DNA, genes and chromosomes Flashcards

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1
Q

differences between prokaryotic and eukaryotic DNA

A

eukaryotic
- linear
- associated with histones (makes it compact into chromosomes = chromatin)

prokaryotic
- shorter
- circular
- no proteins

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2
Q

DNA in chloroplasts and mitochondria

A

prokaryotic like
- circular
- no proteins associated

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3
Q

what is a gene?

A

sequence of amino acids that code for a particular polypeptide
or functional RNA

(multiple in a chromosome)
position of gene in chromosome called locus

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4
Q

what is a chromosome

A

long DNA molecule wrapped around histones
- contains multiple genes

sister chromatids - identical, contain same genes
- make up a chromosome

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5
Q

genome and proteome

A

complete set of genes in a cell

full range of proteins a cell is able to make

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6
Q

what are introns?

A

non coding sections of DNA
(donโ€™t code for an amino acid)
within genes
removed in splicing

(non-coding multiplier repeats found between genes)

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7
Q

what is an allele?

A

different versions of the same gene

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8
Q

what is a homologous pair?

A

chromosomes of the same shape and size that contain the same genes
(could have different alleles, so not genetically identical)

alleles coding for same characteristic found on same locus on each

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9
Q

describe mRNA

A

single polynucleotide strand
- contains codons (3 bases) complementary to anticodon

made during transcription

carries genetic code from DNA to ribosomes for translation

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10
Q

describe tRNA

A

single polynucleotide strand, folded into a clover shape
- held by hydrogen bonds between specific bases

contains anticodon (3 bases) complementary to codon on mRNA

used in translation
- carries specific amino acids to ribosome (complementary to binding site)

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11
Q

steps to making a protein

A

transcription of DNA into pre-mRNA
in nucleus
pre-mRNA spliced to remove introns (only in eukaryotic as prokaryotic have no introns)
= mRNA

mRNA moves to ribosome to be translated
= amino acid chain

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12
Q

features of the genetic code (3)

A

non-overlapping
- each triplet read sequentially and separate

degenerate
- more than one base triplet can code for the same amino acid

universal
- same base triplets code for the same amino acids in all living organisms

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13
Q

similarities between prokaryotic and eukaryotic DNA

A

structure of nucleotides
- phosphate, deoxyribose and base

phosphodiester bonds

bases - A,T,C,G

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14
Q

what is a frame shift?

A

mutation has a knock on effect to bases along the polypeptide
changes how to triplets are read
= change to amino acid sequence

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15
Q

what is a silent mutation?

A

a mutation that doesnโ€™t affect the sequence of amino acids
due to the degenerate nature

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16
Q

what is a mutagenic agent?

A

environmental factors that increase the rate of mutations

  • UV radiation, ionising radiation and chemicals