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biology > genes and health > Flashcards

genes and health Flashcards

1
Q

describe the role of tRNA

A

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

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2
Q

compare and contrast the process of endocytosis and exotycosis

A
  • 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
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3
Q

function of glycoprotein

A

cell recognition/receptors/antigens

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4
Q

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

A

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

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5
Q

how do phopsholipids form bilayer

A

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

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6
Q

why are phospholipids arranged into two layers in a membrane

A

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

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7
Q

function of carrier proteins

A

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

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8
Q

describe the structure of the cell surface membrane

A

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

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9
Q

how does primary sturcture of leptin allow it to be soluble

A

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

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10
Q

how does substitution base affect fucntion of molecule

A

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

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11
Q

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

A

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

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12
Q

compare and contrast globular and fibrous proteins

A

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

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13
Q

how is a peptide bpnd formed

A

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

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14
Q

products when several amino acids are joined toegther

A

water and polypeptide

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15
Q

compare transcription and DNA replication

A

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

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16
Q

what deos a frameshift do

A

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

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17
Q

describe how mRNA is synthesised at a template strand

A

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

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18
Q

compare RNA and DNA

A

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

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19
Q

which type of bond holds strands of dna together

A

hydorgen

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20
Q

describe how nucleotides join together to form dna

A

condensation reaction. phosphodiester bonds. DNA polymerase

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21
Q

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

A

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

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22
Q

why does antibiotics that binds to ribosome affect production of protein

A

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

23
Q

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

A

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

24
Q

describe the roles of translation and transciption

A

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

25
Q

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

A

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

26
Q

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

A

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

27
Q

how many hydrogen bonds between a-t

A

2

28
Q

how many hydrogen bonds between c-g

A

3

29
Q

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

A

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

30
Q

what does CFTR gene code for

A

a channel protein

31
Q

why may parents choose not to do CVS

A

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

32
Q

definition of inherited recessive disorder

A

caused by a faulty allele
only expressed in the homozygous condition

33
Q

what is it called when many different siblings are different genotype

A

incomplete dominance
Both alleles expressed

34
Q

allele definitin

A

alternative form of a gene found
at the same locus

35
Q

how to know if parents are heterozygous

A

if some of the children have the recessive disease

36
Q

what is cvs

A

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

37
Q

amniocentesis definition

A

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

38
Q

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

A

heterozygous
therefore incomplete codominance occurs
because both alleles are expressed

39
Q

advantage of genetic screening

A

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

40
Q

difference between substitution and addition

A

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

41
Q

template

A

RNA nucleotides attach to this strand

42
Q

what is pre implantation genetic diagnosis

A

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

43
Q

fluid mosaic meaning

A

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

44
Q

properites of cells that allow them to enter cells by diffusion

A

small, non-polar, lipid soluble

45
Q

compare facilitated diffusion and active trasnsport

A

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

46
Q

how is channel protein involved in passive transport

A

allows movement of large molecles by diffusion down a concentration gradient

47
Q

why do people with cf hage breathing difficulties

A

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

48
Q

recessive allele

A

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

49
Q

between bases

A

hydrogen bonds

50
Q

Non overlapping

A

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

51
Q

Degenerate

A

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

52
Q

Mono hybrid inheritance

A

Inheritance of single characteristic determined by one gene with two alleles

53
Q

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

A

Preimplantation genetic diagnosis

biology (10 decks)

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