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Chemistryyy > DNA bio > Flashcards

DNA bio Flashcards

1
Q

what is the role of DNA?

A

to hold the genetic info of a cell

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2
Q

what are chromosomes

A

thread like structures in the cell containing DNA

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3
Q

what is DNA

A

deoxyribonucleic acid - a sequence that determines how our bodies are made

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4
Q

what are the four chemicals found in DNA that make up the base sequence (and what are they called)

A

DNA bases - A, T, C and G

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5
Q

What is the shape of DNA

A

a double helix - two strands of nucleotides that wind up around each other (like a twisted ladder)

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6
Q

what is the entire genetic material of an organism called?

A

genome

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7
Q

What is the definition of genetic code

A

sequence of bases within the DNA that (ultimately) codes for proteins

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8
Q

what is a gene?

A

section of DNA that contains instructions for a particular characteristic

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9
Q

DNA is a polymer - which means..?

A

it is made of repeating sub-unite (monomers)

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10
Q

what does 1 DNA nucleotide (monomer contain)

A
  • phosphate group
  • 5 carbon sugar (ribose/deoxyribose)
  • organic nitrogenous base
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11
Q

DNA has ? strands. these strands run ? to each other. each strand has a ? - phosphate backbone which are held together by ? bonds. the 2 strands are held together by ? bonds between bases

A

2, anti parallel, sugar, phospodiester, hydrogen

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12
Q

how many hydrogen bonds bond A and T togther

A

2H bonds

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13
Q

why do A and T bond together

A

as they always pair - since they are complementary

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14
Q

how many bonds between C and G bases?

A

3H bonds

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15
Q

why does DNA spiral into a double helix?

A

in order to protect the bases in the centre - as if exposed to pathogens or carcinogens they could mutate and code for the wrong proteins

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16
Q

what are the two steps in protein synthesis? and what does DNA change to?

A

transcription - DNA —»> mRNA
translation - mRNA —»> protein

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17
Q

where does transcription happen and what is the first step?

A

happens in the nucleus, DNA unwinds out of double helix - into a coding strand and a template strand

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18
Q

most ? codes for proteins, which are called ? . some DNA ? not code - it is a binding site for ? . this section is called an ? . both of these sections are ?

A

DNA, exons, does, enzymes, intron, transcribed

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19
Q

why can’t DNA leave the nucleus?

A

it is too big - and is double stranded

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20
Q

what part of DNA unwinds out of double helix?

A

only the section being coded for

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21
Q
  • ? polymerase binds to the intron and ? the DNA template strand
  • complementary ? nucleotides line up along the DNA ? strand - these are joined up by ? bonds
  • this has built a ? strand - called mRNA
  • introns are cut off the ?
  • mRNA leaves nucleus to go to ?
A

RNA, ‘reads’, RNA, template, phosphodiester, single, mRNA, ribosomes

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22
Q

base ‘T’ doenst exist in RNA so what is it replaced by?

A

‘U’ - uracil

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23
Q

the 3 bases on mRNA are called?

A

a codon

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24
Q

the 3 bases on mRNA are called?

A

a codon

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25
Q

the 3 bases on tRNA are called?

A

an anticodon

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26
Q

first 3 steps of translation:
1. mRNA moves to the ?
2. ribosome reads the ? in groups of 3 bases - a ?
3. tRNA molecule ( carrier ? ) binds to the ? with the complementary anticodon for the first mRNA ?. attached to the tRNA is the corresponding ? acid for the mRNA codon

A

ribosomes
mRNA, codon
molecule, mRNA, codon, amino

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27
Q

first 3 steps of translation:
1. mRNA moves to the ?
2. ribosome reads the ? in groups of 3 bases - a ?
3. tRNA molecule ( carrier ? ) binds to the ? with the complementary anticodon for the first mRNA ?. attached to the tRNA is the corresponding ? acid for the mRNA codon

A

ribosomes
mRNA, codon
molecule, mRNA, codon, amino

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28
Q

last 5 steps of translation

  1. ribosome ‘reads’ the next ?. the tRNA binds to the ? codon with its ?. a second amino ? lines up.
  2. a peptide (strong ? bond) forms between amino ?. the 1st ? can now leave
  3. a ? amino acid is brought in and attached to the ? with a complementary anticodon to mRNA ?. A peptide ? forms
  4. once all the ? had been ‘read’ the ? detaches. there is a chain of ? acids left held togther by ? bonds
  5. many amino acids are called a ?. this folds into a ? shape to become a functioning ?
A
  • codon, mRNA, anticodon, acid,
  • covalent, acids, tRNA
  • third, tRNA, codon, bond,
  • mRNA, ribosome, amino, peptide
  • polypeptide, 3D, Protein
29
Q

what does the t in tRNA stand for

A

transfer

30
Q

what does the m in mRNA stand for

A

messenger

31
Q

how many bases code for 1 amino acid?

A

3 bases (one codon)

32
Q

a change in the DNA base sequence what is this the definition of?

A

a mutation

33
Q

what can cause mutations?

A

pathogens/carcinogens

34
Q

why can mutations be harmful?
if a mutation occurs in a ? cell it may lead to ?. if a mutation occurs in a sperm or ? it can lead to the offspring having a genetic ?

