Cell Biology and Genetic Expression Quiz
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Questions and Answers

What process is necessary for the transport of protein and RNA through nuclear pores?

  • Selective, energy-requiring transport (correct)
  • Simple diffusion
  • Passive transport
  • Osmosis

    • What type of RNA is produced from the genes in the nucleus and is primarily involved in protein synthesis?

  • Ribosomal RNA (rRNA)
  • Small nuclear RNA (snRNA)
  • Transfer RNA (tRNA)
  • Messenger RNA (mRNA) (correct)

    • What effect does phosphorylation have on the protein involved in Na+ transport?

  • Phosphorylation causes the protein to change shape. (correct)
  • Phosphorylation increases Na+ concentration inside the cell.
  • Phosphorylation enhances K+ binding affinity.
  • Phosphorylation prevents Na+ from binding.

    • What is the primary function of mRNA in the context of genetic expression?

    <p>To carry the code for protein synthesis (B)</p> Signup and view all the answers

    What are nucleoli primarily involved in synthesizing?

    <p>Ribosomal RNA (rRNA) (D)</p> Signup and view all the answers

    In the Na+-Glucose symporter, what direction does Na+ flow?

    <p>Down its concentration gradient. (C)</p> Signup and view all the answers

    Which type of endocytosis involves the engulfing of large particles?

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

    How does the number of proteins produced in a cell compare to the number of genes?

    <p>More proteins are produced than there are genes. (A)</p> Signup and view all the answers

    What role do lysosomes play in the cell after phagocytosis?

    <p>They isolate and digest engulfed proteins and lipids. (B)</p> Signup and view all the answers

    What term refers to all of the proteins produced by the genome in an organism?

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

    What stage of genetic expression follows the synthesis of RNA?

    <p>Genetic translation (B)</p> Signup and view all the answers

    Which process is characterized by the selective uptake of specific ligands through receptor binding?

    <p>Receptor-mediated endocytosis (C)</p> Signup and view all the answers

    What is the initial state of a primary lysosome?

    <p>It contains digestive enzymes in an acidic environment. (D)</p> Signup and view all the answers

    Which statement about gene expression is true?

    <p>Some cells can express different genes than others. (B)</p> Signup and view all the answers

    What happens to K+ after it binds to the Na+ transport protein?

    <p>It causes Na+ to be released outside the cell. (B)</p> Signup and view all the answers

    Which type of endocytosis is known for sampling the extracellular environment through fluid intake?

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

    What are the two polypeptide chains of insulin linked by?

    <p>Disulfide bonds (B)</p> Signup and view all the answers

    What type of cell division results in gametes containing half the number of chromosomes?

    <p>Meiosis (C)</p> Signup and view all the answers

    During DNA replication, what is the role of DNA helicases?

    <p>To break the hydrogen bonds between DNA bases (D)</p> Signup and view all the answers

    How many amino acids are in the longer chain of insulin produced from proinsulin?

    <p>30 amino acids (A)</p> Signup and view all the answers

    What is produced at the end of DNA replication?

    <p>Two new double-helix DNA molecules (C)</p> Signup and view all the answers

    What type of bond forms between adenine and thymine during DNA replication?

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

    Which enzyme is responsible for joining nucleotides together to form new DNA strands?

    <p>DNA polymerase (B)</p> Signup and view all the answers

    What is the primary function of proinsulin before its conversion to insulin?

    <p>It serves as a precursor for insulin (D)</p> Signup and view all the answers

    What role do cyclin D proteins play in the cell cycle?

    <p>They activate cyclin-dependent kinases. (C)</p> Signup and view all the answers

    What is the primary mechanism by which gene silencing occurs in epigenetic inheritance?

    <p>Methylation of cytosine bases (D)</p> Signup and view all the answers

    What is the primary function of the p53 protein?

    <p>To stall cell division when DNA is damaged. (C)</p> Signup and view all the answers

    How does the process of acetylation affect gene expression?

    <p>It leads to a more relaxed chromatin structure. (A)</p> Signup and view all the answers

    What characterizes the relationship between oncogenes and proto-oncogenes?

    <p>Oncogenes are altered forms of proto-oncogenes. (A)</p> Signup and view all the answers

    What role does crossing-over play in genetic variation?

    <p>It allows for the recombination of genetic material between homologous chromosomes. (C)</p> Signup and view all the answers

    Which of the following best describes apoptosis?

    <p>Cell shrinkage with intact membranes. (B)</p> Signup and view all the answers

    Which of the following diseases is associated with problems in epigenetic inheritance?

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

    Which factors can lead to the conversion of proto-oncogenes to active oncogenes?

