Top Banner
12.2 Complex patterns of inheritance
12

12.2 Complex patterns of inheritance

Dec 31, 2015

Download

Documents

keelie-nichols

12.2 Complex patterns of inheritance. Complex patterns of inheritance. Mendel’s experiments show simple inheritance with recessive and dominant alleles Some patterns of inheritance are more complex. Complex patterns of inheritance. Incomplete dominance Codominance Multiple alleles - PowerPoint PPT Presentation
Welcome message from author
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
Transcript
Page 1: 12.2 Complex patterns of inheritance

12.2 Complex patterns of inheritance

Page 2: 12.2 Complex patterns of inheritance

Complex patterns of inheritance

Mendel’s experiments show simple inheritance with recessive and dominant alleles

Some patterns of inheritance are more complex

Page 3: 12.2 Complex patterns of inheritance

Complex patterns of inheritance

Incomplete dominance Codominance Multiple alleles Sex-linked inheritance Polygenic inheritance Environmental factors

Page 4: 12.2 Complex patterns of inheritance

Incomplete dominance

Phenotype of the heterozygote is in between the phenotypes of the homozygotes

RR=red pigment

R1R1=white, no pigment

RR1=pink

Page 5: 12.2 Complex patterns of inheritance

Codominance

Phenotypes of both homozygotes are produced in heterozygote, both alleles are expressed equally

BB=black feather

WW= white feather

BW= checkered

Page 6: 12.2 Complex patterns of inheritance

Multiple alleles

Traits controlled by more than two alleles Each pigeon has two alleles

for feather color, but thereare many possible alleles

Page 7: 12.2 Complex patterns of inheritance

Sex-linked inheritance

In humans have 46 chromosomes, 23 pairs 22 pairs autosomes one pair sex chromosomes, determine sex

Page 8: 12.2 Complex patterns of inheritance

Sex-linked inheritance

Sex-linked traits are controlled by genes located on the sex chromosomes

Alleles are carried on the X chromosome,

not the Y chromosome

Page 9: 12.2 Complex patterns of inheritance

Polygenic inheritance A trait that is controlled by

more than one gene Genes may be on different

chromosomes Each gene may have more

than one allele Trait usually expressed in a

continuous range of variability

Page 10: 12.2 Complex patterns of inheritance

Environmental factors

External Gene may not be expressed due to

temperature, nutrition, light, chemicals, infection

For example, this bacteria

is different color when

grown at different temperature

Page 11: 12.2 Complex patterns of inheritance

Environmental factors

InternalMales and females differ due to hormonesAge may change trait expression

Page 12: 12.2 Complex patterns of inheritance

Complex patterns of inheritance

Mendel’s idea that heredity is a composite of many traits still holds

Later researchers have filled in details