Genes Along Chromosomes

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What is the process by which chromosomes and genes are paired in diploid cells and then separated during meiosis?

Mitosis

Meiosis (correct)

Hereditary segregation

Fertilization

What did Gregor Mendel propose in 1860?

The discovery of DNA

The existence of chromosomes

The laws of inheritance (correct)

The process of mitosis

What is the consequence of fertilization on chromosomes and genes?

They are restored to a paired condition (correct)

They are eliminated

They become unpaired

They remain separated

What is the technique used to visualize the location of a particular gene?

Staining with a fluorescent dye Signup and view all the answers

When was the process of mitosis worked out by cytologists?

1875 Signup and view all the answers

What is the name of the biologist who published a drawing of mitosis in 1882?

Walther Flemming Signup and view all the answers

What is the term used to describe traits that are alternatives to the wild type?

Mutant phenotypes Signup and view all the answers

What is the notation used to symbolize the allele for the wild-type trait in Drosophila?

w+ Signup and view all the answers

How are human genes typically written?

In all uppercase letters Signup and view all the answers

What is the origin of the symbol for a gene in Drosophila?

From the first mutant discovered Signup and view all the answers

What is the symbol for the allele for white eyes in Drosophila?

w Signup and view all the answers

What is the concept that suggests that Mendelian genes have specific loci along chromosomes?

Chromosome theory of inheritance Signup and view all the answers

What is the process that accounts for the segregation of alleles of a gene into separate gametes?

Anaphase I Signup and view all the answers

Who first demonstrated that Mendelian inheritance has its physical basis in the behavior of chromosomes?

Thomas Hunt Morgan Signup and view all the answers

What is the name of the common insect used by Morgan for his genetic studies?

Drosophila melanogaster Signup and view all the answers

What is the term for the phenotype most commonly observed in natural populations?

Wild type Signup and view all the answers

How many pairs of chromosomes do fruit flies have?

Four Signup and view all the answers

What is the period of time required to breed a new generation of fruit flies?

Two weeks Signup and view all the answers

What was the characteristic of the single male fly discovered by Morgan?

White eyes Signup and view all the answers

What was the task that Morgan had to do to find naturally occurring variant individuals?

Both A and B Signup and view all the answers

What is the term for the location of a gene on a chromosome?

Locus Signup and view all the answers

What is the term for the random arrangement of chromosome pairs during metaphase I?

Independent assortment Signup and view all the answers

What was the unexpected result observed by Morgan in the F2 offspring?

All the F2 females had red eyes, while half the males had red eyes and half had white eyes Signup and view all the answers

Why did Morgan conclude that the gene for white eyes is located on the X chromosome?

Because the correlation between the trait of white eye color and the male sex of the affected F2 flies suggested a linkage to the X chromosome Signup and view all the answers

Why is it necessary for a female to have two copies of the recessive allele to express the white-eyed trait?

Because females have two X chromosomes, and one of them must carry the recessive allele Signup and view all the answers

What can be inferred about the presence of the wild-type allele in a male fly?

A male fly can have only one copy of the wild-type allele, and it will always be expressed Signup and view all the answers

What is the reason for the 3:1 phenotypic ratio observed in the F2 offspring?

Because the gene for white eyes is recessive Signup and view all the answers

What is the genotype of a male fly that expresses the white-eyed trait?

XwY Signup and view all the answers

What is the primary reason Morgan's finding of the correlation between a particular trait and an individual's sex provided support for the chromosome theory of inheritance?

It showed that genes are located on specific chromosomes. Signup and view all the answers

What is the role of the SRY gene in sex determination in humans?

It is required for the development of testes. Signup and view all the answers

What is the term for a gene located on either sex chromosome?

Sex-linked gene Signup and view all the answers

What is the consequence of fertilization by a sperm cell containing a Y chromosome?

The zygote develops as a male. Signup and view all the answers

What is the difference between the X and Y chromosomes in terms of size?

The Y chromosome is smaller than the X chromosome. Signup and view all the answers

How do the X and Y chromosomes in males pair and behave during meiosis?

