Chapter 12 - Alleles Flashcards
What is an allele?
Two or more versions of a gene that arise by mutation, from the same place on a chromosome
What are alleles responsible for?
Genetic variation
What are homozygous alleles?
Alleles that are the same
What are heterozygous alleles?
Alleles that are different.
What is a recessive allele?
An allele that will not be expressed unless it is paired with the same recessive allele.
What is a dominant allele?
An allele that takes priority over a recessive allele.
How many alleles are there in a blood group gene?
3
What does a blood group gene do?
Makes an enzyme
Which type sugars are present on the surface of red blood cells when the blood type is A?
A type.
Which type sugars are present on the surface of red blood cells when the blood type is B?
B
Which type sugars are present on the surface of red blood cells when the blood type is AB?
A and B type
Which type sugars are present on the surface of red blood cells when the blood type is O?
None.
What does the enzyme produced by the blood group gene do?
Attaches a sugar to the red blood cell
Where is the gene for blood group alleles located?
On chromosome 9
What are blood group alleles represented by?
IA, IB, and io
What is a phenotype?
A blood group
What is a genotype?
A combination of alleles (there are 6 possible combinations)
How many chances do female people have of getting a good allele?
2
How many chances do male people have of getting a good allele?
1
What are mutations that take place outside of genetic code called, and what do they do?
Silent mutations that do nothing.
What effect do mutations to the DNA in front of a gene have on RNA polymerase?
How it binds to DNA. This can cause more, less, or no protein to be produced.
Which allele for a blood group is recessive?
io
Which genotype shows co-dominance?
AB
What is co-dominance?
Dominant alleles that contribute equally to the phenotype.
The ABO gene is said to have multiple alleles. State what this means.
More than two alleles for that gene.
What do stop triplets do?
Tell ribosomes to stop adding amino acids.
Which chromosome carries sex-linked traits?
X
The sex that always passes their chromosome alleles to their offspring is…
Male.
What is haemophilia?
A disorder in which blood clotting after injury is defective.
What is the most common cause of haemophilia?
A mutation in the gene on the X chromosome that produces clotting factor VIII.
When was the Human Genome Project completed?
In 2003.
How many base pairs are there in the human genome?
3.3 billion.
What percentage of bases are the same between individuals?
99%
What percentage if differentiation in base pairs is responsible for all genetic variation?
1%
What benefit is there to having knowledge of a person’s genome?
We can predict what diseases they are more likely to develop, or how they are likely to respond to certain medications.
How many alleles are in the polypeptide that combines to make haemoglobin?
4.
What happens when a mutation occurs in part of the DNA that does not code for amino acids?
Nothing.
What is the effect of a gene mutation?
More or less protein being made.
Characteristics that are caused completely by environmental factors are called…..
Acquired characteristics
Can acquired characteristics be passed on to offspring?
No.
