Molecular Biology Quiz: Genetics and Cancer

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Questions and Answers

What is the function of chromosomal mutations such as deletions and duplications?

They can lead to variation in genetic traits. (correct)

They prevent the division of cells.

They stabilize the chromosome structure.

They help in the correct pairing of chromosomes during meiosis.

Which type of chromosome has its centromere located at the middle?

Acrocentric

Metacentric (correct)

Submetacentric

Telocentric

What is achieved through the process of meiosis in humans?

Production of diploid cells.

Duplication of chromosomes.

Formation of haploid gametes. (correct)

Replication of genetic material without division.

What term describes a segment of a chromosome that has a change in direction?

Inversion Signup and view all the answers

In Mendel's laws of inheritance, what is the definition of a dominant trait?

A trait that masks the expression of a recessive trait. Signup and view all the answers

What stage during meiosis allows for genetic diversity through crossover?

Prophase 1 Signup and view all the answers

What are gametes in terms of chromosomal composition?

Haploid cells containing a single set of chromosomes. Signup and view all the answers

Which of the following best describes the advantage of sexual reproduction?

It boosts genetic diversity and adaptation to changing environments. Signup and view all the answers

What is the role of the Ames test in assessing chemical safety?

It determines the mutagenicity of a chemical. Signup and view all the answers

How do pyrimidine dimers affect DNA functionality?

They distort the DNA helix and cause errors in replication. Signup and view all the answers

What distinguishes a benign tumor from a malignant tumor?

Benign tumors do not spread throughout the body, whereas malignant tumors do. Signup and view all the answers

What role do oncogenes play in cancer development?

They mutate and promote uncontrolled cell growth. Signup and view all the answers

What is xeroderma pigmentosum caused by?

A defect in DNA repair mechanisms. Signup and view all the answers

Which statement about proto-oncogenes is true?

They can mutate to become oncogenes that promote cell growth. Signup and view all the answers

What is metastasis in the context of cancer?

It refers to the spreading of cancer cells to other parts of the body. Signup and view all the answers

Which of the following correctly describes a tumor's development in cancer?

A tumor begins as a single cell that undergoes mutations and abnormal growth. Signup and view all the answers

What occurs during anaphase in mitosis?

Connections between sister chromatids are broken. Signup and view all the answers

How does cytokinesis differ in animal and plant cells?

Animal cells constrict with a drawstring effect. Signup and view all the answers

What is formed during prophase I of meiosis?

Bivalents form through homologous pairing. Signup and view all the answers

What is the major function of crossing over during meiosis?

To promote genetic diversity. Signup and view all the answers

Which phase involves the segregation of homologs during meiosis?

Anaphase I Signup and view all the answers

What is the significance of the synaptonemal complex during meiosis?

It helps in pairing homologous chromosomes. Signup and view all the answers

What structure forms between two daughter cells during plant cell cytokinesis?

Cell plate Signup and view all the answers

What is the end result of meiosis in terms of chromosome number?

Haploid cells with 23 chromosomes. Signup and view all the answers

What is one way HIV can be transmitted?

By transfusion of HIV-infected blood Signup and view all the answers

What role do helper T cells play in the immune system?

They stimulate the activity of other immune cells Signup and view all the answers

What is a consequence of HIV destroying T cells?

Higher susceptibility to opportunistic infections Signup and view all the answers

Why is it difficult to create a vaccine for HIV?

Reverse transcriptase of HIV lacks proofreading function Signup and view all the answers

What is a characteristic of viroids?

Composed of circular RNA Signup and view all the answers

What do prions do to normal proteins?

Convert them to an abnormal form Signup and view all the answers

What are resistance plasmids (R factors) primarily used for?

To confer resistance against antibiotics Signup and view all the answers

What biological process requires the compaction of the bacterial chromosome?

Dna supercoiling Signup and view all the answers

What can be inferred about the gametes in terms of chromosome transmission during fertilization?

Each gamete transmits one set of chromosomes to the offspring. Signup and view all the answers

How does Mendel's Law of Segregation relate to meiosis?

