Genetics Chapter on Inheritance Patterns

Questions and Answers

What are the basic modes of inheritance for single-gene?

Autosomal dominant inheritance

X-linked recessive

Y-linked

All of the above (correct)

Human females produce gametes with two possible combinations of chromosomes.

False

What is the term for traits that display continuous variation due to genetic and environmental factors?

complex or multifactorial inheritance

What type of inheritance is observed when an allele is only expressed if two copies are present?

autosomal recessive Signup and view all the answers

Which type of inheritance primarily involves the X chromosome?

X-linked inheritance Signup and view all the answers

The smaller Y chromosome contains genes responsible for the initiation and maintenance of _____.

maleness Signup and view all the answers

Males express all the alleles present on the single X chromosome they receive from their mother.

True Signup and view all the answers

Who is known for their work in X-linked inheritance using Drosophila?

Thomas Hunt Morgan Signup and view all the answers

An individual heterozygous for an autosomal recessive allele is known as a _____.

carrier Signup and view all the answers

Match the following conditions with their associated chromosome:

Haemophilia = X chromosome Muscular dystrophy = X chromosome Color blindness = X chromosome Maleness = Y chromosome Signup and view all the answers

Study Notes

Pattern of Inheritance

Inheritance patterns depend on whether alleles are on autosomal or sex chromosomes and whether they are dominant or recessive.
Five basic modes of single-gene inheritance:
- Autosomal dominant
- Autosomal recessive
- X-linked dominant
- X-linked recessive
- Y-linked
- Mitochondrial

Homogametic and Heterogametic

Females are homogametic, producing gametes with only X chromosomes (XX).
Males are heterogametic, producing gametes with both X and Y chromosomes (XY).
During meiosis, sex chromosomes are separated into different gametes.

Non-Mendelian Inheritance

Complex traits show continuous variation, influenced by both genetics and environmental factors.
Example traits include human height and weight, affected by gene interactions and environmental influences.
Such traits are classified as complex or multifactorial.

Autosomal Inheritance

Autosomal Dominant:
- Phenotype observed with one copy of the dominant allele (heterozygous or homozygous).
Autosomal Recessive:
- Phenotype observed only with two copies of the recessive allele (homozygous).
- Heterozygous individuals (carriers) do not express the phenotype but can pass it on.

Sex-linked Inheritance

Most sex-linked characteristics are X-linked due to limited genetic information on the Y chromosome.
X chromosome contains hundreds of genes unrelated to sex determination.
Males express all alleles on their single X chromosome, making dominance or recessiveness irrelevant for X-linked traits.
Conditions linked to the X chromosome include haemophilia, muscular dystrophy, and color blindness.

Historical Context

Thomas Hunt Morgan's experiments with Drosophila (fruit flies) advanced understanding of X-linked inheritance.
Morgan aimed to challenge Mendelian ratios and discovered a white-eyed male fly, crucial for his studies.
The notation used: XR indicates the red eye allele (dominant), while Xr indicates the white eye allele (recessive).

Description

Explore the various patterns of inheritance in genetics, including autosomal and sex-linked traits. This quiz covers both Mendelian and non-Mendelian inheritance types, explaining complex traits and their genetic basis. Test your understanding of how these patterns influence phenotype and inheritance in organisms.