    <p>Genetic mutations and chromosome rearrangements. (A)</p> Signup and view all the answers

    What type of cell death is characterized by the swelling and rupture of cells?

    <p>Necrosis. (B)</p> Signup and view all the answers

    What is a consequence of reduced DNA methylation in cancers?

    <p>Activation of normally silenced genes. (C)</p> Signup and view all the answers

    What is the impact of epigenetic changes on identical twins?

    <p>They may show differences in gene expression despite having the same genetic makeup. (B)</p> Signup and view all the answers

    What triggers the intrinsic pathway of apoptosis?

    <p>DNA damage or oxidative stress. (B)</p> Signup and view all the answers

    What is a crucial function of tumor suppressor genes?

    <p>To inhibit the development of cancer. (A)</p> Signup and view all the answers

    What is the role of histone modifications in gene expression?

    <p>They influence how tightly or loosely the chromatin is compacted. (C)</p> Signup and view all the answers

    Which of the following describes gene silencing that is inherited across generations?

    <p>Epigenetic inheritance (B)</p> Signup and view all the answers

    What is a codon?

    <p>A code word for a specific amino acid (D)</p> Signup and view all the answers

    What happens to proteins after they are synthesized on ribosomes attached to the rough endoplasmic reticulum?

    <p>They are modified within the cisternae. (B)</p> Signup and view all the answers

    What role does the leader sequence play in protein synthesis for secretion?

    <p>It serves as an address to direct the protein into the ER. (A)</p> Signup and view all the answers

    Which statement about preproinsulin is true?

    <p>It enters the cisterna as a polypeptide composed of 109 amino acids. (B)</p> Signup and view all the answers

    How does the rough endoplasmic reticulum aid in the transport of proteins destined for secretion?

    <p>It provides a cavity for protein modification and packaging. (A)</p> Signup and view all the answers

    What modification happens to insulin once it is in the rough ER?

    <p>Carbohydrates are added to the protein structure. (C)</p> Signup and view all the answers

    During translation, how is the sequence of specific amino acids determined?

    <p>By the sequence of codons in the mRNA. (B)</p> Signup and view all the answers

    Which of the following best describes the function of polyribosomes?

    <p>They synthesize proteins that remain within the cell. (D)</p> Signup and view all the answers

    Flashcards

    Secondary Active Transport

    Transport of a solute across a membrane using the potential energy stored in a concentration gradient created by a primary transporter.

    Symporter

    A type of secondary active transporter that moves two solutes in the same direction.

    Na+-Glucose Symporter

    A specific example of a symporter that transports sodium and glucose together.

    Exocytosis

    Vesicular transport that moves substances out of a cell.

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    Endocytosis

    Vesicular transport that moves substances into a cell.

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    Phagocytosis

    Endocytosis of large particles, like bacteria

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    Pinocytosis

    Endocytosis of liquid or small particles in fluid.

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    Lysosome

    Membrane-bound organelles containing digestive enzymes.

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    Nuclear Pore

    A channel in the nuclear envelope that allows selective passage of molecules between the nucleus and cytoplasm.

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    mRNA

    Messenger RNA; a type of RNA that carries genetic information from DNA in the nucleus to ribosomes in the cytoplasm for protein synthesis.

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    Gene Expression

    The process by which genetic information encoded in DNA is used to produce a functional product, such as a protein.

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    Genetic Transcription

    The process of copying genetic information from DNA to RNA.

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    Genetic Translation

    The process of translating the genetic code carried by mRNA into a protein.

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    Nucleolus

    A dense region within the nucleus where ribosomal RNA (rRNA) is synthesized.

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    Genome

    The complete set of genes or genetic material present in a cell or organism.

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    Proteome

    The complete set of proteins produced by an organism or cell.

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    Codon

    A sequence of three bases (a base triplet) in mRNA that specifies a particular amino acid.

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    Translation

    The process of converting the sequence of codons in mRNA into a specific sequence of amino acids in a polypeptide chain.

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    What are polyribosomes?

    Groups of ribosomes that float freely in the cytoplasm and produce proteins that are used inside the cell.

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    Rough Endoplasmic Reticulum (RER)

    A network of membranes studded with ribosomes, involved in the synthesis and modification of proteins destined for secretion outside the cell.

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    Cisternae

    Fluid-filled spaces within the endoplasmic reticulum where proteins are modified.

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    Leader Sequence

    A short sequence of hydrophobic amino acids at the beginning of a protein destined for secretion. This sequence helps the protein enter the ER membrane.

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    Preproinsulin

    The original form of the insulin hormone containing a leader sequence.

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    Proinsulin

    The form of insulin after the leader sequence is removed from preproinsulin.

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    Oncogene

    A gene that promotes uncontrolled cell division and can lead to cancer.