A

body, cancer, egg, disorder

35
Q

how could mutations cause a change in the protein (exons)

A
  • could cause a change in the DNA base sequence
  • therefore a different mRNA codon
  • so a different amino acid to be coded for
  • so our polypeptide chain may be different
  • protein would fold up into a different 3D shape and may not function as normal
36
Q

If the protein was an enzyme, why might a different 3D shape be a problem?
Different ? shape means different shaped active ?, so active ? is no longer ? to the substrate. Therefore no binding so no ? or reaction

A

3D, site , site, complementary, breakdown

37
Q

what is a truncated protein?
when a mutation makes a stop ?, to stop building the ? - preventing it from working at ? - meaning it doesn’t code for an ? acid

A

signal, protein, all, amino

38
Q

what is a silent mutation?
when a mutation in ? does ? code for a different ? acid - so the ? is made exactly the same as if there was no mutation. and if it was coding for an ? it may not lose its function

A

DNA, not, amino, protein, enzyme

39
Q

if there is a mutation in the intron which means that the enzyme cannot bind where it should what does this mean?

A

the gene is switched off wheee it should not be - and if the enzyme can’t bind - no protein is made eg antibodies and no substances are broken down

40
Q

if a mutation in an intron means that the RNA polymerase can bind where it should not be able to what does this mean?

A

the gene is switched on when it should be off - meaning there is a waste of energy (prioritizing making useless protein), lack of protein that we do need and excess protein may also be toxic

41
Q

what is an allele?

A

a different version/ form of a gene

42
Q

if an allele is dominant how many copies does the cell need for the trust to be expressed?

A

only one copy

43
Q

if an allele is recessive how many copies does the cell need for the trust to be expressed?

A

two copies

44
Q

what is homozygous dominant?

A

2 dominant alleles

45
Q

what is homozygous recessive?

A

2 recessive alleles

46
Q

what is heterozygous?

A

1 dominant and 1 recessive allele

47
Q

how to do a model diagram for alleles?
1. name the parents ? - what they look like eg green and ?
2. name the ? genotype - the ? eg: EE and ee
3. do the ? in circles eg: ‘E’ and ‘E’ in circles
4. do a ? square - like a multiplying column
5. do f? generation
6. do genotypes and then ? of the generation
7. do the ? of colours, or genes

A

phenotype, yellow
parents, letters
gametes
punnet
1
phenotypes
ratio

48
Q

in genetics what do the two alleles come from?

A

one from the maternal, one from the paternal - they are homologous

49
Q

what is a phenotype?

A

what the gene looks like, how it is expressed

50
Q

what is a genotype?

A

the letters, showing if it is homozygous recessive/dominant or heterozygous

51
Q

who was Mendel?

A

father of genetics

52
Q

why did we only understand how important mendels discoveries were in 20th century?

A
  • as we did not have the understanding of genetics to appreciate his findings
  • other members of the scientific community did not have time to review his work
53
Q

what is sickle cell anaemia caused by?

A

a recessive allele

54
Q

what does it mean if a person is a carrier of a disorder?

A

they aren’t very much affected by the disorder they just carry it, but it also means the allele must be recessive

55
Q

what is polydactyl caused by and what is it?

A

caused by a dominant allele so only need one to have it, and it is a condition where a person has extra fingers or toes

56
Q

what is cystic fibrosis?

A

a disease that affects the cell membrane - meaning mucus is sticker and stickier than usual, making it difficult to breathe (and moving substances in and out of a cell can be difficult)

57
Q

what is cystic fibrosis caused by?

A

a recessive allele

58
Q

what chromosomes do females have?

A

XX

59
Q

what chromosomes do males have?

A

XY

60
Q

how to prove that the population is made up of roughly 50% females and 50% males

A

do a punnet square for female and male and work out there is 50% XX and 50% XY

61
Q

what is embryo screening?
the process whereby a ? cells are taken from the embryo produced by ? and are checked for ? genes

A

few, IVF, defective

62
Q

what does embryonic screening NOT do but do instead?

A

DOES NOT alter the genetic sequence, but does and can detect if the developing embryo is likely to develop a genetic disorder

63
Q

4 steps of embryo screening:
- DNA is isolated from ?
- ? probe is mixed with the ? DNA
- probe then binds to ?
- ? light can be used to show if the alleles are ? for a genetic ?

A

embryo
fluorescent, embryo
DNA
UV, present, disorder

64
Q

4 pros of screening?

A
  • defective genes may lead to a decreased life expectancy ( meaning a decreased quality of life) so can irradiate this genetic disorder
  • could take away suffering from sufferer and caters from a particular disease
  • very carefully monitored, can only be done for a select number of genes
  • less need for healthcare if you take out the defective gene
65
Q

cons of screening? (4 examples)

A
  • potential selection of embryos for social reason, eg a child with blue eyes
  • embryos that aren’t chosen can be frozen or destroyed
  • expensive - high insurance, socio economic divide
  • defective gene may not have immediate life threatening consequences
66
Q

what was the human genome project?

A

when scientists mapped the typical human genome, could determine which genes were linked to which diseases. also what mutations leads to the development of the disease phenotype

67
Q

pros (4)of the human genome project?

A
  • better understanding of what mutation causes what disease
  • personalized medicine more likely to work
  • improved scientific comms/collaboration
  • better understanding of evolution
68
Q

cons(4) if human genome project?

A
  • very expensive - personalised medicine (socio economic divide) and project itself, and insurance
  • increased knowledge doesn’t mean it can solve the problem
  • takes a very long time!
  • risk of editing for non essential reasons, eg: eye colour

Chemistryyy (47 decks)

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