Biology Mendel's Law of Segregation

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Questions and Answers

What is the physical basis of the law of segregation?

Homologous chromosomes separate into different daughter cells in anaphase I of meiosis. (correct)

Chromosome segments pair up and cross over during prophase of meiosis.

Nonhomologous chromosomes assort independently of each other during anaphase I of meiosis.

Duplicated chromosomes align at the metaphase plate during mitosis.

What is the physical basis for the law of independent assortment?

Alleles that are located in close proximity to each other on a chromosome are inherited together.

Alleles on nonhomologous chromosomes separate randomly into gametes during meiosis. (correct)

Homologous chromosomes separate into different daughter cells in anaphase I of meiosis.

Alleles on duplicated chromosomes separate and move to opposite poles during anaphase of mitosis.

What determines an individual's sex in humans?

Eggs that have been fertilized develop into females, whereas unfertilized eggs develop into males.

Males have two of the same sex chromosomes, whereas females have two different sex chromosomes.

High temperature during fetal development produces males, whereas lower temperatures produce females.

The two sex chromosomes in females are alike, whereas the two sex chromosomes in males are different. (correct)

Why do tortoiseshell coats occur primarily in female cats?

Females have two X chromosomes, one of which is randomly inactivated in each cell, so individual cells express different alleles. Signup and view all the answers

Which is the definition of a sex-linked trait?

A trait that is coded by a gene located on a sex chromosome. Signup and view all the answers

Which statements describe the differences between how the trait for red-green color blindness is expressed in males and females? (multiple answers)

Males are more likely to express the trait than females. Signup and view all the answers

Why are linked genes often inherited together?

Linked genes are close together on the same chromosome. Signup and view all the answers

What information about recombination frequencies enables scientists to create linkage maps?

The recombination frequency is proportional to the distance between the two genes. Signup and view all the answers

Which term describes the addition of genetic material to a chromosome through extra replication of a chromosomal section?

Duplication Signup and view all the answers

Which term describes the process of sister chromatids not separating at the centromere during cell division?

Nondisjunction Signup and view all the answers

Which term describes the rearranging of genetic material between nonhomologous chromosomes without a net loss or gain of genetic material?

Translocation Signup and view all the answers

Which term describes a mutation where a chromosome breaks, and its genetic material is reinserted in a different orientation?

Inversion Signup and view all the answers

Classify each description as a characteristic of nondisjunction in meiosis I or nondisjunction in meiosis II.

Meiosis I = Affects all of the resulting daughter cells Meiosis II = Results in two abnormal cells Signup and view all the answers

What did Erwin Chargaff discover about the base pair composition of DNA?

DNA molecules contain similar numbers of A and T bases and similar numbers of G and C bases. Signup and view all the answers

What contribution did James Watson and Francis Crick make to our understanding of DNA?

They modeled the structure of DNA based on the limited data available. Signup and view all the answers

What intermolecular force is responsible for holding the two strands of a DNA double helix together?

Hydrogen bond Signup and view all the answers

Identify the statements that describe the structure of DNA. (multiple answers)

The five-carbon sugar of DNA is called deoxyribose. Signup and view all the answers

How does the structure of DNA encode genetic information?

The sequence of bases Signup and view all the answers

What is the key feature of DNA that allows it to be copied?

Complementary base pairing Signup and view all the answers

Since DNA is replicated semiconservatively, what does each new daughter cell receive from the parent cell after replication and mitosis?

One of the original strands and one new strand Signup and view all the answers

Which enzyme joins fragments of DNA into a continuous strand?

Ligase Signup and view all the answers

Arrange the steps of DNA replication in the order that they occur.

1 = Helicase unwinds the DNA double helix 2 = Single-stranded DNA-binding proteins bind to each template strand 3 = RNA primers are added 4 = DNA polymerase synthesizes DNA 5 = RNA primers are removed 6 = DNA ligase joins DNA fragments together Signup and view all the answers

What are the components of eukaryotic chromosomes? (multiple answers)

Protein Signup and view all the answers

Which statement describes the central dogma of biology?

DNA is transcribed into RNA. RNA is translated into an amino acid sequence. Signup and view all the answers

What RNA sequence is produced during transcription of the given DNA sequence: 3′ CGTAACTAG 5′?

GCAUUGAUC Signup and view all the answers

Arrange the steps of DNA transcription in the order in which they occur.

1 = The RNA polymerase attaches to the DNA strand upstream from a gene 2 = RNA polymerase pairs RNA bases with the DNA bases on the template strand 3 = RNA polymerase releases the RNA strand, and they both leave the DNA strand Signup and view all the answers

What is an exon?

