HEREDITY

1
HEREDITY

• 2-2 Mutations

2
(No Transcript)
3
INTRODUCTION

• In 1886, the Dutch botanist Hugo De Vries made an
  accidental discovery.
• The results of his discovery would take the
  science of genetics beyond the ground-breaking
  work of Gregor Mendel.
• De Vries bred flowers called American evening
  primroses and got results similar to Gregor
  Mendel.
• He also found that every once in a while, new
  variations appeared among the primroses
  variations that could not be explained by the
  laws of genetics at that time.

4
(No Transcript)
5
Genetic Mistakes

• De Vries called the sudden changes he observed in
  the characteristics of primroses MUTATIONS.
• Mutations are genetic mistakes that can affect
  the way in which traits are inherited.
• A mutation is a change in a gene or chromosome.

6
Genetic Mistakes

• If a gene or chromosome mutation occurs in a body
  cell such as a skin cell, the mutation affects
  only the organism that carries it.
• But if a mutation takes place in a sex cell, that
  mutation can be passed on to an offspring.
• The mutation may then cause a change in the
  characteristics of the next generation.

7
Mutagens

• Mutations may occur spontaneously or they may be
  caused by some factor in the environment.
• Factors that cause mutations, such as radiation
  and certain chemicals, are called mutagens.
• Mutagens can be harmful to living things OR
  helpful.
• Ultraviolet radiation may cause skin cancer.
• Radiation can prevent crop-damaging insects from
  reproducing.
• Mutant bacteria can digest oil (clean spills).

8
(No Transcript)
9
Harmful Mutations

• Many mutations are harmful that is, they reduce
  an organisms chance for survival or
  reproduction.
• For example, one mutation in a gene causes a
  serious human blood disease called sickle cell
  anemia.
• Sickle cell anemia results in red blood cells
  that are shaped like a crescent moon.
• People that have two genes for sickle cell anemia
  have difficulty obtaining enough oxygen.

10
(No Transcript)
11
(No Transcript)
12
Helpful Mutations

• Not all mutations are harmful. Some mutations
  are helpful and improve an organisms chances for
  survival OR they cause desirable traits in
  organisms that are useful to humans.
• Crop plants increase size and number.
• Katahdin potato resistant to diseases that
  attack other varieties.
• Seedless navel oranges sweeter and juicier.

13
(No Transcript)