Advanced Biology

1
Advanced Biology

• Mutations

2

• What is a mutation?
• A change (mistake) in the replication of genetic
  material.
• The daughter cell is different from the parent

3

• Most replication errors are corrected by the
  cells built in spell check system.
• However, some do escape detection

4
Gene Mutation

• Deletion Leaving out one nucleotide in the
  sequence, shifts the reading of the sequence to
  the left, creating a totally different set of
  amino acids

5
Gene Mutation

• Normal mRNA reads
• AUG AAG UUU GGC GCA UUG UAA
• Met Lys Phe Gly Ala Leu Stop.
• Mutated mRNA reads
• AUG AAG UUG GCG CAU UGU AA
• Met Lys Leu Ala His Cys

6
Gene Mutation

• Insertion Mutation in which an extra nucleotide
  is added to the chain during replication, shifts
  reading to the right, creating a totally
  different set of amino acids

7
Gene Mutation

• Normal mRNA reads
• AUG AAG UUU GGC GCA UUG UAA
• Met Lys Phe Gly Ala Leu Stop.
• Mutated mRNA reads
• AUG AAG UUU GUG CGC AUU GUA A
• Met Lys Phe Val Arg Ile Val

8
Gene Mutation

• Point Mutation A base substitution occurs. One
  nucleotide is replaced with a different one

9
Gene Mutation

• Normal mRNA reads
• AUG AAG UUU GGC GCA UUG UAA
• Met Lys Phe Gly Ala Leu Stop.
• Mutated mRNA reads
• AUG AAG UUU AGC GCA UUG UAA
• Met Lys Phe Ser Ala Leu Stop.

10
Gene Mutation

• These mutations arise spontaneously during DNA
  replication.
• External agents may cause mutations, called
  mutagens.

11
Chromosome Mutations

• Changes may occur in chromosomes as well as in
  genes.
• Chromosome mutations can have serious effects on
  the distribution of genes to gametes during
  meiosis.

12
Chromosome Mutations

• Deletion
• ABCDE---FGH
• ABCE---FGH

13
Chromosome Mutations

• Duplication
• ABCDE---FGH
• ABCBCDE---FGH

14
Chromosome Mutations

• Inversion
• ABCDE---FGH
• ADCBE---FGH

15
Chromosome Mutations

• Attachment to a different chromosome
• ABCDE---FGH
• WXY---Z
• WXABCDE---FGH
• Y---Z

16
Other causes of genetic variation

• During meiosis, homologous pairs fail to
  separate.
• This would cause the offspring to have an extra
  chromosome.

17
CANCER

• Abnormal cells, go through cell cycle very fast,
  creating new cells like it.
• They reproduce in an uncontrolled way, crowding
  out healthy cells and destroying tissues and
  possibly organs.
• It can spread to other parts of the body

18
Causes of Cancer

• Genes that control the cell cycle mutate, called
  an oncogene.
• Mutations may be inherited or caused by a
  carcinogen, a cancer causing agent in the
  environment.
• Tobacco smoke, radiation and other chemicals.

19
Causes of Cancer

• Viruses may also cause cancer.
• Their presence disrupts normal cell processes.
• They can also carry oncogenes into the host cell.

20
Technology

• Scientists can transfer a gene artificially from
  a donor organism to a bacteria.
• The DNA of the bacterium is called recombinant
  DNA.
• The bacteria will transcribe and translate the
  foreign gene and produce the protein it is coding
  for.

21
Technology

• Small, circular pieces of DNA, called plasmids,
  are where the foreign DNA is placed.

22
Technology

• To obtain a foreign gene, mRNA from a cell is
  isolated and DNA is produced (called reverse
  transcription). This single stranded DNA is
  converted to a double strand and this double
  strand is the desired gene.

23
Technology

• In use today goats that produce a human blood
  clot dissolving factor.
• Plants that are disease resistant.
• Plants that are larger than normal.