CYTOGEN U1
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Questions and Answers

What is the study of heredity and the variation of inherited characteristics called?

  • Cytogenetics
  • Genetics (correct)
  • Epigenesis
  • Preformationism

    • What is the term for the transfer of character or traits from parents to offspring?

  • Mutations
  • Variations
  • Heredity (correct)
  • Genetic Variation

    • What are the alternative forms of a gene called?

  • Alleles (correct)
  • Phenotype
  • Genotype
  • Mutations

    • What is the term for the observable features of an organism?

    <p>Phenotype</p> Signup and view all the answers

    Who proposed the theory of epigenesis in the 1600s?

    <p>William Harvey</p> Signup and view all the answers

    What is the term for the heritable change in the DNA sequence?

    <p>Mutations</p> Signup and view all the answers

    Who proposed the theory of natural selection in 1859?

    <p>Charles Darwin</p> Signup and view all the answers

    What is the term for the set of alleles for a given trait carried by an organism?

    <p>Genotype</p> Signup and view all the answers

    What is the function of the P-site in a ribosome?

    <p>Binding of peptidyl tRNA</p> Signup and view all the answers

    What is the main function of the Rough Endoplasmic Reticulum?

    <p>Manufacturing, processing, and transporting proteins for export</p> Signup and view all the answers

    What is the function of lysosomes?

    <p>Digesting macromolecules, phagocytosing microorganisms, and breaking down old organelles</p> Signup and view all the answers

    What is the function of peroxisomes?

    <p>Catabolism of long chain fatty acids</p> Signup and view all the answers

    What is the function of the Golgi apparatus?

    <p>Synthesis of carbohydrates and modification of proteins</p> Signup and view all the answers

    What is the main function of mitochondria?

    <p>Oxidative phosphorylation and lipid synthesis</p> Signup and view all the answers

    What is the function of the nucleus?

    <p>Control center of the cell, regulates all cell activities</p> Signup and view all the answers

    What is chromatin?

    <p>Complex of DNA and proteins</p> Signup and view all the answers

    What is the function of the Smooth Endoplasmic Reticulum?

    <p>Synthesis of steroids, cholesterol, and triglycerides</p> Signup and view all the answers

    What is the function of the Cytoskeleton?

    <p>Establishment and maintenance of the three-dimensional framework of the cell</p> Signup and view all the answers

    Where is the cell's genetic material, DNA, typically located?

    <p>In the nucleus</p> Signup and view all the answers

    What is the primary function of telomeres?

    <p>To protect the DNA from degradation</p> Signup and view all the answers

    Which type of chromosome has a centromere located near one end, creating a very short arm and a long arm?

    <p>Acrocentric chromosome</p> Signup and view all the answers

    What is the result of crossing over during meiosis?

    <p>An increase in genetic variability</p> Signup and view all the answers

    What is the typical chromosomal composition of a male?

    <p>XY</p> Signup and view all the answers

    What is the term for the chart used to identify an individual's chromosomal composition?

    <p>Karyotype</p> Signup and view all the answers

    What is the term for the 22 pairs of chromosomes that are not sex chromosomes?

    <p>Autosomal chromosomes</p> Signup and view all the answers

    What is the structure found only in female cells?

    <p>Barr body</p> Signup and view all the answers

    What happens to one of the two X chromosomes in female cells during early embryonic development?

    <p>It is inactivated</p> Signup and view all the answers

    What is the term for the process of reduction in the number of chromosomes from 2n to 1n?

    <p>Meiosis</p> Signup and view all the answers

    What is the function of X chromosome inactivation in females?

    <p>To ensure that females have only one functional X chromosome per cell</p> Signup and view all the answers

    In which type of cells is the Barr body often visible as a drumstick-like projection in the nucleus?

    <p>Neutrophils</p> Signup and view all the answers

    During which phase of spermatogenesis does the first meiotic division occur?

    <p>Growth phase</p> Signup and view all the answers

    What is the term for the process by which spermatids mature into spermatozoa?

    <p>Spermiogenesis</p> Signup and view all the answers

    What occurs during meiosis I in spermatogenesis?

    <p>The number of chromosomes is reduced by half</p> Signup and view all the answers

    What happens to the primary oocyte during fetal development?

    <p>It begins meiosis but is arrested in prophase I</p> Signup and view all the answers

    What is the difference between spermatogenesis and oogenesis?

