Transcript Asexual reproduction

Learning Objectives
Know that asexual reproduction involves:
• one parent, and does not require sex cells
or gametes
• New organism is exactly the same as the
parent (clone), as there is no genetic
variation.
Be able to name examples of living things that
can reproduce asexually.
Describe different methods of asexual
reproduction.
ASEXUAL REPRODUCTION
• No fusion of gametes (sex cells)
• Genes from only one parent
• Offspring show NO variation
• Genetically identical offspring (clones)
• Asexual reproduction is where ONE parent
can produce NEW LIFE
• Very often this happens in BACTERIA or
FUNGI.
• One CELL simply divides into TWO to
make a new offspring.
• EVERY new cell is IDENTICAL to the
parent that made it.
• A cell that is identical is called a CLONE.
• All the GENES in every cell are the SAME.
Asexual Reproduction
Fill in the blank spaces with the missing words
Some organisms can reproduce a_______. Only one
parent is needed and....
• there are no g________
• there is no mixing of g_________ information from
two p_________
• there is no genetic v_________ among the offspring
• the o________ are genetically i_________ to each
other and to the parent
• these genetically identical offspring are called c_____
KEYWORDS
offspring, parents, clones, gametes, asexually,
genetic, variation, identical
Twig Video
Click on the link to watch a short
video on asexual reproduction
http://bit.ly/LFHNmP
Asexual reproduction
• Gardeners use asexual reproduction to create new
plants that are identical to the parent plants.
• Cloning allows growers to mass produce plants that may
be difficult to grow from seed.
• All the plants are genetically identical, which is useful
because you can be sure of their characteristics.
• They cannot create new varieties this way.
• But they can produce required plants much quicker
than growing them from seeds produced in sexual
reproduction.
• On the other hand, the lack of genetic variation means
that if the plants become exposed to disease or to
changes in environmental conditions, all of them will be
affected.
How can we make copies of
organisms?
Cloning
Cuttings
Some plants can reproduce asexually. Cuttings from the stem are
taken and then planted. These grow into new plants which are clones
because they are genetically identical to each other and to the single
parent plant.
The most common way for
gardeners to create new
plants asexually is by
taking cuttings and
growing them
These cuttings will
develop their own
roots and grow into
an identical new
plant. Other methods can
also be used.
Layering: Some plants
produce offshoots or
plantlets. These plantlets
can be grown in the soil
still attached to the parent
plant. Once they have
established a root system
they can be detached
from the parent plant to
grow on their own.
Runners
Strawberries
reproduce asexually
They send out runners
over the ground
These runners sprout
roots at various
intervals and new
plants grow
Once the plants are
established, the
runners die and rot
away
Potatoes use tubers to
reproduce.
They send out underground
stems that swell out at the
end into tubers
These are young potatoes and
contain stores of food
(starch)
Each tuber can then grow into
an entire new plant
Bacteria, amoeba and some other single-celled organisms can
reproduce asexually by a process of cell division in which two
daughter cells are produced from the one parent cell.
Hydra
Sponge
Yeast
Some multi-celled organisms, like hydra and some
species of sponge, can reproduce asexually by
budding. Yeast also reproduce by this method. Buds
form in the body wall which grow into miniature adults,
eventually breaking away to become independent.
They are clones of the single parent.
• Aphids, otherwise known as GREENFLY
can reproduce ASEXUALLY.
• This means that they do not need a
partner.
• A a single female aphid could produce 600
billion descendants in one season.
This is not very common but some animals
such as star fish and sea anemone can
reproduce asexually.
Mammals cannot reproduce asexually.
However, scientists have found a way to clone
animals in the lab. The first cloned mammal was Dolly
the sheep. Dolly is an exact genetic duplicate of the
animal from which a single cell was taken to clone
her.
This is a picture of Dolly and her lamb
Bonnie. Dolly lived to the age of 6
years old. Though sheep have a life
span of 11-12 years Dolly developed
arthritis. This was possibly because
she was cloned from a 6 year old
sheep.
Today we will make clones of 2 different
plants.
• I will show you how to make a clone of a
spider plant using the layering technique.
• In your groups you will take a cutting from
a geranium plant.