2.6 - How is cystic fibrosis inherited?

Question 1

What is meant by homozygous dominant?

Answer 1

have 2 of the same dominant alleles

Question 2

What does homozygous recessive mean?

Answer 2

having 2 of the same recessive alleles

Question 3

What does heterozygous mean?

Answer 3

having 2 different alleles

Question 4

Define monohybrid inheritance.

Answer 4

when the inheritance of one single allele from 2 parents is controlled by one gene

Question 5

What are the 5 steps to drawing a complete punnet square diagram?

Answer 5

1. give parents genotypes
2. give possible parents gametes
3. draw & fill in Punnett square
4. make a key matching genotypes -> phenotypes
5. give probability or ratio

Question 6

define codominance.

Answer 6

when both alleles are expressed

Question 7

define incomplete dominance

Answer 7

condition in which a dominant allele does not completely mask effects of recessive allele

Question 8

What are homologous chromosomes?

Answer 8

chromosomes that can pair as they contain sequences for the same genes

Question 9

What is a locus?

Answer 9

position of a gene on a chromosomes (each allele for a characteristics will at the same position on the same chromosome)

Question 10

What do chi squared test determine?

Answer 10

significance between 2 sets of data by allowing us to compare expected to observed results

Question 11

What are the 4 steps of using the chi squared test?

Answer 11

1. work out expected results
2. work out observed results
3. calculate difference between 2 & square difference
4. divide each squared difference by expected value & add up of all of these answers to work out X^2

Question 12

What do critical values tell us?

Answer 12

probability that the difference between our expected & observed results are due to chance

Question 13

In chi-squared tests, what has to happen for the null hypothesis to be rejected?

Answer 13

calculated ‘chi-squared’ value has to be greater than the critical value

Question 14

Why are chi-squared tests important? why are they particularly important in genetics?

Answer 14

used to test the hypothesis that the observed & expected results are different - to verify inheritance patterns

Question 15

What is meant by the degrees of freedom? Why do we do this?

Answer 15

we need to take into account the size of our sample - to compensate for the value of x^2 being large when there are many results

Question 16

How do you calculate the degrees of freedom?

Answer 16

number of classes of data - 1