    <p>Spermatogenesis occurs continuously in males, while oogenesis begins in the female fetus</p> Signup and view all the answers

    What is the term for the mature sperm cells that are capable of fertilizing an egg?

    <p>Spermatozoa</p> Signup and view all the answers

    What is the main contribution of Gregor Johann Mendel?

    <p>Understanding of how traits are inherited</p> Signup and view all the answers

    What is the diploid number of chromosomes in human cells?

    <p>46</p> Signup and view all the answers

    What is the result of meiosis in terms of the number of chromosomes?

    <p>The resulting number of chromosomes is halved</p> Signup and view all the answers

    Who coined the term 'cell'?

    <p>Robert Hook</p> Signup and view all the answers

    What is the characteristic of all cells?

    <p>They have a surrounding membrane</p> Signup and view all the answers

    What is the function of the glycocalyx?

    <p>To provide protection of cell and cell-to-cell recognition</p> Signup and view all the answers

    What is the function of membrane transport proteins?

    <p>To facilitate movement of aqueous molecules and ions across the plasmalemma</p> Signup and view all the answers

    What is the characteristic of prokaryotic cells?

    <p>They have a single chromosome</p> Signup and view all the answers

    What is the function of the cell membrane?

    <p>To control movement of substances and maintain structural integrity</p> Signup and view all the answers

    What is the composition of ribosomes?

    <p>Proteins and ribosomal RNA</p> Signup and view all the answers

    Where is the cell's genetic material, DNA, typically located?

    <p>In the nucleus</p> Signup and view all the answers

    What is the primary function of telomeres?

    <p>To protect the DNA from degradation</p> Signup and view all the answers

    What type of chromosome has a centromere located near one end, creating a very short arm and a long arm?

    <p>Acrocentric chromosome</p> Signup and view all the answers

    What is the result of crossing over during meiosis?

    <p>Recombination of genes</p> Signup and view all the answers

    What is the typical chromosomal composition of a male?

    <p>XY</p> Signup and view all the answers

    What is the term for the chart used to identify an individual's chromosomal composition?

    <p>Karyotype</p> Signup and view all the answers

    What is the term for the 22 pairs of chromosomes that are not sex chromosomes?

    <p>Autosomal chromosomes</p> Signup and view all the answers

    What is the structure found only in female cells?

    <p>Barr body</p> Signup and view all the answers

    What happens to one of the two X chromosomes in female cells during early embryonic development?

    <p>It is inactivated</p> Signup and view all the answers

    What is the term for the process of reduction in the number of chromosomes from 2n to 1n?

    <p>Meiosis</p> Signup and view all the answers

    What is the function of X chromosome inactivation in females?

    <p>To ensure that females have only one functional X chromosome per cell</p> Signup and view all the answers

    What is the structure found only in female cells?

    <p>Barr body</p> Signup and view all the answers

    During which phase of spermatogenesis does the first meiotic division occur?

    <p>Growth Phase</p> Signup and view all the answers

    What is the term for the process by which spermatids mature into spermatozoa?

    <p>Spermiogenesis</p> Signup and view all the answers

    What happens to the primary oocyte during fetal development?

    <p>It begins meiosis but is arrested in prophase I</p> Signup and view all the answers

    What is the main difference between spermatogenesis and oogenesis?

    <p>Spermatogenesis occurs in males, while oogenesis occurs in females</p> Signup and view all the answers

    What is the term for the mature sperm cells that are capable of fertilizing an egg?

    <p>Spermatozoa</p> Signup and view all the answers

    In which type of cells is the Barr body often visible as a drumstick-like projection in the nucleus?

    <p>Neutrophils</p> Signup and view all the answers

    What is the main focus of cytogenetics?

    <p>The study of the structure and function of chromosomes</p> Signup and view all the answers

    What is the source of all genetic variation?

    <p>Mutations</p> Signup and view all the answers

    What is the term for the set of characteristics inherited from parents?

    <p>Heredity</p> Signup and view all the answers

    Who proposed the theory that existing species arose by descent with modification from ancestral species?

    <p>Charles Darwin</p> Signup and view all the answers

    What is the term for the study of the development of an organism from a fertilized egg?

    <p>Epigenesis</p> Signup and view all the answers

    Who proposed the cell theory, which states that all organisms are composed of basic structural units called cells?

