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Questions and Answers

What chromosomal composition defines Turner syndrome?

  • XXX
  • X0 (correct)
  • XX
  • XY

What are some common physical characteristics of individuals with Turner syndrome?

  • Large jaws
  • Very tall stature
  • Broad shoulders
  • Webbed neck (correct)

Which of the following conditions is associated with Triple-X syndrome?

  • Learning difficulties (correct)
  • Infertility
  • Short stature
  • Heart defects

What is a potential benefit of early diagnosis of Turner syndrome?

<p>Growth hormone therapy (B)</p> Signup and view all the answers

What impact does Turner syndrome have on sexual development?

<p>Absence of ovulation (C)</p> Signup and view all the answers

What is a common misconception about individuals with Triple-X syndrome?

<p>They are all infertile (B)</p> Signup and view all the answers

Which of the following statements is true regarding Turner syndrome?

<p>It is associated with a risk of thyroid disease. (C)</p> Signup and view all the answers

Which feature is least likely to occur in women with Triple-X syndrome?

<p>Severe mental retardation (D)</p> Signup and view all the answers

What is the genotype associated with Klinefelter syndrome?

<p>XXY (A)</p> Signup and view all the answers

Which of the following traits is NOT commonly associated with Klinefelter syndrome?

<p>Increased testosterone production (B)</p> Signup and view all the answers

What is a common consequence of Klinefelter syndrome during childhood?

<p>Learning difficulties (B)</p> Signup and view all the answers

What is the primary characteristic of XYY syndrome?

<p>Presence of an extra Y chromosome (C)</p> Signup and view all the answers

Individuals with which syndrome may present with mosaic genotypes?

<p>Klinefelter syndrome (D)</p> Signup and view all the answers

How do the physical traits of individuals with Klinefelter syndrome typically manifest?

<p>Noticeable feminine characteristics (C)</p> Signup and view all the answers

What is the primary role of centrioles in cell division?

<p>Fixing spindle fibers (D)</p> Signup and view all the answers

What common issue do males with Klinefelter syndrome face regarding reproduction?

<p>Inability to produce viable sperm (B)</p> Signup and view all the answers

How do plant cells divide without centrioles?

<p>They use a cell plate during cytokinesis (C)</p> Signup and view all the answers

Which physical trait is typically observed in individuals with XYY syndrome?

<p>Tall height (A)</p> Signup and view all the answers

Who was the first scientist to describe cells after observing cork under a microscope?

<p>Robert Hooke (A)</p> Signup and view all the answers

Which of the following statements is true about the historical understanding of cells?

<p>Thin sections of animal cells were originally difficult to prepare. (C)</p> Signup and view all the answers

Which of the following best summarizes the significance of the discovery of the microscope in cell biology?

<p>It allowed scientists to observe cells for the first time. (D)</p> Signup and view all the answers

What did Nehemiah Grew contribute to the study of plant cells?

<p>He supported the idea that cells can transport fluids. (C)</p> Signup and view all the answers

What underpinning principle about life is suggested in the content?

<p>Cells are the basic unit of living organisms. (A)</p> Signup and view all the answers

What evolutionary concept is discussed in relation to multicellularity?

<p>Division of labor (B)</p> Signup and view all the answers

What are meiocytes primarily responsible for in sexually reproducing organisms?

<p>Formation of gametes (C)</p> Signup and view all the answers

Which of the following correctly describes the ploidy of the zygote after fertilization?

<p>It matches the ploidy of the parent cells. (B)</p> Signup and view all the answers

What occurs during prophase I of meiosis?

<p>Crossing over between homologous chromosomes takes place. (B)</p> Signup and view all the answers

How does meiosis I differ from mitosis in terms of progression after its phases?

<p>Meiosis I proceeds directly to meiosis II without interphase. (A)</p> Signup and view all the answers

During which phase of meiosis I do chromosomes align at the equator of the cell?

<p>Metaphase I (D)</p> Signup and view all the answers

What is the main function of the process known as synapsis during prophase I?

<p>To pair homologous chromosomes. (A)</p> Signup and view all the answers

Which statement is true regarding the genetic recombination in meiosis?

<p>It enhances genetic diversity through allele exchanges. (D)</p> Signup and view all the answers

What happens to the nuclear membrane during metaphase I?

