Module 2 - Foundations in Biology - Cell Structure - 2.1.1-2.1.7

What is the magnification and resolution of an optical microscope?

Magnification is 2000x, Resolution is 200nm

What is the magnification and resolution of a TEM and SEM?

TEM has magnification of 50M, SEM 200K, resolution is 0.002nm

the pros and cons of optical microscopes when compared to electron microscopes

Pros: Optical microscopes are affordable, portable, and easy to use. They provide real-time imaging and can observe live specimens without damaging them, electron microscopes use a metal stain, and are in black and white (SEM can add colour).

Cons: Optical microscopes have limited resolution and cannot visualize objects smaller than the wavelength of light. They are unable to observe fine details and structures at the nanoscale level.

___________ stains DNA and chromosomes dark red.

Acetic orcein is a stain used to visualize DNA and chromosomes. It imparts a dark red color to the chromosomes, allowing for their identification and study.

___________ stains the cytoplasm.

Eosin.

___________ stains cellulose in plant walls yellow.

Iodine in potassium iodide solution.

Structure and function of the nucleus.

Structure: Double membrane, the nuclear envelope, containing pores. Nucleulus doesn’t have a membrane and contains RNA. Chromatin is DNA wound around histone proteins, when not dividing the chromatin is spread out or extended, when about to divide the chromatin condenses and coils tightly into chromosomes.

Function: The envelope separates contents from cell, pores allow larger substances like mRNA to leave, and some steroid hormones or other substances may enter the nucleus through these pores. Ribosomes made in the nucleolus.

Structure and function of the RER.

Structure: System of membranes with cisternae, continuous with nuclear membrane.

Function: Intracellular transport system, cisternae are channels for transporting substances. Large SA for ribosomes to assemble proteins which pass into the cisternae to go to the Golgi.

Structure and function of the SER.

• Structure: Smooth endoplasmic reticulum (SER) is a network of membrane-bound tubules and vesicles, fluid-filled and continuous with the nuclear membrane.

• Function: SER is involved in lipid synthesis, detoxification of drugs and toxins, and calcium ion storage.

• Lipid synthesis: SER synthesizes lipids, including phospholipids and cholesterol, which are essential for cell membrane formation.

Structure and function of the Golgi apparatus.

• Structure: Consists of flattened, membrane-bound sacs called cisternae in stacks.

• Function: Modifies, sorts, and packages proteins and lipids for transport. Folds to 3D structure adds sugar molecules to make glycoproteins, adds lipids to make lipoproteins.

Structure and function of the Mitochondria.

• Structure: Double membrane, outer membrane and inner membrane with fluid-filled intermembrane space. Also matrix.

• Function: The powerhouse of the cell, produces ATP through cellular respiration, self-replicating.

• Endosymbiotic theory: Mitochondria originated from ancient bacteria engulfed by eukaryotic cells

Structure and function of the Chloroplasts.

• Structure: Chloroplasts are double-membrane organelles found in plant cells, consisting of an outer membrane and an inner membrane. They contain a network of membranous sacs called thylakoids, which are stacked into structures called grana. The fluid-filled space inside the chloroplasts is called the stroma. Loops of DNA.

• Function: Chloroplasts are responsible for photosynthesis, the process by which plants convert sunlight into chemical energy. They contain chlorophyll, a pigment that captures light energy, and other molecules necessary for photosynthesis. Chloroplasts also play a role in the synthesis of carbohydrates, lipids, and amino acids.

Structure and function of the vacuole.

• Structure: Membrane-bound sac within the cell, a membrane called the tonoplast.

• Function: Storage of water, ions, nutrients, waste products; regulates osmotic balance, maintains turgor.

Structure and function of the lysosomes.

• Lysosomes are membrane-bound organelles found in animal cells. Membrane keeps enzymes separate.

• They contain digestive enzymes that break down waste materials and cellular debris.

• Lysosomes play a crucial role in cellular recycling and waste disposal.

• They are involved in the degradation of macromolecules, such as proteins, lipids, and carbohydrates.

• Lysosomes maintain an acidic pH to optimize enzyme activity.

