Plant Cells and Biological Membranes
20 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to Lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the overall thickness of the plasma membrane as shown in the electron micrograph?

  • 12 nm
  • 8 nm (correct)
  • 5 nm
  • 10 nm

    • Which of the following is a characteristic of phosphatidylcholine?

  • It has myristic acid as a primary fatty acid
  • It is a fatty acid-anchored protein
  • It contains a glucosamine component
  • It is a type of glycerolipid (correct)

    • Which component is part of a glycosylphosphatidylinositol (GPI)-anchored protein structure?

  • Inositol (correct)
  • Galactose
  • Cystine
  • Palmitic acid

    • Which fatty acid is associated with glycosylphosphatidylinositol (GPI)-anchored proteins?

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

    Which type of protein is linked to the membrane through a prenyl group?

    <p>Prenyl lipid-anchored proteins (A)</p> Signup and view all the answers

    What is the primary function of nucleosomes in the packaging of DNA?

    <p>Coiling DNA around protein complexes (B)</p> Signup and view all the answers

    Which type of chromatin is characterized as being transcriptionally inactive?

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

    What percentage of the DNA in the nucleus is typically composed of heterochromatin?

    <p>10% (D)</p> Signup and view all the answers

    During mitosis, how does chromatin condense?

    <p>By forming a 30 nm chromatin fiber (D)</p> Signup and view all the answers

    What characterizes euchromatin within a cell?

    <p>It is dispersed and transcriptionally active (D)</p> Signup and view all the answers

    What is the primary function of peripheral proteins in a cell membrane?

    <p>To facilitate interactions with the cytoskeleton (C)</p> Signup and view all the answers

    Which component of phospholipids is variable and can influence its functions?

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

    What distinguishes anchored proteins from peripheral proteins?

    <p>Anchored proteins are bound to the membrane via covalent bonds (D)</p> Signup and view all the answers

    Which property of phospholipid molecules contributes to their amphipathic nature?

    <p>The polar nature of the head group (C)</p> Signup and view all the answers

    What role do ionic and hydrogen bonds play in the association of peripheral proteins with the membrane?

    <p>They are reversible and allow easy removal (C)</p> Signup and view all the answers

    What role does the signal peptide play in the process described?

    <p>It mediates the binding of ribosomes to the SRP receptor. (A)</p> Signup and view all the answers

    How are N-linked glycoproteins transported to the Golgi apparatus?

    <p>Using small vesicles that bud off the ER. (A)</p> Signup and view all the answers

    What occurs within the lumens of the Golgi cisternae?

    <p>Oligosaccharide chains undergo enzymatic modification. (C)</p> Signup and view all the answers

    What is the role of the trans Golgi network (TGN) in the process?

    <p>To receive mature proteins before they are exported. (D)</p> Signup and view all the answers

    What happens to the contents as they traverse from one Golgi cisterna to the next?

    <p>They can undergo catalytic reactions within each cisterna. (D)</p> Signup and view all the answers

    Flashcards

    Integral Membrane Proteins

    Proteins that are embedded in the lipid bilayer of membranes.

    Phospholipids

    A class of lipids with two fatty acids linked to glycerol and a phosphate group.

    Peripheral Proteins

    Proteins attached to the membrane surface by noncovalent bonds.

    Amphipathic Molecules

    Molecules with both hydrophilic (polar) and hydrophobic (nonpolar) regions.

    Signup and view all the flashcards

    Head Group (Phospholipids)

    The polar part of a phospholipid that interacts with water.

    Signup and view all the flashcards

    Nucleus Size vs DNA Length

    The DNA in a plant nucleus is millions of times longer than the nucleus diameter.

    Signup and view all the flashcards

    Nucleosome Structure

    A nucleosome consists of DNA coiled around a histone protein octamer.

    Signup and view all the flashcards

    Chromatin Types

    Two types of chromatin are heterochromatin (inactive) and euchromatin (active).

    Signup and view all the flashcards

    Euchromatin Activity

    Euchromatin is mostly transcriptionally inactive but can be active depending on the time.

    Signup and view all the flashcards

    Heterochromatin Features

    Heterochromatin is a compact form of chromatin, about 10% of total DNA.

    Signup and view all the flashcards

    Phosphatidylcholine

    A common phospholipid found in cell membranes that contributes to membrane structure.

    Signup and view all the flashcards

    Galactosylglyceride

    A type of glycolipid found in plant membranes, involved in signaling.

    Signup and view all the flashcards

    Glycosylphosphatidylinositol (GPI)

    A glycolipid that anchors proteins to cell membranes.

    Signup and view all the flashcards

    Fatty acid–anchored proteins

    Proteins that are attached to the membrane through fatty acid chains.

    Signup and view all the flashcards

    Prenyl lipid–anchored proteins

    Proteins attached to the membrane via prenyl groups, allowing membrane association.

    Signup and view all the flashcards

    Signal Recognition Particle (SRP)

    A protein-RNA complex that facilitates ribosome binding to the endoplasmic reticulum.

    Signup and view all the flashcards

    N-linked glycoproteins

    Proteins that have oligosaccharides attached via nitrogen atoms, often synthesized in the ER.