<p>It disappears to allow chromosome movement. (A)</p> Signup and view all the answers

What is the primary reason for the diversity of cell shape in multicellular organisms?

<p>Different roles and functions of cells (D)</p> Signup and view all the answers

Which of the following best describes skin cells?

<p>Flat and platelike (B)</p> Signup and view all the answers

What process describes cells taking new shapes in response to their environment?

<p>Cell signaling (B)</p> Signup and view all the answers

What essential requirement do living cells need to perform their activities?

<p>Energy from nutrients (C)</p> Signup and view all the answers

In multicellular organisms, cells group together based on what criteria?

<p>Their responsibilities and functions (C)</p> Signup and view all the answers

Which of the following cell types is specialized for sending and receiving impulses?

<p>Nerve cells (A)</p> Signup and view all the answers

What is the outcome if cell processes are done inappropriately?

<p>Cells may die or become dysfunctional (A)</p> Signup and view all the answers

What term is used to describe the study of cell shape and structure?

<p>Cell morphology (D)</p> Signup and view all the answers

Who was the first scientist to observe red blood cells and sperm cells under a microscope?

<p>Antony van Leeuwenhoek (A)</p> Signup and view all the answers

What phrase did François Raspail support that is one of the main tenets of cell theory?

<p>Every cell is derived from another cell. (D)</p> Signup and view all the answers

What significant contribution did Henri Dutrochet make regarding cells?

<p>Defining cells as both structural and physiological units. (C)</p> Signup and view all the answers

What did Barthelemy Dumortier describe about cell division?

<p>It is a process of binary fission in plants. (A)</p> Signup and view all the answers

Which of the following best describes Antony van Leeuwenhoek's contribution to microbiology?

<p>He was the first to observe single-celled organisms. (A)</p> Signup and view all the answers

Who proposed that animal tissues are structured like an array of globules?

<p>Henri Milne-Edwards (B)</p> Signup and view all the answers

What was one of the notable limitations of researchers' understanding after Leeuwenhoek's discoveries?

<p>There was a lack of connection between microbial life and cellular structures. (C)</p> Signup and view all the answers

What did Leeuwenhoek mean by referring to microorganisms as 'little animalcules'?

<p>He considered them to be simple animals. (C)</p> Signup and view all the answers

Flashcards

Turner Syndrome

A genetic condition in females where they only inherit one X chromosome (XO). This leads to a number of physical and developmental challenges.

Height in Turner Syndrome

Individuals with Turner Syndrome are generally shorter than average, with an average height around 4 feet 7 inches.

Secondary Sexual Development in Turner Syndrome

Women with Turner Syndrome often experience underdeveloped secondary sexual characteristics, such as breasts and menstrual cycles.

Fertility in Turner Syndrome

Women with Turner Syndrome may have difficulty conceiving naturally due to underdeveloped ovaries.

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Health Risks in Turner Syndrome

People with Turner Syndrome may have an increased risk of certain health issues, such as thyroid disease, heart defects, and autoimmune disorders.

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Triple-X Syndrome

A genetic condition in females where they inherit three X chromosomes (XXX). This is often associated with taller stature and some learning challenges.

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Physical Characteristics of Triple-X Syndrome

Women with Triple-X Syndrome have taller stature and a slender build, often with long legs.

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Learning and Language in Triple-X Syndrome

Though less common, some women with Triple-X Syndrome may experience difficulties with learning, speech, and language development.

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What is Meiosis?

The process of cell division that results in four daughter cells, each with half the number of chromosomes as the parent cell. This ensures that gametes (sperm and eggs) have the correct number of chromosomes for sexual reproduction.

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Klinefelter Syndrome

Klinefelter syndrome is a genetic condition in which males inherit an extra X chromosome, resulting in an XXY genotype. This can lead to various physical characteristics, including tall stature, underdeveloped testes, low testosterone levels, and breast development.

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What is a Meiocyte?

A specialized diploid cell that undergoes meiosis to produce haploid gametes (sperm or egg cells).

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XYY Syndrome

XYY syndrome is a genetic condition in males characterized by the presence of an extra Y chromosome (XYY). It's often associated with increased height and sometimes mild learning difficulties but generally doesn't lead to significant health problems.

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What is Crossing Over?

The exchange of genetic material between homologous chromosomes during prophase I of meiosis. This process shuffles genes between the chromosomes, leading to genetic diversity in offspring.

