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Alevel Biology > Genetic info > Flashcards

Genetic info Flashcards

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1
Q

Gene

A

a section of DNA that contains a
code for making a polypeptide
and functional RNA

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2
Q

locus

A

the location of a particular gene on a chromosome

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3
Q

allele

A

a different version of the same gene

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4
Q

chromosome

A

threadlike structure
composed of tightly coiled DNA
wrapped around histones (if it
is a eukaryotic cell)

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5
Q

homologous chromosome

A

a pair of chromosomes that have the same genes
therefore, they are the same size

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6
Q

eukaryotic DNA

A

DNA is stored as chromosomes inside the nucleus
linear chromosomes
DNA is tightly coiled and wrapped around proteins called histones

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7
Q

prokaryotic DNA

A

DNA molecules are shorter and circular
DNA is not wound around histones. Instead, it supercoils to fit in the cell

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8
Q

codon

A

3 bases on mRNA that code for an amino acid

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9
Q

start codon

A

3 bases at the start of an mRNA sequence which help to initiate
translation

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10
Q

stop codon

A

3 bases at the end of every gene that do not code for an amino acid
this causes ribosomes to detach
and therefore stops translation

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11
Q

genetic code

A

an amino acid is coded for by 3 DNA bases which are described
as the “triplet code”

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12
Q

what is meant by the genetic code is degenerate

A

each amino acid is coded for by
more than one triplet of bases

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13
Q

what is the advantage of the genetic code being degenerate

A

if a substitution mutation occurs, the new triplet of bases may still code for the same amino acid
therefore the mutation will have
no impact on the final protein
produced

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14
Q

what is the advantage of the genetic code being universal

A

genetic engineering is possible a human gene can be inserted into another organism
e.g human gene for insulin
inserted into bacteria to make
insulin

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15
Q

what is the advantage of the genetic code being non-overlapping

A

if a point mutation occurs, it will only affect one codon and therefore one amino acid

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16
Q

triplet code

A

an amino acid is coded for by 3
bases

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17
Q

mutation

A

a change in the DNA
can be a gene or chromosome
mutation

18
Q

what is meant by the genetic code is universal

A

the same triplet of bases codes
for the same amino acid in all
organisms

18
Q

what is meant by the genetic code is non-overlapping

A

each base in a gene is only part of one triplet of bases that
codes for one amino acid therefore each codon is read as a discrete unit

19
Q

introns

A

non-coding sequence of DNA

20
Q

exons

A

sequence of DNA that code for amino acids

21
Q

what is splicing

A

post transcription modification
removing introns

22
Q

genome

A

the complete set of genes in a cell

23
Q

proteome

A

The full range of proteins that a
cell is able to produce

24
Q

anticodon

A

3 bases on the tRNA which are
complementary to the codon on
mRNA.

25
Q

mRNA structure

A

single-stranded
made up of codons
a copy of one gene

26
Q

tRNA structure

A

single-stranded, folded to create a cloverleaf shape
held in place by hydrogen bonds
has an anticodon and amino
acid binding site

27
Q

mRNA function

A

a copy of a gene from DNA
created in the nucleus, and it then leaves the nucleus
to carry the copy of the genetic
code of one gene to a ribosome
in the cytoplasm

28
Q

tRNA function

A

a specific amino attaches at the binding site
transfers this amino acid to the ribosome to create the polypeptide chain

29
Q

transcription

A

the first stage in protein synthesis
one gene in DNA is copied into mRNA
occurs in the nucleus

30
Q

translation

A

the second stage in protein synthesis
the polypeptide chain is created using both the mRNA
base sequence and the tRNA occurs on ribosomes in the cytoplasm

31
Q

which enzymes are involved in transcription

A

DNA helicase
RNA polymerase

32
Q

DNA helicase

A

catalyses the breaking of hydrogen bonds between the two strands of DNA

33
Q

RNA polymerase

A

joins adjacent RNA nucleotides together
forming a phosphodiester bond

34
Q

pre-mRNA

A

mRNA in eukaryotes that still contain the introns

35
Q

How is pre-mRNA modified

A

the introns are removed by a protein called a spliceosome
this leaves just the exons

36
Q

what is ATP used for in translation

A

forming the peptide bond between amino acids

37
Q

Compare the DNA in the mitochondria/ chloroplast to prokaryotic DNA

A

the DNA is similar to prokaryotic DNA, in that it is:
short
circular
not histone bound

38
Q

How does transcription differ between prokaryotes and eukaryotes

A

Transcription in prokaryotic
organisms results in mRNA
that requires no modification
because prokaryotic DNA does
not contain any introns
eukaryotic transcription results
in pre-mRNA that needs introns
removed

39
Q

What is the role of ribosomes in translation

A

it holds two tRNA molecules
to enable peptide bonds to form
between the amino acids

40
Q

What is the role of tRNA in translation

A

it carries a specific amino acid anticodons align opposite
complementary codons on the
mRNA

Alevel Biology (14 decks)

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