Quiz Mendelian Genetics and Extensions of Mendelian Genetics

Ratio for Identical Twins

1 in 285 pregnancies

Ratio of fraternal twins

1 in 80 pregnancies

What happens with fraternal twins

2 separate eggs fuse with different sperm

Zygote has two complete copies of the manual

23 page copy from mom and 23 page copy from dad, 23 homologous pairs of chromosomes

46 chromosomes=

46 page instruction manual- each chromosome is a different page of the manual

bb(Bb) Bb Bb bb bb

50% brown eyes 50% blue eyes 50% heterozygous 50% Homozygous recessive

Mutations can lead to different versions of the same gene

Alleles

Homozygous

Carries two copies of the same allele(RR, rr)

Heterozygous

Carries two different alleles for a gene(Rr)

What happens with monozygotic twins

Cells in an embryo separate from each other, happens early in development

zygote= and how many chromosomes

Diploid, 46

Another name for Fraternal Twins

Dizygotic twins, develop from two different zygotes

Homologous Pairs

Equivalent chromosomes, pairs contain one chromosome received from each parent

Pedigrees

Family tree that follows the inheritance of a genetic trait for many generations of relatives. Used to study human genetics Matings that have already occurred are analyzed Can be used to determine if a trait is dominant, recessive or sex-linked

Dihybrid cross step 3

Fill in the chart! Determine phenotypes

Genotype

Genetic composition of an individual, describes alleles Letters

Gg

Genotype

Homozygous Dominant

Genotype

Egg and sperm cells are and contain how many chromosomes

Haploid, 23 chromosomes

Rr

Heterozygous

Monohybrid Cross

Heterozygous parent+ Homozygous recessive parent BB+bb

Independent Assortment

Homologous move into gametes, randomly and independently of other chromosomes. Random alignment during Metaphase I

RR

Homozygous dominant

rr

Homozygous recessive

Dihybrid cross step 1

Identify the genotypes of the parents Heterozygous for both traits? Heterozygous for one and homozygous recessive for another?

Dihybrid cross step 2

Identify the possible see cells(haploids) for the parents

Segregation

In meiosis, homologous serpente from each other into different gametes.

Another name for Identical Twins

Monozygotic twins, develop from one zygote

Quantitive trait

Multiple genes play a role in the physical trait Can be caused by genetic and environmental variables Not just an on and off quality EX. Skin color, eye color

Fraternal Twins are

Non- identical

Y-Linked Inheritance

Only males are affected, since it is passed on the Y chromosome

Brown Hair?

Phenotype

Eye Color is an example of a

Phenotype

Freckles

Phenotype

Dominant

Phenotype is seen when homozygous or heterozygous

Recessive

Phenotype of an allele is seen only when homozygous

Quantitative trait

Phenotype/physical trait On or off quality, controlled by 1 gene not measured by a number

Phenotype

Physical traits of an individual Photo-what you see

Identical Twins share what percentage

Share 100% of their genes

How do fraternal twins develop

Simultaneously

Autosomal Recessive traits

Trait appears on an autosomal chromosome, recessive Postive individual is homozygous recessive

X- Linked Dominant

Trait occur on the X- chromosome, dominant Postive males carries the trait on his X chromosome

Egg+ Sperm=

Zygote

Errors can occur every time the

cell divides

Each page has many words just like

chromosomes contain many genes

Words can be used in various orders just like

genes can

All genetic material is like an

instruction manual

When we replicate DNA, we are not photocopying this instruction manual, we are

rewriting it

Gametes gets just one copy of each page of

the manual

Autosomal Dominant

trait appears on an autosomal chromosome, dominant Postive individual is either homozygous dominant or heterozygous