DNA, genes, cellular, reproduction and biotechnology lecture 4

Question 1

What is Genetics?

Answer 1

the study of heredity

Question 2

Who was founder of foundations of inheritance principles?

Answer 2

Mendel

Question 3

What did Mendel do his experiments on

Answer 3

pea plants

Question 4

What is hybridization?

Answer 4

-genetic material from both parent plants combined
Plants used in first - generation hybrids called P ( parental generation) plants
- Mendel collected the seeds from the P plants that resulted from each cross and grew them the next year
- Mendel noted characteristics of F1 plants and let them self fertilize naturally
- Mendel collected and grew the seeds from F1 to produce F2 plants

Question 5

What were Mendel’s results from his

Answer 5

Mendel reported the results of his crosses involving seven different characteristics each with two contrasting traits

Question 6

what is traits?

Answer 6

variation in the physical appearance of a heritable characteristic

Example: flower color: traits were white vs violet

Question 7

What are dominant traits?

Answer 7

Those that are inherited unchanged in a hybridization

Question 8

What is recessive traits?

Answer 8

Disappear in the offspring of a hybridization
- would reappear in the progeny of the hybrid offspring

Question 9

Dominant vs recessive trait

Answer 9

• physical observation of a dominant trait meant that organism had two violet genes ( two dominant versions), or one violet and one white gene( one dominant, one recessive)

-observation of a recessive trait meant that the organism had two white genes ( had no dominant versions for this characteristics

Question 10

What are alleles? Provide example.

Answer 10

Are a gene variants that arise by mutation and exist at the same relative locations on homologous chromosomes

Example: one chromosome come from each parent
- genes for pea pods - allele for green vs yellow color

Question 11

What is the difference between phenotype vs genotype? Provide an example for each one.

Answer 11

Phenotype is the observable traits in an organism
Example : yellow seed color in pea plants

Genotype: an organism’s underlying genetic makeup, consisting of both the physically visible and the non - visible alleles
Example: YY or Yy alleles for yellow seed color
- seeds appear equally yellow, even though alleles are different

Question 12

What is the difference between homozygous and heterozygous? Provide example for each one.

Answer 12

Homozygous is the same copy of allele for specific gene
YY, yy
Heterozygous is different copies of allele for specific gene
Yy, yY

Question 13

What is Mendel’s law of segregation ( first law) Provide example

Answer 13

states that genes must segregate equally into gametes such that offspring have an equal likelihood of inheriting either gene

Example: offspring equally likely to inherit y or Y gene from a Yy parent

Question 14

What Mendel’s law of independent assortment (second law) Provide example

Answer 14

states that genes do not influence each other with regard to the sorting of alleles into gametes
- every possible combination of alleles for every gene is equally likely

Example: gene for seed color (Yy) acts independently from gene for seed shape (Rr)

Question 15

What is Mendel’s law of dominance ( third law)

Answer 15

states that some alleles are dominant and others recessive
- Individuals will display the effects of only the dominant allele

Question 16

What are Human discontinuous traits?

Answer 16

albanism vs non - albinism
- both parents are non - albinos ( A phenotype) but carry allele for albinism
- parents both have Aa genotype
- albino child has aa genotype
- two albinos always produce albino children

• Red hair/freckles, cystic fibrosis, huntington’s disease, hemophilia

Question 17

What is PTC?

Answer 17

dominant gene for ability to taste bitter chemical
- bitter chemical is tasteless for those with recessive genes

Question 18

What is incomplete dominance? Provide examples.

Answer 18

One of the alleles appears in the phenotype in the heterozygote, but not to the exclusion of the other, which can also be seen

Example: color in snapdragons ( red dominant, white recessive)

Question 19

What is Co- dominance? Provide example

Answer 19

some discontinuous traits can have two dominant states, which are equally expressed when present
- both alleles for the same characteristic are simultaneously expressed in the heterozygote

Example: human blood group (A, B, O alleles)
O is recessive ( A and B are co - dominant)

Question 20

What is polygenic trait? Provide example.

Answer 20

more than 2 alleles and multiple genes work together additively to produce a phenotype

Example: eye color ( light - dark) controlled by at least 8 genes

Question 21

What is epistasis? Provide example.

Answer 21

when the presence of one gene masks or interferes with the expression of the other

Example: coat pigment in mice