentration gradient trapped bacteria may result in more lung infectioons

Question 48

recessive allele

Answer 48

different forms of a gene and both need ti be present in order for the recessive phenotype to be express

Question 49

between bases

Answer 49

hydrogen bonds

Question 50

Non overlapping

Answer 50

Base triplets don’t share their bases. These are seperate

Question 51

Degenerate

Answer 51

More possible combinations of triplets than there are amino acids. One amino acid can be coded for by more than one base triplet

Question 52

Mono hybrid inheritance

Answer 52

Inheritance of single characteristic determined by one gene with two alleles

Question 53

Screening embryos for genetic disorders before they’re implanted in a woman

Answer 53

Preimplantation genetic diagnosis

Question 54

explain why a fertilised egg cell will contain only maternal mitochondria

Answer 54

only nucleus of sperm enters ovum therefore all mitochondria comes from the egg cell

Question 55

inheritance of parental characteristics in offspring

Answer 55

DNA in nucleus comes from sperm and egg of parents characteristics determined by DNA in nucleus is inherited by parents

Question 56

Exaplin why stem cells from heart can’t be used to grow cells from cornea

Answer 56

Cells aren’t totipotent Some genes already activated/ deactivated Will not be able to specialise into cornea cells