Coding portion of a DNA sequence that is present in mature mRNA. Signup and view all the answers

What is an intron?

Noncoding portion of a DNA sequence that is removed from pre-mRNA. Signup and view all the answers

What is a poly-A tail?

Sequence of adenine nucleotides added to pre-mRNA during RNA processing. Signup and view all the answers

Which statements are true about the RNA editing process after transcription? (multiple answers)

Introns are removed and coding segments are joined. Signup and view all the answers

What statement describes RNA splicing?

Noncoding introns are edited out and removed. Signup and view all the answers

Place the events that take place during translation and protein synthesis in the correct order.

1 = The smaller subunit of the ribosome attaches to the mRNA strand and moves along it 2 = A codon on the mRNA strand binds with the complementary anticodon on a tRNA molecule carrying an amino acid 3 = The ribosome adds a new amino acid to the growing polypeptide 4 = The tRNA molecules that have contributed amino acids to the protein chain leave the ribosome Signup and view all the answers

Classify each feature as describing either transcription or translation.

Transcription = Produces mRNA Translation = Requires tRNA Signup and view all the answers

How do stop codons on mRNA function to end protein synthesis?

Protein synthesis ends at a stop codon because the stop codon does not code for an amino acid, so no new amino acid is added to the polypeptide chain. Signup and view all the answers

Study Notes

Mendel's Laws of Inheritance

The law of segregation states that homologous chromosomes separate into different daughter cells during anaphase I of meiosis.
The law of independent assortment explains that alleles on nonhomologous chromosomes segregate randomly into gametes during meiosis.

Sex Determination in Humans

Females possess two identical sex chromosomes (XX), while males have two different sex chromosomes (XY).
Fertilized eggs typically develop into females, whereas unfertilized ones develop into males.

Tortoiseshell Cats

Tortoiseshell coloring is primarily found in females due to two X chromosomes, allowing random X inactivation in cells, leading to different allele expression.

Sex-Linked Traits

A sex-linked trait is defined as a trait coded by genes located on sex chromosomes.
Red-green color blindness is an X-linked recessive trait; males are more likely to express it than females, who can be carriers.

Genetic Linkage and Recombination

Linked genes are found close together on the same chromosome, which often leads to them being inherited together.
Recombination frequency is a measure of genetic distance between genes; a higher frequency means greater physical distance.

Errors in Meiosis

Duplications occur through the addition of genetic material to a chromosome due to extra replication.
Nondisjunction refers to sister chromatids failing to separate during cell division.

Errors during Chromosome Replication

Translocations involve the rearranging of genetic material between nonhomologous chromosomes without loss or gain of material.
Inversions occur when a chromosome breaks and the genetic material reattaches in a different orientation.

Chargaff's Rules

The proportions of A (adenine) to T (thymine) and G (guanine) to C (cytosine) bases are consistent within a species, varying across different species.
DNA molecules consistently show equal numbers of A and T, and G and C bases.

Watson and Crick's Contribution

They modeled the double helix structure of DNA, integrating various structural data and understanding the role of DNA as the genetic code.

Structure of DNA

The DNA double helix comprises anti-parallel sugar-phosphate backbones with base pairing through hydrogen bonds.
Adenine pairs with thymine, while guanine pairs with cytosine.

DNA Replication

DNA replication is semiconservative; each daughter strand receives one original and one new strand.
Ligase enzyme facilitates the joining of DNA fragments to create continuous strands.

Transcription and Translated Processes

The central dogma of molecular biology describes the flow of genetic information: DNA is transcribed into RNA, which is then translated into proteins.

RNA Processing

Exons are coding sections retained in mature mRNA, whereas introns are noncoding segments removed.
A poly-A tail consists of adenine nucleotides added to mRNA during processing, enhancing stability and translation efficiency.

Translation Process

Translation involves several steps: the ribosome attaches to mRNA, tRNA molecules bring in amino acids, and the polypeptide chain elongates until a stop codon is reached, halting protein synthesis.

Key Features of Transcription and Translation

Transcription occurs in the nucleus, producing mRNA, whereas translation takes place in ribosomes and requires tRNA to synthesize proteins.
Stop codons signal the end of translation by not coding for an amino acid, resulting in the release of the polypeptide chain from the ribosome.

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Description

This quiz explores Mendel's law of segregation and its physical basis in heredity. It covers key concepts such as chromosomes, alleles, and the processes of mitosis and meiosis. Test your understanding of genetic inheritance and cell division.