Lecture 7a+b: Mendelian Genetics and Chromosomal Genetics

Question 1

Genetics

Answer 1

is the branch of biology concerned with heredity and variation of inherited characteristics

Question 2

2 concepts that used to be widely accepted

Answer 2

“blending” theory of inheritance
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Inheritance of acquired characteristics

Question 3

“blending” theory of inheritance

Answer 3

the genetic materials contributed by the male and female parents mix in forming the offspring, and the progeny inherits any characteristic as the average of the parents values of that characteristics

Question 4

inheritance of acquired characters

Answer 4

it was believed that an organism acquires some traits during its life time and they are then passed on to the offspring

Question 5

phenotype

Answer 5

The physical appearance of an organism

Question 6

Genotype

Answer 6

the genetic makeup of an organism (alleles or variants of a gene)

Question 7

cross (hybridization)

Answer 7

the cross-fertilization of 2 different varieties/species

Question 8

Hybrid

Answer 8

the offspring of parents (p generation) of 2 different varieties/species

Question 9

F1 generation

Answer 9

the first generation resulting from a cross

Question 10

F2 generation

Answer 10

the generation of plants from self-fertilization of the F1 offspring

Question 11

Alleles

Answer 11

alternative forms of a gene; genes governing variation of the same character that occupy corresponding positions (loci) on homologous chromosomes

Question 12

homozygous

Answer 12

having 2 identical alleles for a given characteristic

Question 13

Heterozygous

Answer 13

2 different alleles for a given characteristic

Question 14

Hemizygous

Answer 14

a condition in which only one copy of a gene or DNA sequence is present in diploid cells

Question 15

Dominant allele

Answer 15

an allele that is always expressed when it is present, regardless of homo or heterozygous

Question 16

recessive allele

Answer 16

an allele that is not expressed in the heterozygous state

Question 17

Testcross

Answer 17

a cross of an individual of unknown genotype for a particular characteristic with a homozygous-recessive individual for the same characteristic

Question 18

Mendel’s first law- the law of segregation

Answer 18

when any individual produces gametes, the alleles separate, so that each gamete receives only one member of the pair of alleles

Question 19

Mendel’s second law- the law of independent assortment

Answer 19

alleles of 2 (or more) different genes get sorted into gametes independently of one another

Question 20

incomplete dominance

Answer 20

a type of inheritance in which one allele for a specific trait is not completely expressed over its paired allele in F1 hybrids.

Question 21

Codominance

Answer 21

a cross between organisms with 2 different phenotypes produces offspring with a 3rd phenotype in which both traits appear together

Question 22

multiple alleles

Answer 22

occurrence of a gene that exists as 3 or more alleles in a population

Question 23

pleiotropy

Answer 23

the determination of more than one character by a single gene

Question 24

epistasis

Answer 24

occurs when 2 or more different gene loci contribute to the same phenotype

Question 25

polygenic inheritance

Answer 25

the additive effect of 2 or more gene loci on a single phenotypic characteristic

Question 26

crossing over

Answer 26

the exchange of segments between chromatids of homologous chromosomes during the prophase of meiosis I

Question 27

autosome

Answer 27

any chromosome that is not a sex chromosome