Genes and variation Flashcards
(27 cards)
What are the two types of variation in genes?
Environmental and genetic
Give examples of a feature that is purely genetic
Eye colour
Blood group
Inherited disorders
Foot size
How can your height be affected by both genetic and environmental impacts?
You are genetically so high, but whether you eat enough can impact your growth
Where is the genetic material kept in a cell?
The nucleus
Where are genes found?
Genes are in the chromosome and control the development of different characteristics
What are alleles?
Different versions of the same gene (eg different eye colours)
What is the difference between sexual and asexual reproduction?
Sexual - needs two parents and their gametes meet to create a baby
Asexual - only one parent is needed and they can clone themselves to have the exact same genes
What are the disadvantages of asexual and sexual reproduction?
Sexual - genetic diseases can be passed on
Needs two parents
Asexual - if one disease can wipe out one, it can wipe out them all
What are the advantages of asexual and sexual reproduction?
Sexual - species can evolve
Asexual - only needs one parent
What is a gamete?
A sex cell with 23 chromosomes so when the two gametes come together they make 46
What are mutations?
Changes to the genetic code
How can the risk of mutations increase?
Nuclear radiation, x rays, ultraviolet light
Chemicals called mutagens (cigarette smoke has mutagens)
What is cancer?
When mutated cells multiply rapidly in an uncontrollable way
How can mutations be good?
They can benefit the organism, such as bacteria mutating to be resistant to antibiotics
This is natural selection
What is shown in the gene Rr?
The dominant allele
The recessive is not shown
What is homozygous and heterozygous?
Homozygous - two alleles are the same (CC or cc)
Heterozygous - two different alleles (Cc)
How are genetic disorders caused?
By faulty alleles
How is gene therapy treating CF?
Scientists can insert a healthy copy of the gene into the cells with the disease
Why is cloning good for plant farming?
You can take cuttings of a plant and grow a clone cheaply and quickly, meaning you can grow your plants all year round
Why and how have embryo transplants increased selective breeding?
Sperm cells are taken from the best bull and the female is given hormones to make lots of eggs, these eggs are then taken out
The sperm then fertilised the eggs artificially
When embryos form, they check the health of the embryo and keep the healthy ones, splitting them so they clone again so they have loads of clones of good cows
These are then implanted into surrogate mothers
What are the advances and disadvantages of cloning?
Loads of animals can be cloned at once, all being great
There is no evolution or resistance, meaning if one gets a disease, all get the disease and all could die
what is reproductive cloning?
When genetic material is taken from an adult cell to make a new organism that is a clone of that adult
An egg cell’s genetic material is removed and a complete set of chromosomes from the cell of the adult you’re cloning is inserted into the egg cell
Which grows into an embryo of the exact same cow
What is therapeutic cloning?
Produce spare body parts for disease sufferers without them being rejected by the immune system
How do carriers of a genetic disease happen?
If the disease is recessive, the carrier would be heterozygous so they carry the disease but don’t display it
If they have a child and they have two recessive alleles, the disease will be displayed
This means for a child to have it, their parents must either be a carrier or a sufferer