    <p>Matthias Schleiden</p> Signup and view all the answers

    What is the term for the observable features of an organism?

    <p>Phenotype</p> Signup and view all the answers

    What is the term for the alternative forms of a gene?

    <p>Alleles</p> Signup and view all the answers

    What is the main function of the cell membrane?

    <p>To maintain structural integrity of the cell</p> Signup and view all the answers

    Which type of cells have a nucleus?

    <p>Eukaryotic cells</p> Signup and view all the answers

    What is the result of meiosis in terms of the number of chromosomes?

    <p>The number of chromosomes is reduced by half</p> Signup and view all the answers

    What is the function of the glycocalyx?

    <p>To protect the cell and facilitate cell-to-cell recognition</p> Signup and view all the answers

    Who coined the term 'cell'?

    <p>Robert Hook</p> Signup and view all the answers

    What is the characteristic of all cells?

    <p>They have a surrounding membrane</p> Signup and view all the answers

    What is the function of membrane transport proteins?

    <p>To facilitate movement of substances across the cell membrane</p> Signup and view all the answers

    What is the characteristic of prokaryotic cells?

    <p>They lack a nucleus</p> Signup and view all the answers

    What is the composition of ribosomes?

    <p>Proteins and ribosomal RNA</p> Signup and view all the answers

    What is the main contribution of Gregor Johann Mendel?

    <p>Understanding of how traits are inherited</p> Signup and view all the answers

    What is the main function of the Golgi apparatus?

    <p>Synthesis of carbohydrates and modification of proteins</p> Signup and view all the answers

    What is the primary function of lysosomes?

    <p>Digestion of macromolecules</p> Signup and view all the answers

    Which organelle is responsible for the synthesis of proteins?

    <p>Rough Endoplasmic Reticulum</p> Signup and view all the answers

    What is the main function of peroxisomes?

    <p>Catabolism of long chain fatty acids</p> Signup and view all the answers

    What is the main function of the nucleus?

    <p>Storage and regulation of genetic material</p> Signup and view all the answers

    What is the function of the Smooth Endoplasmic Reticulum?

    <p>Sequestering calcium ions from the cytosol</p> Signup and view all the answers

    What is the function of the cytoskeleton?

    <p>Establishment and maintenance of the three-dimensional framework of the cell</p> Signup and view all the answers

    What is the main function of mitochondria?

    <p>Generation of ATP through oxidative phosphorylation</p> Signup and view all the answers

    What is chromatin?

    <p>A complex of DNA and proteins</p> Signup and view all the answers

    What is the function of the nuclear envelope?

    <p>Separation of the nucleus from the cytosol</p> Signup and view all the answers

    What is the significance of the Chromosome Theory of Inheritance in relation to meiosis?

    <p>It predicts the number of chromosomes in gametes produced by meiosis.</p> Signup and view all the answers

    What is the primary function of organelles in eukaryotic cells?

    <p>To perform specific functions for the cell</p> Signup and view all the answers

    What is the difference between the cell membrane and the glycocalyx?

    <p>The glycocalyx is a component of the cell membrane.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of prokaryotic cells?

    <p>They have a cell wall composed of cellulose.</p> Signup and view all the answers

    What is the primary function of channel proteins in the cell membrane?

    <p>To facilitate the movement of molecules across the membrane</p> Signup and view all the answers

    What is the significance of the Cell Theory in understanding the structure and function of living organisms?

    <p>It establishes the cell as the fundamental unit of life.</p> Signup and view all the answers

    What is the primary function of the phospholipid bilayer in the cell membrane?

    <p>To provide structural integrity to the cell</p> Signup and view all the answers

    What is the significance of the discovery of cells by Robert Hook?

    <p>It coined the term 'cell'.</p> Signup and view all the answers

    What is the primary function of ribosomes in eukaryotic cells?

    <p>To synthesize proteins</p> Signup and view all the answers

    What is the significance of meiosis in relation to genetic variation?

    <p>It increases genetic variation through crossing over.</p> Signup and view all the answers

    What is the primary function of the centromere in a chromosome?

    <p>To join the two chromatids together</p> Signup and view all the answers

    What is the term for the process of reducing the number of chromosomes from 2n to 1n during meiosis?

