Chapter 5 - Mendelian Genetics - Patterns of Inheritance (+Ch6)

Question 1

law of dominance

Answer 1

when an organism is hybrid for a pair of contrasting traits, it will show only the dominant trait

Question 2

true breeding organisms

Answer 2

AKA purebred; homozygous for a certain trait; will always pass this trait onto offspring

Question 3

What is the purpose of a monohybrid cross?

Answer 3

a cross designed to study the inheritance of only one trait

Question 4

law of segregation

Answer 4

factors that appear in pairs are separated from each other during gamete formation and recombined at fertilization; cells receive 2 alleles for each gene

Question 5

genotype

Answer 5

combination of alleles (letters); e.g. YY, Yy

Question 6

phenotype

Answer 6

physical expression of a gene in words; e.g. yellow seeds, purple flowers

Question 7

homozygous

Answer 7

2 of the same allele (e.g. YY, yy)

Question 8

heterozygous

Answer 8

2 different alleles (e.g. Yy)

Question 9

contrasting traits

Answer 9

one or the other is expressed; there is no in between

Question 10

Difference between the P, F1 and F2 generations

Answer 10

P gen - parents
F1 gen - offspring
F2 gen - offspring of F1 gen cross

Question 11

incomplete dominance

Answer 11

when 2 alleles are equally dominant; the heterozygous condition results in the blending of traits (e.g. red and white snapdragons creating pink)

Question 12

codominance

Answer 12

when 2 alleles are equally dominant; the heterozygous condition shows both traits equally (e.g. roan cows)

Question 13

What is a pedigree?

Answer 13

A diagram of an individual’s ancestors used in human genetics to analyze the Mendelian inheritance of a certain trait

Question 14

autosomal inheritance

Answer 14

inheritance of alleles located on autosomal (non-sex) chromosomes

Question 15

Chromosome 1-22 are also known as…

Answer 15

Autosomes

Question 16

Difference between monohybrid and dihybrid

Answer 16

Monohybrid is a cross between 2 different true breeding plants that differ in only ONE characteristic (eg, purple flower x white flower); a dihybrid cross involves TWO characteristics/heterozygous alleles (eg, yellow wrinkled x green smooth)

Question 17

Discontinuous variation

Answer 17

The expression of one gene has no effect in the expression of another gene; trait is either expressed or it isn’t

Question 18

Continuous variation

Answer 18

The expression of one gene is affected by the expression of another gene; can be additive allele (have partial influence) or negate expression entirely; expression of a characteristic is the sum of the expression of all alleles involved

Question 19

During which stage of meiosis do homologous chromosomes separate?

Answer 19

Anaphase I

Question 20

Define point mutation and list the different types

Answer 20

A change in one or a few nucleotides of DNA; e.g. base-pair substitution, insertion, deletion

Question 21

What is a nucleotide?

Answer 21

Each section of DNA composed of phosphate, sugar and base

Question 22

Describe sickle cell anemia.

Answer 22

• change in one nucleotide in hemoglobin gene
• recessive disorder
• blood cells distorted and don’t flow properly