Chapter 17: Inherited Change

Question 1

Gene

Answer 1

Length of DNA that codes for a particular polypeptide.

Question 2

Allele

Answer 2

Different forms of a gene.

Question 3

Genotype

Answer 3

Genetic make up of an organism. It describes the alleles an organism has.

Question 4

Phenotype

Answer 4

Observable characteristics of an organism.

Question 5

Homozygous

Answer 5

Alleles on each chromosome are the same.

Question 6

Heterozygous

Answer 6

The two alleles are different.

Question 7

Codominant

Answer 7

When two alleles contribute to the phenotype.

Question 8

Multiple alleles

Answer 8

When a gene has more than two allelic forms.

Question 9

Law of segregation.

Answer 9

In diploid organisms, characteristics are determined by alleles that occur in pairs. Only one of each pair of allele can be present in a single gamete.

Question 10

F1

Answer 10

First filial

Question 11

Ratio

Answer 11

Measure of the relative size of two classes that is expressed as a proportion.

Question 12

What is dihybrid inheritance?

Answer 12

Shows how two characters, determined by two different genes located on different chromosomes, are inherited.

Question 13

Law of independent assortment.

Answer 13

Each member of a pair of alleles may combine randomly with either of another pair.

Question 14

Sex chromosomes in females

Answer 14

XX

Question 15

Sex chromosomes in males

Answer 15

XY

Question 16

What name is given to any gene carried on the X or Y chromosome?

Answer 16

Sex-linked.

Question 17

Is the X or the Y chromosome longer?

Answer 17

X (So for most length of the X chromosome, there is no equivalent homologous portion of the Y chromosome. Those characteristics that are controlled by recessive alleles on this non-homologous portion of the X chromosome will appear more frequently in the male. This is because there is no homologous portion on the Y chromosome that might have the dominant allele, in the presence of which the recessive allele does not express itself).

Question 18

What is an X-linked genetic disorder?

Answer 18

Disorder cause by a defective gene on the X chromosome.

Question 19

Why are pedigree charts useful?

Answer 19

Trace the inheritance of sex-linked characters.

Question 20

What is a male represented by in a pedigree chart?

Answer 20

Square

Question 21

What is a female represented by in a pedigree chart?

Answer 21

Circle

Question 22

What does shading in a pedigree chart represent?

Answer 22

Indicates the presence of a character in the phenotype.

Question 23

What name is given to any two genes that occur on the same chromosome?

Answer 23

Linked.

Question 24

What are the remains 22 chromosomes called?

Answer 24

Autosomes.

Question 25

Autosomal linkage

Answer 25

Name given to the situation where two or more genes are carried on the same autosome.

Question 26

When does epistasis arise?

Answer 26

When the allele of one gene affects or masks the expression of another in the phenotype.

Question 27

What is the chi-squared test used to test?

Answer 27

The null hypothesis.

Question 28

What is the null hypothesis used to examine?

Answer 28

The results of scientific investigations and is based on the assumption that there will be no statistically significant difference between sets of observations, any difference be due to chance alone.

Question 29

The chi-squared test can only be used if certain criteria are met…

Answer 29

• Large sample size
• Only raw counts can be used, not percentages and rates etc
• Data must fall into discrete categories
• Used to compare experimental results with theoretical ones

Question 30

Chi-squared formula…

Answer 30

(Observed - Expected)^2 /

Expected numbers

Question 31

Degrees of freedom

Answer 31

Number of classes minus one.

Question 32

If the probability that the deviation is due to chance is equal to or greater than 0.05/5%, the deviation is said to be…

Answer 32

…not significant.

Question 33

If the deviation is less than 0.05/5%, the deviation is said to be…

Answer 33

…significant.

Some factor other than chance is affecting the results and the null hypothesis must be rejected.