    <p>Gametogenesis</p> Signup and view all the answers

    What is the characteristic of heterochromatin DNA?

    <p>It is generally not very active and compact during interphase</p> Signup and view all the answers

    What is the term for the chart used to identify an individual's chromosomal composition?

    <p>Karyotype</p> Signup and view all the answers

    What is the result of X chromosome inactivation in females?

    <p>One X chromosome becomes inactivated and forms a Barr body</p> Signup and view all the answers

    What type of chromosome has a centromere located in the middle, resulting in arms of equal length?

    <p>Metacentric chromosome</p> Signup and view all the answers

    What is the function of telomeres?

    <p>To protect the DNA from degradation</p> Signup and view all the answers

    What is the term for the 22 pairs of chromosomes that are not sex chromosomes?

    <p>Autosomal chromosomes</p> Signup and view all the answers

    What is the result of meiosis in terms of the number of chromosomes?

    <p>The number of chromosomes is reduced by half</p> Signup and view all the answers

    What is the structure found only in female cells?

    <p>Barr body</p> Signup and view all the answers

    What is the main difference between preformationism and epigenesis?

    <p>Preformationism proposes that the fertilized egg contains a complete miniature adult, whereas epigenesis proposes that an organism develops from the fertilized egg by a succession of developmental events.</p> Signup and view all the answers

    What is the primary source of genetic variation?

    <p>Mutations</p> Signup and view all the answers

    Which scientist proposed the theory that populations tend to produce more offspring than the environment can support, leading to a struggle for survival among individuals?

    <p>Alfred Russell Wallace</p> Signup and view all the answers

    What is the term for the study of the structure and function of the cell, especially the chromosomes?

    <p>Cytogenetics</p> Signup and view all the answers

    What is the term for the set of characteristics inherited from parents found on chromosomes and containing DNA?

    <p>Genes</p> Signup and view all the answers

    Which scientist proposed the theory of natural selection, which states that existing species arose by descent with modification from ancestral species?

    <p>Charles Darwin</p> Signup and view all the answers

    What is the term for the heritable change in the DNA sequence?

    <p>Mutations</p> Signup and view all the answers

    What is the branch of genetics that is concerned with the study of heredity and the variation of inherited characteristics?

    <p>Genetics</p> Signup and view all the answers

    What is the primary function of the nuclear envelope?

    <p>To regulate the movement of molecules into and out of the nucleus</p> Signup and view all the answers

    What is the main function of the intermediate filaments in the cytoskeleton?

    <p>To establish and maintain the three-dimensional framework of the cell</p> Signup and view all the answers

    What is the function of the nucleolus in the nucleus?

    <p>To synthesize and assemble ribosomal units</p> Signup and view all the answers

    What is the primary function of the peroxisomes?

    <p>To break down fatty acids and amino acids</p> Signup and view all the answers

    What is the main function of the smooth endoplasmic reticulum?

    <p>To detoxify toxic substances</p> Signup and view all the answers

    What is the function of the Golgi apparatus in protein synthesis?

    <p>To modify and sort proteins for export</p> Signup and view all the answers

    What is the function of the lysosomes in the cell?

    <p>To break down and recycle cellular waste and foreign substances</p> Signup and view all the answers

    What is the function of the chromatin in the nucleus?

    <p>To store genetic material in a compact form</p> Signup and view all the answers

    What is the primary function of the mitochondria in the cell?

    <p>To generate energy for the cell through oxidative phosphorylation</p> Signup and view all the answers

    What is the function of the nuclear lamina in the nucleus?

    <p>To stabilize the nuclear envelope</p> Signup and view all the answers

    What is the primary function of X chromosome inactivation in females?

    <p>To ensure that females have only one functional X chromosome per cell</p> Signup and view all the answers

    During which phase of oogenesis does the primary oocyte complete meiosis I?

    <p>Prior to ovulation</p> Signup and view all the answers

    What is the result of meiosis I in spermatogenesis?

    <p>The formation of two secondary spermatocytes with half the number of chromosomes</p> Signup and view all the answers

    What is the main difference between spermatogenesis and oogenesis?

    <p>The timing of meiosis in relation to fertilization</p> Signup and view all the answers

    What is the function of spermiogenesis?

    <p>The process by which spermatids mature into spermatozoa</p> Signup and view all the answers

    In which type of cells is the Barr body often visible as a drumstick-like projection in the nucleus?

