Inheritance Flashcards
What is a genome?
The entire DNA of an organism
What is a gene?
A short length of DNA that carries the genetic code that determines characteristics by instruction cells to produce a particular protein
Describe the structure of DNA
A double helix with four bases
Adenine and thymine
Guanine and cytosine
Angry tiger called Greg
What is RNA?
A single stranded molecule
Contains the base uracil instead of thymine
What is a chromosome and where is it found?
A chromosome is a long length of DNA that has been coiled up. They are found in the nucleus of cells.
What is an allele?
Different versions of the same genes, which give different characteristics, are called alleles
What is a dominant allele?
A dominant allele is always expressed, even if one copy is present
What is a recessive allele?
A recessive allele is only expressed if the individual has two copies and does not have the dominant allele of that gene
What does heterozygous mean?
If there are two different alleles for a particular gene
What does homozygous mean?
If there are two alleles the same for a particular gene
What is a phenotype?
The characteristics that alleles produce
What is a genotype?
the collection of alleles that determine an organism’s characteristics
What is codominance?
When neither alleles are recessive, so characteristics from both alleles are shown
What is polygenic inheritance?
Characteristics that are controlled by more than one gene are described as being polygenic. Most characteristics are a result of multiple genes interacting, rather than a single gene. An example of polygenic inheritance is eye colour – while it is true that brown eyes are dominant to blue eyes, it is not as simple as this as eye colour is controlled by several genes
How is the sex of a person controlled?
Of the 23 pairs of chromosomes, one determines sex. Males must have both an X and Y chromosomes and females have 2 X chromosomes.
What are the chances of having a girl or boy?
When you use a genetic diagram to show sex, you would get a 50/50 chance of either sex. This is because sex depends on whether the sperm carries an X or Y chromosome.
What does diploid mean?
The nucleus contains two copies of each chromosome. The diploid number for humans is 46
What does haploid mean?
A nucleus that has a single set of unpaired chromosomes
What is variation caused by?
Genes cause variation, e.g. eye colour, hair colour
Environment also causes variation
Some variation is caused by both e.g. health (genetic risk and lifestyle), intelligence and sporting ability
What is a mutation?
A rare, random change in an organism’s DNA that can be inherited
What is Darwin’s theory of evolution?
Life began as simple organisms and more complex organisms evolved. Organisms with more suitable characteristics for their environment have a better chance of survival and so will pass their genes on. Over time, this characteristic will become more common so the species is better able to survive and the species has adapted to its environment.
How can bacteria become resistant to antibiotics?
- Bacteria mutates and sometimes a mutation can mean the bacteria is less affected by an antibiotic
- The bacteria is better able to survive in the host so live for longer and reproduces much more often
- The allele for resistance is passed on and becomes more popular over time and the bacteria can’t be treated by that antibiotic anymore
- Sometimes drug companies invent new antibiotics but ‘superbugs’ that are resistant to most known antibiotics are becoming more common
