5.3: Mendelian Genetics

Question 1

What substances are the carriers of genetic information?

Answer 1

Nucleic acids like DNA and RNA carry genetic information.

Question 2

What organisms have ribosomes? How does this demonstrate common ancestry?

Answer 2

All have ribosomes, this means that they all evolved from a common ancestor.

Question 3

How does a shared genetic code demonstrate common ancestry?

Answer 3

It means that maximum parsimony, which means that the easiest path to evolution is the most likely one. Therefore, all organisms most likely evolved from a common ancestor.

Question 4

What metabolic process do all organisms undergo which demonstrates common ancestry?

Answer 4

Cellular respiration (whether anaerobic or aerobic, they both contain glycolysis)

Question 5

What is the law of independent assortment?

Answer 5

The alleles for multiple genes are not inherited separately from each other, leading to more possibilities of different combinations of genes, so there is increased genetic variation.

Question 6

What is the law of segregation?

Answer 6

Two alleles in a pair will separate during meiosis into different gametes. This leads to genetic variation.

Question 7

What is the expected result of a monohybrid cross?

Answer 7

monohybrid cross- one trait is inherited

-1 homozygous dominant, 1 homozygous recessive, and 2 heterozygous

Question 8

What is the expected ratio of a dihybrid cross based on Mendel’s laws?

Answer 8

dihybrid cross- how two traits are inherited

-9(dd):3(dr):3(rd):1(rr)

Question 9

pedigree rules

Answer 9

• if skips generations, must be recessive
• if X linked, then males will be more commonly affected (females would need two X linked in order to show the trait usually)
• Y linked is not a thing (for testing purposes)

Question 10

How to use Chi squared

Answer 10

• Used to determine if there is a significant difference between two
• make observed vs expected list (mult total by expected ratios)
• perform equations for each phenotype group and add together
• degrees of freedom=number phenotypes combinations-1
• p value given usually
• use determine critical value
• if chi greater than the critical value, they assort dependently (together)

Question 11

What is complete dominance?

Answer 11

A heterozygote has the same characteristics as a homozygous dominant organism for the same allele

Question 12

What is incomplete dominance?

Answer 12

Heterozygotes have a intermediate phenotype between the two alleles. (red and white=pink)

Question 13

What is codominance?

Answer 13

Both alleles are present in the phenotype and are expressed differently.

Question 14

How are the phenotypic and genotypic ratios of a monohybrid cross different in these different levels of
dominance?

Answer 14

-genotypic-all 1:1:2

• pheno
• incomplete dominance-1:1:2
• complete dominance-3:1
• codominance-1:1:2