1. Genetics and Inheritance Flashcards
In humans what is the name of the female sex cell?
Egg cells
In humans what is the name of the male sex cell?
Sperm cell
When an egg cell and sperm cell fuse, this is called….
Fertilisation
In a normal human body cell (e.g. skin cell) how many chromosomes are in the nucleus?
46 chromosomes
How is DNA arranged in the nuclei of cells?
Into strands called chromosomes
What is a gene?
A gene is a section of a chromosome that codes for a particular characteristic.
How many forms of each gene do we inherit?
We inherit 2 forms of each gene. These are called alleles.
What is the function of the cell membrane?
The cell membrane controls what enters and leaves the cell
What is the function of the nucleus of a cell?
The nucleus contains the DNA (chromosomes)
What do the letters DNA stand for?
Deoxyribonucleic acid (=DNA)
What is an allele?
An allele is a different form of a gene. For example:
Gene is eye colour, the alleles could be brown, blue, green, etc.
In terms of genetics what does the word homozygous alleles mean?
If an individual has 2 identical alleles (e.g. BB, tt) for a characteristic (e.g. two blue eyes alleles) they are said to be homozygous for this characteristic.
In terms of genetics what does the word heterozygous alleles mean?
If an individual has 2 different alleles (e.g. Bb, Tt) for a characteristic (e.g. a blue allele and a brown allele) they are said to be heterozygous for this characteristic.
What sex chromosomes has a male inherited?
XY
What sex chromosomes has a female inherited?
XX
In a human sex cell (e.g. sperm cell or egg cell) how many chromosomes are in the nucleus?
23 chromosomes
Our phenotype (physical expression of our alleles) is due to 2 types of variation. What are these type of variation?
Genetic variation and environmental variation.
Neil fell over when he was young and now has a scar on his arm. What type of variation is this?
Environmental variation
Sajid’s blood group is AB. Was this genetically or environmentally inherited?
Genetically inherited
What is a genetic disorder?
A genetic disorder is a disease caused by a faulty gene or chromosome.
What is a recessive genetic disorder?
This is a genetic disorder where the individual has inherited 2 faulty alleles, one from Mum and one from Dad.
What is a dominant genetic disorder
This is a genetic disorder where the individual has inherited one ONE faulty alleles. Either from Mum or Dad.
What are the stages of selective breeding?
- Choose two parents with the desired characteristic
- Breed them together
- Choose offspring that show the desired characteristic and breed them.
- Repeat over many generations.
What is selective breeding?
Selective breedingis when humans choose parents to breed together.
These parents have particular desirable characteristics toand are likely to produce offspring with the same desirable characteristics.
Give two advantages of breeding crops or animals by selective breeding.
- Increased milk/meat yield from cattle (which may increase profits for farmers).
- Disease resistance in food crops or garden plants e.g. soya beans.
- Can produce domesticated animals with a gentle nature e.g. labradoodle.
- Decorative plants (e.g. with large or unusual/coloured flowers).
- New varieties of crops can be produced.
Give two disadvantages of selective breeding.
- Selective breeding can lead to ‘inbreeding’.
- Because of the smaller genetic pool selective bred organisms are more likely to pass on harmful recessive alleles.
- There they are more likely to be susceptible to diseases.
What does GMO stand for?
Genetically modified organism.
What does the process of genetic engineering involve
It involves changing the genes of an organism
by introducing a gene from another organism to give a desired characteristic.
What are the stages in genetic engineering?
1) Select the desired characteristic (e.g. insulin gene)
2) Isolate the gene responsible for the characteristic (using enzymes)
3) Insert this gene into another organism (e.g. a bacterium)
4) Replication of theorganism.
Give 2 advantages of genetic engineering.
- Improving crop yield.
- Improving resistance to pesticides.
- Extend shelf-life of fruits/veg e.g. tomatoes.
- Manufacture a certain chemical (e.g. Insulin).
Give 2 disadvantages of genetic engineering.
- Inserted genes may have unwanted side effects.
- Possible harm when GM crops are eaten by humans/other animals.
- Damage to food chains.
- GM animals/crops may breed with wild animals/plants thereby reducing biodiversity.
What is cloning?
Cloning is making a genetically identical copy of an individual.
What are the 2 types of clones that can be produced?
Natural cloning and artificial cloning.
Give an example of natural cloning in animals.
Identical twins are natural clones of each other.
Give 2 advantages of cloning.
- Can produce lots of identical offspring with desirable features.
- Study of clones could help treat/cure certain diseases.
- Could help/bring back endangered or extinct species.