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Physical Manifestations of Klinefelter Syndrome

Individuals with Klinefelter Syndrome often experience physical manifestations like tall stature, underdeveloped testes, low testosterone levels, and breast development.

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What is Meiosis I?

The first stage of meiosis, which involves the pairing up and exchange of genetic material between homologous chromosomes through crossing over.

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Hormonal Imbalance in Klinefelter Syndrome

Klinefelter Syndrome can lead to hormonal imbalances during puberty, primarily due to low testosterone levels.

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What is Prophase I?

The first phase of meiosis I, where homologous chromosomes pair up and exchange genetic material through crossing over. It's also when the chromosomes condense and become visible.

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Learning Challenges in Klinefelter Syndrome

Individuals with Klinefelter Syndrome might experience learning challenges, particularly during childhood.

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What is Metaphase I?

The second phase of meiosis I, where paired homologous chromosomes line up at the center of the cell, ready to be separated.

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Social and Mental Functioning in Klinefelter Syndrome

Despite potential physical characteristics, Klinefelter Syndrome doesn't usually affect intelligence or social functioning; individuals can lead fulfilling lives.

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What is Anaphase I?

The third phase of meiosis I, where the homologous chromosome pairs separate and move to opposite poles of the cell. This ensures that each daughter cell receives one chromosome from each pair.

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Fertility Issues in Klinefelter Syndrome

Males with Klinefelter Syndrome can experience fertility issues, though some maintain the ability to have erections and ejaculate.

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What is Telophase I?

The final phase of meiosis I, where the cytoplasm divides, resulting in two daughter cells, each containing half the number of chromosomes as the parent cell.

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Cell Diversity

Cells vary in form and function within a multicellular organism, with each type playing a role in the organism's overall survival.

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Cell Shape and Function

The shape of a cell is often related to its purpose. For example, nerve cells are long and slender to transmit signals quickly.

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Tissue Formation

Cells with similar functions group together to form tissues. Examples include muscle tissue, which allows for movement.

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Organ Formation

Several tissues working together make up an organ, which performs a specific function in the body. An example is the heart, which pumps blood.

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Organ Systems

Organ systems, comprised of several organs, perform major functions in the body. The digestive system breaks down food, while the cardiovascular system transports blood.

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Cellular Energy Requirements

Cells need energy to carry out their processes, including the synthesis of new molecules.

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Intracellular Transport

Cells must manage the movement of molecules to perform their functions, including maintaining their internal environment and communicating with other cells.

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Cell Growth and Division

Cells grow and divide to maintain the organism's structure and function. This requires proper energy production and nutrient supply.

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What are centrioles and their function in cell division?

Centrioles are small, cylindrical structures found in animal cells that play a crucial role in cell division. They are responsible for organizing microtubules into spindle fibers during mitosis and meiosis, which help separate chromosomes into daughter cells.

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How do plant cells divide without centrioles?

Plant cells lack centrioles and instead rely on microtubule-organizing centers (MTOCs) located within the cytoplasm to initiate spindle fiber formation.

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Why is "life is based on cells" a valid statement?

The cell is the fundamental unit of life. It is the smallest unit that can carry out all the processes necessary for life, such as metabolism, growth, reproduction, and response to stimuli.

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What was Robert Hooke's contribution to cell biology?

Robert Hooke's discovery of cells in 1665 marked a significant milestone in cellular biology. His observations of cork cells under a microscope revealed the basic structure of living organisms.

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How did Malpighi and Grew contribute to cellular biology?

Marcello Malpighi and Nehemiah Grew continued Hooke's work on plant cells, furthering our understanding of their structure and function. Their studies provided insights into the cellular organization of plant bodies.

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Why was the discovery of cells revolutionary?

The discovery of cells through microscopy revolutionized our understanding of living organisms. It revealed that all living things are composed of these fundamental units, leading to the development of cell theory.

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What are the key concepts of the cell theory?

The cell theory states that all living organisms are composed of one or more cells, that cells are the basic unit of structure and organization in organisms, and that all cells arise from pre-existing cells.

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Why is studying cell biology important?

Cell biology is a continuously evolving field, constantly pushing the boundaries of our knowledge about cells. Advancements in microscopy, molecular biology, and genetics continue to reveal new insights into the structure, function, and development of cells.

