B1h-variation And Inheritance Flashcards
Where are chromosomes held?
In the nucleus
What is a gene?
A short length of a chromosome that controls inherited characteristics
How many chromosomes do body cells have?
46 (23 pairs)
How many chromosomes do gametes have?
23
What are alleles?
Different versions of the same gene
What are the causes of genetic variation?
-gamete formation
Making sperm and eggs
chromosomes shuffled
-fertilisation
Sperm and egg join to form a new cell with 46 chromosomes
-mutations
Changes to the genes
What human characteristics are a result of both environment and inheritance?
Intelligence
Body mass
Height
When are dominant alleles expressed?
When they are present
When are recessive alleles expressed?
When the dominant allele is absent
What is a monohybrid cross?
When you breed two organisms together to look at a characteristic thats controlled by one gene
What is homozygous?
Two identical alleles
What is heterozygous?
Two different alleles
What is a genotype?
The genetic makeup
What is a phenotype?
The characteristics expressed
What are some examples of inherited disorders?
Red green colour blindness
Sickle cell anaemia
Cystic fibrosis
What are inherited disorders caused by?
Faulty alleles, mostly recessive
What chromosomes do men have?
XY
What chromosomes do women have?
XX
What issues are raised by knowledge of inherited disorders in a family?
All family members tested?
Should someone have children if their at risk?
Should you terminate pregnancy if test is positive?
When are dominant alleles expressed?
When they are present
When are recessive alleles expressed?
When the dominant allele is absent
What is a monohybrid cross?
When you breed two organisms together to look at a characteristic thats controlled by one gene
What is homozygous?
Two identical alleles
What is heterozygous?
Two different alleles