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    Proto-oncogene

    A normal gene that regulates cell division and can be converted into an oncogene by mutations.

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    Tumor Suppressor Gene

    A gene that normally inhibits cell division and can prevent cancer, but mutations in this gene can lead to cancer.

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    p53

    A key tumor suppressor protein that acts as a transcription factor, controlling many genes involved in cell growth and death.

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    Apoptosis

    A programmed process of cell death that removes damaged or unwanted cells, promoting normal cell function and tissue development.

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    Necrosis

    Uncontrolled cell death caused by injury or damage, often leading to inflammation and tissue damage.

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    Extrinsic Pathway of Apoptosis

    Initiated by external signals, such as death ligands binding to death receptors.

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    Intrinsic Pathway of Apoptosis

    Triggered by internal signals, like DNA damage or oxidative stress, within the cell itself.

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    Insulin Production

    Insulin is produced by the removal of a portion of a larger polypeptide chain called proinsulin, resulting in two shorter chains linked by disulfide bonds.

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    DNA Replication

    The process of copying a DNA molecule, creating two identical copies.

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    DNA Helicase

    An enzyme that breaks the hydrogen bonds between complementary base pairs in DNA, separating the two strands.

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    Complementary Base Pairing

    The specific pairing of bases in DNA: adenine (A) with thymine (T), and guanine (G) with cytosine (C).

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    DNA Polymerase

    An enzyme that adds new nucleotides to a growing DNA strand, following the complementary base pairing rules.

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    Mitosis

    A type of cell division that produces two daughter cells, each with the same genetic information as the parent cell.

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    Gametes

    Sex cells (sperm or egg) that contain half the chromosome number of the parent cell.

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    Epigenetic Inheritance

    Changes in gene expression that are not caused by alterations in DNA sequence, but are passed on to daughter cells. This can be due to DNA methylation or histone modification.

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    DNA Methylation

    The addition of a methyl group to a cytosine base in DNA, often leading to gene silencing.

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    Histone Modification

    Changes in histone proteins, such as acetylation or methylation, affecting how tightly DNA is wound around them and influencing gene expression.

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    Gene Silencing

    The process of turning off a gene, preventing its expression.

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    Crossing Over

    The exchange of genetic material between homologous chromosomes during meiosis, leading to genetic variation in offspring.

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    Tetrad

    A pair of homologous chromosomes, each with two sister chromatids, during meiosis.

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    Recombination

    The process of creating new combinations of alleles on a chromosome as a result of crossing over.

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    Study Notes

    The Cell

    • The cell is the fundamental unit of structure and function in the body
    • Cell functions are carried out by subcellular components called organelles
    • Plasma membrane regulates communication between inside and outside the cell, and facilitates movement
    • Cells appear simple under a light microscope, but their complex physiology is evident at subcellular level

    Plasma Membrane and Associated Structures

    • Composed of a phospholipid bilayer with embedded proteins
    • Hydrophobic tails face inwards, hydrophilic heads face outwards
    • Selectively permeable, controlling substances moving in and out
    • Proteins facilitate specific transport and function as receptors, enzymes
    • Contains carbohydrates (glycoproteins/glycolipids) as markers
    • Cholesterol regulates flexibility
    • Bulk transport processes (phagocytosis, endocytosis, exocytosis) enable movement of materials across the membrane

    Cell Components and Functions

    • Plasma membrane: Forms the outer boundary of the cell, controls material passage
    • Cytoplasm: Contains organelles in a jelly-like substance (cytosol)
    • Endoplasmic reticulum(ER): Rough ER (with ribosomes) processes proteins, smooth ER modifies them.
    • Ribosomes: Synthesize proteins
    • Golgi complex: Processes and packages proteins and other materials
    • Mitochondria: Generate energy (ATP) through cellular respiration
    • Lysosomes: Contain enzymes to digest cellular materials
    • Peroxisomes: Detoxify harmful substances
    • Centrosome: Helps organize cell division
    • Vacuoles: Store substances
    • Microfilaments and microtubules: Provide structural support and movement
    • Cilia and flagella: Involved in cell movement
    • Nuclear envelope: Encloses the nucleus, has pores for material passage
    • Nucleolus: Involved in ribosome production
    • Chromatin: Contains DNA, packages genetic material

    Cytoplasm and Cytoskeleton

    • Cytoplasm is the material within a cell encompassing the cytosol and organelles.
    • The cytoskeleton includes microtubules and microfilaments providing structural support and movement.
    • Organelles like the nucleus, vesicles, and proteins use the cytoskeleton as a transport system within the cell.

