Cell Biology: Cell Membrane Structure and Functions

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32 Questions

What is the main function of the cytoskeleton?

Providing structural support and shape to the cell

What type of filaments are desmin, keratin, and dystrophine?

Intermediate filaments

What is the function of lamins in the nuclear envelopment?

To provide structural support

What is the function of histones in the nucleus?

To provide structural support to DNA

What is the main function of microtubules?

To provide structural support to the cell

What is the primary function of the cytosol?

To carry out various metabolic reactions

What is the function of the nuclear pores in the nuclear envelopment?

To facilitate transport of molecules

What is the function of chromatin?

To package DNA in the nucleus

What is the primary function of the Na/K-ATPase protein in the plasmalemma?

Maintaining the cell's sodium and potassium balance

What is the main function of the smooth endoplasmic reticulum (sER)?

Lipid synthesis and detoxification

What is the role of the ribophorin protein in the rough endoplasmic reticulum (rER)?

Synthesis of proteins on ribosomes

What is the primary function of euchromatin?

Transcription of genes

What is the primary function of the Golgi apparatus?

Maturation and packaging of proteins

What is the function of the transferases enzymes in the smooth endoplasmic reticulum (sER)?

Detoxification of xenobiotics

What is the role of facultative heterochromatin?

Temporarily inactivated genes

What is the primary function of the nucleolus?

Ribosome biogenesis

What is the role of the glycosyltransferase enzymes in the Golgi apparatus?

Maturation of proteins

What is the function of the clathrin in the Golgi apparatus?

Packing of vesicles

What is the difference between euchromatin and heterochromatin?

Euchromatin is transcriptionally active, while heterochromatin is transcriptionally inactive

What is the final destination of the proteins synthesized in the rough endoplasmic reticulum (rER)?

Cell membrane

What is the function of constitutive heterochromatin?

Genes that are never transcribed

Where does the biogenesis of ribosomes take place?

Nucleolus

What is the main function of mitochondria in a cell?

To synthesize ATP through energy production

What is the characteristic of euchromatin?

Highly transcribed genes

What is the function of facultative euchromatin?

Genes that are temporarily inactive

What is the function of the enzyme catalase in peroxisomes?

To decompose H2O2

What is the term for the process of hydrolysis of already used components of the cell?

Autophagy

What is the function of protein H^+^ - ATPase in lysosomes?

To pump hydrogen ions out of the lysosome

What is the function of free ribosomes in a cell?

To synthesize proteins for the ribosomes itself

What is the function of the matrix of mitochondria?

To synthesize proteins for the mitochondria

What is the term for the process of hydrolysis of foreign organic substances in lysosomes?

Heterophagy

What is the function of proteases in lysosomes?

To break down proteins

Study Notes

Cell Organelles

  • Plasmalemma (Cell Membrane): a biological barrier, transports substances, receives signals, connects cells, and has immunologic functions.
    • Contains membranous proteins: Na/K-ATPase, Ca-ATPase, Aquaporine, Insuline receptor, LDL receptor, and Opsin.

Endoplasmic Reticulum (ER)

  • Smooth Endoplasmic Reticulum (sER): a membranous organelle with enzymes for lipid synthesis, detoxification of xenobiotics, and synthesizing proteins.

    • Enzymes: synthetases, isomerases, and transferases.
  • Rough Endoplasmic Reticulum (rER): a membranous organelle with ribophorin, synthesizing proteins, and transporting them to the Golgi apparatus.

    • Synthesizes proteins for: rER itself, lysosomes, Golgi apparatus, export, and cell membrane.

Golgi Apparatus

  • Golgi Apparatus: a membranous organelle, matures and sorts proteins, packages them into vesicles, and secretes them.
    • Enzymes: glycosyltransferase, and clathrin for packaging.
    • Functions: maturation, sorting, packing, secretion, and renewing cell membrane.

Mitochondria

  • Mitochondria: a membranous organelle with a double membrane, synthesizes ATP, and replicates its own DNA.
    • Inner membrane: where ATP synthesis occurs.
    • Matrix: contains circular DNA, ribosomes, mRNA, tRNA, rRNA, and proteins for replication, transcription, and translation.

Other Organelles

  • Peroxisomes: a membranous organelle, neutralizes cells' endogenous toxins, and decomposes H2O2.

    • Enzymes: oxidase, peroxydase, and catalase.
  • Lysosomes: a membranous organelle, hydrolyzes foreign substances, excess substances, and old cell components.

    • Contains: hydrolytic enzymes, proteases, lipases, and nucleases.
  • Free Ribosomes: non-membranous cell organelles, synthesizes proteins for: ribosomes, mitochondria, nucleus, cytoskeleton, cytosol, and centrioles.

  • Cell Center/Centrosome: a non-membranous cell organelle, involved in the synthesis of microtubules, and the formation of cilia and flagella.

  • Cytosol: a non-membranous cell organelle, involved in glycolysis, gluconeogenesis, metabolism of amino acids, and synthesis of fatty acids and nucleotides.

  • Nucleus: a membranous organelle, contains DNA, synthesizes proteins, and regulates gene expression.

    • Components: nuclear envelope, nuclear pores, lamins, and histones.
    • Chromatin: euchromatin is active, and heterochromatin is inactive.
    • Nucleolus: involved in the biogenesis of ribosomes.

This quiz covers the structure and functions of cell membranes, including the roles of specific proteins and organelles. It also explores the different types of cell membrane functions and their importance in cellular processes.

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