Cell Ultrastructure and Function Overview

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Questions and Answers

What is produced from ADP and inorganic phosphate ions during aerobic cellular respiration?

FADH2

Glucose

ATP (correct)

NADH

Which structures in cells contain ribosomes and have limited capacity for protein synthesis?

Endoplasmic reticulum and Golgi apparatus

Centrioles and microtubules

Nucleus and ribosomes

Mitochondria and chloroplasts (correct)

What is NOT a function of cilia in cells?

Locomotion

Transport of nutrients

Feeding

Photosynthesis (correct)

Which of the following is a role of flagella in organisms?

Locomotion and reproduction Signup and view all the answers

What is the significance of microtubules in cell structure?

Providing structural support and transportation Signup and view all the answers

What is the primary aqueous component of the cytoplasm called?

Cytosol Signup and view all the answers

Which function is not associated with the rough endoplasmic reticulum?

Transport of lipids Signup and view all the answers

Which of the following biochemicals is typically found in the cytosol?

Amino acids Signup and view all the answers

What structure forms during cell division to organize chromosomes?

Cytoskeleton Signup and view all the answers

What is a defining characteristic of smooth endoplasmic reticulum compared to rough endoplasmic reticulum?

Function in lipid synthesis Signup and view all the answers

What is the approximate diameter of ribosomes?

20nm Signup and view all the answers

Which protein is primarily associated with the cytoskeleton for cell motility?

Actin Signup and view all the answers

Which of the following processes does the cytoplasm NOT participate in?

DNA replication Signup and view all the answers

What is the composition of ribosomes?

RNA and protein Signup and view all the answers

Which structure is primarily responsible for the chemical modification and transport of materials?

Golgi apparatus Signup and view all the answers

What are polyribosomes?

Groups of ribosomes attached to one mRNA Signup and view all the answers

What is the role of lysosomes?

Digestive function and breakdown of materials Signup and view all the answers

What does the inner folding of mitochondria membranes form?

Cristae Signup and view all the answers

Which organelle is known for its association with aerobic cellular respiration?

Mitochondria Signup and view all the answers

What is the significance of the smooth endoplasmic reticulum?

Lipid synthesis and detoxification Signup and view all the answers

What is the function of catalase in peroxisomes?

Decompose hydrogen peroxide Signup and view all the answers

Study Notes

Cell Ultrastructure and Function

Cells are divided into two broad areas: the Nucleus and Cytoplasm. Collectively, these form the protoplasm.
Cytoplasm is an aqueous background, containing organelles and inclusions.
The cytosol is the aqueous component of the cytoplasm and is about 90% water.
The cytosol is transparent and structureless, but contains microfilaments, forming the cytoskeleton.
The cytosol contains contractile protein actin, and is involved in endocytosis/exocytosis and motility (cytoplasmic streaming).
The cytosol contains a wide range of biochemicals like salts, amino acids, glucose etc, in true solution.
Larger molecules like proteins are in colloidal solution in the cytosol. Sol (non-viscous) and Gel (viscous) are forms of this solution.
The Cytoplasm may also act as a site for metabolic pathways, such as glycolysis.
Membranes are described in previous notes.
The Endoplasmic Reticulum (ER) is a complex system of flattened membrane bound vesicles (cisternae).
The ER is arranged in stacks, concentric patterns around other organelles (like mitochondria), or in a tubular form.
There are two distinct types of ER.
Rough ER has ribosomes attached to the external cisternal membrane, and is involved in protein synthesis and transport. It connects to the nuclear envelope.
Small vesicles containing newly synthesised proteins pinch off from the Rough ER, and may either fuse with the Golgi Apparatus, or the cell membrane.
Smooth ER has no ribosomes associated with the cisternal membrane. It is involved in lipid transport (including steroids), detoxification (liver), and calcium storage (skeletal muscle cells).
Ribosomes are 20nm in diameter, function as protein synthesis sites. They are found in association with the Rough ER, or alone in the cytoplasm. These are also found inside mitochondria and chloroplasts. Ribosomes are composed of two subunits, both containing RNA and Protein.
Ribosomes may associate to form chains (polyribosomes)
Golgi Apparatus modifies proteins, lipids, and carbohydrates.
The Golgi Apparatus is a stack of flattened plate-like cisternae (saccules).
New cisternae form on the outer edge of the concave stack, from vesicle fusion.
The Golgi Apparatus discharges contents into vesicles which then fuse with plasma membrane.
Lysosomes are membrane-bound vesicles (0.2-0.5 m diameter).
Lysosomes contain digestive enzymes (lysitic enzymes).
Lysosomes are used to degrade old/surplus organelles, or breakdown whole cells and tissues, and are linked to phagocytosis (1° & 2° Lysosomes).
Mitochondria are small elongated organelles (2-5 m length) found in eukaryotic cells. They're involved in aerobic cellular respiration.
Mitochondria are bounded by a double membrane system (envelope), with a space between them.
The inner mitochondrial membrane is folded inward to form cristae, which project into a matrix. The inner membrane's large surface area allows for contact with enzymes in the matrix. The cristae have stalked ATPase particles covering their surface.
Aerobic cellular respiration produces ATP from ADP and inorganic phosphate ions, through the oxidation of energy-rich substrates (pyruvic acid, derived from sugars like glucose through glycolysis in the cytoplasm).
Mitochondria contain limited DNA and limited capacity for protein synthesis. They also contain ribosomes, abundant in cells needing lots of energy (liver & muscles).
Chloroplasts are found in plant cells and are involved in photosynthesis.
Chloroplasts are surrounded by two membranes. The inner membrane folds into grana, stacks of thylakoids. The stroma is the fluid surrounding the grana.
Thylakoids contain chlorophyll and electron carriers, where the light reactions of photosynthesis occur (reducing NADP/ATP).
Chloroplasts contain limited DNA for protein synthesis and ribosomes.
Vacuoles are large, single fluid-filled spaces in plant cells. They store salts, sugars, and pigments. The cell wall also interacts with the vacuole and creates turgor pressure.
Plant cells have a cell wall, a rigid structure that provides shape and support. It's made of cellulose, and plant cells have plasmodesmata joining them, regions of cytoplasm to connect cells.
Cilia and flagella are used for locomotion in protozoa, feeding (sponges), and reproduction (sperm). Cilia are for movement of ova in mammals.
Microtubules are a component of the cytoskeleton in cells.
Cell junctions, such as tight junctions, gap junctions, desmosome junctions, are used to connect and hold neighboring cells together. Microvilli are finger-like projections present in cells, for increasing surface area for absorption (e.g., small intestine).

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Description

This quiz covers the essentials of cell ultrastructure, focusing on the nucleus, cytoplasm, and the role of cytosol and organelles. It also discusses the importance of cytoplasm in metabolic pathways and cellular processes. Test your knowledge about cell components and their functions.