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biology!🌺🌱 > DNA, genes & protein synthesis > Flashcards

DNA, genes & protein synthesis Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

similarities between eukaryotic DNA & prokaryotic DNA

A
  1. made of DNA nucleotides with identical structure –> deoxyribose, phosphate group & nitrogenous base
  2. nucleotides joined together by phosphodiester bonds
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2
Q

differences between eukaryotic DNA & prokaryotic DNA

A
  1. eukaryotes = longer, prokaryotes = shorter
  2. eukaryotes = linear, prokaryotes = circular
  3. eukaryotes = associated with histones, prolaryotes = no histones
  4. eukaryotes = contain introns, prokaryotes = no introns
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3
Q

what are chromosomes formed from?

A

DNA with histones wrapped around it

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4
Q

how might the struc. of a chromosome differ along its length?

(exam q)

A
  • difference in base sequence
  • difference in histones
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5
Q

which organelles have DNA similar to prokaryotic DNA?

A
  • mitochondria
  • chloroplasts
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6
Q

define ‘gene’

A

a section of DNA that codes for a particular polypeptide eg. eye colour

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7
Q

define ‘locus’

A

the particular, fixed position on a chromosome that a gene occupies

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8
Q

what does a seq. of 3 bases code for?

A

1 amino acid

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9
Q

the name given to a group of 3 bases on mRNA that codes for amino acid

A

a codon

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10
Q

what are the 3 features of the genetic code?

A
  • non-overlapping
  • universal
  • degenerate (more than 1 triplet can code for the same amino acid)
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11
Q

advantage of the genetic code being non-overlapping

A

if a point mutation occurs, only 1 triplet and therefore, 1 amino acid is affected

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12
Q

describe how a gene is a code for the production of a polypeptide

A

1) triplet
2) of bases
3) which determines order of amino acid seq.

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13
Q

define ‘introns’

A

= base sections of DNA that don’t code for polypeptides
* only in eukaryotic DNA
* positioned between genes

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14
Q

define ‘exons’

A

= sections of DNA that do code for polypeptides

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15
Q

why don’t all mutations in the nucleotide seq. of a gene cause a change in the struc. of a polypeptide?

A
  • triplets code for the same amino acid (genetic code = degenerate)
  • may occur in introns
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16
Q

define ‘genome’

A

= complete set of genes in a cell

17
Q

define ‘proteome’

A

= full range of proteins that a cell can produce

18
Q

diff. types of RNA

A
  • rRNA
  • mRNA
  • tRNA
19
Q

rRNA

A
  • combines with proteins to form ribosomes
  • tiny, globular organelle

(ribosomal RNA)

20
Q

mRNA

A
  • short, single-stranded nucleotide chain
  • exposed bases form codons
  • no H-bonds (single stranded duh)
  • copies and transfers genetic code from DNA i nucleus to ribosomes in cytoplasm

(messenger RNA)

21
Q

tRNA

A
  • small, polynucleotide chain
  • looped, ‘clover-leaf’ shape
  • H-bonds
  • carries free a.a’s in cytoplasm to ribosomes
    > has anticodon —> comple. to codon on mRNA

(transfer RNA)

22
Q

stages for protein synthesis

A

1) transcription
2) splicing
3) translation

23
Q

transcription

A
  1. DNA helix unwinds to expose DNA bases, catalysed by DNA helicase
    (DNA helicase breaks H-bonds)
  2. strand with exposed bases acts as a template
  3. free mRNA nucleotides are joined to comple. bases on template strand
  4. formation of phosphodiester bonds between adj. RNA nucleotides catakysed by RNA polymerase
    —> pre-mRNA leaves nucleus via nuclear pore
24
Q

splicing

A
  • in eukaryotes, introns are spliced out by a protein called ‘splicesome’
    (in prokaryotes, transcription directly produces mRNA - prokaryotes don’t contain introns)
25
Q

translation

A
  1. start codon of the mRNA attaches to a ribosome in the cytoplasm
  2. the tRNA molecule with the compl. anticodon to the start codon aligns opposite the mRNA, held in place by the ribosome
  3. the tRNA molecule brings a specific aa
  4. the ribosome moves along one codon on the mRNA —> enables another compl. tRNA to attach to next codon
  5. a c-reaction (using energy from ATP & and an enzyme) creates a peptide bond between the a.a’s delivered by the 2 tRNA’s
  6. process continues until ribosome reaches stop codon on mRNA & detaches
26
Q

differences between DNA & RNA

A
  1. DNA nucleotides contain base ‘thymine’, RNA nucleotides contain base ‘uracil’
  2. DNA nucleotides contain deoxyribose sugar, RNA nucleotides contain ribose sugar

biology!🌺🌱 (14 decks)

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