    <p>Neutrophils</p> Signup and view all the answers

    What is the result of meiosis in terms of the number of chromosomes?

    <p>A decrease in the number of chromosomes from 2n to 1n</p> Signup and view all the answers

    What is the term for the process of reduction in the number of chromosomes from 2n to 1n?

    <p>Meiosis</p> Signup and view all the answers

    Study Notes

    Genetics

    • Genetics is the study of heredity and variation of inherited characteristics.
    • Cytogenetics is a branch of genetics that studies the structure and function of cells, especially chromosomes.
    • Genes are sets of characteristics inherited from parents found on chromosomes and contain DNA.
    • Heredity is the transfer of character or traits from parents to offspring.
    • Variations refer to the similarities and differences between the character or traits among individuals of the same species.
    • Genetic variation occurs due to mutations, which are any heritable change in the DNA sequence.
    • Alleles are alternative forms of a gene, and genotype refers to the set of alleles for a given trait carried by an organism.
    • Phenotype refers to the observable features of an organism.

    Early History of Genetics

    • Aristotle (350 B.C.) proposed the concept of "humors."
    • William Harvey (1600s) proposed epigenesis, which states that an organism develops from a fertilized egg through a series of developmental events.
    • Preformationism, another concept, proposes that a fertilized egg contains a complete miniature adult called a homunculus.
    • Matthias Schleiden and Theodore Schwann (1830) proposed the cell theory, which states that all organisms are composed of basic structural units called cells.
    • Louis Pasteur (1830) proposed that living organisms are derived from pre-existing organisms and consist of cells.
    • Charles Darwin (1859) proposed the theory of natural selection, which states that existing species arose by descent with modification from ancestral species.
    • Alfred Russel Wallace and Gregor Johann Mendel (1866) contributed to the development of modern genetics.

    The Chromosome Theory of Inheritance

    • In most eukaryotes, each species has a characteristic number of chromosomes called the diploid number (2n).
    • Homologous chromosomes exist in pairs in diploid cells.
    • Mitosis is the process by which chromosomes are copied and distributed so that each daughter cell receives a diploid set of chromosomes.
    • Meiosis is the process by which cells produced by meiosis receive only one chromosome from each pair, resulting in a haploid number (n) of chromosomes.

    Implications of Genetics

    • Genetics helps in understanding the causation of diseases.
    • Genetics helps in understanding normal variation between individuals.
    • Genetics has led to possible means of prevention of genetic disorders through genetic counseling and antenatal diagnosis.
    • Genetics serves to solve legal problems, such as disputed parentage.

    Cells

    • The discovery of cells is attributed to Robert Hooke, who observed cork cells in 1665.
    • The cell theory was proposed by Theodor Schwann and Matthias Schleiden in 1839, and later added to by Rudolf Virchow in 1858.
    • The principles of cell theory include:
      • All living things are made of cells.
      • The smallest living unit of structure and function of all organisms is the cell.
      • All cells arise from preexisting cells.
    • Characteristics of all cells include:
      • A surrounding membrane
      • Containing protoplasm
      • Organelles (structures for cell function)
      • A control center with DNA

    Cell Types

    • Prokaryotic cells lack a nucleus and membrane-enclosed organelles.
    • Eukaryotic cells have a nucleus and membrane-enclosed organelles.
    • Organelles perform specific functions for the cell, such as protein synthesis, energy production, and waste management.

    Cell Membrane

    • The cell membrane, also known as the plasmalemma, is a selective permeable barrier between the cytoplasm and external milieu.
    • The cell membrane has various functions, including:
      • Maintaining structural integrity of the cell
      • Controlling movement of substances
      • Regulating cell-to-cell interactions
      • Establishing transport systems
      • Transducing extracellular physical and chemical signals into intracellular events
    • The cell membrane is composed of a phospholipid bilayer with integral and peripheral proteins.

    Organelles

    • Ribosomes are small particles composed of proteins and ribosomal RNA that function in protein synthesis.
    • Endoplasmic reticulum (ER) is a largest membranous system of the cell that participates in protein synthesis, lipid synthesis, and detoxification.
    • Golgi apparatus is a complex of flattened, membrane-bound sacs that function in protein modification and sorting.
    • Lysosomes are membrane-bound sacs that contain hydrolytic enzymes and aid in digesting macromolecules, phagocytosing microorganisms, and cell debris.
    • Peroxisomes are small, membrane-bound organelles that contain oxidative enzymes and participate in the catabolism of long-chain fatty acids.

