B1.7 Genetic Variation Flashcards
What are chromosomes and where are they found?
Chromosomes are found in the cell nucleus and contain genes
What is a gene?
A gene is a section of DNA coding for a particular protein
How many chromosomes do humans have?
46 containing around 30,000 genes
What are examples of inherited variation in humans?
Eye colour
Hair colour
Skin colour
How can the environment cause variation?
Climate Diet Culture Lifestyle Language Religion Flower colour
What factor determines body mass?
Both environmental and inherited factors
What are gametes?
Sex cells
Female = eggs / ova
Male = sperm
What is sexual reproduction?
When male and female sexual gametes fuse, this is called FERTILISATION
How does sexual reproduction lead to genetic variation?
Some of the genetic from each parent mixes causing the offspring to not be identical to either
How many chromosomes are in a gamete?
23
How is asexual reproduction different to sexual reproduction
Only one parent is used
The offspring are genetically identical not varied
What is an example of asexual reproduction in plants?
Underground food storage organs later develop into plants themselves
eg potatos and daffodils
Some plants produce runners with plantlets on them
eg strawberrys
Some plants produce side branches with plantlets
eg Busy lizzy
What are examples of asexual reproduction in animals
Although it is rare, some animals do asexually reproduce
eg
sea anenomes
starfish
What are the commercial benefits of plant cloning?
A plant can be produced efficiently and cheaply on a massive scale
How can a plant be artificially cloned?
- Cuttings
- Tissue cultures
How can plants be cloned with cuttings?
A branch of the plant is cut off and replanted using plant hormones to stimulate root growth
The cutting is usually covered in a plastic bag to ensure optimum warmth and moisture for the first few weeks
It is easy and accessible for gardeners to use
How can plants be clones with tissue cultures?
A tissue sample of the plant is taken and placed in agar jelly with nutrients and auxins
The samples develop into tiny plantlets that can then be transferred into composts
The equipment is very expenisve and more difficult to achieve effective results than cuttings
Why would people want to clone animals?
Animals with the most desirable features such as producing the largest yield of milk or meat can be reproduced
How are animals artificially cloned through embryo transplants?
- A developing embryo is removed from the mother early on before the cells become specialised
- The cells are separated and grown in a lab
- They are transplanted into surrogate mothers
- Multiple, genetically identical, offspring are born
How are animals artificially cloned through adult cell cloning?
- The nucleus is removed and discarded from an unfertilised egg
- The nucleus from an adult body cell is implanted into the egg cell
- The cell is given an electric shock to begin its division
- The ball of cells is implanted into a surrogate mother where it can continue to grow and develop
How is genetic modification different from cloning?
- Produces a unique set of genes not an exact copy
- Genes can be swapped can transferred accros species
How does genetic modification work?
Enzymes are used to remove sections of DNA and join them to a different string of DNA
This can cause the organism to have beneficial characteristics
How can genetic modification be used in crops?
To create resistance against herbicides or pesticides
How can insulin be mass produced using genetic modification?
The section of DNA coding for insulin production in the body is removed and inserted into a bacteria plasmoid
The Insulin can be grown quickly
What are the advantages of genetic modification and cloning?
Can produce ideal plants and animals
Increase in production yield, less costly
Feeding growing / starving population with efficient yield
What are the disadvantages of genetic modification and cloning?
Can reproduce plants or animals with genetic diseases
Is unethical
Unknown effect on plants, wildflowers, human health