They pair and behave like homologs during meiosis. Signup and view all the answers

What is the probability of a male or female offspring being produced in mammals?

50% chance of male, 50% chance of female. Signup and view all the answers

What is the term for the classification of an individual into a group with a shared set of anatomical and physiological traits?

Sex Signup and view all the answers

How many genes are located on the human X chromosome?

Approximately 1,100 genes. Signup and view all the answers

What is the term for the genes located on the Y chromosome?

Y-linked genes Signup and view all the answers

What percentage of genes on the human Y chromosome are expressed only in the testis?

About 50% Signup and view all the answers

What is the function of the WNT4 gene in the development of female gonads?

It promotes ovary development Signup and view all the answers

How are the Y-linked genes typically passed on from one generation to the next?

From father to son Signup and view all the answers

What is the result of an embryo having extra copies of the WNT4 gene?

It develops rudimentary female gonads Signup and view all the answers

What is the current understanding of sex determination?

It is a complex process involving multiple genes Signup and view all the answers

What is the term used to describe individuals born with anatomical features that do not match their sense of gender?

Transgender Signup and view all the answers

What is the main difference in the pattern of inheritance between autosomal genes and X-linked genes?

The number of chromosomes involved Signup and view all the answers

Why do males have a higher incidence of X-linked recessive disorders?

Because they have only one X chromosome Signup and view all the answers

What is the term used to describe the genetic makeup of a male with respect to an X-linked gene?

Hemizygous Signup and view all the answers

Who observed the pattern of inheritance of X-linked genes in Drosophila?

Morgan Signup and view all the answers

What is the condition of red-green color blindness inherited as?

An X-linked recessive trait Signup and view all the answers

Why do females need to inherit two copies of the recessive allele to express the phenotype?

Because they have two X chromosomes Signup and view all the answers

What is the typical life expectancy of an individual with Duchenne muscular dystrophy?

Early 20s Signup and view all the answers

What is the main cause of bleeding in individuals with hemophilia?

Absence of a key protein for blood clotting Signup and view all the answers

Why was Queen Victoria of England significant in the spread of hemophilia?

She was a carrier of the hemophilia allele Signup and view all the answers

What is the current treatment for individuals with hemophilia?

Intravenous injections of the missing blood-clotting protein Signup and view all the answers

What is the role of dystrophin in muscle function?

It is a key protein required for muscle strength Signup and view all the answers

What is the mode of inheritance of Duchenne muscular dystrophy?

X-linked recessive Signup and view all the answers

What is the purpose of X inactivation in female mammals?

To maintain a balance of X-linked gene expression between males and females Signup and view all the answers

What is the compact object formed by the inactivated X chromosome in each cell of a female?

Barr body Signup and view all the answers

What happens to the inactive X chromosome in the ovaries?

It is reactivated Signup and view all the answers

How is the selection of which X chromosome will form the Barr body determined?

Randomly and independently in each embryonic cell Signup and view all the answers

What is the result of X inactivation in terms of cell types in females?

Females have a mosaic of two types of cells Signup and view all the answers

What happens to the inactive X chromosome in subsequent cell divisions?

It remains inactive Signup and view all the answers

What happens in a female who is heterozygous for a sex-linked trait?

About half of her cells will express one allele, while the others will express the alternate allele. Signup and view all the answers

What is involved in the inactivation of an X chromosome?

Modification of DNA and proteins, including the attachment of methyl groups. Signup and view all the answers

What is the role of the XIST gene in X inactivation?

It becomes active only on the chromosome that will become the Barr body. Signup and view all the answers

What is the result of the interaction between the XIST RNA product and the X chromosome?

The X chromosome is inactivated. Signup and view all the answers

Why do females who are heterozygous for a recessive X-linked mutation have patches of normal skin and patches of skin lacking sweat glands?

Because they are heterozygous for the mutation and the X chromosome is inactivated. Signup and view all the answers

What is the significance of the association of the two regions, one on each X chromosome, during embryonic development?

It initiates X inactivation. Signup and view all the answers