    Chromosomes

    • Chromatin is a complex of DNA and proteins that represents the relaxed, uncoiled chromosomes of the interphase nucleus.
    • DNA is the cell's genetic material that resides in the nucleus in the form of chromosomes, which are clearly visible during cell division.
    • Heterochromatin is DNA that is generally not very active, while euchromatin is generally more active.
    • Satellite DNA is a type of heterochromatin that consists of long stretches of repeat sequences.

    Chromosome Structure

    • A chromosome consists of two chromatids, which are identical copies of DNA.
    • The centromere is the central region where the two chromatids are joined together.
    • Telomeres are the ends of the chromosome that protect the DNA from degradation.
    • Chromosomes can be classified into four types based on the position of the centromere: telocentric, acrocentric, sub-metacentric, and metacentric.

    Cell Division

    • Meiosis is a crucial process in reproduction that reduces the number of chromosomes from 2n to 1n, ensuring genetic variability and diversity of the gene pool.

    Reproduction

    • Chromosomes come in pairs, with one of each type of chromosome taken from each parent.
    • The inheritance of gender is determined by the X and Y chromosomes.
    • A karyotype is a chart used to identify the chromosomal composition of an individual and detect chromosomal abnormalities.

    Barr Body

    • The Barr body is a feature seen only in female cells that have two X chromosomes, one of which gets inactivated.
    • X chromosome inactivation is a process that ensures females, like males, have only one functional X chromosome per cell.

    Genetics

    • Genetics is the study of heredity and variation of inherited characteristics.
    • Cytogenetics is a branch of genetics that studies the structure and function of cells, especially chromosomes.
    • Genes are sets of characteristics inherited from parents found on chromosomes and contain DNA.
    • Heredity is the transfer of character or traits from parents to offspring.
    • Variations refer to the similarities and differences between the character or traits among individuals of the same species.
    • Genetic variation occurs due to mutations, which are any heritable change in the DNA sequence.
    • Alleles are alternative forms of a gene, and genotype refers to the set of alleles for a given trait carried by an organism.
    • Phenotype refers to the observable features of an organism.

    Early History of Genetics

    • Aristotle (350 B.C.) proposed the concept of "humors."
    • William Harvey (1600s) proposed epigenesis, which states that an organism develops from a fertilized egg through a series of developmental events.
    • Preformationism, another concept, proposes that a fertilized egg contains a complete miniature adult called a homunculus.
    • Matthias Schleiden and Theodore Schwann (1830) proposed the cell theory, which states that all organisms are composed of basic structural units called cells.
    • Louis Pasteur (1830) proposed that living organisms are derived from pre-existing organisms and consist of cells.
    • Charles Darwin (1859) proposed the theory of natural selection, which states that existing species arose by descent with modification from ancestral species.
    • Alfred Russel Wallace and Gregor Johann Mendel (1866) contributed to the development of modern genetics.

    The Chromosome Theory of Inheritance

    • In most eukaryotes, each species has a characteristic number of chromosomes called the diploid number (2n).
    • Homologous chromosomes exist in pairs in diploid cells.
    • Mitosis is the process by which chromosomes are copied and distributed so that each daughter cell receives a diploid set of chromosomes.
    • Meiosis is the process by which cells produced by meiosis receive only one chromosome from each pair, resulting in a haploid number (n) of chromosomes.

    Implications of Genetics

    • Genetics helps in understanding the causation of diseases.
    • Genetics helps in understanding normal variation between individuals.
    • Genetics has led to possible means of prevention of genetic disorders through genetic counseling and antenatal diagnosis.
    • Genetics serves to solve legal problems, such as disputed parentage.

    Cells

    • The discovery of cells is attributed to Robert Hooke, who observed cork cells in 1665.
    • The cell theory was proposed by Theodor Schwann and Matthias Schleiden in 1839, and later added to by Rudolf Virchow in 1858.
    • The principles of cell theory include:
      • All living things are made of cells.
      • The smallest living unit of structure and function of all organisms is the cell.
      • All cells arise from preexisting cells.
    • Characteristics of all cells include:
      • A surrounding membrane
      • Containing protoplasm
      • Organelles (structures for cell function)
      • A control center with DNA

    Cell Types

    • Prokaryotic cells lack a nucleus and membrane-enclosed organelles.
    • Eukaryotic cells have a nucleus and membrane-enclosed organelles.
    • Organelles perform specific functions for the cell, such as protein synthesis, energy production, and waste management.