• They can fuse with other organelles or engulf foreign particles through a process called endocytosis.

• Lysosomal storage disorders result from the malfunctioning of lysosomal enzymes.

• Autophagy is a process where lysosomes degrade damaged organelles and recycle their components.

• Lysosomes are involved in various cellular processes, including cell death and immune response.

Structure and function of the cilia and undulipodia.

• Structure of cilia and undulipodia:

  • Microtubule-based structures

  • Composed of 9 doublet microtubules surrounding a central pair

  • Covered by plasma membrane

• Function of cilia and undulipodia:

  • Movement of fluid or particles

  • Sensory functions in some cells

  • Aid in cell motility and locomotion

Structure and function of the ribosomes.

• Ribosomes are cellular structures responsible for protein synthesis.

• They are composed of two subunits, the large and small subunits, which come together during protein synthesis.

• Ribosomes can be found in the cytoplasm of prokaryotic cells and on the endoplasmic reticulum in eukaryotic cells.

• Ribosomes play a crucial role in translating the genetic code from mRNA into proteins.

Structure and function of the centrioles.

• Centrioles are small, cylindrical structures found in animal cells.

• They are composed of microtubules arranged in a specific pattern. Made of tubulin.

• Centrioles play a crucial role in cell division, specifically in the formation of the mitotic spindle.

• They are involved in the organization and separation of chromosomes during cell division.

• Centrioles also contribute to the formation of cilia and flagella, which are important for cell motility.

• They are located in the centrosome, a region near the nucleus of the cell.

• Centrioles have a distinct structure, consisting of a pair of centrioles perpendicular to each other.

• Each centriole is composed of nine triplets of microtubules.

• The function of centrioles is regulated by various proteins and signaling pathways.

Structure and function of the cytoskeleton.

Structure of the Cytoskeleton:

• Composed of three main components: microfilaments (actin), intermediate filaments, and microtubules (tubulin). Also motor proteins, myosins, kinesins and dyneins and enzymes to allow hydrolysis of ATP.

Function of the Cytoskeleton:

• Microfilaments provide structural support, maintain cell shape, and facilitate cell movement. Microtubules aid in intracellular transport, form a track for motor proteins and spindle before cell division and makeup cilia etc.

Structure and function of the cellulose cell wall.

Strength and support, maintain shape, permeable to solutions, fungi have chitin cell walls not cellulose.

Stages of making and secreting a protein within a cell.

Stages of Protein Synthesis

1. Transcription: DNA is transcribed into mRNA in the nucleus.

2. mRNA Processing: Introns are removed, and a cap and tail are added to the mRNA.

3. mRNA Export: The processed mRNA is transported out of the nuclear pores and into the cytoplasm.

4. Translation: mRNA is translated into a protein by ribosomes on the RER, and is passed into the cisternae for transport.

5. Protein Folding: The newly synthesized protein folds into its functional three-dimensional structure at the Golgi.

6. Post-Translational Modifications: Additional modifications, such as phosphorylation or glycosylation, may occur.

7. Protein Secretion: The protein is transported to the Golgi apparatus for further processing and packaging.

8. Exocytosis: The Golgi apparatus releases the protein via vesicles, allowing it to be secreted outside the cell by exocytosis (active process).

comparing prokaryotic and eukaryotic cells, summarising the information.

Prokaryotic cells lack a nucleus and membrane-bound organelles, while eukaryotic cells have both. Prokaryotes are smaller and simpler, with circular DNA, while eukaryotes are larger and more complex, with linear DNA. Prokaryotes reproduce asexually by binary fission, while eukaryotes reproduce sexually or asexually. Prokaryotes include bacteria and archaea, while eukaryotes include plants, animals, fungi, and protists.

In addition to lacking a nucleus and membrane-bound organelles, prokaryotic cells have a cell wall made of peptidoglycan. This cell wall provides structural support and protection. Prokaryotes also have a plasma membrane, which controls the movement of substances in and out of the cell. Inside the cell, prokaryotes have a cytoplasm that contains ribosomes, where protein synthesis occurs. Some prokaryotes may also have additional structures like pili, flagella, and capsules, which aid in attachment, movement, and protection.