DNA and protein synthesis Flashcards

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1
Q

what is DNA wound around in eukaryotes

A

histone proteins

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2
Q

which other sub-cellular structures contain DNA

A

mitochondria and chloroplasts

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3
Q

what is mitochondria and chloroplast DNA like

A

prokaryotic DNA as its circular and shorter

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4
Q

how is DNA found in prokaryotes

A

shorter and circular and not wound around histones

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5
Q

define what a gene is

A

a sequence of DNA bases that codes for a polypeptide or functional RNA

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6
Q

what does the sequence of polypeptides form

A

primary structure of protein

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7
Q

how many amino acids code for a gene

A

3

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8
Q

define genome

A

the complete genetic makeup of a cell

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9
Q

define proteome

A

the full rage of proteins that a cell is able to produce

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10
Q

what is an intron

A

a section of a gene that doesnt code for amino acids

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11
Q

what is an exon

A

the part of the gene that does code for amino acids

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12
Q

what happens to introns during protein synthesis

A

they are removed so they dont affect amino acid order

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13
Q

what type of DNA doesnt contain introns

A

prokaryotic

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14
Q

what is a non-coding repeat

A

a section of dna that is non coding and repeats over

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15
Q

alleles coding for the same characteristic can be found where on a chromosome

A

a the same position

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16
Q

what process is mRNA made in

A

transcription

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17
Q

what is the job of mRNA

A

carries the genetic code from DNA to ribosomes where it makes protein

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18
Q

what is the structure of mRNA

A

single polynucleotide strand

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19
Q

what is a codon

A

3 adjacent bases

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21
Q

what is the function of tRNA

A

carries the amino acids used to make proteins to ribosomes

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21
Q

what is the structure of tRNA

A

single polynucleotide strand folded into a clover shape

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22
Q

why does tRNA contain H bonds

A

between base pairs to help hold it in shape

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23
Q

what is an anticodon

A

a specific sequence of three bases a the end of every tRNA molecule

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24
Q

what are at both ends of tRNA

A

an anticodon and an amino acid binding site

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25
Q

where does this mRNA then travel

A

out of the nucleus to the nuclear pore

26
Q

what then happens to the dna strand

A

hydrogen bonds reform and it goes back to double helix

27
Q

whats an intron

A

non coding region

28
Q

whats an exon

A

coding region

29
Q

what happens in splicing

A

Introns are removed and exons joined together

30
Q

where does splicing take place

A

in the nucleus

31
Q

what is the first step in translation

A

mRNA attaches to a ribosome and tRNA molecules carry amino acids to it

32
Q

what allows the tRNA to bond with the codon

A

it has anticodons which form h bonds with codons

33
Q

what will bond to the first tRNA

A

another one next to it which will form a peptide bond

34
Q

what does the two bonded tRNA then do

A

release the first and continue moving down

35
Q

what do gene mutations involve

A

a change in the DNA base sequence

36
Q

what is substitution

A

when one base is substituted with another

37
Q

what is deletion

A

when one base is deleted

38
Q

what does the degenerate code of DNA mean

A

some amino acids are coded for by more then one dna triplet

39
Q

what does the degenerate code of DNA mean for substitution of amino acids

A

not all result in a change of the amino acid sequence

40
Q

what type of mutation will always lead to changed of amino acids

A

deletion

41
Q

what might increase the rate of mutations

A

UV radiation
radiation and some viruses

42
Q

What is a locus

A

Particular position where gene is fixed on a chromosome

43
Q

Name the 3 features of the genetic code

A

Degenerate

Universal

Non-overlapping

44
Q

What is non disjunction

A

When chromosomes or chromatids do not split equally during anaphase

45
Q

What is polyplody

A

Changes in whole sets of chromosomes meaning u have two or three sets of chromosome

46
Q

What is aneupolidy

A

Changes in number of individuals chromosomes

47
Q

What does aneuploidy usually result in

A

Having one more of one fewer chromosomes 

48
Q

What 2 main factors lead to variation in meiosis

A

Independent segregation of homologous chromosomes.
Crossing over between homologous chromosomes.

49
Q

How can cpu calculate the possible combinations of chromosomes

A

2n

N = number of homologous pairs

50
Q

Describe two differences between the structure of tRNA molecule and the structure of mRNA molecule

A

tRNA has a clover like shape, where are is mRNA is linear

TRNA has anticodons at either end, where is mRNA codons only

51
Q

Describe the differences between pre-mRNA and mRNA

A

Pre-mRNA contains entrance, where as Emani doesn’t.
A splicing occurs in pre-mRNA, which removes introns

52
Q

Describe how One amino acid is added to a polypeptide that has been formed at a ribosome during translation.

A

TRNA brings a specific amino acid.
an anti codon bonds with the codon
As this is repeated the base bind together, forming a peptide chain

53
Q

Describe how mRNA is produced from an expose template strand of DNA

A

Free, RNA nucleotides form complimentary base pairs
Phosphodiester bonds form.
By RNA polymerase. 

54
Q

Name the steps of transcription

A

Dna helix unwinds

One chain of dna will act as a template

Winding an unzipping is caused by DNA helicase

Dna helicase breaks the hydrogen bonds

Free mRNA nucleotides align to complementary bases

Enzyme RNA polymerase bonds RNA nucleotides

55
Q

Explain the translation process

A

MRNA attaches to a ribosome in nucleus

Ribosome attaches to start codon

Complementary anticidon aligns with start codon

Ribosome moves along mRNA

Amino acids joined by tRNA

56
Q

give one way the structure of an mRNA molecule is diff from a trna molecule

A

mRNA is linear wheras tRNA is clover shaped

57
Q

explain the difference between pre-mRNA and mRNA

A

pre-MRNA contains introns and exons whereas mRNA only contains exons

58
Q

how is mRNA produced in the nucleus of a cell

A
  • DNA helicase breaks hydrogen bonds
  • one strand is used as template
  • free floating nucleotides bind with complementary bases on template strand
  • rna polymerase joins nucleotides
    pre- mrna sliced to remove introns
59
Q

why is the genetic code described as universal

A

same triplet codes for same amino acids

60
Q

how does a mutation to a tumor suppressor gene result in a tumour?

A
  • tumour suppressor gene inactivated
  • so rate of cell division too fast
61
Q

explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria

A

1- break open cell
2- filter to remove debris
3- use isotonic solution to prevent damage to mitochondria
4- keep cold to reduce damage to enzymes
5-centrifuge at lower speed to reduce damage
6- respin to get mitochondria

62
Q

explain how cell fractionation and ultracentrifugation can be used to isolate mitochondria

A

1- break open cell
2- filter to remove debris
3- use isotonic solution to prevent damage to mitochondria
4- keep cold to reduce damage to enzymes
5-centrifuge at lower speed to reduce damage
6- respin to get mitochondria