    Cell Membrane

    • The cell membrane, also known as the plasmalemma, is a selective permeable barrier between the cytoplasm and external milieu.
    • The cell membrane has various functions, including:
      • Maintaining structural integrity of the cell
      • Controlling movement of substances
      • Regulating cell-to-cell interactions
      • Establishing transport systems
      • Transducing extracellular physical and chemical signals into intracellular events
    • The cell membrane is composed of a phospholipid bilayer with integral and peripheral proteins.

    Organelles

    • Ribosomes are small particles composed of proteins and ribosomal RNA that function in protein synthesis.
    • Endoplasmic reticulum (ER) is a largest membranous system of the cell that participates in protein synthesis, lipid synthesis, and detoxification.
    • Golgi apparatus is a complex of flattened, membrane-bound sacs that function in protein modification and sorting.
    • Lysosomes are membrane-bound sacs that contain hydrolytic enzymes and aid in digesting macromolecules, phagocytosing microorganisms, and cell debris.
    • Peroxisomes are small, membrane-bound organelles that contain oxidative enzymes and participate in the catabolism of long-chain fatty acids.

    Chromosomes

    • Chromatin is a complex of DNA and proteins that represents the relaxed, uncoiled chromosomes of the interphase nucleus.
    • DNA is the cell's genetic material that resides in the nucleus in the form of chromosomes, which are clearly visible during cell division.
    • Heterochromatin is DNA that is generally not very active, while euchromatin is generally more active.
    • Satellite DNA is a type of heterochromatin that consists of long stretches of repeat sequences.

    Chromosome Structure

    • A chromosome consists of two chromatids, which are identical copies of DNA.
    • The centromere is the central region where the two chromatids are joined together.
    • Telomeres are the ends of the chromosome that protect the DNA from degradation.
    • Chromosomes can be classified into four types based on the position of the centromere: telocentric, acrocentric, sub-metacentric, and metacentric.

    Cell Division

    • Meiosis is a crucial process in reproduction that reduces the number of chromosomes from 2n to 1n, ensuring genetic variability and diversity of the gene pool.

    Reproduction

    • Chromosomes come in pairs, with one of each type of chromosome taken from each parent.
    • The inheritance of gender is determined by the X and Y chromosomes.
    • A karyotype is a chart used to identify the chromosomal composition of an individual and detect chromosomal abnormalities.

    Barr Body

    • The Barr body is a feature seen only in female cells that have two X chromosomes, one of which gets inactivated.
    • X chromosome inactivation is a process that ensures females, like males, have only one functional X chromosome per cell.

    Genetics

    • The study of heredity and variation of inherited characteristics
    • Cytogenetics: concerned with the study of the structure and function of cells, especially chromosomes
    • Key concepts:
      • Genes: sets of characteristics inherited from parents found on chromosomes and contain DNA
      • Heredity: the transfer of characteristics or traits from parents to offspring
      • Variations: similarities and differences between characteristics or traits among individuals of the same species
      • Genetic variation: differences in the DNA sequence of individuals
    • Early history of genetics:
      • Aristotle (350 B.C.): concept of "humors"
      • William Harvey (1600s): epigenesis (development from fertilized egg)
      • Matthias Schleiden and Theodore Schwann (1830): cell theory
      • Louis Pasteur (1859): living organisms derived from pre-existing organisms
      • Charles Darwin (1859): theory of natural selection
      • Alfred Russell Wallace (1859): natural selection based on observation of population growth
      • Gregor Johann Mendel (1866): traits passed from generation to generation in pea plants

    The Chromosome Theory of Inheritance

    • Each species has a characteristic number of chromosomes (diploid number)
    • Homologous chromosomes: chromosomes in diploid cells exist in pairs
    • Mitosis: chromosomes are copied and distributed to each daughter cell
    • Meiosis: cells produced by meiosis receive only one chromosome from each pair, resulting in haploid number of chromosomes
    • Implications of genetics:
      • Understanding of disease causation
      • Understanding of normal variation between individuals
      • Possible means of prevention of genetic disorders through genetic counseling and antenatal diagnosis
      • Solving legal problems involving disputed parentage

