Chapter 15: Sex Chromosomes, Linked Genes and Organelle Inheritance

These flashcards cover key concepts from Chapter 15 on inheritance patterns, X-linked genes, and organelle inheritance.

What is the crisscross inheritance pattern associated with?

X-linked genes

Which chromosomes display different inheritance patterns between sexes?

Sex chromosomes

What kind of inheritance do mitochondria and chloroplasts follow?

They follow their own inheritance patterns distinct from nuclear DNA.

What do closely located genes on a chromosome tend to do?

They tend to be inherited together.

From whom do males inherit their X chromosomes?

Their mother.

In a cross involving X-linked traits, what can be observed in the male offspring?

They can express traits based on the mother's X chromosome.

What does it mean if genes are linked?

They are located close together on the same chromosome and do not assort independently.

What results from meiosis in males regarding sex chromosomes?

A 1:1 ratio of X-bearing and Y-bearing sperm.

How do F1 generation progeny from a red-eyed female and a white-eyed male behave?

All have red eyes, showing evidence of X-linked inheritance.

What occurs when F1 progeny are crossed in X-linked inheritance?

A typical recessive inheritance pattern emerges.

What is a significant characteristic of Y-linked genes?

They are passed from father to son.

What happens to the male to female ratio at birth?

There is often a slight excess of males.

What trait is commonly associated with X-linked recessive mutations in humans?

Color blindness.

What happens to daughters of affected males with X-linked traits?

They are usually carriers, potentially having affected sons.

What is significant about the inheritance patterns of hemophilia in the royal family?

It illustrates X-linked recessive inheritance, as seen in multiple generations.

What would you expect in the F2 generation regarding X-linked recessive traits?

White-eyed males reappear, but females maintain red eyes.

What does the term 'nondisjunction' refer to?

The failure of homologous chromosomes to separate properly during meiosis.

What does crossing-over lead to in terms of chromosomes?

It can create recombinant chromosomes through physical exchange.

How is the frequency of recombination between two genes measured?

By observing the number of recombinant versus non-recombinant offspring.

What characterizes the inheritance of mitochondrial DNA?

It is strictly maternally inherited and does not undergo recombination.

What is the typical inheritance pattern for chloroplast DNA?

Paternal inheritance in some organisms.

What are genetic maps used for?

They show the relative positions of genes on a chromosome based on recombination frequencies.

What evidence did Bridges provide supporting the physical presence of genes on chromosomes?

Observations of nondisjunction leading to changes in expected phenotypes.

In terms of sex-linked traits, who is generally more affected by X-linked recessive conditions?

Males.

What is the expected phenotype ratio among males from a cross of heterozygous carrier females?

Half affected and half unaffected males.

What can be used to trace lineage using Y chromosomes?

The accumulation of mutations over time creates different haplotypes.

What is the result of genes being locationally close on the same chromosome?

Higher likelihood of appearing together in the phenotype.

What role do mitochondria play in cellular function?

They carry out essential metabolic processes and contain their own DNA.

What does a recombination frequency above 50% suggest?

Genes are likely on different chromosomes or far apart on the same chromosome.

What does Sturtevant's hypothesis propose regarding recombination frequencies?

They can be used to create a genetic map of a chromosome.

What defines a Y-linked trait's unique inheritance pattern?

Only males exhibit the trait, as females do not inherit the Y chromosome.

What key observation about sex-linked traits was made through T.H. Morgan's experiments?

An unexpected pattern of inheritance that did not align with Mendelian predictions.

What describes nonrecombinant chromosomes?

They retain the same allele configuration as one of the parental chromosomes.

What type of inheritance do all offspring of a mother with a mitochondrial mutation exhibit?

All offspring will also show the trait.

Why is mitochondrial DNA a useful tool for ancestry tracing?

It accumulates mutations over time and is inherited maternally.