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Biology > DNA, Genes And Protein Synthesis Topic 4 > Flashcards

DNA, Genes And Protein Synthesis Topic 4 Flashcards

1
Q

What is a gene?

A

A gene is a section of DNA that contains the coded information for making polypeptides and functional RNA.

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2
Q

What is the coded information?

A

It is in the form of a specific sequence if bases aling the DNA molecule.

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3
Q

What do genes code for?

A

The amino acid sequence of a polypeptide.

A functional RNA, including ribosomal RNA and tRNAs

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4
Q

How many bases code for each amino acid?

A

Three

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5
Q

What is a degenerate code?

A

Where most amino acids are coded for by more than one triplet.

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6
Q

What are stop codes?

A

They mark the end of a polypeptide chain.

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7
Q

What is a non-overlapping code?

A

Where each base in the sequence is only read once.

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8
Q

What is a universal code?

A

Where each triplet codes for the same amino acid in all organisms.

( This is indirect evidence of evolution)

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9
Q

What are exons?

A

They are coding regions in a gene.

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10
Q

What are chromosomes held by in DNA?

A

Histones

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11
Q

What do histones do?

A

They coil and wrap around chromosomes.

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12
Q

What are homologous pairs?

A

Sexually produced organisms are the result of a sperm and an egg, each of which contribute one complete set of chromosomes to the offspring.

One pair from the mother and one from the father.

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13
Q

What is the diploid number?

A

Total number of homologous pairs.

In humans it is 46.

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14
Q

What is an allele?

A

It is one of a number of alternative forms of a gene.

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15
Q

What is a codon?

A

The sequence of three bases on mRNA that codes for a single amino acid.

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16
Q

What is a genome?

A

The complete set of genes in a cell.

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17
Q

What is a proteome?

A

The full range of proteins produced by the genome.

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18
Q

The process of translation.

A
  1. The mRNA travels to a ribosome.
  2. The ribosome reads the mRNA three bases at a time.
  3. it then makes sure that tRNA molecule with complementary anticodon binds to the correct codon.
  4. The ribosome then catalyses the formation of the peptide bond between the aminoacids.
  5. The ribosome then moves along the mRNA until it reaches a stop codon which has no complementary tRNA.
  6. The polypeptide detaches and filds go become a protein.
19
Q

The process of transcription.

A
  1. DNA Helix unwinds
  2. One chain of the DNA acts as a template
  3. This is catalysed by DNA helicase
  4. DNA helicase breaks H bonds
  5. Free mRNA nucleotides align opposite complementary bases
    6 The enzyme RNA polymerase joins together the RNA nucleotides.
20
Q

What is a mutation?

A

Any change to the qaunity or the base sequence of the DNA organism.

21
Q

What is gene mutation?

A

Gene mutations involve a change in the base sequence of chromosomes.

22
Q

What is a substitution of bases?

A

Gene mutation in which a nuclotide in a DNA molecule is replaced by another nucleotide that has a different base.

23
Q

What are deletion of bases?

A

It arises when a nucleotide is lost from the normal DNA sequence.

24
Q

The process of meiosis in the first division.

A

independent segregation.

Homologous chromosomes pair up and their chtomatids wrap around each other.

25
Q

What happens with Meiosis in the second variation?

A

This is introduced through crossing over.

Sections of DNA from the homologous pairs swap over leading to a combination of chromosomes that contain a mix of material and paternal genes.

26
Q

What is chromosome non-disjunction?

A

It can occur during meiosis and means that the chromosomes are not evenly divided between the gamates.

This can lead to ginetic diseases like Down’s syndrome.

27
Q

What is ginetic diversity?

A

The variation of alleles found in a population.

28
Q

What can affect ginetic diversity?

A

Natural selection

Mutation

Migration

29
Q

The process of natural selection.

A

Rondom mutation may result in new alleles with the new population.

Organisms with the new alleles might be better adapted to that environment.

These organims survive and successfully reproduce to pass their advantageous alleles. Those without are less likely to survive to pass on their less advantageous alleles.

Over many generations, the allele frequency of the advantageous allele will increase in the gene pool.

30
Q

What is a gene pool?

A

Total number of different alleles in a population.

31
Q

What are the two types of selection?

A

Directional

Stabilising

32
Q

What is courtship behaviour?

A

The behaviour of members of the same species are more alike then that of members of different species.

Individuals can therefore recognise members of their species by the way they act.

33
Q

Taxonomy order

A 
Domain 
Kingdom 
Phylum 
Class 
Order 
Family 
genus 
Species
34
Q

What is a species?

A

A group of organisms with similar features, both physical and biochemical, that can breed and produce living, fertile offspring.

35
Q

What is species diversity?

A

The number of different species and the number of individuals of each species within a community.

36
Q

Genetic diversity?

A

The variety of genes possesses by the individuals that make up a population of a species.

37
Q

What is ecosystem diversity?

A

The range of different habitats.

38
Q

What is the DNA like in prokaryotic cells?

A

DNA is short and circular and not associated with proteins.

39
Q

What is the DNA like in eukaryotic cells?

A

DNA is linear and long coiled around his tones to make a chromosome.

40
Q

What is species richness?

A

The number of different species in a community.

41
Q

How can you see genetic and identify genetic diversity?

A
  • frequency of observable characteristics.
  • the base sequence of DNA
  • the vase sequence of mRNA
  • amino acid sequence of proteins.
42
Q

What are certain practices done by farmers that have reduced species diversity?

A
  • removal of hedgerows
  • filling in ponds and draining wetland
  • over grazing cattle and sheep
  • use of pesticides
  • intercropping
43
Q

How have farmers maintained species diversity?

A
  • maintaining hedgerows
  • plant hedges
  • leave wet corners of fields
  • use organic fertiliser
  • plant trees
  • create neutral meadows

Biology (16 decks)

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