    Cells

    • Discovery of cells: Robert Hooke (1632)
    • Cell theory:
      • All living things are made of cells
      • The smallest living unit of structure and function of all organisms is the cell
      • All cells arise from pre-existing cells
    • Characteristics of all cells:
      • Surrounding membrane
      • Contains protoplasm
      • Organelles
      • Control center with DNA
    • Types of cells:
      • Prokaryotic cells: no nucleus, no membrane-bound organelles
      • Eukaryotic cells: nucleus, membrane-bound organelles

    Organelles

    • Cell components that perform specific functions
    • Key organelles:
      • Cell membrane (plasmalemma): selective permeable barrier between cytoplasm and external environment
      • Glycocalyx: carbohydrate chain that coats cell surface
      • Ribosomes: small particles composed of proteins and ribosomal RNA, involved in protein synthesis
      • Endoplasmic reticulum: largest membranous system of the cell, involved in protein synthesis and transport
      • Golgi apparatus: composed of flattened, slightly curved membrane-bound cisternae, involved in protein modification and sorting
      • Lysosomes: contain hydrolytic enzymes, aid in digesting macromolecules and recycling cellular waste
      • Peroxisomes: contain oxidative enzymes, involved in oxidizing fatty acids and amino acids
      • Mitochondria: involved in oxidative phosphorylation and lipid synthesis
      • Cytoskeleton: composed of thin filaments, intermediate filaments, and microtubules, provides structural support and shape to the cell
      • Nucleus: control center of the cell, contains DNA, involved in RNA synthesis and protein synthesis

    Chromosomes

    • Chromatin: complex of DNA and proteins, represents the relaxed, uncoiled chromosomes of the interphase nucleus
    • DNA: the cell's genetic material, resides in the nucleus in the form of chromosomes
    • Heterochromatin vs euchromatin:
      • Heterochromatin: generally not very active, compact during interphase
      • Euchromatin: generally more active, not condensed during interphase
    • Chromosome structure:
      • Chromosome arms: short arm and long arm
      • Centromere: central region where the two chromatids are joined together
      • Chromatid: each chromosome consists of two identical copies of DNA
      • Telomere: ends of the chromosome, protect the DNA from degradation
    • Classification of chromosomes:
      • Telocentric chromosome: centromere located at the very end of the chromosome
      • Acrocentric chromosome: centromere located near one end, creating a very short arm (p arm) and a long arm (q arm)
      • Sub-metacentric chromosome: centromere located slightly off-center, resulting in one arm being somewhat shorter than the other
      • Metacentric chromosome: centromere located in the middle, resulting in arms of equal length

    Cell Division

    • Crucial results in meiosis:
      • Reduction in the number of chromosomes from 2n to 1n
      • Recombination of genes, ensuring genetic variability and diversity of the gene pool

    Reproduction

    • Chromosomes and reproduction:
      • Chromosomes come in pairs, one of the pair is maternal and the other is paternal
      • When parents make sex cells, the number of chromosomes must be halved
      • One of each type of chromosome is taken
    • Inheritance of gender:
      • Mother is XX
      • Father is XY
    • Karyotype:
      • Chart used to identify the chromosomal composition of an individual and to detect chromosomal abnormalities
      • Consists of 22 pairs of autosomal chromosomes (numbered 1 to 22) and one pair of sex chromosomes (labeled X and Y)

    Barr Body

    • Only structure found only in females:
      • Barr body: an inactivated X chromosome found in female cells
    • X chromosome inactivation:
      • One of the two X chromosomes is randomly inactivated during early embryonic development
      • Inactivated X chromosome becomes the Barr body
    • Occurrence: seen in cells with two X chromosomes (females), not in cells with one X and one Y chromosome (males)
    • Appearance: visible as a dense, dark spot in the nucleus, often drumstick-like in certain cell types
    • Function: X chromosome inactivation is a process to ensure that females, like males, have only one functional X chromosome per cell

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    This quiz covers the study of heredity and variation of inherited characteristics, including cytogenetics and the structure and function of chromosomes and genes. It also explores heredity, the transfer of characteristics from parents to offspring.

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