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What are 'little animalcules'?

These single-celled organisms, originally called "little animalcules" by Leeuwenhoek, helped to revolutionize our understanding of life.

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What does "Omnis cellula e cellula" mean?

The idea that new cells arise from pre-existing cells, forming the basis of cell theory. This groundbreaking concept challenged previous beliefs about cell generation.

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How did Milne-Edwards describe animal tissues?

Henri Milne-Edwards proposed animal tissues were made up of basic structures, similar to building blocks.

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What did Dutrochet propose about cells?

Dutrochet emphasized the crucial role of the cell as a fundamental unit in both structure and function, highlighting its central role in life processes.

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What did Dumortier discover about plant cells?

Barthelemy Dumortier described the process of binary fission in plants. This is a form of cell division where one cell splits into two identical ones.

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Why was Leeuwenhoek's work important?

Leeuwenhoek's discoveries of single-celled organisms were instrumental in advancing scientists' understanding of life on Earth. He was recognized for his pioneering work in microscopy.

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What is 'cell division'?

This refers to the process of cell division. It's a fundamental process for growth, repair, and reproduction.

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What was the 'proposition by Dutrochet'?

Dutrochet's proposition contributed significantly to cell theory. It highlighted that cells are not only building blocks but also the units of function and that all cells arise from pre-existing cells.

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Study Notes

Cell Biology - Cytoskeleton and Cell Motility

  • The cytoskeleton is a network of fibers forming the infrastructure of eukaryotic, prokaryotic, and archaean cells.
  • Cytoskeleton homologues occur in prokaryotes, but evolutionary relationships are distant, evidenced by similarity in 3D structure and function (not protein sequence alone).
  • Eukaryotic cells use a complex mesh of protein filaments and motor proteins for intracellular and extracellular movement, and to stabilize the cell.
  • Examples of extracellular movement include cell migration during embryonic development and wound healing. Intracellular movement examples include membrane vesicle transport and chromosomal movement during mitosis.

Cell Types: Microfilaments, Microtubules, Intermediate Filaments

  • Microfilaments (actin): 6nm in diameter; important for anchoring plasma membrane proteins, cell movement, and division. They consist of G-actin (globular) and F-actin (filamentous) with a fast-growing and slow-growing end.
  • Microtubules: 25nm in diameter; involved in cell shape, intracellular transport, and cell division. Composed of alpha and beta tubulin subunits forming protofilaments. Possess a plus and minus end.
  • Intermediate filaments: 10nm in diameter; provide structural integrity, linking cell surface to nucleus; composed of a variety of proteins (e.g., keratin, vimentin, neurofilament proteins, nuclear lamins). No defining polarity.

Cytoskeleton Associated Proteins

  • Actin-associated proteins (e.g., profilin, tropomyosin, filamin) modify microfilament network properties.
  • Certain molecules, like Tropomyosin, bind along microfilament length to stiffen the fibers;
  • Villin or filamin proteins connect microfilaments side-by-side forming bundles or meshwork structures.
  • Proteins that cut or cap filaments influence the length of filaments

Microtubules and Motor Proteins

  • Microtubule-associated proteins (MAPs) influence the dynamics of microtubules stabilize or cross-link them.
  • Motor proteins (kinesin and dynein) move along microtubule tracks carrying cargo (e.g., vesicles). Kinesin moves towards the plus end, and dynein towards the minus end
  • Examples, like cilia and flagella, use microtubule structures for motility.

Cellular Abnormalities

  • Cellular abnormalities result from deviations or malformations during cell division/proliferation or from gene mutations
  • Abnormalities can be at the chromosomal level or gene level, and lead to serious genetic mutations and diseases.
  • Defects in chromosomes happen (e.g., irregular number of chromosomes, modifications in chromosome structure). Nondisjunction errors are a cause of these defects.
  • Examples of chromosomal abnormalities include Down syndrome (trisomy 21), Turner syndrome (XO), Klinefelter syndrome(XXY), and Triple-X syndrome (XXX). These result in physical traits and developmental problems

Other Cellular Diseases

  • Sickle cell disease: defects in red blood cells (anemia) caused by abnormal hemoglobin proteins.
  • Alzheimer's Disease: neuron (nerve cell) dysfunction due to protein plaques and neurofibrillary tangles. These conditions frequently result from protein mutations

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