    Cell Membrane and Transport

    • The membrane is selectively permeable allowing some materials to pass but not others.
    • Passive transport happens without energy expenditure. It includes diffusion (simple/facilitated).
    • Osmosis is the movement of water across a membrane from a low concentration of solute to a high one.
    • Active transport employs energy(ATP) to move materials against their concentration gradient.
    • Active transport via vesicles enables the transport of large particles like in phagocytosis, pinocytosis, and receptor-mediated endocytosis

    Cell Nucleus

    • Most cells have a single nucleus. Exceptions include skeletal muscle and mature red blood cells.
    • The nucleus is surrounded by a double membrane (nuclear envelope)
    • Nuclear pores regulate the passage of molecules in and out of the nucleus
    • Chromatin contains DNA which functions as a template for RNA and proteins

    Genome and Proteome

    • Genome refers to all genes in a cell
    • Human genome contains around 25,000 genes
    • Proteome refers to all the proteins that a genome produces
    • The number of proteins exceeds genes because one gene can code for multiple proteins in a single cell.

    RNA Synthesis

    • Genes are DNA segments containing instructions for making specific proteins
    • RNA synthesis copies genetic code from DNA to make mRNA
    • RNA molecules (mRNA, tRNA, and rRNA) are essential in protein synthesis

    Protein Synthesis and Secretion

    • mRNA plays a crucial role in translating the genetic code into amino acid sequences for protein synthesis
    • mRNA binds to ribosomes.
    • Ribosomes translate mRNA's codons into amino acid sequences.
    • Newly formed proteins undergo modifications and are sometimes dispatched from the cell

    DNA Synthesis and Cell Division

    • When a single cell replicates, each old strand serves as a template for a new strand
    • Growth, repair, and reproduction are processes involving cell cycle stages and cell division.

    Mitosis

    • Mitosis involves cell division resulting in two daughter cells with the same number of chromosomes as the original cell
    • Mitosis is the process of dividing a cell's nucleus, before cytoplasmic division
    • The stages of mitosis are prophase, metaphase, anaphase, and telophase

    Meiosis

    • Meiosis is responsible for producing gametes (sperm/ova) with half the number of chromosomes, compared to a parent cell.
    • Meiotic cell division results in four daughter cells.
    • Crossing-over during meiosis promotes genetic diversity.

    Hypertrophy and Hyperplasia

    • Cells can increase in size (hypertrophy) or number (hyperplasia)
    • Muscle growth from exercise is an example of hypertrophy.
    • Callus formation demonstrates hyperplasia

    Cell Death

    • Cell death occurs naturally (apoptosis) or pathologically (necrosis)
    • Apoptosis is a programmed cell suicide process helping the body rid itself of unneeded or damaged cells Apoptosis can be triggered by intrinsic(internal signals) or extrinsic (external factors) mechanisms

    Mitochondria

    • Found in the cells, except mature red blood cells, the main function is to produce energy (ATP)
    • Mitochondria contains their own DNA which allows them to reproduce independently.
    • Mitochondria are enveloped by two membranes, an inner and outer membranes.

    Ribosomes

    • Responsible for the production of proteins
    • Found either free in the cytoplasm or attached to the endoplasmic reticulum.
    • Ribosomes are composed of rRNA

    Endoplasmic Reticulum (ER)

    • A network of membranes extending throughout the cytoplasm
    • There is rough (with ribosomes) and smooth ER

    Golgi Complex

    • A stack of flattened, membrane-bound sacs (cisternae) for the processing and packaging of proteins.
    • Proteins move through the Golgi complex

    Lysosomes

    • Membrane-bound sacs containing digestive enzymes for the breakdown and recycling of cellular components.
    • The role of lysosomes is recycling cell components

    Clinical Applications

    • Cell cycle abnormalities can play a role in tumors
    • Stem cells can differentiate into various cell types, essential for tissue repair and development
    • A malfunctioning cell cycle can lead to diseases like cancer.
    • Apoptosis is a normal process eliminating damaged cells
    • Understanding cell division/cell death can lead to new treatments for diseases

    Epigenetic Inheritance

    • Epigenetic inheritance is the passing of traits without changing the DNA sequence
    • Changes to histone proteins and DNA methylation are examples of epigenetic mechanisms
    • Genes can be silenced or reactivated without alterations to the DNA base sequence.

    Protein Function

    • Proteins play various roles in the cell including transport, catalysis, and structural support.
    • Protein synthesis uses a genetic code translated by mRNA.

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    Description

    Test your knowledge on essential processes in cell biology, focusing on protein synthesis, RNA transport, and gene expression. Questions cover topics such as nuclear pore transport, mRNA functions, and endocytosis mechanisms. Perfect for students looking to solidify their understanding of cellular functions.

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