    Signup and view all the flashcards

    Golgi apparatus

    An organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery.

    Signup and view all the flashcards

    Cisternae

    Flattened membrane-bound compartments in the Golgi apparatus where processing occurs.

    Signup and view all the flashcards

    Trans Golgi Network (TGN)

    The exit site of the Golgi apparatus where vesicles bud off to deliver proteins.

    Signup and view all the flashcards

    Study Notes

    Plant Cells

    • Plants are multicellular organisms with specialized cells
    • All plant cells have a basic eukaryotic organization:
      • Nucleus
      • Cytoplasm
      • Subcellular organelles
      • Enclosed in a membrane
    • Some structures (like the nucleus) might be lost during cell maturation, but all plant cells start with similar organelles

    Biological Membranes

    • All cells are enclosed by a membrane (plasma membrane or plasmalemma), separating the cytoplasm from the external environment
    • The plasma membrane controls the transport of substances into and out of the cell
    • Membranes define boundaries of specialized organelles
    • Made up of a phospholipid bilayer with embedded proteins
      • Phospholipids have hydrophilic heads and hydrophobic tails (amphipathic)
      • Integral proteins are embedded in the bilayer, sometimes spanning the entire width
      • Peripheral proteins are bound to the surface by non-covalent bonds
      • Anchored proteins are bound to the membrane by lipid molecules
    • The fluidity of the membrane is influenced by temperature. Unsaturated fatty acids help maintain fluidity at low temperatures
    • Plastid membranes differ in their lipid composition, mainly containing glycosylglycerides instead of phospholipids.

    The Nucleus

    • Contains the majority of the genetic information in the cell (the nuclear genome)
    • Enclosed by a double membrane (nuclear envelope)
    • Contains nuclear pores for transport of macromolecules
    • Contains chromatin (DNA and proteins) and nucleolus (ribosome synthesis)
    • Sizes of plant nuclear genomes vary significantly

    The Endoplasmic Reticulum (ER)

    • A network of internal membranes creating sacs and tubules (cisternae)
    • Continuous with the outer nuclear membrane
    • Two types:
      • Rough ER (RER) is studded with ribosomes involved in protein synthesis
      • Smooth ER (SER) is involved in lipid synthesis and membrane assembly

    Protein Synthesis

    • Starts in the rough ER, where proteins destined for secretion enter the lumen
    • Signal peptides direct the proteins through the ER.
    • Glycosylation (adding sugars) occurs in the ER and Golgi.
    • Subsequent processing, packaging, and transport of proteins are managed by the Golgi apparatus

    The Golgi Apparatus

    • A series of flattened sacs or cisternae (Golgi bodies/dictyosomes)
    • Has a trans and cis face.
    • Involved in processing, modifying, and packaging proteins and polysaccharides for secretion
    • Modifies glycosylated proteins. Adds or removes sugars, creating different glycoproteins
    • Involved in cell wall formation and secretion. Sends products to cell exterior or vacuoles.

    The Central Vacuole

    • Large, water-filled compartment in mature plant cells
    • Surrounded by a vacuolar membrane (tonoplast)
    • Stores water, solutes (inorganic ions, sugars, enzymes, secondary metabolites)
    • Important for turgor pressure, structural support (in herbaceous plants)
    • Involved in storage and degradation

    Mitochondria and Chloroplasts

    • Organelles involved in energy conversion
    • Mitochondria: respiration (ATP synthesis from glucose)
    • Chloroplasts: photosynthesis (glucose synthesis)
    • Both contain their own DNA and ribosomes (are considered semi-autonomous)
    • Double membranes, with inner membranes forming cristae in mitochondria and thylakoids in chloroplasts

    Microbodies

    • Small, spherical organelles with a single membrane
    • Types: peroxisomes and glyoxysomes
    • Peroxisomes: involved in oxidative reactions, breaking down H₂O₂
    • Glyoxysomes: present in oil-storing seeds, convert stored fatty acids to sugars

    Plasmodesmata

    • Channels that traverse cell walls, connecting neighboring plant cells
    • Allow communication and transport of molecules between cells
    • Essential for symplastic transport (movement of substances through the interconnected cytoplasm)

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Plant Cells PDF

    Description

    Explore the fascinating world of plant cells and biological membranes in this quiz. Learn about the structure and function of eukaryotic plant cells, including their organelles, as well as the vital roles of membranes in cellular transport and structure. Test your knowledge and deepen your understanding of these essential biological concepts.

    More Like This

    Plant Cells Quiz
    14 questions

    Plant Cells Quiz

    AuthoritativeEinsteinium avatar
    AuthoritativeEinsteinium
    Biology Quiz: Plant & Animal Cells
    5 questions

    Biology Quiz: Plant & Animal Cells

    ReasonedWildflowerMeadow7545 avatar
    ReasonedWildflowerMeadow7545
    Celula Vegetală și Plasmalema
    21 questions

    Celula Vegetală și Plasmalema

    SolicitousMaclaurin2817 avatar
    SolicitousMaclaurin2817
    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser