Podcast
Questions and Answers
What distinguishes cytoplasmic inheritance from Mendelian inheritance in terms of parental contribution?
What distinguishes cytoplasmic inheritance from Mendelian inheritance in terms of parental contribution?
Which of the following statements about reciprocal crosses in cytoplasmic inheritance is true?
Which of the following statements about reciprocal crosses in cytoplasmic inheritance is true?
Which characteristic is associated with lack of segregation in cytoplasmic inheritance?
Which characteristic is associated with lack of segregation in cytoplasmic inheritance?
What is plasmagenes?
What is plasmagenes?
Signup and view all the answers
What term is used to describe the totality of genes in a cell's cytoplasm?
What term is used to describe the totality of genes in a cell's cytoplasm?
Signup and view all the answers
Which of the following describes uniparental inheritance?
Which of the following describes uniparental inheritance?
Signup and view all the answers
What did Ris and Plaut demonstrate in 1962 regarding cytoplasmic inheritance?
What did Ris and Plaut demonstrate in 1962 regarding cytoplasmic inheritance?
Signup and view all the answers
What ratio typically represents the segregation of traits in Mendelian inheritance?
What ratio typically represents the segregation of traits in Mendelian inheritance?
Signup and view all the answers
Study Notes
Cytoplasmic Inheritance
- Cytoplasmic inheritance is a process where traits are passed down through structures outside the nucleus, such as mitochondria and chloroplasts.
- This contrasts with Mendelian inheritance, which is based on nuclear genes.
- Traits passed down through cytoplasmic inheritance are often inherited from only one parent, usually the female.
- This leads to differences observed in reciprocal crosses.
Historical Evidence
- The first evidence of cytoplasmic inheritance was discovered in maize, examining leaf variegation.
- This phenomenon, referred to as "plastid inheritance," was presented by Correns and Baur in 1908.
- Later research, such as the discovery of kappa particles in Paramecium and male sterility in maize, further solidified the link between cytoplasm and heredity.
- The presence of DNA in chloroplasts was demonstrated in 1962 by Ris and Plaut.
- Sager observed cytoplasmic heterozygosity in zygotes in 1954, providing further evidence of the influence of cytoplasm in inheritance.
Definitions
- Genetic information located outside the nucleus, and in the cytoplasm, is called extrachromosomal genes or plasmagenes.
- The collective term for all genes in a cell's cytoplasm is the plasmon.
- The term chondriome refers to all the genes present in mitochondria.
Characteristics of Cytoplasmic Inheritance
- Reciprocal Differences: Reciprocal crosses, where the parental roles are reversed, often exhibit distinct results in traits inherited from the female parent. This is referred to as uniparental inheritance.
- Lack of Segregation: Typical Mendelian patterns of segregation of traits are not observed in cytoplasmic inheritance. The F1, F2, and subsequent generations usually do not show segregation for traits inherited from only one parent.
- Irregular Segregation in Biparental Inheritance: Some cases of biparental inheritance (where both parents contribute cytoplasm) display abnormal segregation ratios in the F1 generation. This can be seen in Chlamydomonas zoospores, where segregation occurs after multiple mitotic divisions.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
Description
Explore the fascinating process of cytoplasmic inheritance, where traits are passed through structures like mitochondria and chloroplasts. Discover its historical evidence, key research findings, and how it differs from Mendelian inheritance. Understand the implications this has on genetics and heredity.
