Bio-110 lecture test 3: Genetics

_____ is the outward physical manifestation of the organism.

phenotype

_____ refers to having two different alleles for a single trait.

heterozygote

_____ traits can only be observed in its homozygous form.

recessive

A dwarf stalk (D) is dominate to a tall stalk (d). What would be the genotypic ratio resulting from a cross between a heterozygote dwarf stalk and a tall stalk?

1:1 (50% heterozygote, Dd and 50% homozygote recessive, dd)

A dwarf stalk (D) is dominate to a tall stalk (d). What would be the phenotypic ratio resulting from a cross between a heterozygote dwarf stalk and a tall stalk?

1:1 (50% dwarf and 50% tall)

Tay sachs is a recessive disorder. If two parents who are carriers for the trait (heterozygotes, Tt), what is their chances of a having a baby affected by Tay sachs?

25%

In dogs rough hair (H) is a dominate to smooth hair (h). If a dog has rough hair what is its genotype?

Both HH or Hh are possible

You rescue a smooth haired dog from the pound. Which of these is not a possible genotype of the parents?

HH x Hh

In fruit flies red eyes are dominate to sepia eyes. A fruit fly is displaying the dominate phenotype for eye color (red eyes). How can you determine its genotype of the red eye fruit fly? Be detailed in your answer.

Perform a test cross with a fruit fly displaying the recessive phenotype, sepia eyes. Count the offspring and use the ratio to determine the genotype of the fruit fly in question. Iff all the fruits flies are red eyed you know the original genotype was homozygous dominate. If 50% of the offspring end up with sepia eyes you know the original genotype was heterozygote.

Allele

alternative form to a gene

Homozygous

alleles are the same

Heterozygous

alleles are different

Genotype

coded on your genes (the letters, WW, Ww,ww)

Phenotype

the manifestation of the genotype (widows peak or no widows peak)

DImpled chin is dominant, If two people are heterozygous for dimpled chin what are the chances their child will have a dimpled chin?

25%

Genotypic ratio

the ratio of the genotypes that appear in offspring

Phenotypic ratio

the ratio of phenotypes produced by a cross

Detached earlobes are dominant if a heterozygote and a homozygous recessive are going to have a baby. What are the odds a child is going to have detached earlobes?

50%

Dominant

it will be displayed in the heterozygous form as well as the homozygous

Recessive

will only be displayed in the homozygous recessive

Incomplete Example

blending of traits in the heterozygote. (red and white flowers make pink flowers)

Codominate Example

both traits being expressed in the heterozygote (red and white flower make red and white spotted flower)

Pleiotropy

1 gene contributing to multiple phenotypes (sickle cell disease)

Multiple Genes

(polygenetic) multiple genes contributed to a phenotype

Multiple allelism

blood typing (A, B, O)

Interactions with the environment

heart disease in your family, breastcancer.

Epigenetics

Genes being suppressed or turned up due to conditions during critical points of development

Blood type A Genotype

AA or AO

Blood type B Genotype

BB or BO

Blood type AB Genotype

AB

Blood type O Genotype

OO

Blood type A antigens

A antigens

Blood type B antigens

B antigens

Blood type AB antigens

AB antigens

Blood type O antigens

No antigens

Blood Type A antibodies

B antibodies

Blood Type B antibodies

A antibodies

Blood Type AB antibodies

no antibodies

Blood Type O antibodies

A and B antibodies

The universal donor

Type O blood

universal recipient blood type

AB

Blood type A can donate to

A or AB

Blood type B can donate to

B or AB

Blood type AB can donate to

AB only

Blood type O can donate to

A, B, AB, O

Blood type A can accept blood from

A and O

Blood type B can accept blood from

B and O

Blood type AB can accept blood from

O, A, AB, B (all)

Blood type O can accept blood from

O

If someone who is type AB has a child with someone who is also AB what are the chances they will have a child who is bloodtype AB?

50%

If someone is blood type AO and their partner is BO what are the chances they will have a kid with blood type O?

25%

Sex Linkage

The trait is located on a sex chromosome. (x or y), which is why males tend to get sex linked disorders more often

The female is a carrier for color blindness and the male has typical color vision. What are the chances they will have a child who is color blind? (FOR SON)

25%

Autosomal Mendelian Human Traits

Hitch hikers thumb

widows peak

dimpled chin

freckles

tongue curl

First Consequence of Segregation

each gamete receives only 1 of the 2 copies of a gene

Second Consequence of Segregation

impossible to know which alley goes with which gamete an which gamete will be involved in fertilization

Codominance Definition

a cross between organisms with 2 different phenotype produces offspring with a third phenotype in which both of the parental traits appear together

incomplete dominance Definition

dominance, a cross between organisms with 2 different phenotypes produces offspring with a third phenotype that is a blending of the parental traits

Pleiotrophy

one gene influences multiple, different traits

Mendel's Law of Independent Assortment

the inheritance pattern of one trait doesn't usually influence the inheritance of another trait

Incomplete

blending of traits in the heterozygote. (red and white flowers make pink flowers)