It is based on the segregation of homologous chromosomes during meiosis. Signup and view all the answers

What distinguishes an autosomal dominant disease from an autosomal recessive disease?

Individuals with one copy of the dominant allele show disease symptoms. Signup and view all the answers

What is true about the Law of Independent Assortment?

The alignment of chromosome pairs during meiosis I is random. Signup and view all the answers

What is the role of locus in genetics?

It labels the physical location of a gene on a chromosome. Signup and view all the answers

In which inheritance pattern is Huntington disease categorized?

Autosomal dominant Signup and view all the answers

Which of the following statements about sex chromosomes is correct?

Females can sometimes be heterozygous for sex-linked traits. Signup and view all the answers

What characterizes the haplo-diploid system in bees?

Males are haploid and females are diploid. Signup and view all the answers

Study Notes

Ames Test

Detects the mutagenic potential of chemicals
Uses Salmonella typhimurium strains with a mutation preventing histidine synthesis
Detects mutations that allow the bacteria to regain the ability to synthesize histidine

DNA Repair and Xeroderma Pigmentosum

Inherited disease caused by a defect in the UV repair pathway
Individuals with XP are highly sensitive to UV radiation

Cancer

Develops from a single cell that accumulates genetic changes
Benign tumors are non-invasive and do not metastasize
Malignant tumors invade surrounding tissues and metastasize

Oncogenes and Proto-oncogenes

Oncogenes promote uncontrolled cell growth by being overactive
Proto-oncogenes are normal genes that can become oncogenes when mutated
Examples of oncogene mutations involve growth factors and receptors

Mitosis

Cell division that produces two daughter cells genetically identical to the parent cell
Includes the stages: prophase, metaphase, anaphase, telophase, and cytokinesis
Involves the separation of sister chromatids, reformation of nuclear membranes, and division of the cytoplasm

Meiosis

Cell division that produces four haploid daughter cells from a diploid parent cell
Involves two rounds of division: meiosis I and meiosis II
Includes the processes of synapsis, crossing over, and segregation of homologous chromosomes

Chromosome Identification

Chromosomes are identified based on size, centromere location, and banding patterns
Centromere location is described as metacentric, submetacentric, acrocentric, or telocentric
Banding patterns are observed under a light microscope after staining

Chromosomal Mutations

Deletions: loss of a chromosome segment
Duplications: repeated segment of chromosome
Inversions: segment is flipped in direction
Translocations: segment attaches to another chromosome

Sex Chromosomes

Sex chromosomes determine an individual's sex
X-Y system: males XY, females XX
X-O system: females XX, males X or XO
Z-W system: males ZZ, females ZW

HIV

Human immunodeficiency virus, causes AIDS
Targets and destroys helper T cells, weakening the immune system
Can be spread through sexual contact, blood transfusions, sharing of needles, and mother-to-child transmission
Reverse transcriptase lacks proofreading function, leading to rapid mutation and making vaccine development difficult

Viroids

Single-stranded circular RNA molecules infecting plant cells
Replicate in the nucleus or chloroplast
Do not encode proteins

Prions

Infectious proteins that cause neurodegenerative diseases
PrP protein in a different conformation causes disease
Prions convert other normal PrP proteins to the abnormal form
Can cause transmissible spongiform encephalopathies (TSE)

Bacterial Chromosome Compaction

Bacterial chromosomes are supercoiled to fit within the cell
Topoisomerases control the degree of supercoiling

Plasmids

Small, circular pieces of DNA independent of the bacterial chromosome
Can replicate independently and provide growth advantages
Episomes can integrate into the bacterial chromosome
Include resistance plasmids, degradative plasmids, virulence plasmids, and fertility plasmids

Bacterial Reproduction

Bacteria reproduce asexually through binary fission.
The bacterial chromosome is replicated and the cell divides into two daughter cells.
This process is rapid and allows bacteria to quickly populate a suitable environment.

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Description

Test your knowledge on key topics in molecular biology, including the Ames Test, DNA repair mechanisms, cancer biology, and the role of oncogenes. This quiz covers essential concepts related to genetics and cell division, providing insights into how genetic changes lead to diseases like cancer.