Lecture 4:Single gene inheritance

Question 1

Alleles is

Answer 1

alternate forms of a gene

Question 2

Single factor cross is

Answer 2

Single-factor cross investigates inheritance of a single gene
Use true or pure-breeding parents
Each parent comes from a variety in which:
All members express the same characteristics
Breeding within a variety produces offspring that all show the same characteristics as each other and their parents
Choose parents that differ in one characteristic

Question 3

Cross fertilization

Answer 3

Between pure-breeding parents produces the F1 generation

Question 4

Phenotypic ratio is

Answer 4

Crossing follows a theoretical phenotypic ratio
Large numbers are required to observe ratios
Ratios are rarely exact
Approximations of ratios are observed

Question 5

Mendels law of segregation of alleles

Answer 5

Explains the ratios that Mendel observed
States that two copies of a gene segregate from each other during transmission from parent to offspring

Question 6

Predicting the outcome of crosses

Answer 6

By considering patterns of inheritance, predictions can be made about likely phenotypes and genotypes in future generations
Important in breeding
Genetic predictions are not absolute!
Predictions give only the chance or probability of certain outcomes

Question 7

Importance of large numbers in genetic guesing

Answer 7

Probability gives theoretical expectations based on all possible outcomes being equally likely
Deviations from the expected are fewer the more times a probability event is performed: the observed result is more likely to equal the expected

Question 8

Test cross is

Answer 8

Crossing an individual of dominant phenotype, but unknown genotype, with a recessive homozygote is a common and useful test of genotype
If about 50% of offspring show the recessive phenotype, then it can be concluded that the individual showing the dominant phenotype is heterozygous

Question 9

Short legs dominant or recessive

Answer 9

Short legs relative to body size – a form of achondroplasia
Short legs caused by autosomal dominant allele

Question 10

Overall hair length on back and ribs is determined by

Answer 10

Long hair is autosomal recessive
Single nucleotide change

Question 11

Straight versus curly hair in genetics

Answer 11

Curly coat is autosomal recessive
Single base pair change

Question 12

Wiry coat is caused by

Answer 12

(moustache or extended eyebrows) caused by an autosomal dominant allele

Question 13

Alleles are caused by

Answer 13

Alleles segregate into gametes at meiosis and come randomly together again when gametes unite at fertilization